Add more from the std

Cargo.toml

@@ -1,6 +1,6 @@
 [workspace]
 resolver = "3"
-members = ["crates/bytes-struct","crates/io","crates/os-std", "crates/shared", "user/*"]
+members = ["crates/bytes-struct","crates/io","crates/std", "crates/shared", "user/*"]
 
 [package]
 name = "kernel-rust"

crates/os-std/src/io.rs

@@ -1 +0,0 @@
-pub use io::SeekFrom;

crates/os-std/src/lib.rs

@@ -1,62 +0,0 @@
-#![no_std]
-
-extern crate alloc;
-
-pub mod io;
-pub mod prelude;
-
-pub use shared::fs;
-pub use shared::syscall;
-
-#[macro_export]
-macro_rules! custom_std_setup {
-    () => {
-        use $crate::prelude::*;
-
-        extern crate alloc;
-
-        struct GlobalAllocator;
-
-        #[global_allocator]
-        static GLOBAL_ALLOCATOR: GlobalAllocator = GlobalAllocator;
-
-        unsafe impl core::alloc::GlobalAlloc for GlobalAllocator {
-            unsafe fn alloc(&self, layout: core::alloc::Layout) -> *mut u8 {
-                $crate::syscall::alloc(layout)
-            }
-
-            unsafe fn dealloc(&self, ptr: *mut u8, layout: core::alloc::Layout) {
-                $crate::syscall::dealloc(ptr, layout)
-            }
-        }
-
-        #[panic_handler]
-        fn panic(_panic_info: &core::panic::PanicInfo) -> ! {
-            // TODO print
-            loop {}
-        }
-
-        #[unsafe(no_mangle)]
-        pub extern "C" fn _start() {
-            main()
-        }
-    };
-}
-
-#[macro_export]
-macro_rules! print {
-    ($($args:expr),*) => {
-        $crate::syscall::write_string_temp(&format!($($args),*))
-    };
-}
-#[macro_export]
-macro_rules! println {
-    () => {
-        $crate::print!("");
-        // $crate::print!("\n\r");
-    };
-    ($($args:expr),*) => {
-        $crate::print!($($args),*);
-        // $crate::println!();
-    };
-}

crates/os-std/src/prelude.rs

@@ -1,5 +0,0 @@
-pub use crate::print;
-pub use crate::println;
-pub use alloc::format;
-pub use alloc::string::String;
-pub use alloc::vec;

crates/shared/src/fs.rs

@@ -1,3 +1,7 @@
+use io::{IoBase, Read, Write};
+
+use crate::syscall;
+
 #[derive(Debug)]
 pub struct File {
     fd: u64,
@@ -6,7 +10,7 @@ pub struct File {
 impl File {
     /// # Safety
     /// The file descriptor must be valid
-    pub unsafe fn new(fd: u64) -> Self {
+    pub unsafe fn from_raw_fd(fd: u64) -> Self {
         Self { fd }
     }
 
@@ -14,3 +18,23 @@ impl File {
         self.fd
     }
 }
+
+impl IoBase for File {
+    type Error = ();
+}
+
+impl Read for File {
+    fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
+        Ok(syscall::read(self.as_fd(), buf) as usize)
+    }
+}
+
+impl Write for File {
+    fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
+        Ok(syscall::write(self.as_fd(), buf) as usize)
+    }
+
+    fn flush(&mut self) -> Result<(), Self::Error> {
+        todo!()
+    }
+}

crates/shared/src/syscall.rs

@@ -10,9 +10,12 @@ pub enum SysCall {
     Read = 0,
     Write = 1,
     Open = 2,
+    Close = 3,
     Seek = 8,
     Alloc = 40,
     Dealloc = 41,
+    Spawn = 58,
+    ExecVE = 59,
     Exit = 60,
     NanoSleep = 101,
     WriteIntTemp = 998,
@@ -26,9 +29,12 @@ impl From<u64> for SysCall {
             0 => SysCall::Read,
             1 => SysCall::Write,
             2 => SysCall::Open,
+            3 => SysCall::Close,
             8 => SysCall::Seek,
             40 => SysCall::Alloc,
             41 => SysCall::Dealloc,
+            58 => SysCall::Spawn,
+            59 => SysCall::ExecVE,
             60 => SysCall::Exit,
             101 => SysCall::NanoSleep,
             998 => SysCall::WriteIntTemp,
@@ -143,30 +149,53 @@ pub fn open<P: AsRef<Path>>(path: P) -> File {
         let ptr = path_str.as_ptr();
         let size = path_str.len();
         let (fd, ..) = syscall!(SysCall::Open, ptr as u64, size as u64);
-        File::new(fd)
+        File::from_raw_fd(fd)
     }
 }
-pub fn write(file: &mut File, buf: &[u8]) {
+pub fn close(file_descriptor: u64) {
+    unsafe {
+        syscall!(SysCall::Close, file_descriptor);
+    }
+}
+pub fn write(file_descriptor: u64, buf: &[u8]) -> u64 {
     unsafe {
         let ptr = buf.as_ptr();
         let size = buf.len();
-        syscall!(SysCall::Write, file.as_fd(), ptr as u64, size as u64);
+        let (len, ..) = syscall!(SysCall::Write, file_descriptor, ptr as u64, size as u64);
+        len
     }
 }
-pub fn read(file: &mut File, buf: &mut [u8]) {
+pub fn read(file_descriptor: u64, buf: &mut [u8]) -> u64 {
     unsafe {
         let ptr = buf.as_ptr();
         let size = buf.len();
-        syscall!(SysCall::Read, file.as_fd(), ptr as u64, size as u64);
+        let (len, ..) = syscall!(SysCall::Read, file_descriptor, ptr as u64, size as u64);
+        len
     }
 }
-pub fn seek(file: &mut File, seek: SeekFrom) {
+pub fn seek(file_descriptor: u64, seek: SeekFrom) {
     unsafe {
         let (discriminant, value) = match seek {
             SeekFrom::Start(v) => (0, v),
             SeekFrom::End(v) => (1, v as u64),
             SeekFrom::Current(v) => (2, v as u64),
         };
-        syscall!(SysCall::Seek, file.as_fd(), discriminant, value);
+        syscall!(SysCall::Seek, file_descriptor, discriminant, value);
+    }
+}
+pub fn spawn<P: AsRef<Path>>(path: P) {
+    unsafe {
+        let path_str = path.as_ref().as_str();
+        let ptr = path_str.as_ptr();
+        let size = path_str.len();
+        syscall!(SysCall::Spawn, ptr as u64, size as u64);
+    }
+}
+pub fn execve<P: AsRef<Path>>(path: P) {
+    unsafe {
+        let path_str = path.as_ref().as_str();
+        let ptr = path_str.as_ptr();
+        let size = path_str.len();
+        syscall!(SysCall::ExecVE, ptr as u64, size as u64);
     }
 }

crates/std/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "os-std"
+name = "std"
 version = "0.1.0"
 edition = "2024"
 

crates/std/src/alloc.rs

@@ -0,0 +1,490 @@
+//! Memory allocation APIs.
+//!
+//! In a given program, the standard library has one “global” memory allocator
+//! that is used for example by `Box<T>` and `Vec<T>`.
+//!
+//! Currently the default global allocator is unspecified. Libraries, however,
+//! like `cdylib`s and `staticlib`s are guaranteed to use the [`System`] by
+//! default.
+//!
+//! # The `#[global_allocator]` attribute
+//!
+//! This attribute allows configuring the choice of global allocator.
+//! You can use this to implement a completely custom global allocator
+//! to route all[^system-alloc] default allocation requests to a custom object.
+//!
+//! ```rust
+//! use std::alloc::{GlobalAlloc, System, Layout};
+//!
+//! struct MyAllocator;
+//!
+//! unsafe impl GlobalAlloc for MyAllocator {
+//!     unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+//!         unsafe { System.alloc(layout) }
+//!     }
+//!
+//!     unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+//!         unsafe { System.dealloc(ptr, layout) }
+//!     }
+//! }
+//!
+//! #[global_allocator]
+//! static GLOBAL: MyAllocator = MyAllocator;
+//!
+//! fn main() {
+//!     // This `Vec` will allocate memory through `GLOBAL` above
+//!     let mut v = Vec::new();
+//!     v.push(1);
+//! }
+//! ```
+//!
+//! The attribute is used on a `static` item whose type implements the
+//! [`GlobalAlloc`] trait. This type can be provided by an external library:
+//!
+//! ```rust,ignore (demonstrates crates.io usage)
+//! use jemallocator::Jemalloc;
+//!
+//! #[global_allocator]
+//! static GLOBAL: Jemalloc = Jemalloc;
+//!
+//! fn main() {}
+//! ```
+//!
+//! The `#[global_allocator]` can only be used once in a crate
+//! or its recursive dependencies.
+//!
+//! [^system-alloc]: Note that the Rust standard library internals may still
+//! directly call [`System`] when necessary (for example for the runtime
+//! support typically required to implement a global allocator, see [re-entrance] on [`GlobalAlloc`]
+//! for more details).
+//!
+//! [re-entrance]: trait.GlobalAlloc.html#re-entrance
+
+#![deny(unsafe_op_in_unsafe_fn)]
+#![stable(feature = "alloc_module", since = "1.28.0")]
+
+use core::ptr::NonNull;
+use core::sync::atomic::{AtomicBool, AtomicPtr, Ordering};
+use core::{hint, mem, ptr};
+
+#[stable(feature = "alloc_module", since = "1.28.0")]
+#[doc(inline)]
+pub use alloc_crate::alloc::*;
+
+/// The default memory allocator provided by the operating system.
+///
+/// This is based on `malloc` on Unix platforms and `HeapAlloc` on Windows,
+/// plus related functions. However, it is not valid to mix use of the backing
+/// system allocator with `System`, as this implementation may include extra
+/// work, such as to serve alignment requests greater than the alignment
+/// provided directly by the backing system allocator.
+///
+/// This type implements the [`GlobalAlloc`] trait. Currently the default
+/// global allocator is unspecified. Libraries, however, like `cdylib`s and
+/// `staticlib`s are guaranteed to use the [`System`] by default and as such
+/// work as if they had this definition:
+///
+/// ```rust
+/// use std::alloc::System;
+///
+/// #[global_allocator]
+/// static A: System = System;
+///
+/// fn main() {
+///     let a = Box::new(4); // Allocates from the system allocator.
+///     println!("{a}");
+/// }
+/// ```
+///
+/// You can also define your own wrapper around `System` if you'd like, such as
+/// keeping track of the number of all bytes allocated:
+///
+/// ```rust
+/// use std::alloc::{System, GlobalAlloc, Layout};
+/// use std::sync::atomic::{AtomicUsize, Ordering::Relaxed};
+///
+/// struct Counter;
+///
+/// static ALLOCATED: AtomicUsize = AtomicUsize::new(0);
+///
+/// unsafe impl GlobalAlloc for Counter {
+///     unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+///         let ret = unsafe { System.alloc(layout) };
+///         if !ret.is_null() {
+///             ALLOCATED.fetch_add(layout.size(), Relaxed);
+///         }
+///         ret
+///     }
+///
+///     unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+///         unsafe { System.dealloc(ptr, layout); }
+///         ALLOCATED.fetch_sub(layout.size(), Relaxed);
+///     }
+/// }
+///
+/// #[global_allocator]
+/// static A: Counter = Counter;
+///
+/// fn main() {
+///     println!("allocated bytes before main: {}", ALLOCATED.load(Relaxed));
+/// }
+/// ```
+///
+/// It can also be used directly to allocate memory independently of whatever
+/// global allocator has been selected for a Rust program. For example if a Rust
+/// program opts in to using jemalloc as the global allocator, `System` will
+/// still allocate memory using `malloc` and `HeapAlloc`.
+#[stable(feature = "alloc_system_type", since = "1.28.0")]
+#[derive(Debug, Default, Copy, Clone)]
+pub struct System;
+
+impl System {
+    #[inline]
+    fn alloc_impl(&self, layout: Layout, zeroed: bool) -> Result<NonNull<[u8]>, AllocError> {
+        match layout.size() {
+            0 => Ok(NonNull::slice_from_raw_parts(layout.dangling_ptr(), 0)),
+            // SAFETY: `layout` is non-zero in size,
+            size => unsafe {
+                let raw_ptr = if zeroed {
+                    GlobalAlloc::alloc_zeroed(self, layout)
+                } else {
+                    GlobalAlloc::alloc(self, layout)
+                };
+                let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?;
+                Ok(NonNull::slice_from_raw_parts(ptr, size))
+            },
+        }
+    }
+
+    // SAFETY: Same as `Allocator::grow`
+    #[inline]
+    unsafe fn grow_impl(
+        &self,
+        ptr: NonNull<u8>,
+        old_layout: Layout,
+        new_layout: Layout,
+        zeroed: bool,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        debug_assert!(
+            new_layout.size() >= old_layout.size(),
+            "`new_layout.size()` must be greater than or equal to `old_layout.size()`"
+        );
+
+        match old_layout.size() {
+            0 => self.alloc_impl(new_layout, zeroed),
+
+            // SAFETY: `new_size` is non-zero as `new_size` is greater than or equal to `old_size`
+            // as required by safety conditions and the `old_size == 0` case was handled in the
+            // previous match arm. Other conditions must be upheld by the caller
+            old_size if old_layout.align() == new_layout.align() => unsafe {
+                let new_size = new_layout.size();
+
+                // `realloc` probably checks for `new_size >= old_layout.size()` or something similar.
+                hint::assert_unchecked(new_size >= old_layout.size());
+
+                let raw_ptr = GlobalAlloc::realloc(self, ptr.as_ptr(), old_layout, new_size);
+                let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?;
+                if zeroed {
+                    raw_ptr.add(old_size).write_bytes(0, new_size - old_size);
+                }
+                Ok(NonNull::slice_from_raw_parts(ptr, new_size))
+            },
+
+            // SAFETY: because `new_layout.size()` must be greater than or equal to `old_size`,
+            // both the old and new memory allocation are valid for reads and writes for `old_size`
+            // bytes. Also, because the old allocation wasn't yet deallocated, it cannot overlap
+            // `new_ptr`. Thus, the call to `copy_nonoverlapping` is safe. The safety contract
+            // for `dealloc` must be upheld by the caller.
+            old_size => unsafe {
+                let new_ptr = self.alloc_impl(new_layout, zeroed)?;
+                ptr::copy_nonoverlapping(ptr.as_ptr(), new_ptr.as_mut_ptr(), old_size);
+                Allocator::deallocate(self, ptr, old_layout);
+                Ok(new_ptr)
+            },
+        }
+    }
+}
+
+// The Allocator impl checks the layout size to be non-zero and forwards to the GlobalAlloc impl,
+// which is in `std::sys::*::alloc`.
+#[unstable(feature = "allocator_api", issue = "32838")]
+unsafe impl Allocator for System {
+    #[inline]
+    fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> {
+        self.alloc_impl(layout, false)
+    }
+
+    #[inline]
+    fn allocate_zeroed(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> {
+        self.alloc_impl(layout, true)
+    }
+
+    #[inline]
+    unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
+        if layout.size() != 0 {
+            // SAFETY: `layout` is non-zero in size,
+            // other conditions must be upheld by the caller
+            unsafe { GlobalAlloc::dealloc(self, ptr.as_ptr(), layout) }
+        }
+    }
+
+    #[inline]
+    unsafe fn grow(
+        &self,
+        ptr: NonNull<u8>,
+        old_layout: Layout,
+        new_layout: Layout,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        // SAFETY: all conditions must be upheld by the caller
+        unsafe { self.grow_impl(ptr, old_layout, new_layout, false) }
+    }
+
+    #[inline]
+    unsafe fn grow_zeroed(
+        &self,
+        ptr: NonNull<u8>,
+        old_layout: Layout,
+        new_layout: Layout,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        // SAFETY: all conditions must be upheld by the caller
+        unsafe { self.grow_impl(ptr, old_layout, new_layout, true) }
+    }
+
+    #[inline]
+    unsafe fn shrink(
+        &self,
+        ptr: NonNull<u8>,
+        old_layout: Layout,
+        new_layout: Layout,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        debug_assert!(
+            new_layout.size() <= old_layout.size(),
+            "`new_layout.size()` must be smaller than or equal to `old_layout.size()`"
+        );
+
+        match new_layout.size() {
+            // SAFETY: conditions must be upheld by the caller
+            0 => unsafe {
+                Allocator::deallocate(self, ptr, old_layout);
+                Ok(NonNull::slice_from_raw_parts(new_layout.dangling_ptr(), 0))
+            },
+
+            // SAFETY: `new_size` is non-zero. Other conditions must be upheld by the caller
+            new_size if old_layout.align() == new_layout.align() => unsafe {
+                // `realloc` probably checks for `new_size <= old_layout.size()` or something similar.
+                hint::assert_unchecked(new_size <= old_layout.size());
+
+                let raw_ptr = GlobalAlloc::realloc(self, ptr.as_ptr(), old_layout, new_size);
+                let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?;
+                Ok(NonNull::slice_from_raw_parts(ptr, new_size))
+            },
+
+            // SAFETY: because `new_size` must be smaller than or equal to `old_layout.size()`,
+            // both the old and new memory allocation are valid for reads and writes for `new_size`
+            // bytes. Also, because the old allocation wasn't yet deallocated, it cannot overlap
+            // `new_ptr`. Thus, the call to `copy_nonoverlapping` is safe. The safety contract
+            // for `dealloc` must be upheld by the caller.
+            new_size => unsafe {
+                let new_ptr = Allocator::allocate(self, new_layout)?;
+                ptr::copy_nonoverlapping(ptr.as_ptr(), new_ptr.as_mut_ptr(), new_size);
+                Allocator::deallocate(self, ptr, old_layout);
+                Ok(new_ptr)
+            },
+        }
+    }
+}
+
+static HOOK: AtomicPtr<()> = AtomicPtr::new(ptr::null_mut());
+
+/// Registers a custom allocation error hook, replacing any that was previously registered.
+///
+/// The allocation error hook is invoked when an infallible memory allocation fails — that is,
+/// as a consequence of calling [`handle_alloc_error`] — before the runtime aborts.
+///
+/// The allocation error hook is a global resource. [`take_alloc_error_hook`] may be used to
+/// retrieve a previously registered hook and wrap or discard it.
+///
+/// # What the provided `hook` function should expect
+///
+/// The hook function is provided with a [`Layout`] struct which contains information
+/// about the allocation that failed.
+///
+/// The hook function may choose to panic or abort; in the event that it returns normally, this
+/// will cause an immediate abort.
+///
+/// Since [`take_alloc_error_hook`] is a safe function that allows retrieving the hook, the hook
+/// function must be _sound_ to call even if no memory allocations were attempted.
+///
+/// # The default hook
+///
+/// The default hook, used if [`set_alloc_error_hook`] is never called, prints a message to
+/// standard error (and then returns, causing the runtime to abort the process).
+/// Compiler options may cause it to panic instead, and the default behavior may be changed
+/// to panicking in future versions of Rust.
+///
+/// # Examples
+///
+/// ```
+/// #![feature(alloc_error_hook)]
+///
+/// use std::alloc::{Layout, set_alloc_error_hook};
+///
+/// fn custom_alloc_error_hook(layout: Layout) {
+///    panic!("memory allocation of {} bytes failed", layout.size());
+/// }
+///
+/// set_alloc_error_hook(custom_alloc_error_hook);
+/// ```
+#[unstable(feature = "alloc_error_hook", issue = "51245")]
+pub fn set_alloc_error_hook(hook: fn(Layout)) {
+    HOOK.store(hook as *mut (), Ordering::Release);
+}
+
+// /// Unregisters the current allocation error hook, returning it.
+// ///
+// /// *See also the function [`set_alloc_error_hook`].*
+// ///
+// /// If no custom hook is registered, the default hook will be returned.
+// #[unstable(feature = "alloc_error_hook", issue = "51245")]
+// pub fn take_alloc_error_hook() -> fn(Layout) {
+//     let hook = HOOK.swap(ptr::null_mut(), Ordering::Acquire);
+//     if hook.is_null() { default_alloc_error_hook } else { unsafe { mem::transmute(hook) } }
+// }
+
+// #[optimize(size)]
+// fn default_alloc_error_hook(layout: Layout) {
+//     if cfg!(panic = "immediate-abort") {
+//         return;
+//     }
+
+//     // This is the default path taken on OOM, and the only path taken on stable with std.
+//     // Crucially, it does *not* call any user-defined code, and therefore users do not have to
+//     // worry about allocation failure causing reentrancy issues. That makes it different from
+//     // the default `__rdl_alloc_error_handler` defined in alloc (i.e., the default alloc error
+//     // handler that is  called when there is no `#[alloc_error_handler]`), which triggers a
+//     // regular panic and thus can invoke a user-defined panic hook, executing arbitrary
+//     // user-defined code.
+
+//     static PREV_ALLOC_FAILURE: AtomicBool = AtomicBool::new(false);
+//     if PREV_ALLOC_FAILURE.swap(true, Ordering::Relaxed) {
+//         // Don't try to print a backtrace if a previous alloc error happened. This likely means
+//         // there is not enough memory to print a backtrace, although it could also mean that two
+//         // threads concurrently run out of memory.
+//         rtprintpanic!(
+//             "memory allocation of {} bytes failed\nskipping backtrace printing to avoid potential recursion\n",
+//             layout.size()
+//         );
+//         return;
+//     } else {
+//         rtprintpanic!("memory allocation of {} bytes failed\n", layout.size());
+//     }
+
+//     let Some(mut out) = crate::sys::stdio::panic_output() else {
+//         return;
+//     };
+
+//     // Use a lock to prevent mixed output in multithreading context.
+//     // Some platforms also require it when printing a backtrace, like `SymFromAddr` on Windows.
+//     // Make sure to not take this lock until after checking PREV_ALLOC_FAILURE to avoid deadlocks
+//     // when there is too little memory to print a backtrace.
+//     let mut lock = crate::sys::backtrace::lock();
+
+//     match crate::panic::get_backtrace_style() {
+//         Some(crate::panic::BacktraceStyle::Short) => {
+//             drop(lock.print(&mut out, crate::backtrace_rs::PrintFmt::Short))
+//         }
+//         Some(crate::panic::BacktraceStyle::Full) => {
+//             drop(lock.print(&mut out, crate::backtrace_rs::PrintFmt::Full))
+//         }
+//         Some(crate::panic::BacktraceStyle::Off) => {
+//             use crate::io::Write;
+//             let _ = writeln!(
+//                 out,
+//                 "note: run with `RUST_BACKTRACE=1` environment variable to display a \
+//                              backtrace"
+//             );
+//             if cfg!(miri) {
+//                 let _ = writeln!(
+//                     out,
+//                     "note: in Miri, you may have to set `MIRIFLAGS=-Zmiri-env-forward=RUST_BACKTRACE` \
+//                                 for the environment variable to have an effect"
+//                 );
+//             }
+//         }
+//         // If backtraces aren't supported or are forced-off, do nothing.
+//         None => {}
+//     }
+// }
+
+// #[cfg(not(test))]
+// #[doc(hidden)]
+// #[alloc_error_handler]
+// #[unstable(feature = "alloc_internals", issue = "none")]
+// pub fn rust_oom(layout: Layout) -> ! {
+//     crate::sys::backtrace::__rust_end_short_backtrace(|| {
+//         let hook = HOOK.load(Ordering::Acquire);
+//         let hook: fn(Layout) =
+//             if hook.is_null() { default_alloc_error_hook } else { unsafe { mem::transmute(hook) } };
+//         hook(layout);
+//         crate::process::abort()
+//     })
+// }
+
+#[cfg(not(test))]
+#[doc(hidden)]
+#[allow(unused_attributes)]
+#[unstable(feature = "alloc_internals", issue = "none")]
+pub mod __default_lib_allocator {
+    use super::{GlobalAlloc, Layout, System};
+    // These magic symbol names are used as a fallback for implementing the
+    // `__rust_alloc` etc symbols (see `src/liballoc/alloc.rs`) when there is
+    // no `#[global_allocator]` attribute.
+
+    // for symbol names src/librustc_ast/expand/allocator.rs
+    // for signatures src/librustc_allocator/lib.rs
+
+    // linkage directives are provided as part of the current compiler allocator
+    // ABI
+
+    #[rustc_std_internal_symbol]
+    pub unsafe extern "C" fn __rdl_alloc(size: usize, align: usize) -> *mut u8 {
+        // SAFETY: see the guarantees expected by `Layout::from_size_align` and
+        // `GlobalAlloc::alloc`.
+        unsafe {
+            let layout = Layout::from_size_align_unchecked(size, align);
+            System.alloc(layout)
+        }
+    }
+
+    #[rustc_std_internal_symbol]
+    pub unsafe extern "C" fn __rdl_dealloc(ptr: *mut u8, size: usize, align: usize) {
+        // SAFETY: see the guarantees expected by `Layout::from_size_align` and
+        // `GlobalAlloc::dealloc`.
+        unsafe { System.dealloc(ptr, Layout::from_size_align_unchecked(size, align)) }
+    }
+
+    #[rustc_std_internal_symbol]
+    pub unsafe extern "C" fn __rdl_realloc(
+        ptr: *mut u8,
+        old_size: usize,
+        align: usize,
+        new_size: usize,
+    ) -> *mut u8 {
+        // SAFETY: see the guarantees expected by `Layout::from_size_align` and
+        // `GlobalAlloc::realloc`.
+        unsafe {
+            let old_layout = Layout::from_size_align_unchecked(old_size, align);
+            System.realloc(ptr, old_layout, new_size)
+        }
+    }
+
+    #[rustc_std_internal_symbol]
+    pub unsafe extern "C" fn __rdl_alloc_zeroed(size: usize, align: usize) -> *mut u8 {
+        // SAFETY: see the guarantees expected by `Layout::from_size_align` and
+        // `GlobalAlloc::alloc_zeroed`.
+        unsafe {
+            let layout = Layout::from_size_align_unchecked(size, align);
+            System.alloc_zeroed(layout)
+        }
+    }
+}

crates/std/src/error.rs

@@ -0,0 +1,4 @@
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use core::error::Error;
+#[unstable(feature = "error_generic_member_access", issue = "99301")]
+pub use core::error::{Request, request_ref, request_value};

crates/std/src/ffi/c_str.rs

@@ -0,0 +1,14 @@
+//! [`CStr`], [`CString`], and related types.
+
+#[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
+pub use alloc_crate::ffi::c_str::FromVecWithNulError;
+#[stable(feature = "cstring_into", since = "1.7.0")]
+pub use alloc_crate::ffi::c_str::IntoStringError;
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use alloc_crate::ffi::c_str::{CString, NulError};
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use core::ffi::c_str::CStr;
+#[stable(feature = "cstr_from_bytes_until_nul", since = "1.69.0")]
+pub use core::ffi::c_str::FromBytesUntilNulError;
+#[stable(feature = "cstr_from_bytes", since = "1.10.0")]
+pub use core::ffi::c_str::FromBytesWithNulError;

crates/std/src/ffi/mod.rs

@@ -0,0 +1,207 @@
+//! Utilities related to FFI bindings.
+//!
+//! This module provides utilities to handle data across non-Rust
+//! interfaces, like other programming languages and the underlying
+//! operating system. It is mainly of use for FFI (Foreign Function
+//! Interface) bindings and code that needs to exchange C-like strings
+//! with other languages.
+//!
+//! # Overview
+//!
+//! Rust represents owned strings with the [`String`] type, and
+//! borrowed slices of strings with the [`str`] primitive. Both are
+//! always in UTF-8 encoding, and may contain nul bytes in the middle,
+//! i.e., if you look at the bytes that make up the string, there may
+//! be a `\0` among them. Both `String` and `str` store their length
+//! explicitly; there are no nul terminators at the end of strings
+//! like in C.
+//!
+//! C strings are different from Rust strings:
+//!
+//! * **Encodings** - Rust strings are UTF-8, but C strings may use
+//! other encodings. If you are using a string from C, you should
+//! check its encoding explicitly, rather than just assuming that it
+//! is UTF-8 like you can do in Rust.
+//!
+//! * **Character size** - C strings may use `char` or `wchar_t`-sized
+//! characters; please **note** that C's `char` is different from Rust's.
+//! The C standard leaves the actual sizes of those types open to
+//! interpretation, but defines different APIs for strings made up of
+//! each character type. Rust strings are always UTF-8, so different
+//! Unicode characters will be encoded in a variable number of bytes
+//! each. The Rust type [`char`] represents a '[Unicode scalar
+//! value]', which is similar to, but not the same as, a '[Unicode
+//! code point]'.
+//!
+//! * **Nul terminators and implicit string lengths** - Often, C
+//! strings are nul-terminated, i.e., they have a `\0` character at the
+//! end. The length of a string buffer is not stored, but has to be
+//! calculated; to compute the length of a string, C code must
+//! manually call a function like `strlen()` for `char`-based strings,
+//! or `wcslen()` for `wchar_t`-based ones. Those functions return
+//! the number of characters in the string excluding the nul
+//! terminator, so the buffer length is really `len+1` characters.
+//! Rust strings don't have a nul terminator; their length is always
+//! stored and does not need to be calculated. While in Rust
+//! accessing a string's length is an *O*(1) operation (because the
+//! length is stored); in C it is an *O*(*n*) operation because the
+//! length needs to be computed by scanning the string for the nul
+//! terminator.
+//!
+//! * **Internal nul characters** - When C strings have a nul
+//! terminator character, this usually means that they cannot have nul
+//! characters in the middle — a nul character would essentially
+//! truncate the string. Rust strings *can* have nul characters in
+//! the middle, because nul does not have to mark the end of the
+//! string in Rust.
+//!
+//! # Representations of non-Rust strings
+//!
+//! [`CString`] and [`CStr`] are useful when you need to transfer
+//! UTF-8 strings to and from languages with a C ABI, like Python.
+//!
+//! * **From Rust to C:** [`CString`] represents an owned, C-friendly
+//! string: it is nul-terminated, and has no internal nul characters.
+//! Rust code can create a [`CString`] out of a normal string (provided
+//! that the string doesn't have nul characters in the middle), and
+//! then use a variety of methods to obtain a raw <code>\*mut [u8]</code> that can
+//! then be passed as an argument to functions which use the C
+//! conventions for strings.
+//!
+//! * **From C to Rust:** [`CStr`] represents a borrowed C string; it
+//! is what you would use to wrap a raw <code>\*const [u8]</code> that you got from
+//! a C function. A [`CStr`] is guaranteed to be a nul-terminated array
+//! of bytes. Once you have a [`CStr`], you can convert it to a Rust
+//! <code>&[str]</code> if it's valid UTF-8, or lossily convert it by adding
+//! replacement characters.
+//!
+//! [`OsString`] and [`OsStr`] are useful when you need to transfer
+//! strings to and from the operating system itself, or when capturing
+//! the output of external commands. Conversions between [`OsString`],
+//! [`OsStr`] and Rust strings work similarly to those for [`CString`]
+//! and [`CStr`].
+//!
+//! * [`OsString`] losslessly represents an owned platform string. However, this
+//! representation is not necessarily in a form native to the platform.
+//! In the Rust standard library, various APIs that transfer strings to/from the operating
+//! system use [`OsString`] instead of plain strings. For example,
+//! [`env::var_os()`] is used to query environment variables; it
+//! returns an <code>[Option]<[OsString]></code>. If the environment variable
+//! exists you will get a <code>[Some]\(os_string)</code>, which you can
+//! *then* try to convert to a Rust string. This yields a [`Result`], so that
+//! your code can detect errors in case the environment variable did
+//! not in fact contain valid Unicode data.
+//!
+//! * [`OsStr`] losslessly represents a borrowed reference to a platform string.
+//! However, this representation is not necessarily in a form native to the platform.
+//! It can be converted into a UTF-8 Rust string slice in a similar way to
+//! [`OsString`].
+//!
+//! # Conversions
+//!
+//! ## On Unix
+//!
+//! On Unix, [`OsStr`] implements the
+//! <code>std::os::unix::ffi::[OsStrExt][unix.OsStrExt]</code> trait, which
+//! augments it with two methods, [`from_bytes`] and [`as_bytes`].
+//! These do inexpensive conversions from and to byte slices.
+//!
+//! Additionally, on Unix [`OsString`] implements the
+//! <code>std::os::unix::ffi::[OsStringExt][unix.OsStringExt]</code> trait,
+//! which provides [`from_vec`] and [`into_vec`] methods that consume
+//! their arguments, and take or produce vectors of [`u8`].
+//!
+//! ## On Windows
+//!
+//! An [`OsStr`] can be losslessly converted to a native Windows string. And
+//! a native Windows string can be losslessly converted to an [`OsString`].
+//!
+//! On Windows, [`OsStr`] implements the
+//! <code>std::os::windows::ffi::[OsStrExt][windows.OsStrExt]</code> trait,
+//! which provides an [`encode_wide`] method. This provides an
+//! iterator that can be [`collect`]ed into a vector of [`u16`]. After a nul
+//! characters is appended, this is the same as a native Windows string.
+//!
+//! Additionally, on Windows [`OsString`] implements the
+//! <code>std::os::windows:ffi::[OsStringExt][windows.OsStringExt]</code>
+//! trait, which provides a [`from_wide`] method to convert a native Windows
+//! string (without the terminating nul character) to an [`OsString`].
+//!
+//! ## Other platforms
+//!
+//! Many other platforms provide their own extension traits in a
+//! `std::os::*::ffi` module.
+//!
+//! ## On all platforms
+//!
+//! On all platforms, [`OsStr`] consists of a sequence of bytes that is encoded as a superset of
+//! UTF-8; see [`OsString`] for more details on its encoding on different platforms.
+//!
+//! For limited, inexpensive conversions from and to bytes, see [`OsStr::as_encoded_bytes`] and
+//! [`OsStr::from_encoded_bytes_unchecked`].
+//!
+//! For basic string processing, see [`OsStr::slice_encoded_bytes`].
+//!
+//! [Unicode scalar value]: https://www.unicode.org/glossary/#unicode_scalar_value
+//! [Unicode code point]: https://www.unicode.org/glossary/#code_point
+//! [`env::set_var()`]: crate::env::set_var "env::set_var"
+//! [`env::var_os()`]: crate::env::var_os "env::var_os"
+//! [unix.OsStringExt]: crate::os::unix::ffi::OsStringExt "os::unix::ffi::OsStringExt"
+//! [`from_vec`]: crate::os::unix::ffi::OsStringExt::from_vec "os::unix::ffi::OsStringExt::from_vec"
+//! [`into_vec`]: crate::os::unix::ffi::OsStringExt::into_vec "os::unix::ffi::OsStringExt::into_vec"
+//! [unix.OsStrExt]: crate::os::unix::ffi::OsStrExt "os::unix::ffi::OsStrExt"
+//! [`from_bytes`]: crate::os::unix::ffi::OsStrExt::from_bytes "os::unix::ffi::OsStrExt::from_bytes"
+//! [`as_bytes`]: crate::os::unix::ffi::OsStrExt::as_bytes "os::unix::ffi::OsStrExt::as_bytes"
+//! [`OsStrExt`]: crate::os::unix::ffi::OsStrExt "os::unix::ffi::OsStrExt"
+//! [windows.OsStrExt]: crate::os::windows::ffi::OsStrExt "os::windows::ffi::OsStrExt"
+//! [`encode_wide`]: crate::os::windows::ffi::OsStrExt::encode_wide "os::windows::ffi::OsStrExt::encode_wide"
+//! [`collect`]: crate::iter::Iterator::collect "iter::Iterator::collect"
+//! [windows.OsStringExt]: crate::os::windows::ffi::OsStringExt "os::windows::ffi::OsStringExt"
+//! [`from_wide`]: crate::os::windows::ffi::OsStringExt::from_wide "os::windows::ffi::OsStringExt::from_wide"
+
+#![stable(feature = "rust1", since = "1.0.0")]
+
+#[stable(feature = "c_str_module", since = "1.88.0")]
+pub mod c_str;
+
+#[stable(feature = "core_c_void", since = "1.30.0")]
+pub use core::ffi::c_void;
+#[unstable(
+    feature = "c_variadic",
+    reason = "the `c_variadic` feature has not been properly tested on \
+              all supported platforms",
+    issue = "44930"
+)]
+pub use core::ffi::{VaArgSafe, VaList};
+#[stable(feature = "core_ffi_c", since = "1.64.0")]
+pub use core::ffi::{
+    c_char, c_double, c_float, c_int, c_long, c_longlong, c_schar, c_short, c_uchar, c_uint,
+    c_ulong, c_ulonglong, c_ushort,
+};
+#[unstable(feature = "c_size_t", issue = "88345")]
+pub use core::ffi::{c_ptrdiff_t, c_size_t, c_ssize_t};
+
+#[doc(inline)]
+#[stable(feature = "cstr_from_bytes_until_nul", since = "1.69.0")]
+pub use self::c_str::FromBytesUntilNulError;
+#[doc(inline)]
+#[stable(feature = "cstr_from_bytes", since = "1.10.0")]
+pub use self::c_str::FromBytesWithNulError;
+#[doc(inline)]
+#[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
+pub use self::c_str::FromVecWithNulError;
+#[doc(inline)]
+#[stable(feature = "cstring_into", since = "1.7.0")]
+pub use self::c_str::IntoStringError;
+#[doc(inline)]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use self::c_str::NulError;
+#[doc(inline)]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use self::c_str::{CStr, CString};
+#[stable(feature = "rust1", since = "1.0.0")]
+#[doc(inline)]
+pub use self::os_str::{OsStr, OsString};
+
+#[stable(feature = "os_str_display", since = "1.87.0")]
+pub mod os_str;

crates/std/src/ffi/os_str/tests.rs

@@ -0,0 +1,311 @@
+use super::*;
+use crate::mem::MaybeUninit;
+use crate::ptr;
+
+#[test]
+fn test_os_string_with_capacity() {
+    let os_string = OsString::with_capacity(0);
+    assert_eq!(0, os_string.inner.into_inner().capacity());
+
+    let os_string = OsString::with_capacity(10);
+    assert_eq!(10, os_string.inner.into_inner().capacity());
+
+    let mut os_string = OsString::with_capacity(0);
+    os_string.push("abc");
+    assert!(os_string.inner.into_inner().capacity() >= 3);
+}
+
+#[test]
+fn test_os_string_clear() {
+    let mut os_string = OsString::from("abc");
+    assert_eq!(3, os_string.inner.as_inner().len());
+
+    os_string.clear();
+    assert_eq!(&os_string, "");
+    assert_eq!(0, os_string.inner.as_inner().len());
+}
+
+#[test]
+fn test_os_string_leak() {
+    let os_string = OsString::from("have a cake");
+    let (len, cap) = (os_string.len(), os_string.capacity());
+    let leaked = os_string.leak();
+    assert_eq!(leaked.as_encoded_bytes(), b"have a cake");
+    unsafe { drop(String::from_raw_parts(leaked as *mut OsStr as _, len, cap)) }
+}
+
+#[test]
+fn test_os_string_capacity() {
+    let os_string = OsString::with_capacity(0);
+    assert_eq!(0, os_string.capacity());
+
+    let os_string = OsString::with_capacity(10);
+    assert_eq!(10, os_string.capacity());
+
+    let mut os_string = OsString::with_capacity(0);
+    os_string.push("abc");
+    assert!(os_string.capacity() >= 3);
+}
+
+#[test]
+fn test_os_string_reserve() {
+    let mut os_string = OsString::new();
+    assert_eq!(os_string.capacity(), 0);
+
+    os_string.reserve(2);
+    assert!(os_string.capacity() >= 2);
+
+    for _ in 0..16 {
+        os_string.push("a");
+    }
+
+    assert!(os_string.capacity() >= 16);
+    os_string.reserve(16);
+    assert!(os_string.capacity() >= 32);
+
+    os_string.push("a");
+
+    os_string.reserve(16);
+    assert!(os_string.capacity() >= 33)
+}
+
+#[test]
+fn test_os_string_reserve_exact() {
+    let mut os_string = OsString::new();
+    assert_eq!(os_string.capacity(), 0);
+
+    os_string.reserve_exact(2);
+    assert!(os_string.capacity() >= 2);
+
+    for _ in 0..16 {
+        os_string.push("a");
+    }
+
+    assert!(os_string.capacity() >= 16);
+    os_string.reserve_exact(16);
+    assert!(os_string.capacity() >= 32);
+
+    os_string.push("a");
+
+    os_string.reserve_exact(16);
+    assert!(os_string.capacity() >= 33)
+}
+
+#[test]
+fn test_os_string_join() {
+    let strings = [OsStr::new("hello"), OsStr::new("dear"), OsStr::new("world")];
+    assert_eq!("hello", strings[..1].join(OsStr::new(" ")));
+    assert_eq!("hello dear world", strings.join(OsStr::new(" ")));
+    assert_eq!("hellodearworld", strings.join(OsStr::new("")));
+    assert_eq!("hello.\n dear.\n world", strings.join(OsStr::new(".\n ")));
+
+    assert_eq!("dear world", strings[1..].join(&OsString::from(" ")));
+
+    let strings_abc = [OsString::from("a"), OsString::from("b"), OsString::from("c")];
+    assert_eq!("a b c", strings_abc.join(OsStr::new(" ")));
+}
+
+#[test]
+fn test_os_string_default() {
+    let os_string: OsString = Default::default();
+    assert_eq!("", &os_string);
+}
+
+#[test]
+fn test_os_str_is_empty() {
+    let mut os_string = OsString::new();
+    assert!(os_string.is_empty());
+
+    os_string.push("abc");
+    assert!(!os_string.is_empty());
+
+    os_string.clear();
+    assert!(os_string.is_empty());
+}
+
+#[test]
+fn test_os_str_len() {
+    let mut os_string = OsString::new();
+    assert_eq!(0, os_string.len());
+
+    os_string.push("abc");
+    assert_eq!(3, os_string.len());
+
+    os_string.clear();
+    assert_eq!(0, os_string.len());
+}
+
+#[test]
+fn test_os_str_default() {
+    let os_str: &OsStr = Default::default();
+    assert_eq!("", os_str);
+}
+
+#[test]
+fn into_boxed() {
+    let orig = "Hello, world!";
+    let os_str = OsStr::new(orig);
+    let boxed: Box<OsStr> = Box::from(os_str);
+    let os_string = os_str.to_owned().into_boxed_os_str().into_os_string();
+    assert_eq!(os_str, &*boxed);
+    assert_eq!(&*boxed, &*os_string);
+    assert_eq!(&*os_string, os_str);
+}
+
+#[test]
+fn boxed_default() {
+    let boxed = <Box<OsStr>>::default();
+    assert!(boxed.is_empty());
+}
+
+#[test]
+fn test_os_str_clone_into() {
+    let mut os_string = OsString::with_capacity(123);
+    os_string.push("hello");
+    let os_str = OsStr::new("bonjour");
+    os_str.clone_into(&mut os_string);
+    assert_eq!(os_str, os_string);
+    assert!(os_string.capacity() >= 123);
+}
+
+#[test]
+fn into_rc() {
+    let orig = "Hello, world!";
+    let os_str = OsStr::new(orig);
+    let rc: Rc<OsStr> = Rc::from(os_str);
+    let arc: Arc<OsStr> = Arc::from(os_str);
+
+    assert_eq!(&*rc, os_str);
+    assert_eq!(&*arc, os_str);
+
+    let rc2: Rc<OsStr> = Rc::from(os_str.to_owned());
+    let arc2: Arc<OsStr> = Arc::from(os_str.to_owned());
+
+    assert_eq!(&*rc2, os_str);
+    assert_eq!(&*arc2, os_str);
+}
+
+#[test]
+fn slice_encoded_bytes() {
+    let os_str = OsStr::new("123θგ🦀");
+    // ASCII
+    let digits = os_str.slice_encoded_bytes(..3);
+    assert_eq!(digits, "123");
+    let three = os_str.slice_encoded_bytes(2..3);
+    assert_eq!(three, "3");
+    // 2-byte UTF-8
+    let theta = os_str.slice_encoded_bytes(3..5);
+    assert_eq!(theta, "θ");
+    // 3-byte UTF-8
+    let gani = os_str.slice_encoded_bytes(5..8);
+    assert_eq!(gani, "გ");
+    // 4-byte UTF-8
+    let crab = os_str.slice_encoded_bytes(8..);
+    assert_eq!(crab, "🦀");
+}
+
+#[test]
+#[should_panic]
+fn slice_out_of_bounds() {
+    let crab = OsStr::new("🦀");
+    let _ = crab.slice_encoded_bytes(..5);
+}
+
+#[test]
+#[should_panic]
+fn slice_mid_char() {
+    let crab = OsStr::new("🦀");
+    let _ = crab.slice_encoded_bytes(..2);
+}
+
+#[cfg(unix)]
+#[test]
+#[should_panic(expected = "byte index 1 is not an OsStr boundary")]
+fn slice_invalid_data() {
+    use crate::os::unix::ffi::OsStrExt;
+
+    let os_string = OsStr::from_bytes(b"\xFF\xFF");
+    let _ = os_string.slice_encoded_bytes(1..);
+}
+
+#[cfg(unix)]
+#[test]
+#[should_panic(expected = "byte index 1 is not an OsStr boundary")]
+fn slice_partial_utf8() {
+    use crate::os::unix::ffi::{OsStrExt, OsStringExt};
+
+    let part_crab = OsStr::from_bytes(&"🦀".as_bytes()[..3]);
+    let mut os_string = OsString::from_vec(vec![0xFF]);
+    os_string.push(part_crab);
+    let _ = os_string.slice_encoded_bytes(1..);
+}
+
+#[cfg(unix)]
+#[test]
+fn slice_invalid_edge() {
+    use crate::os::unix::ffi::{OsStrExt, OsStringExt};
+
+    let os_string = OsStr::from_bytes(b"a\xFFa");
+    assert_eq!(os_string.slice_encoded_bytes(..1), "a");
+    assert_eq!(os_string.slice_encoded_bytes(1..), OsStr::from_bytes(b"\xFFa"));
+    assert_eq!(os_string.slice_encoded_bytes(..2), OsStr::from_bytes(b"a\xFF"));
+    assert_eq!(os_string.slice_encoded_bytes(2..), "a");
+
+    let os_string = OsStr::from_bytes(&"abc🦀".as_bytes()[..6]);
+    assert_eq!(os_string.slice_encoded_bytes(..3), "abc");
+    assert_eq!(os_string.slice_encoded_bytes(3..), OsStr::from_bytes(b"\xF0\x9F\xA6"));
+
+    let mut os_string = OsString::from_vec(vec![0xFF]);
+    os_string.push("🦀");
+    assert_eq!(os_string.slice_encoded_bytes(..1), OsStr::from_bytes(b"\xFF"));
+    assert_eq!(os_string.slice_encoded_bytes(1..), "🦀");
+}
+
+#[cfg(windows)]
+#[test]
+#[should_panic(expected = "byte index 3 lies between surrogate codepoints")]
+fn slice_between_surrogates() {
+    use crate::os::windows::ffi::OsStringExt;
+
+    let os_string = OsString::from_wide(&[0xD800, 0xD800]);
+    assert_eq!(os_string.as_encoded_bytes(), &[0xED, 0xA0, 0x80, 0xED, 0xA0, 0x80]);
+    let _ = os_string.slice_encoded_bytes(..3);
+}
+
+#[cfg(windows)]
+#[test]
+fn slice_surrogate_edge() {
+    use crate::os::windows::ffi::OsStringExt;
+
+    let surrogate = OsString::from_wide(&[0xD800]);
+    let mut pre_crab = surrogate.clone();
+    pre_crab.push("🦀");
+    assert_eq!(pre_crab.slice_encoded_bytes(..3), surrogate);
+    assert_eq!(pre_crab.slice_encoded_bytes(3..), "🦀");
+
+    let mut post_crab = OsString::from("🦀");
+    post_crab.push(&surrogate);
+    assert_eq!(post_crab.slice_encoded_bytes(..4), "🦀");
+    assert_eq!(post_crab.slice_encoded_bytes(4..), surrogate);
+}
+
+#[test]
+fn clone_to_uninit() {
+    let a = OsStr::new("hello.txt");
+
+    let mut storage = vec![MaybeUninit::<u8>::uninit(); size_of_val::<OsStr>(a)];
+    unsafe { a.clone_to_uninit(ptr::from_mut::<[_]>(storage.as_mut_slice()).cast()) };
+    assert_eq!(a.as_encoded_bytes(), unsafe { storage.assume_init_ref() });
+
+    let mut b: Box<OsStr> = OsStr::new("world.exe").into();
+    assert_eq!(size_of_val::<OsStr>(a), size_of_val::<OsStr>(&b));
+    assert_ne!(a, &*b);
+    unsafe { a.clone_to_uninit(ptr::from_mut::<OsStr>(&mut b).cast()) };
+    assert_eq!(a, &*b);
+}
+
+#[test]
+fn debug() {
+    let s = "'single quotes'";
+    assert_eq!(format!("{:?}", OsStr::new(s)), format!("{:?}", s));
+}

crates/std/src/hash/mod.rs

@@ -0,0 +1,91 @@
+//! Generic hashing support.
+//!
+//! This module provides a generic way to compute the [hash] of a value.
+//! Hashes are most commonly used with [`HashMap`] and [`HashSet`].
+//!
+//! [hash]: https://en.wikipedia.org/wiki/Hash_function
+//! [`HashMap`]: ../../std/collections/struct.HashMap.html
+//! [`HashSet`]: ../../std/collections/struct.HashSet.html
+//!
+//! The simplest way to make a type hashable is to use `#[derive(Hash)]`:
+//!
+//! # Examples
+//!
+//! ```rust
+//! use std::hash::{DefaultHasher, Hash, Hasher};
+//!
+//! #[derive(Hash)]
+//! struct Person {
+//!     id: u32,
+//!     name: String,
+//!     phone: u64,
+//! }
+//!
+//! let person1 = Person {
+//!     id: 5,
+//!     name: "Janet".to_string(),
+//!     phone: 555_666_7777,
+//! };
+//! let person2 = Person {
+//!     id: 5,
+//!     name: "Bob".to_string(),
+//!     phone: 555_666_7777,
+//! };
+//!
+//! assert!(calculate_hash(&person1) != calculate_hash(&person2));
+//!
+//! fn calculate_hash<T: Hash>(t: &T) -> u64 {
+//!     let mut s = DefaultHasher::new();
+//!     t.hash(&mut s);
+//!     s.finish()
+//! }
+//! ```
+//!
+//! If you need more control over how a value is hashed, you need to implement
+//! the [`Hash`] trait:
+//!
+//! ```rust
+//! use std::hash::{DefaultHasher, Hash, Hasher};
+//!
+//! struct Person {
+//!     id: u32,
+//!     # #[allow(dead_code)]
+//!     name: String,
+//!     phone: u64,
+//! }
+//!
+//! impl Hash for Person {
+//!     fn hash<H: Hasher>(&self, state: &mut H) {
+//!         self.id.hash(state);
+//!         self.phone.hash(state);
+//!     }
+//! }
+//!
+//! let person1 = Person {
+//!     id: 5,
+//!     name: "Janet".to_string(),
+//!     phone: 555_666_7777,
+//! };
+//! let person2 = Person {
+//!     id: 5,
+//!     name: "Bob".to_string(),
+//!     phone: 555_666_7777,
+//! };
+//!
+//! assert_eq!(calculate_hash(&person1), calculate_hash(&person2));
+//!
+//! fn calculate_hash<T: Hash>(t: &T) -> u64 {
+//!     let mut s = DefaultHasher::new();
+//!     t.hash(&mut s);
+//!     s.finish()
+//! }
+//! ```
+#![stable(feature = "rust1", since = "1.0.0")]
+
+pub(crate) mod random;
+
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use core::hash::*;
+
+#[stable(feature = "std_hash_exports", since = "1.76.0")]
+pub use self::random::{DefaultHasher, RandomState};

crates/std/src/hash/random.rs

@@ -0,0 +1,159 @@
+//! This module exists to isolate [`RandomState`] and [`DefaultHasher`] outside of the
+//! [`collections`] module without actually publicly exporting them, so that parts of that
+//! implementation can more easily be moved to the [`alloc`] crate.
+//!
+//! Although its items are public and contain stability attributes, they can't actually be accessed
+//! outside this crate.
+//!
+//! [`collections`]: crate::collections
+
+use super::{BuildHasher, Hasher, SipHasher13};
+use crate::cell::Cell;
+use crate::fmt;
+use crate::sys::random::hashmap_random_keys;
+
+/// `RandomState` is the default state for [`HashMap`] types.
+///
+/// A particular instance `RandomState` will create the same instances of
+/// [`Hasher`], but the hashers created by two different `RandomState`
+/// instances are unlikely to produce the same result for the same values.
+///
+/// [`HashMap`]: crate::collections::HashMap
+///
+/// # Examples
+///
+/// ```
+/// use std::collections::HashMap;
+/// use std::hash::RandomState;
+///
+/// let s = RandomState::new();
+/// let mut map = HashMap::with_hasher(s);
+/// map.insert(1, 2);
+/// ```
+#[stable(feature = "hashmap_build_hasher", since = "1.7.0")]
+#[derive(Clone)]
+pub struct RandomState {
+    k0: u64,
+    k1: u64,
+}
+
+impl RandomState {
+    /// Constructs a new `RandomState` that is initialized with random keys.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::hash::RandomState;
+    ///
+    /// let s = RandomState::new();
+    /// ```
+    #[inline]
+    #[allow(deprecated)]
+    // rand
+    #[must_use]
+    #[stable(feature = "hashmap_build_hasher", since = "1.7.0")]
+    pub fn new() -> RandomState {
+        // Historically this function did not cache keys from the OS and instead
+        // simply always called `rand::thread_rng().gen()` twice. In #31356 it
+        // was discovered, however, that because we re-seed the thread-local RNG
+        // from the OS periodically that this can cause excessive slowdown when
+        // many hash maps are created on a thread. To solve this performance
+        // trap we cache the first set of randomly generated keys per-thread.
+        //
+        // Later in #36481 it was discovered that exposing a deterministic
+        // iteration order allows a form of DOS attack. To counter that we
+        // increment one of the seeds on every RandomState creation, giving
+        // every corresponding HashMap a different iteration order.
+        thread_local!(static KEYS: Cell<(u64, u64)> = {
+            Cell::new(hashmap_random_keys())
+        });
+
+        KEYS.with(|keys| {
+            let (k0, k1) = keys.get();
+            keys.set((k0.wrapping_add(1), k1));
+            RandomState { k0, k1 }
+        })
+    }
+}
+
+#[stable(feature = "hashmap_build_hasher", since = "1.7.0")]
+impl BuildHasher for RandomState {
+    type Hasher = DefaultHasher;
+    #[inline]
+    fn build_hasher(&self) -> DefaultHasher {
+        DefaultHasher(SipHasher13::new_with_keys(self.k0, self.k1))
+    }
+}
+
+/// The default [`Hasher`] used by [`RandomState`].
+///
+/// The internal algorithm is not specified, and so it and its hashes should
+/// not be relied upon over releases.
+#[derive(Clone, Debug)]
+#[stable(feature = "hashmap_build_hasher", since = "1.7.0")]
+pub struct DefaultHasher(SipHasher13);
+
+impl DefaultHasher {
+    /// Creates a new `DefaultHasher`.
+    ///
+    /// This hasher is not guaranteed to be the same as all other
+    /// `DefaultHasher` instances, but is the same as all other `DefaultHasher`
+    /// instances created through `new` or `default`.
+    #[stable(feature = "hashmap_default_hasher", since = "1.13.0")]
+    #[inline]
+    #[rustc_const_unstable(feature = "const_default", issue = "143894")]
+    #[must_use]
+    pub const fn new() -> DefaultHasher {
+        DefaultHasher(SipHasher13::new_with_keys(0, 0))
+    }
+}
+
+#[stable(feature = "hashmap_default_hasher", since = "1.13.0")]
+#[rustc_const_unstable(feature = "const_default", issue = "143894")]
+impl const Default for DefaultHasher {
+    /// Creates a new `DefaultHasher` using [`new`].
+    /// See its documentation for more.
+    ///
+    /// [`new`]: DefaultHasher::new
+    #[inline]
+    fn default() -> DefaultHasher {
+        DefaultHasher::new()
+    }
+}
+
+#[stable(feature = "hashmap_default_hasher", since = "1.13.0")]
+impl Hasher for DefaultHasher {
+    // The underlying `SipHasher13` doesn't override the other
+    // `write_*` methods, so it's ok not to forward them here.
+
+    #[inline]
+    fn write(&mut self, msg: &[u8]) {
+        self.0.write(msg)
+    }
+
+    #[inline]
+    fn write_str(&mut self, s: &str) {
+        self.0.write_str(s);
+    }
+
+    #[inline]
+    fn finish(&self) -> u64 {
+        self.0.finish()
+    }
+}
+
+#[stable(feature = "hashmap_build_hasher", since = "1.7.0")]
+impl Default for RandomState {
+    /// Constructs a new `RandomState`.
+    #[inline]
+    fn default() -> RandomState {
+        RandomState::new()
+    }
+}
+
+#[stable(feature = "std_debug", since = "1.16.0")]
+impl fmt::Debug for RandomState {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("RandomState").finish_non_exhaustive()
+    }
+}

crates/std/src/io.rs

@@ -0,0 +1,71 @@
+use crate::fs::File;
+use io::IoBase;
+pub use io::Read;
+pub use io::Seek;
+pub use io::SeekFrom;
+pub use io::Write;
+
+pub struct Stdin;
+
+impl IoBase for Stdin {
+    type Error = ();
+}
+
+impl Read for Stdin {
+    fn read(&mut self, buf: &mut [u8]) -> core::result::Result<usize, Self::Error> {
+        unsafe { File::from_raw_fd(0).read(buf) }
+    }
+}
+
+pub fn stdin() -> Stdin {
+    Stdin
+}
+
+pub type Result<T> = core::result::Result<T, Error>;
+
+pub(super) struct Repr();
+
+// Part took from the real std
+#[rustc_macro_transparency = "semiopaque"]
+#[unstable(feature = "io_const_error", issue = "133448")]
+#[allow_internal_unstable(hint_must_use, io_const_error_internals)]
+pub macro const_error($kind:expr, $message:expr $(,)?) {
+    crate::io::Error::new()
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+pub struct Error {
+    repr: Repr,
+}
+
+impl Error {
+    pub const fn new() -> Self {
+        Self { repr: Repr() }
+    }
+}
+
+#[allow(dead_code)]
+impl Error {
+    pub(crate) const INVALID_UTF8: Self =
+        const_error!(ErrorKind::InvalidData, "stream did not contain valid UTF-8");
+
+    pub(crate) const READ_EXACT_EOF: Self =
+        const_error!(ErrorKind::UnexpectedEof, "failed to fill whole buffer");
+
+    pub(crate) const UNKNOWN_THREAD_COUNT: Self = const_error!(
+        ErrorKind::NotFound,
+        "the number of hardware threads is not known for the target platform",
+    );
+
+    pub(crate) const UNSUPPORTED_PLATFORM: Self =
+        const_error!(ErrorKind::Unsupported, "operation not supported on this platform");
+
+    pub(crate) const WRITE_ALL_EOF: Self =
+        const_error!(ErrorKind::WriteZero, "failed to write whole buffer");
+
+    pub(crate) const ZERO_TIMEOUT: Self =
+        const_error!(ErrorKind::InvalidInput, "cannot set a 0 duration timeout");
+
+    pub(crate) const NO_ADDRESSES: Self =
+        const_error!(ErrorKind::InvalidInput, "could not resolve to any addresses");
+}

crates/std/src/lib.rs

@@ -0,0 +1,314 @@
+#![unstable(feature = "custom_std", issue = "none")]
+#![no_std]
+//
+// Lints:
+#![warn(deprecated_in_future)]
+// #![warn(missing_docs)]
+// #![warn(missing_debug_implementations)]
+#![allow(explicit_outlives_requirements)]
+#![allow(unused_lifetimes)]
+#![allow(internal_features)]
+#![deny(fuzzy_provenance_casts)]
+#![deny(unsafe_op_in_unsafe_fn)]
+#![allow(rustdoc::redundant_explicit_links)]
+#![warn(rustdoc::unescaped_backticks)]
+// Ensure that std can be linked against panic_abort despite compiled with `-C panic=unwind`
+#![deny(ffi_unwind_calls)]
+// std may use features in a platform-specific way
+#![allow(unused_features)]
+//
+// Features:
+#![cfg_attr(
+    test,
+    feature(internal_output_capture, print_internals, update_panic_count, rt)
+)]
+#![cfg_attr(
+    all(target_vendor = "fortanix", target_env = "sgx"),
+    feature(slice_index_methods, coerce_unsized, sgx_platform)
+)]
+#![cfg_attr(all(test, target_os = "uefi"), feature(uefi_std))]
+#![cfg_attr(target_family = "wasm", feature(stdarch_wasm_atomic_wait))]
+#![cfg_attr(target_arch = "wasm64", feature(simd_wasm64))]
+//
+// Language features:
+// tidy-alphabetical-start
+#![feature(alloc_error_handler)]
+#![feature(allocator_internals)]
+#![feature(allow_internal_unsafe)]
+#![feature(allow_internal_unstable)]
+#![feature(asm_experimental_arch)]
+#![feature(autodiff)]
+#![feature(cfg_sanitizer_cfi)]
+#![feature(cfg_target_thread_local)]
+#![feature(cfi_encoding)]
+#![feature(const_default)]
+#![feature(const_trait_impl)]
+#![feature(core_float_math)]
+#![feature(decl_macro)]
+#![feature(deprecated_suggestion)]
+#![feature(doc_cfg)]
+#![feature(doc_masked)]
+#![feature(doc_notable_trait)]
+#![feature(dropck_eyepatch)]
+#![feature(f16)]
+#![feature(f128)]
+#![feature(ffi_const)]
+#![feature(formatting_options)]
+#![feature(funnel_shifts)]
+#![feature(if_let_guard)]
+#![feature(intra_doc_pointers)]
+#![feature(iter_advance_by)]
+#![feature(iter_next_chunk)]
+#![feature(lang_items)]
+#![feature(link_cfg)]
+#![feature(linkage)]
+#![feature(macro_metavar_expr_concat)]
+#![feature(maybe_uninit_fill)]
+#![feature(min_specialization)]
+#![feature(must_not_suspend)]
+#![feature(needs_panic_runtime)]
+#![feature(negative_impls)]
+#![feature(never_type)]
+#![feature(optimize_attribute)]
+#![feature(prelude_import)]
+#![feature(rustc_attrs)]
+#![feature(rustdoc_internals)]
+#![feature(staged_api)]
+#![feature(stmt_expr_attributes)]
+#![feature(strict_provenance_lints)]
+#![feature(thread_local)]
+#![feature(try_blocks)]
+#![feature(try_trait_v2)]
+#![feature(type_alias_impl_trait)]
+// tidy-alphabetical-end
+//
+// Library features (core):
+// tidy-alphabetical-start
+#![feature(bstr)]
+#![feature(bstr_internals)]
+#![feature(cast_maybe_uninit)]
+#![feature(cfg_select)]
+#![feature(char_internals)]
+#![feature(clone_to_uninit)]
+#![feature(const_convert)]
+#![feature(core_intrinsics)]
+#![feature(core_io_borrowed_buf)]
+#![feature(drop_guard)]
+#![feature(duration_constants)]
+#![feature(error_generic_member_access)]
+#![feature(error_iter)]
+#![feature(exact_size_is_empty)]
+#![feature(exclusive_wrapper)]
+#![feature(extend_one)]
+#![feature(float_algebraic)]
+// #![feature(float_gamma)]
+#![feature(float_minimum_maximum)]
+#![feature(fmt_internals)]
+#![feature(fn_ptr_trait)]
+#![feature(generic_atomic)]
+#![feature(hasher_prefixfree_extras)]
+#![feature(hashmap_internals)]
+#![feature(hint_must_use)]
+#![feature(int_from_ascii)]
+#![feature(ip)]
+#![feature(maybe_uninit_array_assume_init)]
+#![feature(panic_can_unwind)]
+#![feature(panic_internals)]
+#![feature(pin_coerce_unsized_trait)]
+#![feature(pointer_is_aligned_to)]
+#![feature(portable_simd)]
+#![feature(ptr_as_uninit)]
+#![feature(ptr_mask)]
+#![feature(random)]
+#![feature(slice_internals)]
+#![feature(slice_ptr_get)]
+#![feature(slice_range)]
+#![feature(slice_split_once)]
+#![feature(std_internals)]
+#![feature(str_internals)]
+#![feature(sync_unsafe_cell)]
+#![feature(temporary_niche_types)]
+#![feature(ub_checks)]
+#![feature(used_with_arg)]
+// tidy-alphabetical-end
+//
+// Library features (alloc):
+// tidy-alphabetical-start
+#![feature(alloc_layout_extra)]
+#![feature(allocator_api)]
+#![feature(clone_from_ref)]
+#![feature(get_mut_unchecked)]
+#![feature(map_try_insert)]
+#![feature(slice_concat_trait)]
+#![feature(thin_box)]
+#![feature(try_reserve_kind)]
+#![feature(try_with_capacity)]
+#![feature(unique_rc_arc)]
+#![feature(wtf8_internals)]
+// tidy-alphabetical-end
+//
+// Library features (unwind):
+// tidy-alphabetical-start
+// #![feature(panic_unwind)]
+// tidy-alphabetical-end
+//
+// Library features (std_detect):
+// tidy-alphabetical-start
+// #![feature(stdarch_internal)]
+// tidy-alphabetical-end
+//
+// Only for re-exporting:
+// tidy-alphabetical-start
+#![feature(assert_matches)]
+#![feature(async_iterator)]
+#![feature(c_variadic)]
+#![feature(cfg_accessible)]
+#![feature(cfg_eval)]
+#![feature(concat_bytes)]
+#![feature(const_format_args)]
+#![feature(custom_test_frameworks)]
+#![feature(edition_panic)]
+#![feature(format_args_nl)]
+#![feature(log_syntax)]
+#![feature(test)]
+#![feature(trace_macros)]
+// tidy-alphabetical-end
+//
+// Only used in tests/benchmarks:
+//
+// Only for const-ness:
+// tidy-alphabetical-start
+#![feature(io_const_error)]
+// tidy-alphabetical-end
+//
+#![feature(c_size_t, unsafe_binders)]
+#![allow(clippy::doc_lazy_continuation, clippy::all)]
+#![allow(stable_features, incomplete_features, unexpected_cfgs)]
+#![allow(unused)]
+
+#[macro_use]
+extern crate alloc as alloc_crate;
+
+pub use core::any;
+pub use core::array;
+pub use core::async_iter;
+pub use core::cell;
+pub use core::char;
+pub use core::clone;
+pub use core::cmp;
+pub use core::convert;
+pub use core::default;
+pub use core::future;
+pub use core::hint;
+#[allow(deprecated, deprecated_in_future)]
+pub use core::i8;
+#[allow(deprecated, deprecated_in_future)]
+pub use core::i16;
+#[allow(deprecated, deprecated_in_future)]
+pub use core::i32;
+#[allow(deprecated, deprecated_in_future)]
+pub use core::i64;
+#[allow(deprecated, deprecated_in_future)]
+pub use core::i128;
+pub use core::intrinsics;
+#[allow(deprecated, deprecated_in_future)]
+pub use core::isize;
+pub use core::iter;
+pub use core::marker;
+pub use core::mem;
+pub use core::ops;
+pub use core::option;
+pub use core::pin;
+pub use core::ptr;
+pub use core::range;
+pub use core::result;
+#[allow(deprecated, deprecated_in_future)]
+pub use core::u8;
+#[allow(deprecated, deprecated_in_future)]
+pub use core::u16;
+#[allow(deprecated, deprecated_in_future)]
+pub use core::u32;
+#[allow(deprecated, deprecated_in_future)]
+pub use core::u64;
+#[allow(deprecated, deprecated_in_future)]
+pub use core::u128;
+pub use core::unsafe_binder;
+#[allow(deprecated, deprecated_in_future)]
+pub use core::usize;
+
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use alloc_crate::borrow;
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use alloc_crate::boxed;
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use alloc_crate::fmt;
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use alloc_crate::format;
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use alloc_crate::rc;
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use alloc_crate::slice;
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use alloc_crate::str;
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use alloc_crate::string;
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use alloc_crate::vec;
+
+#[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
+pub use core::{
+    assert, cfg, column, compile_error, concat, const_format_args, env, file, format_args,
+    format_args_nl, include, include_bytes, include_str, line, log_syntax, module_path, option_env,
+    stringify, trace_macros,
+};
+
+pub mod ffi;
+pub mod hash;
+pub mod io;
+// pub mod fs;
+pub mod error;
+pub mod num;
+pub mod path;
+pub mod prelude;
+pub mod process;
+#[macro_use]
+pub mod rt;
+pub mod alloc;
+pub mod sync;
+pub mod sys;
+pub mod thread;
+pub mod time;
+
+#[prelude_import]
+#[allow(unused_imports)]
+pub use prelude::rust_2024::*;
+
+#[allow(unused)]
+mod sealed {
+    /// This trait being unreachable from outside the crate
+    /// prevents outside implementations of our extension traits.
+    /// This allows adding more trait methods in the future.
+    #[unstable(feature = "sealed", issue = "none")]
+    pub trait Sealed {}
+}
+
+pub use shared::fs;
+pub use shared::syscall;
+
+#[macro_export]
+macro_rules! print {
+    ($($args:expr),*) => {
+        $crate::syscall::write_string_temp(&format!($($args),*))
+    };
+}
+#[macro_export]
+macro_rules! println {
+    () => {
+        $crate::print!("");
+        // $crate::print!("\n\r");
+    };
+    ($($args:expr),*) => {
+        $crate::print!($($args),*);
+        // $crate::println!();
+    };
+}

crates/std/src/num/mod.rs

@@ -0,0 +1,28 @@
+//! Additional functionality for numerics.
+//!
+//! This module provides some extra types that are useful when doing numerical
+//! work. See the individual documentation for each piece for more information.
+
+#![stable(feature = "rust1", since = "1.0.0")]
+#![allow(missing_docs)]
+
+#[stable(feature = "int_error_matching", since = "1.55.0")]
+pub use core::num::IntErrorKind;
+#[stable(feature = "generic_nonzero", since = "1.79.0")]
+pub use core::num::NonZero;
+#[stable(feature = "saturating_int_impl", since = "1.74.0")]
+pub use core::num::Saturating;
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use core::num::Wrapping;
+#[unstable(
+    feature = "nonzero_internals",
+    reason = "implementation detail which may disappear or be replaced at any time",
+    issue = "none"
+)]
+pub use core::num::ZeroablePrimitive;
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use core::num::{FpCategory, ParseFloatError, ParseIntError, TryFromIntError};
+#[stable(feature = "signed_nonzero", since = "1.34.0")]
+pub use core::num::{NonZeroI8, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI128, NonZeroIsize};
+#[stable(feature = "nonzero", since = "1.28.0")]
+pub use core::num::{NonZeroU8, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU128, NonZeroUsize};

crates/std/src/prelude.rs

@@ -0,0 +1,181 @@
+pub mod rust_2024 {
+    pub use crate::print;
+    pub use crate::println;
+    pub use alloc::format;
+    pub use alloc::vec;
+
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[doc(no_inline)]
+    pub use crate::borrow::ToOwned;
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[doc(no_inline)]
+    pub use crate::boxed::Box;
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[doc(no_inline)]
+    pub use crate::string::{String, ToString};
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[doc(no_inline)]
+    pub use crate::vec::Vec;
+
+    // Re-exported built-in macros and traits
+    #[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
+    #[doc(no_inline)]
+    #[expect(deprecated)]
+    pub use core::prelude::v1::{
+        Clone, Copy, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd, assert, assert_eq,
+        assert_ne, cfg, column, compile_error, concat, debug_assert, debug_assert_eq,
+        debug_assert_ne, env, file, format_args, include, include_bytes, include_str, line,
+        matches, module_path, option_env, stringify, todo, r#try, unimplemented, unreachable,
+        write, writeln,
+    };
+
+    #[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
+    #[doc(no_inline)]
+    pub use crate::thread_local;
+
+    #[stable(feature = "cfg_select", since = "1.95.0")]
+    #[doc(no_inline)]
+    pub use core::prelude::v1::cfg_select;
+
+    #[unstable(
+        feature = "concat_bytes",
+        issue = "87555",
+        reason = "`concat_bytes` is not stable enough for use and is subject to change"
+    )]
+    #[doc(no_inline)]
+    pub use core::prelude::v1::concat_bytes;
+
+    #[unstable(feature = "const_format_args", issue = "none")]
+    #[doc(no_inline)]
+    pub use core::prelude::v1::const_format_args;
+
+    #[unstable(
+        feature = "log_syntax",
+        issue = "29598",
+        reason = "`log_syntax!` is not stable enough for use and is subject to change"
+    )]
+    #[doc(no_inline)]
+    pub use core::prelude::v1::log_syntax;
+
+    #[unstable(
+        feature = "trace_macros",
+        issue = "29598",
+        reason = "`trace_macros` is not stable enough for use and is subject to change"
+    )]
+    #[doc(no_inline)]
+    pub use core::prelude::v1::trace_macros;
+
+    // Do not `doc(no_inline)` so that they become doc items on their own
+    // (no public module for them to be re-exported from).
+    #[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
+    pub use core::prelude::v1::{
+        alloc_error_handler, bench, derive, global_allocator, test, test_case,
+    };
+
+    #[unstable(feature = "derive_const", issue = "118304")]
+    pub use core::prelude::v1::derive_const;
+
+    // Do not `doc(no_inline)` either.
+    #[unstable(
+        feature = "cfg_accessible",
+        issue = "64797",
+        reason = "`cfg_accessible` is not fully implemented"
+    )]
+    pub use core::prelude::v1::cfg_accessible;
+
+    // Do not `doc(no_inline)` either.
+    #[unstable(
+        feature = "cfg_eval",
+        issue = "82679",
+        reason = "`cfg_eval` is a recently implemented feature"
+    )]
+    pub use core::prelude::v1::cfg_eval;
+
+    // Do not `doc(no_inline)` either.
+    #[unstable(
+        feature = "type_ascription",
+        issue = "23416",
+        reason = "placeholder syntax for type ascription"
+    )]
+    pub use core::prelude::v1::type_ascribe;
+
+    // Do not `doc(no_inline)` either.
+    #[unstable(
+        feature = "deref_patterns",
+        issue = "87121",
+        reason = "placeholder syntax for deref patterns"
+    )]
+    pub use core::prelude::v1::deref;
+
+    // Do not `doc(no_inline)` either.
+    #[unstable(
+        feature = "type_alias_impl_trait",
+        issue = "63063",
+        reason = "`type_alias_impl_trait` has open design concerns"
+    )]
+    pub use core::prelude::v1::define_opaque;
+
+    #[unstable(feature = "extern_item_impls", issue = "125418")]
+    pub use core::prelude::v1::{eii, unsafe_eii};
+
+    #[unstable(feature = "eii_internals", issue = "none")]
+    pub use core::prelude::v1::eii_declaration;
+
+    #[stable(feature = "prelude_2021", since = "1.55.0")]
+    #[doc(no_inline)]
+    pub use core::prelude::rust_2021::*;
+
+    #[stable(feature = "prelude_2024", since = "1.85.0")]
+    #[doc(no_inline)]
+    pub use core::prelude::rust_2024::*;
+
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[doc(no_inline)]
+    pub use crate::convert::{AsMut, AsRef, From, Into};
+
+    extern crate alloc;
+
+    struct GlobalAllocator;
+
+    #[core::prelude::v1::global_allocator]
+    static GLOBAL_ALLOCATOR: GlobalAllocator = GlobalAllocator;
+
+    unsafe impl core::alloc::GlobalAlloc for GlobalAllocator {
+        unsafe fn alloc(&self, layout: core::alloc::Layout) -> *mut u8 {
+            crate::syscall::alloc(layout)
+        }
+
+        unsafe fn dealloc(&self, ptr: *mut u8, layout: core::alloc::Layout) {
+            crate::syscall::dealloc(ptr, layout)
+        }
+    }
+
+    #[panic_handler]
+    fn panic(_panic_info: &core::panic::PanicInfo) -> ! {
+        // TODO print
+        loop {}
+    }
+
+    /// # Safety
+    /// `argc` and `argv` are passed by the kernel
+    #[unsafe(no_mangle)]
+    pub unsafe extern "C" fn _start(argc: isize, argv: *const *const u8) -> isize {
+        unsafe extern "Rust" {
+            fn main(argc: isize, argv: *const *const u8) -> isize;
+        }
+
+        unsafe { main(argc, argv) }
+    }
+
+    #[lang = "start"]
+    pub fn lang_start<T: crate::process::Termination + 'static>(
+        main: fn() -> T,
+        argc: isize,
+        argv: *const *const u8,
+        _sigpipe: u8,
+    ) -> isize {
+        println!("{}", argc);
+        println!("{:?}", argv);
+        main().report().to_isize()
+    }
+}

crates/std/src/process.rs

@@ -0,0 +1,29 @@
+pub struct ExitCode(isize);
+
+impl ExitCode {
+    pub const SUCCESS: ExitCode = ExitCode(0);
+
+    pub fn to_isize(self) -> isize {
+        self.0
+    }
+}
+
+#[lang = "termination"]
+pub trait Termination {
+    /// Is called to get the representation of the value as status code.
+    /// This status code is returned to the operating system.
+    fn report(self) -> ExitCode;
+}
+
+impl Termination for () {
+    #[inline]
+    fn report(self) -> ExitCode {
+        ExitCode::SUCCESS
+    }
+}
+impl Termination for isize {
+    #[inline]
+    fn report(self) -> ExitCode {
+        ExitCode(self)
+    }
+}

crates/std/src/rt.rs

@@ -0,0 +1,6 @@
+macro_rules! rtabort {
+    ($($t:tt)*) => {{}};
+}
+macro_rules! rtprintpanic {
+    ($($t:tt)*) => {{}};
+}

crates/std/src/sync.rs

@@ -0,0 +1,14 @@
+pub mod once {
+    use crate::sys::sync as sys;
+    pub struct OnceState {
+        pub(crate) inner: sys::OnceState,
+    }
+    /// Used for the internal implementation of `sys::sync::once` on different platforms and the
+    /// [`LazyLock`](crate::sync::LazyLock) implementation.
+    pub(crate) enum OnceExclusiveState {
+        Incomplete,
+        Poisoned,
+        Complete,
+    }
+}
+pub use once::OnceState;

crates/std/src/sys/alloc/mod.rs

@@ -0,0 +1,113 @@
+#![forbid(unsafe_op_in_unsafe_fn)]
+
+use crate::alloc::{GlobalAlloc, Layout, System};
+use crate::ptr;
+
+// The minimum alignment guaranteed by the architecture. This value is used to
+// add fast paths for low alignment values.
+#[allow(dead_code)]
+const MIN_ALIGN: usize = if cfg!(any(
+    all(target_arch = "riscv32", any(target_os = "espidf", target_os = "zkvm")),
+    all(target_arch = "xtensa", target_os = "espidf"),
+)) {
+    // The allocator on the esp-idf and zkvm platforms guarantees 4 byte alignment.
+    4
+} else if cfg!(any(
+    target_arch = "x86",
+    target_arch = "arm",
+    target_arch = "m68k",
+    target_arch = "csky",
+    target_arch = "loongarch32",
+    target_arch = "mips",
+    target_arch = "mips32r6",
+    target_arch = "powerpc",
+    target_arch = "powerpc64",
+    target_arch = "sparc",
+    target_arch = "wasm32",
+    target_arch = "hexagon",
+    target_arch = "riscv32",
+    target_arch = "xtensa",
+)) {
+    8
+} else if cfg!(any(
+    target_arch = "x86_64",
+    target_arch = "aarch64",
+    target_arch = "arm64ec",
+    target_arch = "loongarch64",
+    target_arch = "mips64",
+    target_arch = "mips64r6",
+    target_arch = "s390x",
+    target_arch = "sparc64",
+    target_arch = "riscv64",
+    target_arch = "wasm64",
+)) {
+    16
+} else {
+    panic!("add a value for MIN_ALIGN")
+};
+
+#[allow(dead_code)]
+unsafe fn realloc_fallback(
+    alloc: &System,
+    ptr: *mut u8,
+    old_layout: Layout,
+    new_size: usize,
+) -> *mut u8 {
+    // SAFETY: Docs for GlobalAlloc::realloc require this to be valid
+    unsafe {
+        let new_layout = Layout::from_size_align_unchecked(new_size, old_layout.align());
+
+        let new_ptr = GlobalAlloc::alloc(alloc, new_layout);
+        if !new_ptr.is_null() {
+            let size = usize::min(old_layout.size(), new_size);
+            ptr::copy_nonoverlapping(ptr, new_ptr, size);
+            GlobalAlloc::dealloc(alloc, ptr, old_layout);
+        }
+
+        new_ptr
+    }
+}
+
+cfg_select! {
+    any(
+        target_family = "unix",
+        target_os = "wasi",
+        target_os = "teeos",
+        target_os = "trusty",
+    ) => {
+        mod unix;
+    }
+    target_os = "windows" => {
+        mod windows;
+    }
+    target_os = "hermit" => {
+        mod hermit;
+    }
+    target_os = "motor" => {
+        mod motor;
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
+        mod sgx;
+    }
+    target_os = "solid_asp3" => {
+        mod solid;
+    }
+    target_os = "uefi" => {
+        mod uefi;
+    }
+    target_os = "vexos" => {
+        mod vexos;
+    }
+    target_family = "wasm" => {
+        mod wasm;
+    }
+    target_os = "xous" => {
+        mod xous;
+    }
+    target_os = "zkvm" => {
+        mod zkvm;
+    }
+    target_os = "survos" => {
+        mod survos;
+    }
+}

crates/std/src/sys/alloc/survos.rs

@@ -0,0 +1,14 @@
+use crate::alloc::{GlobalAlloc, Layout, System};
+
+#[stable(feature = "alloc_system_type", since = "1.28.0")]
+unsafe impl GlobalAlloc for System {
+    #[inline]
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        unsafe { crate::syscall::alloc(layout) }
+    }
+
+    #[inline]
+    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+        unsafe { crate::syscall::dealloc(ptr, layout) }
+    }
+}

crates/std/src/sys/cmath.rs

@@ -0,0 +1,114 @@
+#![cfg(not(test))]
+
+// These symbols are all defined by `libm`,
+// or by `compiler-builtins` on unsupported platforms.
+unsafe extern "C" {
+    pub safe fn acos(n: f64) -> f64;
+    pub safe fn asin(n: f64) -> f64;
+    pub safe fn atan(n: f64) -> f64;
+    pub safe fn atan2(a: f64, b: f64) -> f64;
+    pub safe fn cosh(n: f64) -> f64;
+    pub safe fn expm1(n: f64) -> f64;
+    pub safe fn expm1f(n: f32) -> f32;
+    #[cfg_attr(target_env = "msvc", link_name = "_hypot")]
+    pub safe fn hypot(x: f64, y: f64) -> f64;
+    #[cfg_attr(target_env = "msvc", link_name = "_hypotf")]
+    pub safe fn hypotf(x: f32, y: f32) -> f32;
+    pub safe fn log1p(n: f64) -> f64;
+    pub safe fn log1pf(n: f32) -> f32;
+    pub safe fn sinh(n: f64) -> f64;
+    pub safe fn tan(n: f64) -> f64;
+    pub safe fn tanh(n: f64) -> f64;
+    pub safe fn tgamma(n: f64) -> f64;
+    pub safe fn tgammaf(n: f32) -> f32;
+    pub safe fn lgamma_r(n: f64, s: &mut i32) -> f64;
+    #[cfg(not(target_os = "aix"))]
+    pub safe fn lgammaf_r(n: f32, s: &mut i32) -> f32;
+    pub safe fn erf(n: f64) -> f64;
+    pub safe fn erff(n: f32) -> f32;
+    pub safe fn erfc(n: f64) -> f64;
+    pub safe fn erfcf(n: f32) -> f32;
+
+    pub safe fn acosf128(n: f128) -> f128;
+    pub safe fn asinf128(n: f128) -> f128;
+    pub safe fn atanf128(n: f128) -> f128;
+    pub safe fn atan2f128(a: f128, b: f128) -> f128;
+    pub safe fn cbrtf128(n: f128) -> f128;
+    pub safe fn coshf128(n: f128) -> f128;
+    pub safe fn expm1f128(n: f128) -> f128;
+    pub safe fn hypotf128(x: f128, y: f128) -> f128;
+    pub safe fn log1pf128(n: f128) -> f128;
+    pub safe fn sinhf128(n: f128) -> f128;
+    pub safe fn tanf128(n: f128) -> f128;
+    pub safe fn tanhf128(n: f128) -> f128;
+    pub safe fn tgammaf128(n: f128) -> f128;
+    pub safe fn lgammaf128_r(n: f128, s: &mut i32) -> f128;
+    pub safe fn erff128(n: f128) -> f128;
+    pub safe fn erfcf128(n: f128) -> f128;
+}
+
+cfg_select! {
+    all(target_os = "windows", target_env = "msvc", target_arch = "x86") => {
+        // On 32-bit x86 MSVC these functions aren't defined, so we just define shims
+        // which promote everything to f64, perform the calculation, and then demote
+        // back to f32. While not precisely correct should be "correct enough" for now.
+        #[inline]
+        pub fn acosf(n: f32) -> f32 {
+            f64::acos(n as f64) as f32
+        }
+
+        #[inline]
+        pub fn asinf(n: f32) -> f32 {
+            f64::asin(n as f64) as f32
+        }
+
+        #[inline]
+        pub fn atan2f(n: f32, b: f32) -> f32 {
+            f64::atan2(n as f64, b as f64) as f32
+        }
+
+        #[inline]
+        pub fn atanf(n: f32) -> f32 {
+            f64::atan(n as f64) as f32
+        }
+
+        #[inline]
+        pub fn coshf(n: f32) -> f32 {
+            f64::cosh(n as f64) as f32
+        }
+
+        #[inline]
+        pub fn sinhf(n: f32) -> f32 {
+            f64::sinh(n as f64) as f32
+        }
+
+        #[inline]
+        pub fn tanf(n: f32) -> f32 {
+            f64::tan(n as f64) as f32
+        }
+
+        #[inline]
+        pub fn tanhf(n: f32) -> f32 {
+            f64::tanh(n as f64) as f32
+        }
+    }
+    _ => {
+        unsafe extern "C" {
+            pub safe fn acosf(n: f32) -> f32;
+            pub safe fn asinf(n: f32) -> f32;
+            pub safe fn atan2f(a: f32, b: f32) -> f32;
+            pub safe fn atanf(n: f32) -> f32;
+            pub safe fn coshf(n: f32) -> f32;
+            pub safe fn sinhf(n: f32) -> f32;
+            pub safe fn tanf(n: f32) -> f32;
+            pub safe fn tanhf(n: f32) -> f32;
+        }
+    }
+}
+
+// On AIX, we don't have lgammaf_r only the f64 version, so we can
+// use the f64 version lgamma_r
+#[cfg(target_os = "aix")]
+pub fn lgammaf_r(n: f32, s: &mut i32) -> f32 {
+    lgamma_r(n.into(), s) as f32
+}

crates/std/src/sys/configure_builtins.rs

@@ -0,0 +1,62 @@
+//! The configure builtins provides runtime support compiler-builtin features
+//! which require dynamic initialization to work as expected, e.g. aarch64
+//! outline-atomics.
+
+/// Enable LSE atomic operations at startup, if supported.
+///
+/// Linker sections are based on what [`ctor`] does, with priorities to run slightly before user
+/// code:
+///
+/// - Apple uses the section `__mod_init_func`, `mod_init_funcs` is needed to set
+///   `S_MOD_INIT_FUNC_POINTERS`. There doesn't seem to be a way to indicate priorities.
+/// - Windows uses `.CRT$XCT`, which is run before user constructors (these should use `.CRT$XCU`).
+/// - ELF uses `.init_array` with a priority of 90, which runs before our `ARGV_INIT_ARRAY`
+///   initializer (priority 99). Both are within the 0-100 implementation-reserved range, per docs
+///   for the [`prio-ctor-dtor`] warning, and this matches compiler-rt's `CONSTRUCTOR_PRIORITY`.
+///
+/// To save startup time, the initializer is only run if outline atomic routines from
+/// compiler-builtins may be used. If LSE is known to be available then the calls are never
+/// emitted, and if we build the C intrinsics then it has its own initializer using the symbol
+/// `__aarch64_have_lse_atomics`.
+///
+/// Initialization is done in a global constructor to so we get the same behavior regardless of
+/// whether Rust's `init` is used, or if we are in a `dylib` or `no_main` situation (as opposed
+/// to doing it as part of pre-main startup). This also matches C implementations.
+///
+/// Ideally `core` would have something similar, but detecting the CPU features requires the
+/// auxiliary vector from the OS. We do the initialization in `std` rather than as part of
+/// `compiler-builtins` because a builtins->std dependency isn't possible, and inlining parts of
+/// `std-detect` would be much messier.
+///
+/// [`ctor`]: https://github.com/mmastrac/rust-ctor/blob/63382b833ddcbfb8b064f4e86bfa1ed4026ff356/shared/src/macros/mod.rs#L522-L534
+/// [`prio-ctor-dtor`]: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
+#[cfg(all(
+    target_arch = "aarch64",
+    target_feature = "outline-atomics",
+    not(target_feature = "lse"),
+    not(feature = "compiler-builtins-c"),
+))]
+#[used]
+#[cfg_attr(target_vendor = "apple", unsafe(link_section = "__DATA,__mod_init_func,mod_init_funcs"))]
+#[cfg_attr(target_os = "windows", unsafe(link_section = ".CRT$XCT"))]
+#[cfg_attr(
+    not(any(target_vendor = "apple", target_os = "windows")),
+    unsafe(link_section = ".init_array.90")
+)]
+static RUST_LSE_INIT: extern "C" fn() = {
+    extern "C" fn init_lse() {
+        use crate::arch;
+
+        // This is provided by compiler-builtins::aarch64_outline_atomics.
+        unsafe extern "C" {
+            fn __rust_enable_lse();
+        }
+
+        if arch::is_aarch64_feature_detected!("lse") {
+            unsafe {
+                __rust_enable_lse();
+            }
+        }
+    }
+    init_lse
+};

crates/std/src/sys/env/common.rs

@@ -0,0 +1,31 @@
+use crate::ffi::OsString;
+use crate::{fmt, vec};
+
+pub struct Env {
+    iter: vec::IntoIter<(OsString, OsString)>,
+}
+
+impl Env {
+    pub(super) fn new(env: Vec<(OsString, OsString)>) -> Self {
+        Env { iter: env.into_iter() }
+    }
+}
+
+impl fmt::Debug for Env {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self.iter.as_slice()).finish()
+    }
+}
+
+impl !Send for Env {}
+impl !Sync for Env {}
+
+impl Iterator for Env {
+    type Item = (OsString, OsString);
+    fn next(&mut self) -> Option<(OsString, OsString)> {
+        self.iter.next()
+    }
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}

crates/std/src/sys/env/mod.rs

@@ -0,0 +1,62 @@
+//! Platform-dependent environment variables abstraction.
+
+#![forbid(unsafe_op_in_unsafe_fn)]
+
+#[cfg(any(
+    target_family = "unix",
+    target_os = "hermit",
+    target_os = "motor",
+    all(target_vendor = "fortanix", target_env = "sgx"),
+    target_os = "solid_asp3",
+    target_os = "uefi",
+    target_os = "wasi",
+    target_os = "xous",
+))]
+mod common;
+
+cfg_select! {
+    target_family = "unix" => {
+        mod unix;
+        pub use unix::*;
+    }
+    target_family = "windows" => {
+        mod windows;
+        pub use windows::*;
+    }
+    target_os = "hermit" => {
+        mod hermit;
+        pub use hermit::*;
+    }
+    target_os = "motor" => {
+        mod motor;
+        pub use motor::*;
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
+        mod sgx;
+        pub use sgx::*;
+    }
+    target_os = "solid_asp3" => {
+        mod solid;
+        pub use solid::*;
+    }
+    target_os = "uefi" => {
+        mod uefi;
+        pub use uefi::*;
+    }
+    target_os = "wasi" => {
+        mod wasi;
+        pub use wasi::*;
+    }
+    target_os = "xous" => {
+        mod xous;
+        pub use xous::*;
+    }
+    target_os = "zkvm" => {
+        mod zkvm;
+        pub use zkvm::*;
+    }
+    _ => {
+        mod unsupported;
+        pub use unsupported::*;
+    }
+}

crates/std/src/sys/env/unsupported.rs

@@ -0,0 +1,33 @@
+use crate::ffi::{OsStr, OsString};
+use crate::{fmt, io};
+
+pub struct Env(!);
+
+impl fmt::Debug for Env {
+    fn fmt(&self, _: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0
+    }
+}
+
+impl Iterator for Env {
+    type Item = (OsString, OsString);
+    fn next(&mut self) -> Option<(OsString, OsString)> {
+        self.0
+    }
+}
+
+pub fn env() -> Env {
+    panic!("not supported on this platform")
+}
+
+pub fn getenv(_: &OsStr) -> Option<OsString> {
+    None
+}
+
+pub unsafe fn setenv(_: &OsStr, _: &OsStr) -> io::Result<()> {
+    Err(io::const_error!(io::ErrorKind::Unsupported, "cannot set env vars on this platform"))
+}
+
+pub unsafe fn unsetenv(_: &OsStr) -> io::Result<()> {
+    Err(io::const_error!(io::ErrorKind::Unsupported, "cannot unset env vars on this platform"))
+}

crates/std/src/sys/env_consts.rs

@@ -0,0 +1,426 @@
+//! Constants associated with each target.
+
+// Replaces the #[else] gate with #[cfg(not(any(…)))] of all the other gates.
+// This ensures that they must be mutually exclusive and do not have precedence
+// like cfg_select!.
+macro cfg_unordered(
+    $(#[cfg($cfg:meta)] $os:item)*
+    #[else] $fallback:item
+) {
+    $(#[cfg($cfg)] $os)*
+    #[cfg(not(any($($cfg),*)))] $fallback
+}
+
+// Keep entries sorted alphabetically and mutually exclusive.
+
+cfg_unordered! {
+
+#[cfg(target_os = "aix")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "aix";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".a";
+    pub const DLL_EXTENSION: &str = "a";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "android")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "android";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "cygwin")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "cygwin";
+    pub const DLL_PREFIX: &str = "";
+    pub const DLL_SUFFIX: &str = ".dll";
+    pub const DLL_EXTENSION: &str = "dll";
+    pub const EXE_SUFFIX: &str = ".exe";
+    pub const EXE_EXTENSION: &str = "exe";
+}
+
+#[cfg(target_os = "dragonfly")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "dragonfly";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "emscripten")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "emscripten";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = ".js";
+    pub const EXE_EXTENSION: &str = "js";
+}
+
+#[cfg(target_os = "espidf")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "espidf";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "freebsd")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "freebsd";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "fuchsia")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "fuchsia";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "haiku")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "haiku";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "hermit")]
+pub mod os {
+    pub const FAMILY: &str = "";
+    pub const OS: &str = "hermit";
+    pub const DLL_PREFIX: &str = "";
+    pub const DLL_SUFFIX: &str = "";
+    pub const DLL_EXTENSION: &str = "";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "horizon")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "horizon";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = ".elf";
+    pub const EXE_EXTENSION: &str = "elf";
+}
+
+#[cfg(target_os = "hurd")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "hurd";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "illumos")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "illumos";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "ios")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "ios";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".dylib";
+    pub const DLL_EXTENSION: &str = "dylib";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "l4re")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "l4re";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "linux")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "linux";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "macos")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "macos";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".dylib";
+    pub const DLL_EXTENSION: &str = "dylib";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "netbsd")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "netbsd";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "nto")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "nto";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "nuttx")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "nuttx";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "openbsd")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "openbsd";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "redox")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "redox";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "rtems")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "rtems";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(all(target_vendor = "fortanix", target_env = "sgx"))]
+pub mod os {
+    pub const FAMILY: &str = "";
+    pub const OS: &str = "";
+    pub const DLL_PREFIX: &str = "";
+    pub const DLL_SUFFIX: &str = ".sgxs";
+    pub const DLL_EXTENSION: &str = "sgxs";
+    pub const EXE_SUFFIX: &str = ".sgxs";
+    pub const EXE_EXTENSION: &str = "sgxs";
+}
+
+#[cfg(target_os = "solaris")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "solaris";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "solid_asp3")]
+pub mod os {
+    pub const FAMILY: &str = "itron";
+    pub const OS: &str = "solid";
+    pub const DLL_PREFIX: &str = "";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "tvos")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "tvos";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".dylib";
+    pub const DLL_EXTENSION: &str = "dylib";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "uefi")]
+pub mod os {
+    pub const FAMILY: &str = "";
+    pub const OS: &str = "uefi";
+    pub const DLL_PREFIX: &str = "";
+    pub const DLL_SUFFIX: &str = "";
+    pub const DLL_EXTENSION: &str = "";
+    pub const EXE_SUFFIX: &str = ".efi";
+    pub const EXE_EXTENSION: &str = "efi";
+}
+
+#[cfg(target_os = "vexos")]
+pub mod os {
+    pub const FAMILY: &str = "";
+    pub const OS: &str = "vexos";
+    pub const DLL_PREFIX: &str = "";
+    pub const DLL_SUFFIX: &str = "";
+    pub const DLL_EXTENSION: &str = "";
+    pub const EXE_SUFFIX: &str = ".bin";
+    pub const EXE_EXTENSION: &str = "bin";
+}
+
+#[cfg(target_os = "visionos")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "visionos";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".dylib";
+    pub const DLL_EXTENSION: &str = "dylib";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "vita")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "vita";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = ".elf";
+    pub const EXE_EXTENSION: &str = "elf";
+}
+
+#[cfg(target_os = "vxworks")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "vxworks";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(all(target_family = "wasm", not(any(target_os = "emscripten", target_os = "linux"))))]
+pub mod os {
+    pub const FAMILY: &str = "";
+    pub const OS: &str = "";
+    pub const DLL_PREFIX: &str = "";
+    pub const DLL_SUFFIX: &str = ".wasm";
+    pub const DLL_EXTENSION: &str = "wasm";
+    pub const EXE_SUFFIX: &str = ".wasm";
+    pub const EXE_EXTENSION: &str = "wasm";
+}
+
+#[cfg(target_os = "watchos")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "watchos";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".dylib";
+    pub const DLL_EXTENSION: &str = "dylib";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+#[cfg(target_os = "windows")]
+pub mod os {
+    pub const FAMILY: &str = "windows";
+    pub const OS: &str = "windows";
+    pub const DLL_PREFIX: &str = "";
+    pub const DLL_SUFFIX: &str = ".dll";
+    pub const DLL_EXTENSION: &str = "dll";
+    pub const EXE_SUFFIX: &str = ".exe";
+    pub const EXE_EXTENSION: &str = "exe";
+}
+
+#[cfg(target_os = "zkvm")]
+pub mod os {
+    pub const FAMILY: &str = "";
+    pub const OS: &str = "";
+    pub const DLL_PREFIX: &str = "";
+    pub const DLL_SUFFIX: &str = ".elf";
+    pub const DLL_EXTENSION: &str = "elf";
+    pub const EXE_SUFFIX: &str = ".elf";
+    pub const EXE_EXTENSION: &str = "elf";
+}
+
+// The fallback when none of the other gates match.
+#[else]
+pub mod os {
+    pub const FAMILY: &str = "";
+    pub const OS: &str = "";
+    pub const DLL_PREFIX: &str = "";
+    pub const DLL_SUFFIX: &str = "";
+    pub const DLL_EXTENSION: &str = "";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
+}

crates/std/src/sys/exit.rs

@@ -0,0 +1,143 @@
+cfg_select! {
+    target_os = "linux" => {
+        /// Mitigation for <https://github.com/rust-lang/rust/issues/126600>
+        ///
+        /// On glibc, `libc::exit` has been observed to not always be thread-safe.
+        /// It is currently unclear whether that is a glibc bug or allowed by the standard.
+        /// To mitigate this problem, we ensure that only one
+        /// Rust thread calls `libc::exit` (or returns from `main`) by calling this function before
+        /// calling `libc::exit` (or returning from `main`).
+        ///
+        /// Technically, this is not enough to ensure soundness, since other code directly calling
+        /// `libc::exit` will still race with this.
+        ///
+        /// *This function does not itself call `libc::exit`.* This is so it can also be used
+        /// to guard returning from `main`.
+        ///
+        /// This function will return only the first time it is called in a process.
+        ///
+        /// * If it is called again on the same thread as the first call, it will abort.
+        /// * If it is called again on a different thread, it will wait in a loop
+        ///   (waiting for the process to exit).
+        pub fn unique_thread_exit() {
+            use crate::ffi::c_int;
+            use crate::ptr;
+            use crate::sync::atomic::AtomicPtr;
+            use crate::sync::atomic::Ordering::{Acquire, Relaxed};
+
+            static EXITING_THREAD_ID: AtomicPtr<c_int> = AtomicPtr::new(ptr::null_mut());
+
+            // We use the address of `errno` as a cheap and safe way to identify
+            // threads. As the C standard mandates that `errno` must have thread
+            // storage duration, we can rely on its address not changing over the
+            // lifetime of the thread. Additionally, accesses to `errno` are
+            // async-signal-safe, so this function is available in all imaginable
+            // circumstances.
+            let this_thread_id = crate::sys::io::errno_location();
+            match EXITING_THREAD_ID.compare_exchange(ptr::null_mut(), this_thread_id, Acquire, Relaxed) {
+                Ok(_) => {
+                    // This is the first thread to call `unique_thread_exit`,
+                    // and this is the first time it is called. Continue exiting.
+                }
+                Err(exiting_thread_id) if exiting_thread_id == this_thread_id => {
+                    // This is the first thread to call `unique_thread_exit`,
+                    // but this is the second time it is called.
+                    // Abort the process.
+                    core::panicking::panic_nounwind("std::process::exit called re-entrantly")
+                }
+                Err(_) => {
+                    // This is not the first thread to call `unique_thread_exit`.
+                    // Pause until the process exits.
+                    loop {
+                        // Safety: libc::pause is safe to call.
+                        unsafe { libc::pause(); }
+                    }
+                }
+            }
+        }
+    }
+    _ => {
+        /// Mitigation for <https://github.com/rust-lang/rust/issues/126600>
+        ///
+        /// Mitigation is ***NOT*** implemented on this platform, either because this platform
+        /// is not affected, or because mitigation is not yet implemented for this platform.
+        #[cfg_attr(any(test, doctest), expect(dead_code))]
+        pub fn unique_thread_exit() {
+            // Mitigation not required on platforms where `exit` is thread-safe.
+        }
+    }
+}
+
+pub fn exit(code: i32) -> ! {
+    cfg_select! {
+        target_os = "hermit" => {
+            unsafe { hermit_abi::exit(code) }
+        }
+        target_os = "linux" => {
+            unsafe {
+                unique_thread_exit();
+                libc::exit(code)
+            }
+        }
+        target_os = "motor" => {
+            moto_rt::process::exit(code)
+        }
+        all(target_vendor = "fortanix", target_env = "sgx") => {
+            crate::sys::pal::abi::exit_with_code(code as _)
+        }
+        target_os = "solid_asp3" => {
+            rtabort!("exit({}) called", code)
+        }
+        target_os = "teeos" => {
+            let _ = code;
+            panic!("TA should not call `exit`")
+        }
+        target_os = "uefi" => {
+            use r_efi::base::Status;
+
+            use crate::os::uefi::env;
+
+            if let (Some(boot_services), Some(handle)) =
+                (env::boot_services(), env::try_image_handle())
+            {
+                let boot_services = boot_services.cast::<r_efi::efi::BootServices>();
+                let _ = unsafe {
+                    ((*boot_services.as_ptr()).exit)(
+                        handle.as_ptr(),
+                        Status::from_usize(code as usize),
+                        0,
+                        crate::ptr::null_mut(),
+                    )
+                };
+            }
+            crate::intrinsics::abort()
+        }
+        any(
+            target_family = "unix",
+            target_os = "wasi",
+        ) => {
+            unsafe { libc::exit(code as crate::ffi::c_int) }
+        }
+        target_os = "vexos" => {
+            let _ = code;
+
+            unsafe {
+                vex_sdk::vexSystemExitRequest();
+
+                loop {
+                    vex_sdk::vexTasksRun();
+                }
+            }
+        }
+        target_os = "windows" => {
+            unsafe { crate::sys::pal::c::ExitProcess(code as u32) }
+        }
+        target_os = "xous" => {
+            crate::os::xous::ffi::exit(code as u32)
+        }
+        _ => {
+            let _ = code;
+            crate::intrinsics::abort()
+        }
+    }
+}

crates/std/src/sys/fs/common.rs

@@ -0,0 +1,81 @@
+#![allow(dead_code)] // not used on all platforms
+
+use crate::io::{self, Error, ErrorKind};
+use crate::path::{Path, PathBuf};
+use crate::sys::fs::{File, OpenOptions};
+use crate::sys::helpers::ignore_notfound;
+use crate::{fmt, fs};
+
+pub(crate) const NOT_FILE_ERROR: Error = io::const_error!(
+    ErrorKind::InvalidInput,
+    "the source path is neither a regular file nor a symlink to a regular file",
+);
+
+pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
+    let mut reader = fs::File::open(from)?;
+    let metadata = reader.metadata()?;
+
+    if !metadata.is_file() {
+        return Err(NOT_FILE_ERROR);
+    }
+
+    let mut writer = fs::File::create(to)?;
+    let perm = metadata.permissions();
+
+    let ret = io::copy(&mut reader, &mut writer)?;
+    writer.set_permissions(perm)?;
+    Ok(ret)
+}
+
+pub fn remove_dir_all(path: &Path) -> io::Result<()> {
+    let filetype = fs::symlink_metadata(path)?.file_type();
+    if filetype.is_symlink() { fs::remove_file(path) } else { remove_dir_all_recursive(path) }
+}
+
+fn remove_dir_all_recursive(path: &Path) -> io::Result<()> {
+    for child in fs::read_dir(path)? {
+        let result: io::Result<()> = try {
+            let child = child?;
+            if child.file_type()?.is_dir() {
+                remove_dir_all_recursive(&child.path())?;
+            } else {
+                fs::remove_file(&child.path())?;
+            }
+        };
+        // ignore internal NotFound errors to prevent race conditions
+        if let Err(err) = &result
+            && err.kind() != io::ErrorKind::NotFound
+        {
+            return result;
+        }
+    }
+    ignore_notfound(fs::remove_dir(path))
+}
+
+pub fn exists(path: &Path) -> io::Result<bool> {
+    match fs::metadata(path) {
+        Ok(_) => Ok(true),
+        Err(error) if error.kind() == io::ErrorKind::NotFound => Ok(false),
+        Err(error) => Err(error),
+    }
+}
+
+pub struct Dir {
+    path: PathBuf,
+}
+
+impl Dir {
+    pub fn open(path: &Path, _opts: &OpenOptions) -> io::Result<Self> {
+        path.canonicalize().map(|path| Self { path })
+    }
+
+    pub fn open_file(&self, path: &Path, opts: &OpenOptions) -> io::Result<File> {
+        File::open(&self.path.join(path), &opts)
+    }
+}
+
+impl fmt::Debug for Dir {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Dir").field("path", &self.path).finish()
+    }
+}

crates/std/src/sys/fs/mod.rs

@@ -0,0 +1,173 @@
+#![deny(unsafe_op_in_unsafe_fn)]
+
+use crate::io;
+use crate::path::{Path, PathBuf};
+
+pub mod common;
+
+cfg_select! {
+    any(target_family = "unix", target_os = "wasi") => {
+        mod unix;
+        use unix as imp;
+        #[cfg(not(target_os = "wasi"))]
+        pub use unix::{chown, fchown, lchown, mkfifo};
+        #[cfg(not(any(target_os = "fuchsia", target_os = "wasi")))]
+        pub use unix::chroot;
+        #[cfg(not(target_os = "wasi"))]
+        pub(crate) use unix::debug_assert_fd_is_open;
+        #[cfg(any(target_os = "linux", target_os = "android"))]
+        pub(super) use unix::CachedFileMetadata;
+        use crate::sys::helpers::run_path_with_cstr as with_native_path;
+    }
+    target_os = "windows" => {
+        mod windows;
+        use windows as imp;
+        pub use windows::{symlink_inner, junction_point};
+        use crate::sys::path::with_native_path;
+    }
+    target_os = "hermit" => {
+        mod hermit;
+        use hermit as imp;
+    }
+    target_os = "motor" => {
+        mod motor;
+        use motor as imp;
+    }
+    target_os = "solid_asp3" => {
+        mod solid;
+        use solid as imp;
+    }
+    target_os = "uefi" => {
+        mod uefi;
+        use uefi as imp;
+    }
+    target_os = "vexos" => {
+        mod vexos;
+        use vexos as imp;
+    }
+    _ => {
+        mod unsupported;
+        use unsupported as imp;
+    }
+}
+
+// FIXME: Replace this with platform-specific path conversion functions.
+#[cfg(not(any(target_family = "unix", target_os = "windows", target_os = "wasi")))]
+#[inline]
+pub fn with_native_path<T>(path: &Path, f: &dyn Fn(&Path) -> io::Result<T>) -> io::Result<T> {
+    f(path)
+}
+
+pub use imp::{
+    Dir, DirBuilder, DirEntry, File, FileAttr, FilePermissions, FileTimes, FileType, OpenOptions,
+    ReadDir,
+};
+
+pub fn read_dir(path: &Path) -> io::Result<ReadDir> {
+    // FIXME: use with_native_path on all platforms
+    imp::readdir(path)
+}
+
+pub fn remove_file(path: &Path) -> io::Result<()> {
+    with_native_path(path, &imp::unlink)
+}
+
+pub fn rename(old: &Path, new: &Path) -> io::Result<()> {
+    with_native_path(old, &|old| with_native_path(new, &|new| imp::rename(old, new)))
+}
+
+pub fn remove_dir(path: &Path) -> io::Result<()> {
+    with_native_path(path, &imp::rmdir)
+}
+
+pub fn remove_dir_all(path: &Path) -> io::Result<()> {
+    // FIXME: use with_native_path on all platforms
+    #[cfg(not(windows))]
+    return imp::remove_dir_all(path);
+    #[cfg(windows)]
+    with_native_path(path, &imp::remove_dir_all)
+}
+
+pub fn read_link(path: &Path) -> io::Result<PathBuf> {
+    with_native_path(path, &imp::readlink)
+}
+
+pub fn symlink(original: &Path, link: &Path) -> io::Result<()> {
+    // FIXME: use with_native_path on all platforms
+    #[cfg(windows)]
+    return imp::symlink(original, link);
+    #[cfg(not(windows))]
+    with_native_path(original, &|original| {
+        with_native_path(link, &|link| imp::symlink(original, link))
+    })
+}
+
+pub fn hard_link(original: &Path, link: &Path) -> io::Result<()> {
+    with_native_path(original, &|original| {
+        with_native_path(link, &|link| imp::link(original, link))
+    })
+}
+
+pub fn metadata(path: &Path) -> io::Result<FileAttr> {
+    with_native_path(path, &imp::stat)
+}
+
+pub fn symlink_metadata(path: &Path) -> io::Result<FileAttr> {
+    with_native_path(path, &imp::lstat)
+}
+
+pub fn set_permissions(path: &Path, perm: FilePermissions) -> io::Result<()> {
+    with_native_path(path, &|path| imp::set_perm(path, perm.clone()))
+}
+
+#[cfg(all(unix, not(target_os = "vxworks")))]
+pub fn set_permissions_nofollow(path: &Path, perm: crate::fs::Permissions) -> io::Result<()> {
+    use crate::fs::OpenOptions;
+
+    let mut options = OpenOptions::new();
+
+    // ESP-IDF and Horizon do not support O_NOFOLLOW, so we skip setting it.
+    // Their filesystems do not have symbolic links, so no special handling is required.
+    #[cfg(not(any(target_os = "espidf", target_os = "horizon")))]
+    {
+        use crate::os::unix::fs::OpenOptionsExt;
+        options.custom_flags(libc::O_NOFOLLOW);
+    }
+
+    options.open(path)?.set_permissions(perm)
+}
+
+#[cfg(any(not(unix), target_os = "vxworks"))]
+pub fn set_permissions_nofollow(_path: &Path, _perm: crate::fs::Permissions) -> io::Result<()> {
+    crate::unimplemented!(
+        "`set_permissions_nofollow` is currently only implemented on Unix platforms"
+    )
+}
+
+pub fn canonicalize(path: &Path) -> io::Result<PathBuf> {
+    with_native_path(path, &imp::canonicalize)
+}
+
+pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
+    // FIXME: use with_native_path on all platforms
+    #[cfg(not(windows))]
+    return imp::copy(from, to);
+    #[cfg(windows)]
+    with_native_path(from, &|from| with_native_path(to, &|to| imp::copy(from, to)))
+}
+
+pub fn exists(path: &Path) -> io::Result<bool> {
+    // FIXME: use with_native_path on all platforms
+    #[cfg(not(windows))]
+    return imp::exists(path);
+    #[cfg(windows)]
+    with_native_path(path, &imp::exists)
+}
+
+pub fn set_times(path: &Path, times: FileTimes) -> io::Result<()> {
+    with_native_path(path, &|path| imp::set_times(path, times.clone()))
+}
+
+pub fn set_times_nofollow(path: &Path, times: FileTimes) -> io::Result<()> {
+    with_native_path(path, &|path| imp::set_times_nofollow(path, times.clone()))
+}

crates/std/src/sys/fs/unsupported.rs

@@ -0,0 +1,362 @@
+use crate::ffi::OsString;
+use crate::fmt;
+use crate::fs::TryLockError;
+use crate::hash::{Hash, Hasher};
+use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut, SeekFrom};
+use crate::path::{Path, PathBuf};
+pub use crate::sys::fs::common::Dir;
+use crate::sys::time::SystemTime;
+use crate::sys::unsupported;
+
+pub struct File(!);
+
+pub struct FileAttr(!);
+
+pub struct ReadDir(!);
+
+pub struct DirEntry(!);
+
+#[derive(Clone, Debug)]
+pub struct OpenOptions {}
+
+#[derive(Copy, Clone, Debug, Default)]
+pub struct FileTimes {}
+
+pub struct FilePermissions(!);
+
+pub struct FileType(!);
+
+#[derive(Debug)]
+pub struct DirBuilder {}
+
+impl FileAttr {
+    pub fn size(&self) -> u64 {
+        self.0
+    }
+
+    pub fn perm(&self) -> FilePermissions {
+        self.0
+    }
+
+    pub fn file_type(&self) -> FileType {
+        self.0
+    }
+
+    pub fn modified(&self) -> io::Result<SystemTime> {
+        self.0
+    }
+
+    pub fn accessed(&self) -> io::Result<SystemTime> {
+        self.0
+    }
+
+    pub fn created(&self) -> io::Result<SystemTime> {
+        self.0
+    }
+}
+
+impl Clone for FileAttr {
+    fn clone(&self) -> FileAttr {
+        self.0
+    }
+}
+
+impl FilePermissions {
+    pub fn readonly(&self) -> bool {
+        self.0
+    }
+
+    pub fn set_readonly(&mut self, _readonly: bool) {
+        self.0
+    }
+}
+
+impl Clone for FilePermissions {
+    fn clone(&self) -> FilePermissions {
+        self.0
+    }
+}
+
+impl PartialEq for FilePermissions {
+    fn eq(&self, _other: &FilePermissions) -> bool {
+        self.0
+    }
+}
+
+impl Eq for FilePermissions {}
+
+impl fmt::Debug for FilePermissions {
+    fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0
+    }
+}
+
+impl FileTimes {
+    pub fn set_accessed(&mut self, _t: SystemTime) {}
+    pub fn set_modified(&mut self, _t: SystemTime) {}
+}
+
+impl FileType {
+    pub fn is_dir(&self) -> bool {
+        self.0
+    }
+
+    pub fn is_file(&self) -> bool {
+        self.0
+    }
+
+    pub fn is_symlink(&self) -> bool {
+        self.0
+    }
+}
+
+impl Clone for FileType {
+    fn clone(&self) -> FileType {
+        self.0
+    }
+}
+
+impl Copy for FileType {}
+
+impl PartialEq for FileType {
+    fn eq(&self, _other: &FileType) -> bool {
+        self.0
+    }
+}
+
+impl Eq for FileType {}
+
+impl Hash for FileType {
+    fn hash<H: Hasher>(&self, _h: &mut H) {
+        self.0
+    }
+}
+
+impl fmt::Debug for FileType {
+    fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0
+    }
+}
+
+impl fmt::Debug for ReadDir {
+    fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0
+    }
+}
+
+impl Iterator for ReadDir {
+    type Item = io::Result<DirEntry>;
+
+    fn next(&mut self) -> Option<io::Result<DirEntry>> {
+        self.0
+    }
+}
+
+impl DirEntry {
+    pub fn path(&self) -> PathBuf {
+        self.0
+    }
+
+    pub fn file_name(&self) -> OsString {
+        self.0
+    }
+
+    pub fn metadata(&self) -> io::Result<FileAttr> {
+        self.0
+    }
+
+    pub fn file_type(&self) -> io::Result<FileType> {
+        self.0
+    }
+}
+
+impl OpenOptions {
+    pub fn new() -> OpenOptions {
+        OpenOptions {}
+    }
+
+    pub fn read(&mut self, _read: bool) {}
+    pub fn write(&mut self, _write: bool) {}
+    pub fn append(&mut self, _append: bool) {}
+    pub fn truncate(&mut self, _truncate: bool) {}
+    pub fn create(&mut self, _create: bool) {}
+    pub fn create_new(&mut self, _create_new: bool) {}
+}
+
+impl File {
+    pub fn open(_path: &Path, _opts: &OpenOptions) -> io::Result<File> {
+        unsupported()
+    }
+
+    pub fn file_attr(&self) -> io::Result<FileAttr> {
+        self.0
+    }
+
+    pub fn fsync(&self) -> io::Result<()> {
+        self.0
+    }
+
+    pub fn datasync(&self) -> io::Result<()> {
+        self.0
+    }
+
+    pub fn lock(&self) -> io::Result<()> {
+        self.0
+    }
+
+    pub fn lock_shared(&self) -> io::Result<()> {
+        self.0
+    }
+
+    pub fn try_lock(&self) -> Result<(), TryLockError> {
+        self.0
+    }
+
+    pub fn try_lock_shared(&self) -> Result<(), TryLockError> {
+        self.0
+    }
+
+    pub fn unlock(&self) -> io::Result<()> {
+        self.0
+    }
+
+    pub fn truncate(&self, _size: u64) -> io::Result<()> {
+        self.0
+    }
+
+    pub fn read(&self, _buf: &mut [u8]) -> io::Result<usize> {
+        self.0
+    }
+
+    pub fn read_vectored(&self, _bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
+        self.0
+    }
+
+    pub fn is_read_vectored(&self) -> bool {
+        self.0
+    }
+
+    pub fn read_buf(&self, _cursor: BorrowedCursor<'_>) -> io::Result<()> {
+        self.0
+    }
+
+    pub fn write(&self, _buf: &[u8]) -> io::Result<usize> {
+        self.0
+    }
+
+    pub fn write_vectored(&self, _bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        self.0
+    }
+
+    pub fn is_write_vectored(&self) -> bool {
+        self.0
+    }
+
+    pub fn flush(&self) -> io::Result<()> {
+        self.0
+    }
+
+    pub fn seek(&self, _pos: SeekFrom) -> io::Result<u64> {
+        self.0
+    }
+
+    pub fn size(&self) -> Option<io::Result<u64>> {
+        self.0
+    }
+
+    pub fn tell(&self) -> io::Result<u64> {
+        self.0
+    }
+
+    pub fn duplicate(&self) -> io::Result<File> {
+        self.0
+    }
+
+    pub fn set_permissions(&self, _perm: FilePermissions) -> io::Result<()> {
+        self.0
+    }
+
+    pub fn set_times(&self, _times: FileTimes) -> io::Result<()> {
+        self.0
+    }
+}
+
+impl DirBuilder {
+    pub fn new() -> DirBuilder {
+        DirBuilder {}
+    }
+
+    pub fn mkdir(&self, _p: &Path) -> io::Result<()> {
+        unsupported()
+    }
+}
+
+impl fmt::Debug for File {
+    fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0
+    }
+}
+
+pub fn readdir(_p: &Path) -> io::Result<ReadDir> {
+    unsupported()
+}
+
+pub fn unlink(_p: &Path) -> io::Result<()> {
+    unsupported()
+}
+
+pub fn rename(_old: &Path, _new: &Path) -> io::Result<()> {
+    unsupported()
+}
+
+pub fn set_perm(_p: &Path, perm: FilePermissions) -> io::Result<()> {
+    match perm.0 {}
+}
+
+pub fn set_times(_p: &Path, _times: FileTimes) -> io::Result<()> {
+    unsupported()
+}
+
+pub fn set_times_nofollow(_p: &Path, _times: FileTimes) -> io::Result<()> {
+    unsupported()
+}
+
+pub fn rmdir(_p: &Path) -> io::Result<()> {
+    unsupported()
+}
+
+pub fn remove_dir_all(_path: &Path) -> io::Result<()> {
+    unsupported()
+}
+
+pub fn exists(_path: &Path) -> io::Result<bool> {
+    unsupported()
+}
+
+pub fn readlink(_p: &Path) -> io::Result<PathBuf> {
+    unsupported()
+}
+
+pub fn symlink(_original: &Path, _link: &Path) -> io::Result<()> {
+    unsupported()
+}
+
+pub fn link(_src: &Path, _dst: &Path) -> io::Result<()> {
+    unsupported()
+}
+
+pub fn stat(_p: &Path) -> io::Result<FileAttr> {
+    unsupported()
+}
+
+pub fn lstat(_p: &Path) -> io::Result<FileAttr> {
+    unsupported()
+}
+
+pub fn canonicalize(_p: &Path) -> io::Result<PathBuf> {
+    unsupported()
+}
+
+pub fn copy(_from: &Path, _to: &Path) -> io::Result<u64> {
+    unsupported()
+}

crates/std/src/sys/mod.rs

@@ -0,0 +1,36 @@
+pub mod cmath;
+pub mod configure_builtins;
+pub mod env;
+pub mod env_consts;
+pub mod exit;
+pub mod os_str;
+pub mod path;
+pub mod sync;
+pub mod thread;
+pub mod time;
+pub mod random;
+pub mod thread_local;
+pub mod alloc;
+// pub mod fs;
+
+/// A trait for viewing representations from std types.
+#[cfg_attr(not(target_os = "linux"), allow(unused))]
+pub(crate) trait AsInner<Inner: ?Sized> {
+    fn as_inner(&self) -> &Inner;
+}
+
+/// A trait for viewing representations from std types.
+#[cfg_attr(not(target_os = "linux"), allow(unused))]
+pub(crate) trait AsInnerMut<Inner: ?Sized> {
+    fn as_inner_mut(&mut self) -> &mut Inner;
+}
+
+/// A trait for extracting representations from std types.
+pub(crate) trait IntoInner<Inner> {
+    fn into_inner(self) -> Inner;
+}
+
+/// A trait for creating std types from internal representations.
+pub(crate) trait FromInner<Inner> {
+    fn from_inner(inner: Inner) -> Self;
+}

crates/std/src/sys/os_str/bytes.rs

@@ -0,0 +1,363 @@
+//! The underlying OsString/OsStr implementation on Unix and many other
+//! systems: just a `Vec<u8>`/`[u8]`.
+
+use core::clone::CloneToUninit;
+
+use crate::borrow::Cow;
+use alloc_crate::bstr::ByteStr;
+use alloc_crate::collections::TryReserveError;
+use crate::rc::Rc;
+use alloc_crate::sync::Arc;
+use crate::sys::{AsInner, FromInner, IntoInner};
+use crate::{fmt, mem, str};
+
+#[cfg(test)]
+mod tests;
+
+#[derive(Hash)]
+#[repr(transparent)]
+pub struct Buf {
+    pub inner: Vec<u8>,
+}
+
+#[repr(transparent)]
+pub struct Slice {
+    pub inner: [u8],
+}
+
+impl IntoInner<Vec<u8>> for Buf {
+    fn into_inner(self) -> Vec<u8> {
+        self.inner
+    }
+}
+
+impl FromInner<Vec<u8>> for Buf {
+    fn from_inner(inner: Vec<u8>) -> Self {
+        Buf { inner }
+    }
+}
+
+impl AsInner<[u8]> for Buf {
+    #[inline]
+    fn as_inner(&self) -> &[u8] {
+        &self.inner
+    }
+}
+
+impl fmt::Debug for Buf {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(self.as_slice(), f)
+    }
+}
+
+impl fmt::Display for Buf {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(self.as_slice(), f)
+    }
+}
+
+impl fmt::Debug for Slice {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&self.inner.utf8_chunks().debug(), f)
+    }
+}
+
+impl fmt::Display for Slice {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(ByteStr::new(&self.inner), f)
+    }
+}
+
+impl Clone for Buf {
+    #[inline]
+    fn clone(&self) -> Self {
+        Buf { inner: self.inner.clone() }
+    }
+
+    #[inline]
+    fn clone_from(&mut self, source: &Self) {
+        self.inner.clone_from(&source.inner)
+    }
+}
+
+impl Buf {
+    #[inline]
+    pub fn into_encoded_bytes(self) -> Vec<u8> {
+        self.inner
+    }
+
+    #[inline]
+    pub unsafe fn from_encoded_bytes_unchecked(s: Vec<u8>) -> Self {
+        Self { inner: s }
+    }
+
+    #[inline]
+    pub fn into_string(self) -> Result<String, Buf> {
+        String::from_utf8(self.inner).map_err(|p| Buf { inner: p.into_bytes() })
+    }
+
+    #[inline]
+    pub const fn from_string(s: String) -> Buf {
+        Buf { inner: s.into_bytes() }
+    }
+
+    #[inline]
+    pub fn with_capacity(capacity: usize) -> Buf {
+        Buf { inner: Vec::with_capacity(capacity) }
+    }
+
+    #[inline]
+    pub fn clear(&mut self) {
+        self.inner.clear()
+    }
+
+    #[inline]
+    pub fn capacity(&self) -> usize {
+        self.inner.capacity()
+    }
+
+    #[inline]
+    pub fn push_slice(&mut self, s: &Slice) {
+        self.inner.extend_from_slice(&s.inner)
+    }
+
+    #[inline]
+    pub fn push_str(&mut self, s: &str) {
+        self.inner.extend_from_slice(s.as_bytes());
+    }
+
+    #[inline]
+    pub fn reserve(&mut self, additional: usize) {
+        self.inner.reserve(additional)
+    }
+
+    #[inline]
+    pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> {
+        self.inner.try_reserve(additional)
+    }
+
+    #[inline]
+    pub fn reserve_exact(&mut self, additional: usize) {
+        self.inner.reserve_exact(additional)
+    }
+
+    #[inline]
+    pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), TryReserveError> {
+        self.inner.try_reserve_exact(additional)
+    }
+
+    #[inline]
+    pub fn shrink_to_fit(&mut self) {
+        self.inner.shrink_to_fit()
+    }
+
+    #[inline]
+    pub fn shrink_to(&mut self, min_capacity: usize) {
+        self.inner.shrink_to(min_capacity)
+    }
+
+    #[inline]
+    pub fn as_slice(&self) -> &Slice {
+        // SAFETY: Slice is just a wrapper for [u8],
+        // and self.inner.as_slice() returns &[u8].
+        // Therefore, transmuting &[u8] to &Slice is safe.
+        unsafe { mem::transmute(self.inner.as_slice()) }
+    }
+
+    #[inline]
+    pub fn as_mut_slice(&mut self) -> &mut Slice {
+        // SAFETY: Slice is just a wrapper for [u8],
+        // and self.inner.as_mut_slice() returns &mut [u8].
+        // Therefore, transmuting &mut [u8] to &mut Slice is safe.
+        unsafe { mem::transmute(self.inner.as_mut_slice()) }
+    }
+
+    #[inline]
+    pub fn leak<'a>(self) -> &'a mut Slice {
+        unsafe { mem::transmute(self.inner.leak()) }
+    }
+
+    #[inline]
+    pub fn into_box(self) -> Box<Slice> {
+        unsafe { mem::transmute(self.inner.into_boxed_slice()) }
+    }
+
+    #[inline]
+    pub fn from_box(boxed: Box<Slice>) -> Buf {
+        let inner: Box<[u8]> = unsafe { mem::transmute(boxed) };
+        Buf { inner: inner.into_vec() }
+    }
+
+    #[inline]
+    pub fn into_arc(&self) -> Arc<Slice> {
+        self.as_slice().into_arc()
+    }
+
+    #[inline]
+    pub fn into_rc(&self) -> Rc<Slice> {
+        self.as_slice().into_rc()
+    }
+
+    /// Provides plumbing to `Vec::truncate` without giving full mutable access
+    /// to the `Vec`.
+    ///
+    /// # Safety
+    ///
+    /// The length must be at an `OsStr` boundary, according to
+    /// `Slice::check_public_boundary`.
+    #[inline]
+    pub unsafe fn truncate_unchecked(&mut self, len: usize) {
+        self.inner.truncate(len);
+    }
+
+    /// Provides plumbing to `Vec::extend_from_slice` without giving full
+    /// mutable access to the `Vec`.
+    ///
+    /// # Safety
+    ///
+    /// The slice must be valid for the platform encoding (as described in
+    /// `OsStr::from_encoded_bytes_unchecked`). This encoding has no safety
+    /// requirements.
+    #[inline]
+    pub unsafe fn extend_from_slice_unchecked(&mut self, other: &[u8]) {
+        self.inner.extend_from_slice(other);
+    }
+}
+
+impl Slice {
+    #[inline]
+    pub fn as_encoded_bytes(&self) -> &[u8] {
+        &self.inner
+    }
+
+    #[inline]
+    pub unsafe fn from_encoded_bytes_unchecked(s: &[u8]) -> &Slice {
+        unsafe { mem::transmute(s) }
+    }
+
+    #[track_caller]
+    #[inline]
+    pub fn check_public_boundary(&self, index: usize) {
+        if index == 0 || index == self.inner.len() {
+            return;
+        }
+        if index < self.inner.len()
+            && (self.inner[index - 1].is_ascii() || self.inner[index].is_ascii())
+        {
+            return;
+        }
+
+        slow_path(&self.inner, index);
+
+        /// We're betting that typical splits will involve an ASCII character.
+        ///
+        /// Putting the expensive checks in a separate function generates notably
+        /// better assembly.
+        #[track_caller]
+        #[inline(never)]
+        fn slow_path(bytes: &[u8], index: usize) {
+            let (before, after) = bytes.split_at(index);
+
+            // UTF-8 takes at most 4 bytes per codepoint, so we don't
+            // need to check more than that.
+            let after = after.get(..4).unwrap_or(after);
+            match str::from_utf8(after) {
+                Ok(_) => return,
+                Err(err) if err.valid_up_to() != 0 => return,
+                Err(_) => (),
+            }
+
+            for len in 2..=4.min(index) {
+                let before = &before[index - len..];
+                if str::from_utf8(before).is_ok() {
+                    return;
+                }
+            }
+
+            panic!("byte index {index} is not an OsStr boundary");
+        }
+    }
+
+    #[inline]
+    pub fn from_str(s: &str) -> &Slice {
+        unsafe { Slice::from_encoded_bytes_unchecked(s.as_bytes()) }
+    }
+
+    #[inline]
+    pub fn to_str(&self) -> Result<&str, crate::str::Utf8Error> {
+        str::from_utf8(&self.inner)
+    }
+
+    #[inline]
+    pub fn to_string_lossy(&self) -> Cow<'_, str> {
+        String::from_utf8_lossy(&self.inner)
+    }
+
+    #[inline]
+    pub fn to_owned(&self) -> Buf {
+        Buf { inner: self.inner.to_vec() }
+    }
+
+    #[inline]
+    pub fn clone_into(&self, buf: &mut Buf) {
+        self.inner.clone_into(&mut buf.inner)
+    }
+
+    #[inline]
+    pub fn empty_box() -> Box<Slice> {
+        let boxed: Box<[u8]> = Default::default();
+        unsafe { mem::transmute(boxed) }
+    }
+
+    #[inline]
+    pub fn into_arc(&self) -> Arc<Slice> {
+        let arc: Arc<[u8]> = Arc::from(&self.inner);
+        unsafe { Arc::from_raw(Arc::into_raw(arc) as *const Slice) }
+    }
+
+    #[inline]
+    pub fn into_rc(&self) -> Rc<Slice> {
+        let rc: Rc<[u8]> = Rc::from(&self.inner);
+        unsafe { Rc::from_raw(Rc::into_raw(rc) as *const Slice) }
+    }
+
+    #[inline]
+    pub fn make_ascii_lowercase(&mut self) {
+        self.inner.make_ascii_lowercase()
+    }
+
+    #[inline]
+    pub fn make_ascii_uppercase(&mut self) {
+        self.inner.make_ascii_uppercase()
+    }
+
+    #[inline]
+    pub fn to_ascii_lowercase(&self) -> Buf {
+        Buf { inner: self.inner.to_ascii_lowercase() }
+    }
+
+    #[inline]
+    pub fn to_ascii_uppercase(&self) -> Buf {
+        Buf { inner: self.inner.to_ascii_uppercase() }
+    }
+
+    #[inline]
+    pub fn is_ascii(&self) -> bool {
+        self.inner.is_ascii()
+    }
+
+    #[inline]
+    pub fn eq_ignore_ascii_case(&self, other: &Self) -> bool {
+        self.inner.eq_ignore_ascii_case(&other.inner)
+    }
+}
+
+#[unstable(feature = "clone_to_uninit", issue = "126799")]
+unsafe impl CloneToUninit for Slice {
+    #[inline]
+    #[cfg_attr(debug_assertions, track_caller)]
+    unsafe fn clone_to_uninit(&self, dst: *mut u8) {
+        // SAFETY: we're just a transparent wrapper around [u8]
+        unsafe { self.inner.clone_to_uninit(dst) }
+    }
+}

crates/std/src/sys/os_str/bytes/tests.rs

@@ -0,0 +1,17 @@
+use super::*;
+
+#[test]
+fn slice_debug_output() {
+    let input = unsafe { Slice::from_encoded_bytes_unchecked(b"\xF0hello,\tworld") };
+    let expected = r#""\xF0hello,\tworld""#;
+    let output = format!("{input:?}");
+
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn display() {
+    assert_eq!("Hello\u{FFFD}\u{FFFD} There\u{FFFD} Goodbye", unsafe {
+        Slice::from_encoded_bytes_unchecked(b"Hello\xC0\x80 There\xE6\x83 Goodbye").to_string()
+    },);
+}

crates/std/src/sys/os_str/mod.rs

@@ -0,0 +1,16 @@
+#![forbid(unsafe_op_in_unsafe_fn)]
+
+cfg_select! {
+    any(target_os = "windows", target_os = "uefi") => {
+        mod wtf8;
+        pub use wtf8::{Buf, Slice};
+    }
+    any(target_os = "motor") => {
+        mod utf8;
+        pub use utf8::{Buf, Slice};
+    }
+    _ => {
+        mod bytes;
+        pub use bytes::{Buf, Slice};
+    }
+}

crates/std/src/sys/path/mod.rs

@@ -0,0 +1,28 @@
+cfg_select! {
+    target_os = "windows" => {
+        mod windows;
+        mod windows_prefix;
+        pub use windows::*;
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
+        mod sgx;
+        pub use sgx::*;
+    }
+    target_os = "solid_asp3" => {
+        mod unsupported_backslash;
+        pub use unsupported_backslash::*;
+    }
+    target_os = "uefi" => {
+        mod uefi;
+        pub use uefi::*;
+    }
+    target_os = "cygwin" => {
+        mod cygwin;
+        mod windows_prefix;
+        pub use cygwin::*;
+    }
+    _ => {
+        mod unix;
+        pub use unix::*;
+    }
+}

crates/std/src/sys/path/unix.rs

@@ -0,0 +1,72 @@
+use crate::ffi::OsStr;
+use crate::path::{Path, PathBuf, Prefix};
+use crate::{env, io};
+
+#[inline]
+pub fn is_sep_byte(b: u8) -> bool {
+    b == b'/'
+}
+
+#[inline]
+pub fn is_verbatim_sep(b: u8) -> bool {
+    b == b'/'
+}
+
+#[inline]
+pub fn parse_prefix(_: &OsStr) -> Option<Prefix<'_>> {
+    None
+}
+
+pub const HAS_PREFIXES: bool = false;
+pub const MAIN_SEP_STR: &str = "/";
+pub const MAIN_SEP: char = '/';
+
+/// Make a POSIX path absolute without changing its semantics.
+pub(crate) fn absolute(path: &Path) -> io::Result<PathBuf> {
+    // This is mostly a wrapper around collecting `Path::components`, with
+    // exceptions made where this conflicts with the POSIX specification.
+    // See 4.13 Pathname Resolution, IEEE Std 1003.1-2017
+    // https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_13
+
+    // Get the components, skipping the redundant leading "." component if it exists.
+    let mut components = path.strip_prefix(".").unwrap_or(path).components();
+    let path_os = path.as_os_str().as_encoded_bytes();
+
+    let mut normalized = if path.is_absolute() {
+        // "If a pathname begins with two successive <slash> characters, the
+        // first component following the leading <slash> characters may be
+        // interpreted in an implementation-defined manner, although more than
+        // two leading <slash> characters shall be treated as a single <slash>
+        // character."
+        if path_os.starts_with(b"//") && !path_os.starts_with(b"///") {
+            components.next();
+            PathBuf::from("//")
+        } else {
+            PathBuf::new()
+        }
+    } else {
+        // env::current_dir()?
+        todo!()
+    };
+    normalized.extend(components);
+
+    // "Interfaces using pathname resolution may specify additional constraints
+    // when a pathname that does not name an existing directory contains at
+    // least one non- <slash> character and contains one or more trailing
+    // <slash> characters".
+    // A trailing <slash> is also meaningful if "a symbolic link is
+    // encountered during pathname resolution".
+    if path_os.ends_with(b"/") {
+        normalized.push("");
+    }
+
+    Ok(normalized)
+}
+
+pub(crate) fn is_absolute(path: &Path) -> bool {
+    if cfg!(any(unix, target_os = "hermit", target_os = "wasi", target_os = "motor")) {
+        path.has_root()
+    } else {
+        path.has_root() && path.prefix().is_some()
+    }
+}

crates/std/src/sys/random/mod.rs

@@ -0,0 +1,134 @@
+cfg_select! {
+    // Tier 1
+    any(target_os = "linux", target_os = "android") => {
+        mod linux;
+        pub use linux::{fill_bytes, hashmap_random_keys};
+    }
+    target_os = "windows" => {
+        mod windows;
+        pub use windows::fill_bytes;
+    }
+    target_vendor = "apple" => {
+        mod apple;
+        pub use apple::fill_bytes;
+    // Others, in alphabetical ordering.
+    }
+    any(
+        target_os = "dragonfly",
+        target_os = "freebsd",
+        target_os = "haiku",
+        target_os = "illumos",
+        target_os = "netbsd",
+        target_os = "openbsd",
+        target_os = "rtems",
+        target_os = "solaris",
+        target_os = "vita",
+        target_os = "nuttx",
+    ) => {
+        mod arc4random;
+        pub use arc4random::fill_bytes;
+    }
+    target_os = "emscripten" => {
+        mod getentropy;
+        pub use getentropy::fill_bytes;
+    }
+    target_os = "espidf" => {
+        mod espidf;
+        pub use espidf::fill_bytes;
+    }
+    target_os = "fuchsia" => {
+        mod fuchsia;
+        pub use fuchsia::fill_bytes;
+    }
+    target_os = "hermit" => {
+        mod hermit;
+        pub use hermit::fill_bytes;
+    }
+    any(target_os = "horizon", target_os = "cygwin") => {
+        // FIXME(horizon): add arc4random_buf to shim-3ds
+        mod getrandom;
+        pub use getrandom::fill_bytes;
+    }
+    any(
+        target_os = "aix",
+        target_os = "hurd",
+        target_os = "l4re",
+        target_os = "nto",
+    ) => {
+        mod unix_legacy;
+        pub use unix_legacy::fill_bytes;
+    }
+    target_os = "redox" => {
+        mod redox;
+        pub use redox::fill_bytes;
+    }
+    target_os = "motor" => {
+        mod motor;
+        pub use motor::fill_bytes;
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
+        mod sgx;
+        pub use sgx::fill_bytes;
+    }
+    target_os = "solid_asp3" => {
+        mod solid;
+        pub use solid::fill_bytes;
+    }
+    target_os = "teeos" => {
+        mod teeos;
+        pub use teeos::fill_bytes;
+    }
+    target_os = "trusty" => {
+        mod trusty;
+        pub use trusty::fill_bytes;
+    }
+    target_os = "uefi" => {
+        mod uefi;
+        pub use uefi::fill_bytes;
+    }
+    target_os = "vxworks" => {
+        mod vxworks;
+        pub use vxworks::fill_bytes;
+    }
+    all(target_os = "wasi", target_env = "p1") => {
+        mod wasip1;
+        pub use wasip1::fill_bytes;
+    }
+    all(target_os = "wasi", any(target_env = "p2", target_env = "p3")) => {
+        mod wasip2;
+        pub use wasip2::{fill_bytes, hashmap_random_keys};
+    }
+    target_os = "zkvm" => {
+        mod zkvm;
+        pub use zkvm::fill_bytes;
+    }
+    any(
+        all(target_family = "wasm", target_os = "unknown"),
+        target_os = "xous",
+        target_os = "vexos",
+target_os = "survos",
+    ) => {
+        // FIXME: finally remove std support for wasm32-unknown-unknown
+        // FIXME: add random data generation to xous
+        mod unsupported;
+        pub use unsupported::{fill_bytes, hashmap_random_keys};
+    }
+    _ => {}
+}
+
+#[cfg(not(any(
+    target_os = "linux",
+    target_os = "android",
+    all(target_family = "wasm", target_os = "unknown"),
+    all(target_os = "wasi", not(target_env = "p1")),
+    target_os = "xous",
+    target_os = "vexos",
+target_os = "survos",
+)))]
+pub fn hashmap_random_keys() -> (u64, u64) {
+    let mut buf = [0; 16];
+    fill_bytes(&mut buf);
+    let k1 = u64::from_ne_bytes(buf[..8].try_into().unwrap());
+    let k2 = u64::from_ne_bytes(buf[8..].try_into().unwrap());
+    (k1, k2)
+}

crates/std/src/sys/random/unsupported.rs

@@ -0,0 +1,15 @@
+use crate::ptr;
+
+pub fn fill_bytes(_: &mut [u8]) {
+    panic!("this target does not support random data generation");
+}
+
+pub fn hashmap_random_keys() -> (u64, u64) {
+    // Use allocation addresses for a bit of randomness. This isn't
+    // particularly secure, but there isn't really an alternative.
+    let stack = 0u8;
+    let heap = Box::new(0u8);
+    let k1 = ptr::from_ref(&stack).addr() as u64;
+    let k2 = ptr::from_ref(&*heap).addr() as u64;
+    (k1, k2)
+}

crates/std/src/sys/sync/condvar/mod.rs

@@ -0,0 +1,44 @@
+cfg_select! {
+    any(
+        all(target_os = "windows", not(target_vendor="win7")),
+        target_os = "linux",
+        target_os = "android",
+        target_os = "freebsd",
+        target_os = "openbsd",
+        target_os = "dragonfly",
+        target_os = "motor",
+        target_os = "fuchsia",
+        all(target_family = "wasm", target_feature = "atomics"),
+        target_os = "hermit",
+    ) => {
+        mod futex;
+        pub use futex::Condvar;
+    }
+    any(
+        target_family = "unix",
+        target_os = "teeos",
+    ) => {
+        mod pthread;
+        pub use pthread::Condvar;
+    }
+    all(target_os = "windows", target_vendor = "win7") => {
+        mod windows7;
+        pub use windows7::Condvar;
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
+        mod sgx;
+        pub use sgx::Condvar;
+    }
+    target_os = "solid_asp3" => {
+        mod itron;
+        pub use itron::Condvar;
+    }
+    target_os = "xous" => {
+        mod xous;
+        pub use xous::Condvar;
+    }
+    _ => {
+        mod no_threads;
+        pub use no_threads::Condvar;
+    }
+}

crates/std/src/sys/sync/condvar/no_threads.rs

@@ -0,0 +1,27 @@
+use crate::sys::sync::Mutex;
+use crate::thread::sleep;
+use crate::time::Duration;
+
+pub struct Condvar {}
+
+impl Condvar {
+    #[inline]
+    pub const fn new() -> Condvar {
+        Condvar {}
+    }
+
+    #[inline]
+    pub fn notify_one(&self) {}
+
+    #[inline]
+    pub fn notify_all(&self) {}
+
+    pub unsafe fn wait(&self, _mutex: &Mutex) {
+        panic!("condvar wait not supported")
+    }
+
+    pub unsafe fn wait_timeout(&self, _mutex: &Mutex, dur: Duration) -> bool {
+        sleep(dur);
+        false
+    }
+}

crates/std/src/sys/sync/mod.rs

@@ -0,0 +1,9 @@
+mod condvar;
+mod mutex;
+mod once;
+mod rwlock;
+
+pub use condvar::Condvar;
+pub use mutex::Mutex;
+pub use once::{Once, OnceState};
+pub use rwlock::RwLock;

crates/std/src/sys/sync/mutex/mod.rs

@@ -0,0 +1,47 @@
+cfg_select! {
+    any(
+        all(target_os = "windows", not(target_vendor = "win7")),
+        target_os = "linux",
+        target_os = "android",
+        target_os = "freebsd",
+        target_os = "openbsd",
+        target_os = "motor",
+        target_os = "dragonfly",
+        all(target_family = "wasm", target_feature = "atomics"),
+        target_os = "hermit",
+    ) => {
+        mod futex;
+        pub use futex::Mutex;
+    }
+    target_os = "fuchsia" => {
+        mod fuchsia;
+        pub use fuchsia::Mutex;
+    }
+    any(
+        target_family = "unix",
+        target_os = "teeos",
+    ) => {
+        mod pthread;
+        pub use pthread::Mutex;
+    }
+    all(target_os = "windows", target_vendor = "win7") => {
+        mod windows7;
+        pub use windows7::{Mutex, raw};
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
+        mod sgx;
+        pub use sgx::Mutex;
+    }
+    target_os = "solid_asp3" => {
+        mod itron;
+        pub use itron::Mutex;
+    }
+    target_os = "xous" => {
+        mod xous;
+        pub use xous::Mutex;
+    }
+    _ => {
+        mod no_threads;
+        pub use no_threads::Mutex;
+    }
+}

crates/std/src/sys/sync/mutex/no_threads.rs

@@ -0,0 +1,31 @@
+use crate::cell::Cell;
+
+pub struct Mutex {
+    // This platform has no threads, so we can use a Cell here.
+    locked: Cell<bool>,
+}
+
+unsafe impl Send for Mutex {}
+unsafe impl Sync for Mutex {} // no threads on this platform
+
+impl Mutex {
+    #[inline]
+    pub const fn new() -> Mutex {
+        Mutex { locked: Cell::new(false) }
+    }
+
+    #[inline]
+    pub fn lock(&self) {
+        assert_eq!(self.locked.replace(true), false, "cannot recursively acquire mutex");
+    }
+
+    #[inline]
+    pub unsafe fn unlock(&self) {
+        self.locked.set(false);
+    }
+
+    #[inline]
+    pub fn try_lock(&self) -> bool {
+        self.locked.replace(true) == false
+    }
+}

crates/std/src/sys/sync/once/mod.rs

@@ -0,0 +1,40 @@
+// A "once" is a relatively simple primitive, and it's also typically provided
+// by the OS as well (see `pthread_once` or `InitOnceExecuteOnce`). The OS
+// primitives, however, tend to have surprising restrictions, such as the Unix
+// one doesn't allow an argument to be passed to the function.
+//
+// As a result, we end up implementing it ourselves in the standard library.
+// This also gives us the opportunity to optimize the implementation a bit which
+// should help the fast path on call sites.
+
+cfg_select! {
+    any(
+        all(target_os = "windows", not(target_vendor="win7")),
+        target_os = "linux",
+        target_os = "android",
+        all(target_arch = "wasm32", target_feature = "atomics"),
+        target_os = "freebsd",
+        target_os = "motor",
+        target_os = "openbsd",
+        target_os = "dragonfly",
+        target_os = "fuchsia",
+        target_os = "hermit",
+    ) => {
+        mod futex;
+        pub use futex::{Once, OnceState};
+    }
+    any(
+        windows,
+        target_family = "unix",
+        all(target_vendor = "fortanix", target_env = "sgx"),
+        target_os = "solid_asp3",
+        target_os = "xous",
+    ) => {
+        mod queue;
+        pub use queue::{Once, OnceState};
+    }
+    _ => {
+        mod no_threads;
+        pub use no_threads::{Once, OnceState};
+    }
+}

crates/std/src/sys/sync/once/no_threads.rs

@@ -0,0 +1,114 @@
+use crate::cell::Cell;
+use crate::sync as public;
+use crate::sync::once::OnceExclusiveState;
+
+pub struct Once {
+    state: Cell<State>,
+}
+
+pub struct OnceState {
+    poisoned: bool,
+    set_state_to: Cell<State>,
+}
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+enum State {
+    Incomplete,
+    Poisoned,
+    Running,
+    Complete,
+}
+
+struct CompletionGuard<'a> {
+    state: &'a Cell<State>,
+    set_state_on_drop_to: State,
+}
+
+impl<'a> Drop for CompletionGuard<'a> {
+    fn drop(&mut self) {
+        self.state.set(self.set_state_on_drop_to);
+    }
+}
+
+// Safety: threads are not supported on this platform.
+unsafe impl Sync for Once {}
+
+impl Once {
+    #[inline]
+    pub const fn new() -> Once {
+        Once { state: Cell::new(State::Incomplete) }
+    }
+
+    #[inline]
+    pub fn is_completed(&self) -> bool {
+        self.state.get() == State::Complete
+    }
+
+    #[inline]
+    pub(crate) fn state(&mut self) -> OnceExclusiveState {
+        match self.state.get() {
+            State::Incomplete => OnceExclusiveState::Incomplete,
+            State::Poisoned => OnceExclusiveState::Poisoned,
+            State::Complete => OnceExclusiveState::Complete,
+            _ => unreachable!("invalid Once state"),
+        }
+    }
+
+    #[inline]
+    pub(crate) fn set_state(&mut self, new_state: OnceExclusiveState) {
+        self.state.set(match new_state {
+            OnceExclusiveState::Incomplete => State::Incomplete,
+            OnceExclusiveState::Poisoned => State::Poisoned,
+            OnceExclusiveState::Complete => State::Complete,
+        });
+    }
+
+    #[cold]
+    #[track_caller]
+    pub fn wait(&self, _ignore_poisoning: bool) {
+        panic!("not implementable on this target");
+    }
+
+    #[cold]
+    #[track_caller]
+    pub fn call(&self, ignore_poisoning: bool, f: &mut impl FnMut(&public::OnceState)) {
+        let state = self.state.get();
+        match state {
+            State::Poisoned if !ignore_poisoning => {
+                // Panic to propagate the poison.
+                panic!("Once instance has previously been poisoned");
+            }
+            State::Incomplete | State::Poisoned => {
+                self.state.set(State::Running);
+                // `guard` will set the new state on drop.
+                let mut guard =
+                    CompletionGuard { state: &self.state, set_state_on_drop_to: State::Poisoned };
+                // Run the function, letting it know if we're poisoned or not.
+                let f_state = public::OnceState {
+                    inner: OnceState {
+                        poisoned: state == State::Poisoned,
+                        set_state_to: Cell::new(State::Complete),
+                    },
+                };
+                f(&f_state);
+                guard.set_state_on_drop_to = f_state.inner.set_state_to.get();
+            }
+            State::Running => {
+                panic!("one-time initialization may not be performed recursively");
+            }
+            State::Complete => {}
+        }
+    }
+}
+
+impl OnceState {
+    #[inline]
+    pub fn is_poisoned(&self) -> bool {
+        self.poisoned
+    }
+
+    #[inline]
+    pub fn poison(&self) {
+        self.set_state_to.set(State::Poisoned)
+    }
+}

crates/std/src/sys/sync/rwlock/mod.rs

@@ -0,0 +1,35 @@
+cfg_select! {
+    any(
+        all(target_os = "windows", not(target_vendor = "win7")),
+        target_os = "linux",
+        target_os = "android",
+        target_os = "freebsd",
+        target_os = "openbsd",
+        target_os = "dragonfly",
+        target_os = "fuchsia",
+        all(target_family = "wasm", target_feature = "atomics"),
+        target_os = "hermit",
+       target_os = "motor",
+    ) => {
+        mod futex;
+        pub use futex::RwLock;
+    }
+    any(
+        target_family = "unix",
+        all(target_os = "windows", target_vendor = "win7"),
+        all(target_vendor = "fortanix", target_env = "sgx"),
+        target_os = "xous",
+        target_os = "teeos",
+    ) => {
+        mod queue;
+        pub use queue::RwLock;
+    }
+    target_os = "solid_asp3" => {
+        mod solid;
+        pub use solid::RwLock;
+    }
+    _ => {
+        mod no_threads;
+        pub use no_threads::RwLock;
+    }
+}

crates/std/src/sys/sync/rwlock/no_threads.rs

@@ -0,0 +1,69 @@
+use crate::cell::Cell;
+
+pub struct RwLock {
+    // This platform has no threads, so we can use a Cell here.
+    mode: Cell<isize>,
+}
+
+unsafe impl Send for RwLock {}
+unsafe impl Sync for RwLock {} // no threads on this platform
+
+impl RwLock {
+    #[inline]
+    pub const fn new() -> RwLock {
+        RwLock { mode: Cell::new(0) }
+    }
+
+    #[inline]
+    pub fn read(&self) {
+        let m = self.mode.get();
+        if m >= 0 {
+            self.mode.set(m + 1);
+        } else {
+            rtabort!("rwlock locked for writing");
+        }
+    }
+
+    #[inline]
+    pub fn try_read(&self) -> bool {
+        let m = self.mode.get();
+        if m >= 0 {
+            self.mode.set(m + 1);
+            true
+        } else {
+            false
+        }
+    }
+
+    #[inline]
+    pub fn write(&self) {
+        if self.mode.replace(-1) != 0 {
+            rtabort!("rwlock locked for reading")
+        }
+    }
+
+    #[inline]
+    pub fn try_write(&self) -> bool {
+        if self.mode.get() == 0 {
+            self.mode.set(-1);
+            true
+        } else {
+            false
+        }
+    }
+
+    #[inline]
+    pub unsafe fn read_unlock(&self) {
+        self.mode.set(self.mode.get() - 1);
+    }
+
+    #[inline]
+    pub unsafe fn write_unlock(&self) {
+        assert_eq!(self.mode.replace(0), -1);
+    }
+
+    #[inline]
+    pub unsafe fn downgrade(&self) {
+        assert_eq!(self.mode.replace(1), -1);
+    }
+}

crates/std/src/sys/thread/mod.rs

@@ -0,0 +1,154 @@
+cfg_select! {
+    target_os = "hermit" => {
+        mod hermit;
+        pub use hermit::{Thread, available_parallelism, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{current_os_id, set_name};
+    }
+    target_os = "motor" => {
+        mod motor;
+        pub use motor::*;
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
+        mod sgx;
+        pub use sgx::{Thread, current_os_id, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+
+        // SGX should protect in-enclave data from outside attackers, so there
+        // must not be any data leakage to the OS, particularly no 1-1 mapping
+        // between SGX thread names and OS thread names. Hence `set_name` is
+        // intentionally a no-op.
+        //
+        // Note that the internally visible SGX thread name is already provided
+        // by the platform-agnostic Rust thread code. This can be observed in
+        // the [`std::thread::tests::test_named_thread`] test, which succeeds
+        // as-is with the SGX target.
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{available_parallelism, set_name};
+    }
+    target_os = "solid_asp3" => {
+        mod solid;
+        pub use solid::{Thread, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{available_parallelism, current_os_id, set_name};
+    }
+    target_os = "teeos" => {
+        mod teeos;
+        pub use teeos::{Thread, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{available_parallelism, current_os_id, set_name};
+    }
+    target_os = "uefi" => {
+        mod uefi;
+        pub use uefi::{available_parallelism, sleep};
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{Thread, current_os_id, set_name, yield_now, DEFAULT_MIN_STACK_SIZE};
+    }
+    any(target_family = "unix", target_os = "wasi") => {
+        mod unix;
+        pub use unix::{Thread, available_parallelism, current_os_id, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+        #[cfg(not(any(
+            target_env = "newlib",
+            target_os = "l4re",
+            target_os = "emscripten",
+            target_os = "redox",
+            target_os = "hurd",
+            target_os = "aix",
+            target_os = "wasi",
+        )))]
+        pub use unix::set_name;
+        #[cfg(any(
+            target_os = "freebsd",
+            target_os = "netbsd",
+            target_os = "linux",
+            target_os = "android",
+            target_os = "solaris",
+            target_os = "illumos",
+            target_os = "dragonfly",
+            target_os = "hurd",
+            target_os = "vxworks",
+            target_os = "wasi",
+            target_vendor = "apple",
+        ))]
+        pub use unix::sleep_until;
+        #[expect(dead_code)]
+        mod unsupported;
+        #[cfg(any(
+            target_env = "newlib",
+            target_os = "l4re",
+            target_os = "emscripten",
+            target_os = "redox",
+            target_os = "hurd",
+            target_os = "aix",
+            target_os = "wasi",
+        ))]
+        pub use unsupported::set_name;
+    }
+    target_os = "vexos" => {
+        mod vexos;
+        pub use vexos::{sleep, sleep_until, yield_now};
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{Thread, available_parallelism, current_os_id, set_name, DEFAULT_MIN_STACK_SIZE};
+    }
+    all(target_family = "wasm", target_feature = "atomics") => {
+        mod wasm;
+        pub use wasm::sleep;
+
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{Thread, available_parallelism, current_os_id, set_name, yield_now, DEFAULT_MIN_STACK_SIZE};
+    }
+    target_os = "windows" => {
+        mod windows;
+        pub use windows::{Thread, available_parallelism, current_os_id, set_name, set_name_wide, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+    }
+    target_os = "xous" => {
+        mod xous;
+        pub use xous::{Thread, available_parallelism, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{current_os_id, set_name};
+    }
+    _ => {
+        mod unsupported;
+        pub use unsupported::{Thread, available_parallelism, current_os_id, set_name, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+    }
+}
+
+#[cfg(not(any(
+    target_os = "freebsd",
+    target_os = "netbsd",
+    target_os = "linux",
+    target_os = "android",
+    target_os = "solaris",
+    target_os = "illumos",
+    target_os = "dragonfly",
+    target_os = "hurd",
+    target_os = "vxworks",
+    target_os = "wasi",
+    target_vendor = "apple",
+    target_os = "motor",
+    target_os = "vexos"
+)))]
+pub fn sleep_until(deadline: crate::time::Instant) {
+    use crate::time::Instant;
+
+    // The clock source used for `sleep` might not be the same used for `Instant`.
+    // Since this function *must not* return before the deadline, we recheck the
+    // time after every call to `sleep`. See #149935 for an example of this
+    // occurring on older Windows systems.
+    while let Some(delay) = deadline.checked_duration_since(Instant::now()) {
+        // Sleep for the estimated time remaining until the deadline.
+        //
+        // If your system has a better way of estimating the delay time or
+        // provides a way to sleep until an absolute time, specialize this
+        // function for your system.
+        sleep(delay);
+    }
+}

crates/std/src/sys/thread/unsupported.rs

@@ -0,0 +1,46 @@
+use crate::ffi::CStr;
+use crate::io;
+use crate::num::NonZero;
+use crate::thread::ThreadInit;
+use crate::time::Duration;
+
+// Silence dead code warnings for the otherwise unused ThreadInit::init() call.
+#[expect(dead_code)]
+fn dummy_init_call(init: Box<ThreadInit>) {
+    drop(init.init());
+}
+
+pub struct Thread(!);
+
+pub const DEFAULT_MIN_STACK_SIZE: usize = 64 * 1024;
+
+impl Thread {
+    // unsafe: see thread::Builder::spawn_unchecked for safety requirements
+    pub unsafe fn new(_stack: usize, _init: Box<ThreadInit>) -> io::Result<Thread> {
+        Err(io::Error::UNSUPPORTED_PLATFORM)
+    }
+
+    pub fn join(self) {
+        self.0
+    }
+}
+
+pub fn available_parallelism() -> io::Result<NonZero<usize>> {
+    Err(io::Error::UNKNOWN_THREAD_COUNT)
+}
+
+pub fn current_os_id() -> Option<u64> {
+    None
+}
+
+pub fn yield_now() {
+    // do nothing
+}
+
+pub fn set_name(_name: &CStr) {
+    // nope
+}
+
+pub fn sleep(_dur: Duration) {
+    panic!("can't sleep");
+}

crates/std/src/sys/thread_local/mod.rs

@@ -0,0 +1,227 @@
+//! Implementation of the `thread_local` macro.
+//!
+//! There are three different thread-local implementations:
+//! * Some targets lack threading support, and hence have only one thread, so
+//!   the TLS data is stored in a normal `static`.
+//! * Some targets support TLS natively via the dynamic linker and C runtime.
+//! * On some targets, the OS provides a library-based TLS implementation. The
+//!   TLS data is heap-allocated and referenced using a TLS key.
+//!
+//! Each implementation provides a macro which generates the `LocalKey` `const`
+//! used to reference the TLS variable, along with the necessary helper structs
+//! to track the initialization/destruction state of the variable.
+//!
+//! Additionally, this module contains abstractions for the OS interfaces used
+//! for these implementations.
+
+#![cfg_attr(test, allow(unused))]
+#![doc(hidden)]
+#![forbid(unsafe_op_in_unsafe_fn)]
+#![unstable(
+    feature = "thread_local_internals",
+    reason = "internal details of the thread_local macro",
+    issue = "none"
+)]
+
+cfg_select! {
+    any(
+        all(target_family = "wasm", not(target_feature = "atomics")),
+        target_os = "uefi",
+        target_os = "zkvm",
+        target_os = "trusty",
+        target_os = "vexos",
+        target_os = "survos",
+    ) => {
+        mod no_threads;
+        pub use no_threads::{EagerStorage, LazyStorage, thread_local_inner};
+        pub(crate) use no_threads::{LocalPointer, local_pointer};
+    }
+    target_thread_local => {
+        mod native;
+        pub use native::{EagerStorage, LazyStorage, thread_local_inner};
+        pub(crate) use native::{LocalPointer, local_pointer};
+    }
+    _ => {
+        mod os;
+        pub use os::{Storage, thread_local_inner, value_align};
+        pub(crate) use os::{LocalPointer, local_pointer};
+    }
+}
+
+/// The native TLS implementation needs a way to register destructors for its data.
+/// This module contains platform-specific implementations of that register.
+///
+/// It turns out however that most platforms don't have a way to register a
+/// destructor for each variable. On these platforms, we keep track of the
+/// destructors ourselves and register (through the [`guard`] module) only a
+/// single callback that runs all of the destructors in the list.
+#[cfg(all(target_thread_local, not(all(target_family = "wasm", not(target_feature = "atomics")))))]
+pub(crate) mod destructors {
+    cfg_select! {
+        any(
+            target_os = "linux",
+            target_os = "android",
+            target_os = "fuchsia",
+            target_os = "redox",
+            target_os = "hurd",
+            target_os = "netbsd",
+            target_os = "dragonfly"
+        ) => {
+            mod linux_like;
+            mod list;
+            pub(super) use linux_like::register;
+            pub(super) use list::run;
+        }
+        _ => {
+            mod list;
+            pub(super) use list::register;
+            pub(crate) use list::run;
+        }
+    }
+}
+
+/// This module provides a way to schedule the execution of the destructor list
+/// and the [runtime cleanup](crate::rt::thread_cleanup) function. Calling `enable`
+/// should ensure that these functions are called at the right times.
+pub(crate) mod guard {
+    cfg_select! {
+        all(target_thread_local, target_vendor = "apple") => {
+            mod apple;
+            pub(crate) use apple::enable;
+        }
+        target_os = "windows" => {
+            mod windows;
+            pub(crate) use windows::enable;
+        }
+        any(
+            all(target_family = "wasm", not(
+                all(target_os = "wasi", target_env = "p1", target_feature = "atomics")
+            )),
+            target_os = "uefi",
+            target_os = "zkvm",
+            target_os = "trusty",
+            target_os = "vexos",
+        ) => {
+            pub(crate) fn enable() {
+                // FIXME: Right now there is no concept of "thread exit" on
+                // wasm, but this is likely going to show up at some point in
+                // the form of an exported symbol that the wasm runtime is going
+                // to be expected to call. For now we just leak everything, but
+                // if such a function starts to exist it will probably need to
+                // iterate the destructor list with these functions:
+                #[cfg(all(target_family = "wasm", target_feature = "atomics"))]
+                #[allow(unused)]
+                use super::destructors::run;
+                #[allow(unused)]
+                use crate::rt::thread_cleanup;
+            }
+        }
+        any(
+            target_os = "hermit",
+            target_os = "xous",
+        ) => {
+            // `std` is the only runtime, so it just calls the destructor functions
+            // itself when the time comes.
+            pub(crate) fn enable() {}
+        }
+        target_os = "solid_asp3" => {
+            mod solid;
+            pub(crate) use solid::enable;
+        }
+        target_os = "survos" => {
+            // todo
+            pub(crate) fn enable() {}
+        }
+        _ => {
+            mod key;
+            pub(crate) use key::enable;
+        }
+    }
+}
+
+/// `const`-creatable TLS keys.
+///
+/// Most OSs without native TLS will provide a library-based way to create TLS
+/// storage. For each TLS variable, we create a key, which can then be used to
+/// reference an entry in a thread-local table. This then associates each key
+/// with a pointer which we can get and set to store our data.
+pub(crate) mod key {
+    cfg_select! {
+        any(
+            all(
+                not(target_vendor = "apple"),
+                not(target_family = "wasm"),
+                target_family = "unix",
+            ),
+            all(not(target_thread_local), target_vendor = "apple"),
+            target_os = "teeos",
+            all(target_os = "wasi", target_env = "p1", target_feature = "atomics"),
+        ) => {
+            mod racy;
+            mod unix;
+            #[cfg(test)]
+            mod tests;
+            pub(super) use racy::LazyKey;
+            pub(super) use unix::{Key, set};
+            #[cfg(any(not(target_thread_local), test))]
+            pub(super) use unix::get;
+            use unix::{create, destroy};
+        }
+        all(not(target_thread_local), target_os = "windows") => {
+            #[cfg(test)]
+            mod tests;
+            mod windows;
+            pub(super) use windows::{Key, LazyKey, get, run_dtors, set};
+        }
+        all(target_vendor = "fortanix", target_env = "sgx") => {
+            mod racy;
+            mod sgx;
+            #[cfg(test)]
+            mod tests;
+            pub(super) use racy::LazyKey;
+            pub(super) use sgx::{Key, get, set};
+            use sgx::{create, destroy};
+        }
+        target_os = "xous" => {
+            mod racy;
+            #[cfg(test)]
+            mod tests;
+            mod xous;
+            pub(super) use racy::LazyKey;
+            pub(crate) use xous::destroy_tls;
+            pub(super) use xous::{Key, get, set};
+            use xous::{create, destroy};
+        }
+        target_os = "motor" => {
+            mod racy;
+            #[cfg(test)]
+            mod tests;
+            pub(super) use racy::LazyKey;
+            pub(super) use moto_rt::tls::{Key, get, set};
+            use moto_rt::tls::{create, destroy};
+        }
+        _ => {}
+    }
+}
+
+/// Run a callback in a scenario which must not unwind (such as a `extern "C"
+/// fn` declared in a user crate). If the callback unwinds anyway, then
+/// `rtabort` with a message about thread local panicking on drop.
+#[inline]
+#[allow(dead_code)]
+fn abort_on_dtor_unwind(f: impl FnOnce()) {
+    // Using a guard like this is lower cost.
+    let guard = DtorUnwindGuard;
+    f();
+    core::mem::forget(guard);
+
+    struct DtorUnwindGuard;
+    impl Drop for DtorUnwindGuard {
+        #[inline]
+        fn drop(&mut self) {
+            // This is not terribly descriptive, but it doesn't need to be as we'll
+            // already have printed a panic message at this point.
+            rtabort!("thread local panicked on drop");
+        }
+    }
+}

crates/std/src/sys/thread_local/no_threads.rs

@@ -0,0 +1,150 @@
+//! On some targets like wasm there's no threads, so no need to generate
+//! thread locals and we can instead just use plain statics!
+
+use crate::cell::{Cell, UnsafeCell};
+use crate::mem::MaybeUninit;
+use crate::ptr;
+
+#[doc(hidden)]
+#[allow_internal_unstable(thread_local_internals)]
+#[allow_internal_unsafe]
+#[unstable(feature = "thread_local_internals", issue = "none")]
+#[rustc_macro_transparency = "semiopaque"]
+pub macro thread_local_inner {
+    // used to generate the `LocalKey` value for const-initialized thread locals
+    (@key $t:ty, $(#[$align_attr:meta])*, const $init:expr) => {{
+        const __RUST_STD_INTERNAL_INIT: $t = $init;
+
+        // NOTE: Please update the shadowing test in `tests/thread.rs` if these types are renamed.
+        unsafe {
+            $crate::thread::LocalKey::new(|_| {
+                $(#[$align_attr])*
+                static __RUST_STD_INTERNAL_VAL: $crate::thread::local_impl::EagerStorage<$t> =
+                    $crate::thread::local_impl::EagerStorage { value: __RUST_STD_INTERNAL_INIT };
+                &__RUST_STD_INTERNAL_VAL.value
+            })
+        }
+    }},
+
+    // used to generate the `LocalKey` value for `thread_local!`
+    (@key $t:ty, $(#[$align_attr:meta])*, $init:expr) => {{
+        #[inline]
+        fn __rust_std_internal_init_fn() -> $t { $init }
+
+        unsafe {
+            $crate::thread::LocalKey::new(|__rust_std_internal_init| {
+                $(#[$align_attr])*
+                static __RUST_STD_INTERNAL_VAL: $crate::thread::local_impl::LazyStorage<$t> = $crate::thread::local_impl::LazyStorage::new();
+                __RUST_STD_INTERNAL_VAL.get(__rust_std_internal_init, __rust_std_internal_init_fn)
+            })
+        }
+    }},
+}
+
+#[allow(missing_debug_implementations)]
+#[repr(transparent)] // Required for correctness of `#[rustc_align_static]`
+pub struct EagerStorage<T> {
+    pub value: T,
+}
+
+// SAFETY: the target doesn't have threads.
+unsafe impl<T> Sync for EagerStorage<T> {}
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+enum State {
+    Initial,
+    Alive,
+    Destroying,
+}
+
+#[allow(missing_debug_implementations)]
+#[repr(C)]
+pub struct LazyStorage<T> {
+    // This field must be first, for correctness of `#[rustc_align_static]`
+    value: UnsafeCell<MaybeUninit<T>>,
+    state: Cell<State>,
+}
+
+impl<T> LazyStorage<T> {
+    pub const fn new() -> LazyStorage<T> {
+        LazyStorage {
+            value: UnsafeCell::new(MaybeUninit::uninit()),
+            state: Cell::new(State::Initial),
+        }
+    }
+
+    /// Gets a pointer to the TLS value, potentially initializing it with the
+    /// provided parameters.
+    ///
+    /// The resulting pointer may not be used after reentrant inialialization
+    /// has occurred.
+    #[inline]
+    pub fn get(&'static self, i: Option<&mut Option<T>>, f: impl FnOnce() -> T) -> *const T {
+        if self.state.get() == State::Alive {
+            self.value.get() as *const T
+        } else {
+            self.initialize(i, f)
+        }
+    }
+
+    #[cold]
+    fn initialize(&'static self, i: Option<&mut Option<T>>, f: impl FnOnce() -> T) -> *const T {
+        let value = i.and_then(Option::take).unwrap_or_else(f);
+
+        // Destroy the old value if it is initialized
+        // FIXME(#110897): maybe panic on recursive initialization.
+        if self.state.get() == State::Alive {
+            self.state.set(State::Destroying);
+            // Safety: we check for no initialization during drop below
+            unsafe {
+                ptr::drop_in_place(self.value.get() as *mut T);
+            }
+            self.state.set(State::Initial);
+        }
+
+        // Guard against initialization during drop
+        if self.state.get() == State::Destroying {
+            panic!("Attempted to initialize thread-local while it is being dropped");
+        }
+
+        unsafe {
+            self.value.get().write(MaybeUninit::new(value));
+        }
+        self.state.set(State::Alive);
+
+        self.value.get() as *const T
+    }
+}
+
+// SAFETY: the target doesn't have threads.
+unsafe impl<T> Sync for LazyStorage<T> {}
+
+#[rustc_macro_transparency = "semiopaque"]
+pub(crate) macro local_pointer {
+    () => {},
+    ($vis:vis static $name:ident; $($rest:tt)*) => {
+        $vis static $name: $crate::sys::thread_local::LocalPointer = $crate::sys::thread_local::LocalPointer::__new();
+        $crate::sys::thread_local::local_pointer! { $($rest)* }
+    },
+}
+
+pub(crate) struct LocalPointer {
+    p: Cell<*mut ()>,
+}
+
+impl LocalPointer {
+    pub const fn __new() -> LocalPointer {
+        LocalPointer { p: Cell::new(ptr::null_mut()) }
+    }
+
+    pub fn get(&self) -> *mut () {
+        self.p.get()
+    }
+
+    pub fn set(&self, p: *mut ()) {
+        self.p.set(p)
+    }
+}
+
+// SAFETY: the target doesn't have threads.
+unsafe impl Sync for LocalPointer {}

crates/std/src/sys/thread_local/os.rs

@@ -0,0 +1,289 @@
+use super::key::{Key, LazyKey, get, set};
+use super::{abort_on_dtor_unwind, guard};
+use crate::alloc::{self, GlobalAlloc, Layout, System};
+use crate::cell::Cell;
+use crate::marker::PhantomData;
+use crate::mem::ManuallyDrop;
+use crate::ops::Deref;
+use crate::panic::{AssertUnwindSafe, catch_unwind, resume_unwind};
+use crate::ptr::{self, NonNull};
+
+#[doc(hidden)]
+#[allow_internal_unstable(thread_local_internals)]
+#[allow_internal_unsafe]
+#[unstable(feature = "thread_local_internals", issue = "none")]
+#[rustc_macro_transparency = "semiopaque"]
+pub macro thread_local_inner {
+    // NOTE: we cannot import `Storage` or `LocalKey` with a `use` because that can shadow user
+    // provided type or type alias with a matching name. Please update the shadowing test in
+    // `tests/thread.rs` if these types are renamed.
+
+    // used to generate the `LocalKey` value for `thread_local!`.
+    (@key $t:ty, $($(#[$($align_attr:tt)*])+)?, $init:expr) => {{
+        #[inline]
+        fn __rust_std_internal_init_fn() -> $t { $init }
+
+        // NOTE: this cannot import `LocalKey` or `Storage` with a `use` because that can shadow
+        // user provided type or type alias with a matching name. Please update the shadowing test
+        // in `tests/thread.rs` if these types are renamed.
+        unsafe {
+            $crate::thread::LocalKey::new(|__rust_std_internal_init| {
+                static __RUST_STD_INTERNAL_VAL: $crate::thread::local_impl::Storage<$t, {
+                    $({
+                        // Ensure that attributes have valid syntax
+                        // and that the proper feature gate is enabled
+                        $(#[$($align_attr)*])+
+                        #[allow(unused)]
+                        static DUMMY: () = ();
+                    })?
+
+                    #[allow(unused_mut)]
+                    let mut final_align = $crate::thread::local_impl::value_align::<$t>();
+                    $($($crate::thread::local_impl::thread_local_inner!(@align final_align, $($align_attr)*);)+)?
+                    final_align
+                }>
+                    = $crate::thread::local_impl::Storage::new();
+                __RUST_STD_INTERNAL_VAL.get(__rust_std_internal_init, __rust_std_internal_init_fn)
+            })
+        }
+    }},
+
+    // process a single `rustc_align_static` attribute
+    (@align $final_align:ident, rustc_align_static($($align:tt)*) $(, $($attr_rest:tt)+)?) => {
+        let new_align: $crate::primitive::usize = $($align)*;
+        if new_align > $final_align {
+            $final_align = new_align;
+        }
+
+        $($crate::thread::local_impl::thread_local_inner!(@align $final_align, $($attr_rest)+);)?
+    },
+
+    // process a single `cfg_attr` attribute
+    // by translating it into a `cfg`ed block and recursing.
+    // https://doc.rust-lang.org/reference/conditional-compilation.html#railroad-ConfigurationPredicate
+
+    (@align $final_align:ident, cfg_attr(true, $($cfg_rhs:tt)*) $(, $($attr_rest:tt)+)?) => {
+        #[cfg(true)]
+        {
+            $crate::thread::local_impl::thread_local_inner!(@align $final_align, $($cfg_rhs)*);
+        }
+
+        $($crate::thread::local_impl::thread_local_inner!(@align $final_align, $($attr_rest)+);)?
+    },
+
+    (@align $final_align:ident, cfg_attr(false, $($cfg_rhs:tt)*) $(, $($attr_rest:tt)+)?) => {
+        #[cfg(false)]
+        {
+            $crate::thread::local_impl::thread_local_inner!(@align $final_align, $($cfg_rhs)*);
+        }
+
+        $($crate::thread::local_impl::thread_local_inner!(@align $final_align, $($attr_rest)+);)?
+    },
+
+    (@align $final_align:ident, cfg_attr($cfg_pred:meta, $($cfg_rhs:tt)*) $(, $($attr_rest:tt)+)?) => {
+        #[cfg($cfg_pred)]
+        {
+            $crate::thread::local_impl::thread_local_inner!(@align $final_align, $($cfg_rhs)*);
+        }
+
+        $($crate::thread::local_impl::thread_local_inner!(@align $final_align, $($attr_rest)+);)?
+    },
+}
+
+/// Use a regular global static to store this key; the state provided will then be
+/// thread-local.
+/// INVARIANT: ALIGN must be a valid alignment, and no less than `value_align::<T>`.
+#[allow(missing_debug_implementations)]
+pub struct Storage<T, const ALIGN: usize> {
+    key: LazyKey,
+    marker: PhantomData<Cell<T>>,
+}
+
+unsafe impl<T, const ALIGN: usize> Sync for Storage<T, ALIGN> {}
+
+#[repr(C)]
+struct Value<T: 'static> {
+    // This field must be first, for correctness of `#[rustc_align_static]`
+    value: T,
+    // INVARIANT: if this value is stored under a TLS key, `key` must be that `key`.
+    key: Key,
+}
+
+pub const fn value_align<T: 'static>() -> usize {
+    crate::mem::align_of::<Value<T>>()
+}
+
+/// Equivalent to `Box<Value<T>, System>`, but potentially over-aligned.
+struct AlignedSystemBox<T: 'static, const ALIGN: usize> {
+    ptr: NonNull<Value<T>>,
+}
+
+impl<T: 'static, const ALIGN: usize> AlignedSystemBox<T, ALIGN> {
+    #[inline]
+    fn new(v: Value<T>) -> Self {
+        let layout = Layout::new::<Value<T>>().align_to(ALIGN).unwrap();
+
+        // We use the System allocator here to avoid interfering with a potential
+        // Global allocator using thread-local storage.
+        let ptr: *mut Value<T> = (unsafe { System.alloc(layout) }).cast();
+        let Some(ptr) = NonNull::new(ptr) else {
+            alloc::handle_alloc_error(layout);
+        };
+        unsafe { ptr.write(v) };
+        Self { ptr }
+    }
+
+    #[inline]
+    fn into_raw(b: Self) -> *mut Value<T> {
+        let md = ManuallyDrop::new(b);
+        md.ptr.as_ptr()
+    }
+
+    #[inline]
+    unsafe fn from_raw(ptr: *mut Value<T>) -> Self {
+        Self { ptr: unsafe { NonNull::new_unchecked(ptr) } }
+    }
+}
+
+impl<T: 'static, const ALIGN: usize> Deref for AlignedSystemBox<T, ALIGN> {
+    type Target = Value<T>;
+
+    #[inline]
+    fn deref(&self) -> &Self::Target {
+        unsafe { &*(self.ptr.as_ptr()) }
+    }
+}
+
+impl<T: 'static, const ALIGN: usize> Drop for AlignedSystemBox<T, ALIGN> {
+    #[inline]
+    fn drop(&mut self) {
+        let layout = Layout::new::<Value<T>>().align_to(ALIGN).unwrap();
+
+        unsafe {
+            let unwind_result = catch_unwind(AssertUnwindSafe(|| self.ptr.drop_in_place()));
+            System.dealloc(self.ptr.as_ptr().cast(), layout);
+            if let Err(payload) = unwind_result {
+                resume_unwind(payload);
+            }
+        }
+    }
+}
+
+impl<T: 'static, const ALIGN: usize> Storage<T, ALIGN> {
+    pub const fn new() -> Storage<T, ALIGN> {
+        Storage { key: LazyKey::new(Some(destroy_value::<T, ALIGN>)), marker: PhantomData }
+    }
+
+    /// Gets a pointer to the TLS value, potentially initializing it with the
+    /// provided parameters. If the TLS variable has been destroyed, a null
+    /// pointer is returned.
+    ///
+    /// The resulting pointer may not be used after reentrant inialialization
+    /// or thread destruction has occurred.
+    pub fn get(&'static self, i: Option<&mut Option<T>>, f: impl FnOnce() -> T) -> *const T {
+        let key = self.key.force();
+        let ptr = unsafe { get(key) as *mut Value<T> };
+        if ptr.addr() > 1 {
+            // SAFETY: the check ensured the pointer is safe (its destructor
+            // is not running) + it is coming from a trusted source (self).
+            unsafe { &(*ptr).value }
+        } else {
+            // SAFETY: trivially correct.
+            unsafe { Self::try_initialize(key, ptr, i, f) }
+        }
+    }
+
+    /// # Safety
+    /// * `key` must be the result of calling `self.key.force()`
+    /// * `ptr` must be the current value associated with `key`.
+    unsafe fn try_initialize(
+        key: Key,
+        ptr: *mut Value<T>,
+        i: Option<&mut Option<T>>,
+        f: impl FnOnce() -> T,
+    ) -> *const T {
+        if ptr.addr() == 1 {
+            // destructor is running
+            return ptr::null();
+        }
+
+        let value = AlignedSystemBox::<T, ALIGN>::new(Value {
+            value: i.and_then(Option::take).unwrap_or_else(f),
+            key,
+        });
+        let ptr = AlignedSystemBox::into_raw(value);
+
+        // SAFETY:
+        // * key came from a `LazyKey` and is thus correct.
+        // * `ptr` is a correct pointer that can be destroyed by the key destructor.
+        // * the value is stored under the key that it contains.
+        let old = unsafe {
+            let old = get(key) as *mut Value<T>;
+            set(key, ptr as *mut u8);
+            old
+        };
+
+        if !old.is_null() {
+            // If the variable was recursively initialized, drop the old value.
+            // SAFETY: We cannot be inside a `LocalKey::with` scope, as the
+            // initializer has already returned and the next scope only starts
+            // after we return the pointer. Therefore, there can be no references
+            // to the old value.
+            drop(unsafe { AlignedSystemBox::<T, ALIGN>::from_raw(old) });
+        }
+
+        // SAFETY: We just created this value above.
+        unsafe { &(*ptr).value }
+    }
+}
+
+unsafe extern "C" fn destroy_value<T: 'static, const ALIGN: usize>(ptr: *mut u8) {
+    // SAFETY:
+    //
+    // The OS TLS ensures that this key contains a null value when this
+    // destructor starts to run. We set it back to a sentinel value of 1 to
+    // ensure that any future calls to `get` for this thread will return
+    // `None`.
+    //
+    // Note that to prevent an infinite loop we reset it back to null right
+    // before we return from the destructor ourselves.
+    abort_on_dtor_unwind(|| {
+        let ptr = unsafe { AlignedSystemBox::<T, ALIGN>::from_raw(ptr as *mut Value<T>) };
+        let key = ptr.key;
+        // SAFETY: `key` is the TLS key `ptr` was stored under.
+        unsafe { set(key, ptr::without_provenance_mut(1)) };
+        drop(ptr);
+        // SAFETY: `key` is the TLS key `ptr` was stored under.
+        unsafe { set(key, ptr::null_mut()) };
+        // Make sure that the runtime cleanup will be performed
+        // after the next round of TLS destruction.
+        guard::enable();
+    });
+}
+
+#[rustc_macro_transparency = "semiopaque"]
+pub(crate) macro local_pointer {
+    () => {},
+    ($vis:vis static $name:ident; $($rest:tt)*) => {
+        $vis static $name: $crate::sys::thread_local::LocalPointer = $crate::sys::thread_local::LocalPointer::__new();
+        $crate::sys::thread_local::local_pointer! { $($rest)* }
+    },
+}
+
+pub(crate) struct LocalPointer {
+    key: LazyKey,
+}
+
+impl LocalPointer {
+    pub const fn __new() -> LocalPointer {
+        LocalPointer { key: LazyKey::new(None) }
+    }
+
+    pub fn get(&'static self) -> *mut () {
+        unsafe { get(self.key.force()) as *mut () }
+    }
+
+    pub fn set(&'static self, p: *mut ()) {
+        unsafe { set(self.key.force(), p as *mut u8) }
+    }
+}

crates/std/src/sys/time/mod.rs

@@ -0,0 +1,53 @@
+cfg_select! {
+    target_os = "hermit" => {
+        mod hermit;
+        use hermit as imp;
+    }
+    target_os = "motor" => {
+        use moto_rt::time as imp;
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
+        mod sgx;
+        use sgx as imp;
+    }
+    target_os = "solid_asp3" => {
+        mod solid;
+        use solid as imp;
+    }
+    target_os = "uefi" => {
+        mod uefi;
+        use uefi as imp;
+    }
+    any(
+        target_os = "teeos",
+        target_family = "unix",
+        target_os = "wasi",
+    ) => {
+        mod unix;
+        use unix as imp;
+    }
+    target_os = "vexos" => {
+        mod vexos;
+        #[expect(unused)]
+        mod unsupported;
+
+        mod imp {
+            pub use super::vexos::Instant;
+            pub use super::unsupported::{SystemTime, UNIX_EPOCH};
+        }
+    }
+    target_os = "windows" => {
+        mod windows;
+        use windows as imp;
+    }
+    target_os = "xous" => {
+        mod xous;
+        use xous as imp;
+    }
+    _ => {
+        mod unsupported;
+        use unsupported as imp;
+    }
+}
+
+pub use imp::{Instant, SystemTime, UNIX_EPOCH};

crates/std/src/sys/time/unsupported.rs

@@ -0,0 +1,49 @@
+use crate::time::Duration;
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
+pub struct Instant(Duration);
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
+pub struct SystemTime(Duration);
+
+pub const UNIX_EPOCH: SystemTime = SystemTime(Duration::from_secs(0));
+
+impl Instant {
+    pub fn now() -> Instant {
+        panic!("time not implemented on this platform")
+    }
+
+    pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
+        self.0.checked_sub(other.0)
+    }
+
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
+        Some(Instant(self.0.checked_add(*other)?))
+    }
+
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
+        Some(Instant(self.0.checked_sub(*other)?))
+    }
+}
+
+impl SystemTime {
+    pub const MAX: SystemTime = SystemTime(Duration::MAX);
+
+    pub const MIN: SystemTime = SystemTime(Duration::ZERO);
+
+    pub fn now() -> SystemTime {
+        panic!("time not implemented on this platform")
+    }
+
+    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
+        self.0.checked_sub(other.0).ok_or_else(|| other.0 - self.0)
+    }
+
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
+        Some(SystemTime(self.0.checked_add(*other)?))
+    }
+
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
+        Some(SystemTime(self.0.checked_sub(*other)?))
+    }
+}

crates/std/src/thread.rs

@@ -0,0 +1,24 @@
+pub mod local;
+
+pub use crate::sys::thread::*;
+pub use local::LocalKey;
+
+// Implementation details used by the thread_local!{} macro.
+#[doc(hidden)]
+#[unstable(feature = "thread_local_internals", issue = "none")]
+pub mod local_impl {
+    pub use super::local::thread_local_process_attrs;
+    pub use crate::sys::thread_local::*;
+}
+
+pub struct ThreadInit {
+    pub handle: Thread,
+    pub rust_start: Box<dyn FnOnce() + Send>,
+}
+impl ThreadInit {
+    /// Initialize the 'current thread' mechanism on this thread, returning the
+    /// Rust entry point.
+    pub fn init(self: Box<Self>) -> Box<dyn FnOnce() + Send> {
+        todo!()
+    }
+}

crates/std/src/thread/local.rs

@@ -0,0 +1,865 @@
+//! Thread local storage
+
+#![unstable(feature = "thread_local_internals", issue = "none")]
+
+use crate::cell::{Cell, RefCell};
+use crate::error::Error;
+use crate::fmt;
+
+/// A thread local storage (TLS) key which owns its contents.
+///
+/// This key uses the fastest implementation available on the target platform.
+/// It is instantiated with the [`thread_local!`] macro and the
+/// primary method is the [`with`] method, though there are helpers to make
+/// working with [`Cell`] types easier.
+///
+/// The [`with`] method yields a reference to the contained value which cannot
+/// outlive the current thread or escape the given closure.
+///
+/// [`thread_local!`]: crate::thread_local
+///
+/// # Initialization and Destruction
+///
+/// Initialization is dynamically performed on the first call to a setter (e.g.
+/// [`with`]) within a thread, and values that implement [`Drop`] get
+/// destructed when a thread exits. Some platform-specific caveats apply, which
+/// are explained below.
+/// Note that, should the destructor panic, the whole process will be [aborted].
+/// On platforms where initialization requires memory allocation, this is
+/// performed directly through [`System`], allowing the [global allocator]
+/// to make use of thread local storage.
+///
+/// A `LocalKey`'s initializer cannot recursively depend on itself. Using a
+/// `LocalKey` in this way may cause panics, aborts, or infinite recursion on
+/// the first call to `with`.
+///
+/// [`System`]: crate::alloc::System
+/// [global allocator]: crate::alloc
+/// [aborted]: crate::process::abort
+///
+/// # Single-thread Synchronization
+///
+/// Though there is no potential race with other threads, it is still possible to
+/// obtain multiple references to the thread-local data in different places on
+/// the call stack. For this reason, only shared (`&T`) references may be obtained.
+///
+/// To allow obtaining an exclusive mutable reference (`&mut T`), typically a
+/// [`Cell`] or [`RefCell`] is used (see the [`std::cell`] for more information
+/// on how exactly this works). To make this easier there are specialized
+/// implementations for [`LocalKey<Cell<T>>`] and [`LocalKey<RefCell<T>>`].
+///
+/// [`std::cell`]: `crate::cell`
+/// [`LocalKey<Cell<T>>`]: struct.LocalKey.html#impl-LocalKey<Cell<T>>
+/// [`LocalKey<RefCell<T>>`]: struct.LocalKey.html#impl-LocalKey<RefCell<T>>
+///
+///
+/// # Examples
+///
+/// ```
+/// use std::cell::Cell;
+/// use std::thread;
+///
+/// // explicit `const {}` block enables more efficient initialization
+/// thread_local!(static FOO: Cell<u32> = const { Cell::new(1) });
+///
+/// assert_eq!(FOO.get(), 1);
+/// FOO.set(2);
+///
+/// // each thread starts out with the initial value of 1
+/// let t = thread::spawn(move || {
+///     assert_eq!(FOO.get(), 1);
+///     FOO.set(3);
+/// });
+///
+/// // wait for the thread to complete and bail out on panic
+/// t.join().unwrap();
+///
+/// // we retain our original value of 2 despite the child thread
+/// assert_eq!(FOO.get(), 2);
+/// ```
+///
+/// # Platform-specific behavior
+///
+/// Note that a "best effort" is made to ensure that destructors for types
+/// stored in thread local storage are run, but not all platforms can guarantee
+/// that destructors will be run for all types in thread local storage. For
+/// example, there are a number of known caveats where destructors are not run:
+///
+/// 1. On Unix systems when pthread-based TLS is being used, destructors will
+///    not be run for TLS values on the main thread when it exits. Note that the
+///    application will exit immediately after the main thread exits as well.
+/// 2. On all platforms it's possible for TLS to re-initialize other TLS slots
+///    during destruction. Some platforms ensure that this cannot happen
+///    infinitely by preventing re-initialization of any slot that has been
+///    destroyed, but not all platforms have this guard. Those platforms that do
+///    not guard typically have a synthetic limit after which point no more
+///    destructors are run.
+/// 3. When the process exits on Windows systems, TLS destructors may only be
+///    run on the thread that causes the process to exit. This is because the
+///    other threads may be forcibly terminated.
+///
+/// ## Synchronization in thread-local destructors
+///
+/// On Windows, synchronization operations (such as [`JoinHandle::join`]) in
+/// thread local destructors are prone to deadlocks and so should be avoided.
+/// This is because the [loader lock] is held while a destructor is run. The
+/// lock is acquired whenever a thread starts or exits or when a DLL is loaded
+/// or unloaded. Therefore these events are blocked for as long as a thread
+/// local destructor is running.
+///
+/// [loader lock]: https://docs.microsoft.com/en-us/windows/win32/dlls/dynamic-link-library-best-practices
+/// [`JoinHandle::join`]: crate::thread::JoinHandle::join
+/// [`with`]: LocalKey::with
+#[cfg_attr(not(test), rustc_diagnostic_item = "LocalKey")]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub struct LocalKey<T: 'static> {
+    // This outer `LocalKey<T>` type is what's going to be stored in statics,
+    // but actual data inside will sometimes be tagged with #[thread_local].
+    // It's not valid for a true static to reference a #[thread_local] static,
+    // so we get around that by exposing an accessor through a layer of function
+    // indirection (this thunk).
+    //
+    // Note that the thunk is itself unsafe because the returned lifetime of the
+    // slot where data lives, `'static`, is not actually valid. The lifetime
+    // here is actually slightly shorter than the currently running thread!
+    //
+    // Although this is an extra layer of indirection, it should in theory be
+    // trivially devirtualizable by LLVM because the value of `inner` never
+    // changes and the constant should be readonly within a crate. This mainly
+    // only runs into problems when TLS statics are exported across crates.
+    inner: fn(Option<&mut Option<T>>) -> *const T,
+}
+
+#[stable(feature = "std_debug", since = "1.16.0")]
+impl<T: 'static> fmt::Debug for LocalKey<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("LocalKey").finish_non_exhaustive()
+    }
+}
+
+#[doc(hidden)]
+#[allow_internal_unstable(thread_local_internals)]
+#[unstable(feature = "thread_local_internals", issue = "none")]
+#[rustc_macro_transparency = "semiopaque"]
+pub macro thread_local_process_attrs {
+
+    // Parse `cfg_attr` to figure out whether it's a `rustc_align_static`.
+    // Each `cfg_attr` can have zero or more attributes on the RHS, and can be nested.
+
+    // finished parsing the `cfg_attr`, it had no `rustc_align_static`
+    (
+        [] [$(#[$($prev_other_attrs:tt)*])*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [] };
+        [$($prev_align_attrs_ret:tt)*] [$($prev_other_attrs_ret:tt)*];
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs_ret)*] [$($prev_other_attrs_ret)* #[cfg_attr($($predicate)*, $($($prev_other_attrs)*),*)]];
+            $($rest)*
+        );
+    ),
+
+    // finished parsing the `cfg_attr`, it had nothing but `rustc_align_static`
+    (
+        [$(#[$($prev_align_attrs:tt)*])+] [];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [] };
+        [$($prev_align_attrs_ret:tt)*] [$($prev_other_attrs_ret:tt)*];
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs_ret)*  #[cfg_attr($($predicate)*, $($($prev_align_attrs)*),+)]] [$($prev_other_attrs_ret)*];
+            $($rest)*
+        );
+    ),
+
+    // finished parsing the `cfg_attr`, it had a mix of `rustc_align_static` and other attrs
+    (
+        [$(#[$($prev_align_attrs:tt)*])+] [$(#[$($prev_other_attrs:tt)*])+];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [] };
+        [$($prev_align_attrs_ret:tt)*] [$($prev_other_attrs_ret:tt)*];
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs_ret)*  #[cfg_attr($($predicate)*, $($($prev_align_attrs)*),+)]] [$($prev_other_attrs_ret)* #[cfg_attr($($predicate)*, $($($prev_other_attrs)*),+)]];
+            $($rest)*
+        );
+    ),
+
+    // it's a `rustc_align_static`
+    (
+        [$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [rustc_align_static($($align_static_args:tt)*) $(, $($attr_rhs:tt)*)?] };
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)* #[rustc_align_static($($align_static_args)*)]] [$($prev_other_attrs)*];
+            @processing_cfg_attr { pred: ($($predicate)*), rhs: [$($($attr_rhs)*)?] };
+            $($rest)*
+        );
+    ),
+
+    // it's a nested `cfg_attr(true, ...)`; recurse into RHS
+    (
+        [$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [cfg_attr(true, $($cfg_rhs:tt)*) $(, $($attr_rhs:tt)*)?] };
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: (true), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            @processing_cfg_attr { pred: ($($predicate)*), rhs: [$($($attr_rhs)*)?] };
+            $($rest)*
+        );
+    ),
+
+    // it's a nested `cfg_attr(false, ...)`; recurse into RHS
+    (
+        [$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [cfg_attr(false, $($cfg_rhs:tt)*) $(, $($attr_rhs:tt)*)?] };
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: (false), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            @processing_cfg_attr { pred: ($($predicate)*), rhs: [$($($attr_rhs)*)?] };
+            $($rest)*
+        );
+    ),
+
+
+    // it's a nested `cfg_attr(..., ...)`; recurse into RHS
+    (
+        [$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [cfg_attr($cfg_lhs:meta, $($cfg_rhs:tt)*) $(, $($attr_rhs:tt)*)?] };
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: ($cfg_lhs), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            @processing_cfg_attr { pred: ($($predicate)*), rhs: [$($($attr_rhs)*)?] };
+            $($rest)*
+        );
+    ),
+
+    // it's some other attribute
+    (
+        [$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [$meta:meta $(, $($attr_rhs:tt)*)?] };
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)*] [$($prev_other_attrs)* #[$meta]];
+            @processing_cfg_attr { pred: ($($predicate)*), rhs: [$($($attr_rhs)*)?] };
+            $($rest)*
+        );
+    ),
+
+
+    // Separate attributes into `rustc_align_static` and everything else:
+
+    // `rustc_align_static` attribute
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; #[rustc_align_static $($attr_rest:tt)*] $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)* #[rustc_align_static $($attr_rest)*]] [$($prev_other_attrs)*];
+            $($rest)*
+        );
+    ),
+
+    // `cfg_attr(true, ...)` attribute; parse it
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; #[cfg_attr(true, $($cfg_rhs:tt)*)] $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: (true), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            $($rest)*
+        );
+    ),
+
+    // `cfg_attr(false, ...)` attribute; parse it
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; #[cfg_attr(false, $($cfg_rhs:tt)*)] $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: (false), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            $($rest)*
+        );
+    ),
+
+    // `cfg_attr(..., ...)` attribute; parse it
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; #[cfg_attr($cfg_pred:meta, $($cfg_rhs:tt)*)] $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: ($cfg_pred), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            $($rest)*
+        );
+    ),
+
+    // doc comment not followed by any other attributes; process it all at once to avoid blowing recursion limit
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; $(#[doc $($doc_rhs:tt)*])+ $vis:vis static $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)*] [$($prev_other_attrs)* $(#[doc $($doc_rhs)*])+];
+            $vis static $($rest)*
+        );
+    ),
+
+    // 8 lines of doc comment; process them all at once to avoid blowing recursion limit
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+     #[doc $($doc_rhs_1:tt)*] #[doc $($doc_rhs_2:tt)*] #[doc $($doc_rhs_3:tt)*] #[doc $($doc_rhs_4:tt)*]
+     #[doc $($doc_rhs_5:tt)*] #[doc $($doc_rhs_6:tt)*] #[doc $($doc_rhs_7:tt)*] #[doc $($doc_rhs_8:tt)*]
+     $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*
+            #[doc $($doc_rhs_1)*] #[doc $($doc_rhs_2)*] #[doc $($doc_rhs_3)*] #[doc $($doc_rhs_4)*]
+            #[doc $($doc_rhs_5)*] #[doc $($doc_rhs_6)*] #[doc $($doc_rhs_7)*] #[doc $($doc_rhs_8)*]];
+            $($rest)*
+        );
+    ),
+
+    // other attribute
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; #[$($attr:tt)*] $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)*] [$($prev_other_attrs)* #[$($attr)*]];
+            $($rest)*
+        );
+    ),
+
+
+    // Delegate to `thread_local_inner` once attributes are fully categorized:
+
+    // process `const` declaration and recurse
+    ([$($align_attrs:tt)*] [$($other_attrs:tt)*]; $vis:vis static $name:ident: $t:ty = const $init:block $(; $($($rest:tt)+)?)?) => (
+        $($other_attrs)* $vis const $name: $crate::thread::LocalKey<$t> =
+            $crate::thread::local_impl::thread_local_inner!(@key $t, $($align_attrs)*, const $init);
+
+        $($($crate::thread::local_impl::thread_local_process_attrs!([] []; $($rest)+);)?)?
+    ),
+
+    // process non-`const` declaration and recurse
+    ([$($align_attrs:tt)*] [$($other_attrs:tt)*]; $vis:vis static $name:ident: $t:ty = $init:expr $(; $($($rest:tt)+)?)?) => (
+        $($other_attrs)* $vis const $name: $crate::thread::LocalKey<$t> =
+            $crate::thread::local_impl::thread_local_inner!(@key $t, $($align_attrs)*, $init);
+
+        $($($crate::thread::local_impl::thread_local_process_attrs!([] []; $($rest)+);)?)?
+    ),
+}
+
+/// Declare a new thread local storage key of type [`std::thread::LocalKey`].
+///
+/// # Syntax
+///
+/// The macro wraps any number of static declarations and makes them thread local.
+/// Publicity and attributes for each static are allowed. Example:
+///
+/// ```
+/// use std::cell::{Cell, RefCell};
+///
+/// thread_local! {
+///     pub static FOO: Cell<u32> = const { Cell::new(1) };
+///
+///     static BAR: RefCell<Vec<f32>> = RefCell::new(vec![1.0, 2.0]);
+/// }
+///
+/// assert_eq!(FOO.get(), 1);
+/// BAR.with_borrow(|v| assert_eq!(v[1], 2.0));
+/// ```
+///
+/// Note that only shared references (`&T`) to the inner data may be obtained, so a
+/// type such as [`Cell`] or [`RefCell`] is typically used to allow mutating access.
+///
+/// This macro supports a special `const {}` syntax that can be used
+/// when the initialization expression can be evaluated as a constant.
+/// This can enable a more efficient thread local implementation that
+/// can avoid lazy initialization. For types that do not
+/// [need to be dropped][crate::mem::needs_drop], this can enable an
+/// even more efficient implementation that does not need to
+/// track any additional state.
+///
+/// ```
+/// use std::cell::RefCell;
+///
+/// thread_local! {
+///     pub static FOO: RefCell<Vec<u32>> = const { RefCell::new(Vec::new()) };
+/// }
+///
+/// FOO.with_borrow(|v| assert_eq!(v.len(), 0));
+/// ```
+///
+/// See [`LocalKey` documentation][`std::thread::LocalKey`] for more
+/// information.
+///
+/// [`std::thread::LocalKey`]: crate::thread::LocalKey
+#[macro_export]
+#[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(not(test), rustc_diagnostic_item = "thread_local_macro")]
+#[allow_internal_unstable(thread_local_internals)]
+macro_rules! thread_local {
+    () => {};
+
+    ($($tt:tt)+) => {
+        $crate::thread::local_impl::thread_local_process_attrs!([] []; $($tt)+);
+    };
+}
+
+/// An error returned by [`LocalKey::try_with`](struct.LocalKey.html#method.try_with).
+#[stable(feature = "thread_local_try_with", since = "1.26.0")]
+#[non_exhaustive]
+#[derive(Clone, Copy, Eq, PartialEq)]
+pub struct AccessError;
+
+#[stable(feature = "thread_local_try_with", since = "1.26.0")]
+impl fmt::Debug for AccessError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("AccessError").finish()
+    }
+}
+
+#[stable(feature = "thread_local_try_with", since = "1.26.0")]
+impl fmt::Display for AccessError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt("already destroyed", f)
+    }
+}
+
+#[stable(feature = "thread_local_try_with", since = "1.26.0")]
+impl Error for AccessError {}
+
+// This ensures the panicking code is outlined from `with` for `LocalKey`.
+#[cfg_attr(not(panic = "immediate-abort"), inline(never))]
+#[track_caller]
+#[cold]
+fn panic_access_error(err: AccessError) -> ! {
+    panic!("cannot access a Thread Local Storage value during or after destruction: {err:?}")
+}
+
+impl<T: 'static> LocalKey<T> {
+    #[doc(hidden)]
+    #[unstable(
+        feature = "thread_local_internals",
+        reason = "recently added to create a key",
+        issue = "none"
+    )]
+    pub const unsafe fn new(inner: fn(Option<&mut Option<T>>) -> *const T) -> LocalKey<T> {
+        LocalKey { inner }
+    }
+
+    /// Acquires a reference to the value in this TLS key.
+    ///
+    /// This will lazily initialize the value if this thread has not referenced
+    /// this key yet.
+    ///
+    /// # Panics
+    ///
+    /// This function will `panic!()` if the key currently has its
+    /// destructor running, and it **may** panic if the destructor has
+    /// previously been run for this thread.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// thread_local! {
+    ///     pub static STATIC: String = String::from("I am");
+    /// }
+    ///
+    /// assert_eq!(
+    ///     STATIC.with(|original_value| format!("{original_value} initialized")),
+    ///     "I am initialized",
+    /// );
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn with<F, R>(&'static self, f: F) -> R
+    where
+        F: FnOnce(&T) -> R,
+    {
+        match self.try_with(f) {
+            Ok(r) => r,
+            Err(err) => panic_access_error(err),
+        }
+    }
+
+    /// Acquires a reference to the value in this TLS key.
+    ///
+    /// This will lazily initialize the value if this thread has not referenced
+    /// this key yet. If the key has been destroyed (which may happen if this is called
+    /// in a destructor), this function will return an [`AccessError`].
+    ///
+    /// # Panics
+    ///
+    /// This function will still `panic!()` if the key is uninitialized and the
+    /// key's initializer panics.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// thread_local! {
+    ///     pub static STATIC: String = String::from("I am");
+    /// }
+    ///
+    /// assert_eq!(
+    ///     STATIC.try_with(|original_value| format!("{original_value} initialized")),
+    ///     Ok(String::from("I am initialized")),
+    /// );
+    /// ```
+    #[stable(feature = "thread_local_try_with", since = "1.26.0")]
+    #[inline]
+    pub fn try_with<F, R>(&'static self, f: F) -> Result<R, AccessError>
+    where
+        F: FnOnce(&T) -> R,
+    {
+        let thread_local = unsafe { (self.inner)(None).as_ref().ok_or(AccessError)? };
+        Ok(f(thread_local))
+    }
+
+    /// Acquires a reference to the value in this TLS key, initializing it with
+    /// `init` if it wasn't already initialized on this thread.
+    ///
+    /// If `init` was used to initialize the thread local variable, `None` is
+    /// passed as the first argument to `f`. If it was already initialized,
+    /// `Some(init)` is passed to `f`.
+    ///
+    /// # Panics
+    ///
+    /// This function will panic if the key currently has its destructor
+    /// running, and it **may** panic if the destructor has previously been run
+    /// for this thread.
+    fn initialize_with<F, R>(&'static self, init: T, f: F) -> R
+    where
+        F: FnOnce(Option<T>, &T) -> R,
+    {
+        let mut init = Some(init);
+
+        let reference = unsafe {
+            match (self.inner)(Some(&mut init)).as_ref() {
+                Some(r) => r,
+                None => panic_access_error(AccessError),
+            }
+        };
+
+        f(init, reference)
+    }
+}
+
+impl<T: 'static> LocalKey<Cell<T>> {
+    /// Sets or initializes the contained value.
+    ///
+    /// Unlike the other methods, this will *not* run the lazy initializer of
+    /// the thread local. Instead, it will be directly initialized with the
+    /// given value if it wasn't initialized yet.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the key currently has its destructor running,
+    /// and it **may** panic if the destructor has previously been run for this thread.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::cell::Cell;
+    ///
+    /// thread_local! {
+    ///     static X: Cell<i32> = panic!("!");
+    /// }
+    ///
+    /// // Calling X.get() here would result in a panic.
+    ///
+    /// X.set(123); // But X.set() is fine, as it skips the initializer above.
+    ///
+    /// assert_eq!(X.get(), 123);
+    /// ```
+    #[stable(feature = "local_key_cell_methods", since = "1.73.0")]
+    pub fn set(&'static self, value: T) {
+        self.initialize_with(Cell::new(value), |value, cell| {
+            if let Some(value) = value {
+                // The cell was already initialized, so `value` wasn't used to
+                // initialize it. So we overwrite the current value with the
+                // new one instead.
+                cell.set(value.into_inner());
+            }
+        });
+    }
+
+    /// Returns a copy of the contained value.
+    ///
+    /// This will lazily initialize the value if this thread has not referenced
+    /// this key yet.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the key currently has its destructor running,
+    /// and it **may** panic if the destructor has previously been run for this thread.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::cell::Cell;
+    ///
+    /// thread_local! {
+    ///     static X: Cell<i32> = const { Cell::new(1) };
+    /// }
+    ///
+    /// assert_eq!(X.get(), 1);
+    /// ```
+    #[stable(feature = "local_key_cell_methods", since = "1.73.0")]
+    pub fn get(&'static self) -> T
+    where
+        T: Copy,
+    {
+        self.with(Cell::get)
+    }
+
+    /// Takes the contained value, leaving `Default::default()` in its place.
+    ///
+    /// This will lazily initialize the value if this thread has not referenced
+    /// this key yet.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the key currently has its destructor running,
+    /// and it **may** panic if the destructor has previously been run for this thread.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::cell::Cell;
+    ///
+    /// thread_local! {
+    ///     static X: Cell<Option<i32>> = const { Cell::new(Some(1)) };
+    /// }
+    ///
+    /// assert_eq!(X.take(), Some(1));
+    /// assert_eq!(X.take(), None);
+    /// ```
+    #[stable(feature = "local_key_cell_methods", since = "1.73.0")]
+    pub fn take(&'static self) -> T
+    where
+        T: Default,
+    {
+        self.with(Cell::take)
+    }
+
+    /// Replaces the contained value, returning the old value.
+    ///
+    /// This will lazily initialize the value if this thread has not referenced
+    /// this key yet.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the key currently has its destructor running,
+    /// and it **may** panic if the destructor has previously been run for this thread.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::cell::Cell;
+    ///
+    /// thread_local! {
+    ///     static X: Cell<i32> = const { Cell::new(1) };
+    /// }
+    ///
+    /// assert_eq!(X.replace(2), 1);
+    /// assert_eq!(X.replace(3), 2);
+    /// ```
+    #[stable(feature = "local_key_cell_methods", since = "1.73.0")]
+    #[rustc_confusables("swap")]
+    pub fn replace(&'static self, value: T) -> T {
+        self.with(|cell| cell.replace(value))
+    }
+
+    /// Updates the contained value using a function.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(local_key_cell_update)]
+    /// use std::cell::Cell;
+    ///
+    /// thread_local! {
+    ///     static X: Cell<i32> = const { Cell::new(5) };
+    /// }
+    ///
+    /// X.update(|x| x + 1);
+    /// assert_eq!(X.get(), 6);
+    /// ```
+    #[unstable(feature = "local_key_cell_update", issue = "143989")]
+    pub fn update(&'static self, f: impl FnOnce(T) -> T)
+    where
+        T: Copy,
+    {
+        self.with(|cell| cell.update(f))
+    }
+}
+
+impl<T: 'static> LocalKey<RefCell<T>> {
+    /// Acquires a reference to the contained value.
+    ///
+    /// This will lazily initialize the value if this thread has not referenced
+    /// this key yet.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the value is currently mutably borrowed.
+    ///
+    /// Panics if the key currently has its destructor running,
+    /// and it **may** panic if the destructor has previously been run for this thread.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::cell::RefCell;
+    ///
+    /// thread_local! {
+    ///     static X: RefCell<Vec<i32>> = RefCell::new(Vec::new());
+    /// }
+    ///
+    /// X.with_borrow(|v| assert!(v.is_empty()));
+    /// ```
+    #[stable(feature = "local_key_cell_methods", since = "1.73.0")]
+    pub fn with_borrow<F, R>(&'static self, f: F) -> R
+    where
+        F: FnOnce(&T) -> R,
+    {
+        self.with(|cell| f(&cell.borrow()))
+    }
+
+    /// Acquires a mutable reference to the contained value.
+    ///
+    /// This will lazily initialize the value if this thread has not referenced
+    /// this key yet.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the value is currently borrowed.
+    ///
+    /// Panics if the key currently has its destructor running,
+    /// and it **may** panic if the destructor has previously been run for this thread.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::cell::RefCell;
+    ///
+    /// thread_local! {
+    ///     static X: RefCell<Vec<i32>> = RefCell::new(Vec::new());
+    /// }
+    ///
+    /// X.with_borrow_mut(|v| v.push(1));
+    ///
+    /// X.with_borrow(|v| assert_eq!(*v, vec![1]));
+    /// ```
+    #[stable(feature = "local_key_cell_methods", since = "1.73.0")]
+    pub fn with_borrow_mut<F, R>(&'static self, f: F) -> R
+    where
+        F: FnOnce(&mut T) -> R,
+    {
+        self.with(|cell| f(&mut cell.borrow_mut()))
+    }
+
+    /// Sets or initializes the contained value.
+    ///
+    /// Unlike the other methods, this will *not* run the lazy initializer of
+    /// the thread local. Instead, it will be directly initialized with the
+    /// given value if it wasn't initialized yet.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the value is currently borrowed.
+    ///
+    /// Panics if the key currently has its destructor running,
+    /// and it **may** panic if the destructor has previously been run for this thread.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::cell::RefCell;
+    ///
+    /// thread_local! {
+    ///     static X: RefCell<Vec<i32>> = panic!("!");
+    /// }
+    ///
+    /// // Calling X.with() here would result in a panic.
+    ///
+    /// X.set(vec![1, 2, 3]); // But X.set() is fine, as it skips the initializer above.
+    ///
+    /// X.with_borrow(|v| assert_eq!(*v, vec![1, 2, 3]));
+    /// ```
+    #[stable(feature = "local_key_cell_methods", since = "1.73.0")]
+    pub fn set(&'static self, value: T) {
+        self.initialize_with(RefCell::new(value), |value, cell| {
+            if let Some(value) = value {
+                // The cell was already initialized, so `value` wasn't used to
+                // initialize it. So we overwrite the current value with the
+                // new one instead.
+                *cell.borrow_mut() = value.into_inner();
+            }
+        });
+    }
+
+    /// Takes the contained value, leaving `Default::default()` in its place.
+    ///
+    /// This will lazily initialize the value if this thread has not referenced
+    /// this key yet.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the value is currently borrowed.
+    ///
+    /// Panics if the key currently has its destructor running,
+    /// and it **may** panic if the destructor has previously been run for this thread.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::cell::RefCell;
+    ///
+    /// thread_local! {
+    ///     static X: RefCell<Vec<i32>> = RefCell::new(Vec::new());
+    /// }
+    ///
+    /// X.with_borrow_mut(|v| v.push(1));
+    ///
+    /// let a = X.take();
+    ///
+    /// assert_eq!(a, vec![1]);
+    ///
+    /// X.with_borrow(|v| assert!(v.is_empty()));
+    /// ```
+    #[stable(feature = "local_key_cell_methods", since = "1.73.0")]
+    pub fn take(&'static self) -> T
+    where
+        T: Default,
+    {
+        self.with(RefCell::take)
+    }
+
+    /// Replaces the contained value, returning the old value.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the value is currently borrowed.
+    ///
+    /// Panics if the key currently has its destructor running,
+    /// and it **may** panic if the destructor has previously been run for this thread.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::cell::RefCell;
+    ///
+    /// thread_local! {
+    ///     static X: RefCell<Vec<i32>> = RefCell::new(Vec::new());
+    /// }
+    ///
+    /// let prev = X.replace(vec![1, 2, 3]);
+    /// assert!(prev.is_empty());
+    ///
+    /// X.with_borrow(|v| assert_eq!(*v, vec![1, 2, 3]));
+    /// ```
+    #[stable(feature = "local_key_cell_methods", since = "1.73.0")]
+    #[rustc_confusables("swap")]
+    pub fn replace(&'static self, value: T) -> T {
+        self.with(|cell| cell.replace(value))
+    }
+}

crates/std/src/time.rs

@@ -0,0 +1,859 @@
+//! Temporal quantification.
+//!
+//! # Examples
+//!
+//! There are multiple ways to create a new [`Duration`]:
+//!
+//! ```
+//! # use std::time::Duration;
+//! let five_seconds = Duration::from_secs(5);
+//! assert_eq!(five_seconds, Duration::from_millis(5_000));
+//! assert_eq!(five_seconds, Duration::from_micros(5_000_000));
+//! assert_eq!(five_seconds, Duration::from_nanos(5_000_000_000));
+//!
+//! let ten_seconds = Duration::from_secs(10);
+//! let seven_nanos = Duration::from_nanos(7);
+//! let total = ten_seconds + seven_nanos;
+//! assert_eq!(total, Duration::new(10, 7));
+//! ```
+//!
+//! Using [`Instant`] to calculate how long a function took to run:
+//!
+//! ```ignore (incomplete)
+//! let now = Instant::now();
+//!
+//! // Calling a slow function, it may take a while
+//! slow_function();
+//!
+//! let elapsed_time = now.elapsed();
+//! println!("Running slow_function() took {} seconds.", elapsed_time.as_secs());
+//! ```
+
+#![stable(feature = "time", since = "1.3.0")]
+
+#[stable(feature = "time", since = "1.3.0")]
+pub use core::time::Duration;
+#[stable(feature = "duration_checked_float", since = "1.66.0")]
+pub use core::time::TryFromFloatSecsError;
+
+use crate::error::Error;
+use crate::fmt;
+use crate::ops::{Add, AddAssign, Sub, SubAssign};
+use crate::sys::{FromInner, IntoInner, time};
+
+/// A measurement of a monotonically nondecreasing clock.
+/// Opaque and useful only with [`Duration`].
+///
+/// Instants are always guaranteed, barring [platform bugs], to be no less than any previously
+/// measured instant when created, and are often useful for tasks such as measuring
+/// benchmarks or timing how long an operation takes.
+///
+/// Note, however, that instants are **not** guaranteed to be **steady**. In other
+/// words, each tick of the underlying clock might not be the same length (e.g.
+/// some seconds may be longer than others). An instant may jump forwards or
+/// experience time dilation (slow down or speed up), but it will never go
+/// backwards.
+/// As part of this non-guarantee it is also not specified whether system suspends count as
+/// elapsed time or not. The behavior varies across platforms and Rust versions.
+///
+/// Instants are opaque types that can only be compared to one another. There is
+/// no method to get "the number of seconds" from an instant. Instead, it only
+/// allows measuring the duration between two instants (or comparing two
+/// instants).
+///
+/// The size of an `Instant` struct may vary depending on the target operating
+/// system.
+///
+/// Example:
+///
+/// ```no_run
+/// use std::time::{Duration, Instant};
+/// use std::thread::sleep;
+///
+/// fn main() {
+///    let now = Instant::now();
+///
+///    // we sleep for 2 seconds
+///    sleep(Duration::new(2, 0));
+///    // it prints '2'
+///    println!("{}", now.elapsed().as_secs());
+/// }
+/// ```
+///
+/// [platform bugs]: Instant#monotonicity
+///
+/// # OS-specific behaviors
+///
+/// An `Instant` is a wrapper around system-specific types and it may behave
+/// differently depending on the underlying operating system. For example,
+/// the following snippet is fine on Linux but panics on macOS:
+///
+/// ```no_run
+/// use std::time::{Instant, Duration};
+///
+/// let now = Instant::now();
+/// let days_per_10_millennia = 365_2425;
+/// let solar_seconds_per_day = 60 * 60 * 24;
+/// let millennium_in_solar_seconds = 31_556_952_000;
+/// assert_eq!(millennium_in_solar_seconds, days_per_10_millennia * solar_seconds_per_day / 10);
+///
+/// let duration = Duration::new(millennium_in_solar_seconds, 0);
+/// println!("{:?}", now + duration);
+/// ```
+///
+/// For cross-platform code, you can comfortably use durations of up to around one hundred years.
+///
+/// # Underlying System calls
+///
+/// The following system calls are [currently] being used by `now()` to find out
+/// the current time:
+///
+/// |  Platform |               System call                                            |
+/// |-----------|----------------------------------------------------------------------|
+/// | SGX       | [`insecure_time` usercall]. More information on [timekeeping in SGX] |
+/// | UNIX      | [clock_gettime] with `CLOCK_MONOTONIC`                               |
+/// | Darwin    | [clock_gettime] with `CLOCK_UPTIME_RAW`                              |
+/// | VXWorks   | [clock_gettime] with `CLOCK_MONOTONIC`                               |
+/// | SOLID     | `get_tim`                                                            |
+/// | WASI      | [__wasi_clock_time_get] with `monotonic`                             |
+/// | Windows   | [QueryPerformanceCounter]                                            |
+///
+/// [currently]: crate::io#platform-specific-behavior
+/// [QueryPerformanceCounter]: https://docs.microsoft.com/en-us/windows/win32/api/profileapi/nf-profileapi-queryperformancecounter
+/// [`insecure_time` usercall]: https://edp.fortanix.com/docs/api/fortanix_sgx_abi/struct.Usercalls.html#method.insecure_time
+/// [timekeeping in SGX]: https://edp.fortanix.com/docs/concepts/rust-std/#codestdtimecode
+/// [__wasi_clock_time_get]: https://github.com/WebAssembly/WASI/blob/main/legacy/preview1/docs.md#clock_time_get
+/// [clock_gettime]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/clock_getres.html
+///
+/// **Disclaimer:** These system calls might change over time.
+///
+/// > Note: mathematical operations like [`add`] may panic if the underlying
+/// > structure cannot represent the new point in time.
+///
+/// [`add`]: Instant::add
+///
+/// ## Monotonicity
+///
+/// On all platforms `Instant` will try to use an OS API that guarantees monotonic behavior
+/// if available, which is the case for all [tier 1] platforms.
+/// In practice such guarantees are – under rare circumstances – broken by hardware, virtualization
+/// or operating system bugs. To work around these bugs and platforms not offering monotonic clocks
+/// [`duration_since`], [`elapsed`] and [`sub`] saturate to zero. In older Rust versions this
+/// lead to a panic instead. [`checked_duration_since`] can be used to detect and handle situations
+/// where monotonicity is violated, or `Instant`s are subtracted in the wrong order.
+///
+/// This workaround obscures programming errors where earlier and later instants are accidentally
+/// swapped. For this reason future Rust versions may reintroduce panics.
+///
+/// [tier 1]: https://doc.rust-lang.org/rustc/platform-support.html
+/// [`duration_since`]: Instant::duration_since
+/// [`elapsed`]: Instant::elapsed
+/// [`sub`]: Instant::sub
+/// [`checked_duration_since`]: Instant::checked_duration_since
+///
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[stable(feature = "time2", since = "1.8.0")]
+#[cfg_attr(not(test), rustc_diagnostic_item = "Instant")]
+pub struct Instant(time::Instant);
+
+/// A measurement of the system clock, useful for talking to
+/// external entities like the file system or other processes.
+///
+/// Distinct from the [`Instant`] type, this time measurement **is not
+/// monotonic**. This means that you can save a file to the file system, then
+/// save another file to the file system, **and the second file has a
+/// `SystemTime` measurement earlier than the first**. In other words, an
+/// operation that happens after another operation in real time may have an
+/// earlier `SystemTime`!
+///
+/// Consequently, comparing two `SystemTime` instances to learn about the
+/// duration between them returns a [`Result`] instead of an infallible [`Duration`]
+/// to indicate that this sort of time drift may happen and needs to be handled.
+///
+/// Although a `SystemTime` cannot be directly inspected, the [`UNIX_EPOCH`]
+/// constant is provided in this module as an anchor in time to learn
+/// information about a `SystemTime`. By calculating the duration from this
+/// fixed point in time, a `SystemTime` can be converted to a human-readable time,
+/// or perhaps some other string representation.
+///
+/// The size of a `SystemTime` struct may vary depending on the target operating
+/// system.
+///
+/// A `SystemTime` does not count leap seconds.
+/// `SystemTime::now()`'s behavior around a leap second
+/// is the same as the operating system's wall clock.
+/// The precise behavior near a leap second
+/// (e.g. whether the clock appears to run slow or fast, or stop, or jump)
+/// depends on platform and configuration,
+/// so should not be relied on.
+///
+/// Example:
+///
+/// ```no_run
+/// use std::time::{Duration, SystemTime};
+/// use std::thread::sleep;
+///
+/// fn main() {
+///    let now = SystemTime::now();
+///
+///    // we sleep for 2 seconds
+///    sleep(Duration::new(2, 0));
+///    match now.elapsed() {
+///        Ok(elapsed) => {
+///            // it prints '2'
+///            println!("{}", elapsed.as_secs());
+///        }
+///        Err(e) => {
+///            // the system clock went backwards!
+///            println!("Great Scott! {e:?}");
+///        }
+///    }
+/// }
+/// ```
+///
+/// # Platform-specific behavior
+///
+/// The precision of `SystemTime` can depend on the underlying OS-specific time format.
+/// For example, on Windows the time is represented in 100 nanosecond intervals whereas Linux
+/// can represent nanosecond intervals.
+///
+/// The following system calls are [currently] being used by `now()` to find out
+/// the current time:
+///
+/// |  Platform |               System call                                            |
+/// |-----------|----------------------------------------------------------------------|
+/// | SGX       | [`insecure_time` usercall]. More information on [timekeeping in SGX] |
+/// | UNIX      | [clock_gettime (Realtime Clock)]                                     |
+/// | Darwin    | [clock_gettime (Realtime Clock)]                                     |
+/// | VXWorks   | [clock_gettime (Realtime Clock)]                                     |
+/// | SOLID     | `SOLID_RTC_ReadTime`                                                 |
+/// | WASI      | [__wasi_clock_time_get (Realtime Clock)]                             |
+/// | Windows   | [GetSystemTimePreciseAsFileTime] / [GetSystemTimeAsFileTime]         |
+///
+/// [currently]: crate::io#platform-specific-behavior
+/// [`insecure_time` usercall]: https://edp.fortanix.com/docs/api/fortanix_sgx_abi/struct.Usercalls.html#method.insecure_time
+/// [timekeeping in SGX]: https://edp.fortanix.com/docs/concepts/rust-std/#codestdtimecode
+/// [clock_gettime (Realtime Clock)]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/clock_getres.html
+/// [__wasi_clock_time_get (Realtime Clock)]: https://github.com/WebAssembly/WASI/blob/main/legacy/preview1/docs.md#clock_time_get
+/// [GetSystemTimePreciseAsFileTime]: https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/nf-sysinfoapi-getsystemtimepreciseasfiletime
+/// [GetSystemTimeAsFileTime]: https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/nf-sysinfoapi-getsystemtimeasfiletime
+///
+/// **Disclaimer:** These system calls might change over time.
+///
+/// > Note: mathematical operations like [`add`] may panic if the underlying
+/// > structure cannot represent the new point in time.
+///
+/// [`add`]: SystemTime::add
+/// [`UNIX_EPOCH`]: SystemTime::UNIX_EPOCH
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[stable(feature = "time2", since = "1.8.0")]
+pub struct SystemTime(time::SystemTime);
+
+/// An error returned from the `duration_since` and `elapsed` methods on
+/// `SystemTime`, used to learn how far in the opposite direction a system time
+/// lies.
+///
+/// # Examples
+///
+/// ```no_run
+/// use std::thread::sleep;
+/// use std::time::{Duration, SystemTime};
+///
+/// let sys_time = SystemTime::now();
+/// sleep(Duration::from_secs(1));
+/// let new_sys_time = SystemTime::now();
+/// match sys_time.duration_since(new_sys_time) {
+///     Ok(_) => {}
+///     Err(e) => println!("SystemTimeError difference: {:?}", e.duration()),
+/// }
+/// ```
+#[derive(Clone, Debug)]
+#[stable(feature = "time2", since = "1.8.0")]
+pub struct SystemTimeError(Duration);
+
+impl Instant {
+    /// Returns an instant corresponding to "now".
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::time::Instant;
+    ///
+    /// let now = Instant::now();
+    /// ```
+    #[must_use]
+    #[stable(feature = "time2", since = "1.8.0")]
+    #[cfg_attr(not(test), rustc_diagnostic_item = "instant_now")]
+    pub fn now() -> Instant {
+        Instant(time::Instant::now())
+    }
+
+    /// Returns the amount of time elapsed from another instant to this one,
+    /// or zero duration if that instant is later than this one.
+    ///
+    /// # Panics
+    ///
+    /// Previous Rust versions panicked when `earlier` was later than `self`. Currently this
+    /// method saturates. Future versions may reintroduce the panic in some circumstances.
+    /// See [Monotonicity].
+    ///
+    /// [Monotonicity]: Instant#monotonicity
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::time::{Duration, Instant};
+    /// use std::thread::sleep;
+    ///
+    /// let now = Instant::now();
+    /// sleep(Duration::new(1, 0));
+    /// let new_now = Instant::now();
+    /// println!("{:?}", new_now.duration_since(now));
+    /// println!("{:?}", now.duration_since(new_now)); // 0ns
+    /// ```
+    #[must_use]
+    #[stable(feature = "time2", since = "1.8.0")]
+    pub fn duration_since(&self, earlier: Instant) -> Duration {
+        self.checked_duration_since(earlier).unwrap_or_default()
+    }
+
+    /// Returns the amount of time elapsed from another instant to this one,
+    /// or None if that instant is later than this one.
+    ///
+    /// Due to [monotonicity bugs], even under correct logical ordering of the passed `Instant`s,
+    /// this method can return `None`.
+    ///
+    /// [monotonicity bugs]: Instant#monotonicity
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::time::{Duration, Instant};
+    /// use std::thread::sleep;
+    ///
+    /// let now = Instant::now();
+    /// sleep(Duration::new(1, 0));
+    /// let new_now = Instant::now();
+    /// println!("{:?}", new_now.checked_duration_since(now));
+    /// println!("{:?}", now.checked_duration_since(new_now)); // None
+    /// ```
+    #[must_use]
+    #[stable(feature = "checked_duration_since", since = "1.39.0")]
+    pub fn checked_duration_since(&self, earlier: Instant) -> Option<Duration> {
+        self.0.checked_sub_instant(&earlier.0)
+    }
+
+    /// Returns the amount of time elapsed from another instant to this one,
+    /// or zero duration if that instant is later than this one.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::time::{Duration, Instant};
+    /// use std::thread::sleep;
+    ///
+    /// let now = Instant::now();
+    /// sleep(Duration::new(1, 0));
+    /// let new_now = Instant::now();
+    /// println!("{:?}", new_now.saturating_duration_since(now));
+    /// println!("{:?}", now.saturating_duration_since(new_now)); // 0ns
+    /// ```
+    #[must_use]
+    #[stable(feature = "checked_duration_since", since = "1.39.0")]
+    pub fn saturating_duration_since(&self, earlier: Instant) -> Duration {
+        self.checked_duration_since(earlier).unwrap_or_default()
+    }
+
+    /// Returns the amount of time elapsed since this instant.
+    ///
+    /// # Panics
+    ///
+    /// Previous Rust versions panicked when the current time was earlier than self. Currently this
+    /// method returns a Duration of zero in that case. Future versions may reintroduce the panic.
+    /// See [Monotonicity].
+    ///
+    /// [Monotonicity]: Instant#monotonicity
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::thread::sleep;
+    /// use std::time::{Duration, Instant};
+    ///
+    /// let instant = Instant::now();
+    /// let three_secs = Duration::from_secs(3);
+    /// sleep(three_secs);
+    /// assert!(instant.elapsed() >= three_secs);
+    /// ```
+    #[must_use]
+    #[stable(feature = "time2", since = "1.8.0")]
+    pub fn elapsed(&self) -> Duration {
+        Instant::now() - *self
+    }
+
+    /// Returns `Some(t)` where `t` is the time `self + duration` if `t` can be represented as
+    /// `Instant` (which means it's inside the bounds of the underlying data structure), `None`
+    /// otherwise.
+    #[stable(feature = "time_checked_add", since = "1.34.0")]
+    pub fn checked_add(&self, duration: Duration) -> Option<Instant> {
+        self.0.checked_add_duration(&duration).map(Instant)
+    }
+
+    /// Returns `Some(t)` where `t` is the time `self - duration` if `t` can be represented as
+    /// `Instant` (which means it's inside the bounds of the underlying data structure), `None`
+    /// otherwise.
+    #[stable(feature = "time_checked_add", since = "1.34.0")]
+    pub fn checked_sub(&self, duration: Duration) -> Option<Instant> {
+        self.0.checked_sub_duration(&duration).map(Instant)
+    }
+
+    // Used by platform specific `sleep_until` implementations such as the one used on Linux.
+    #[cfg_attr(
+        not(target_os = "linux"),
+        allow(unused, reason = "not every platform has a specific `sleep_until`")
+    )]
+    pub(crate) fn into_inner(self) -> time::Instant {
+        self.0
+    }
+}
+
+#[stable(feature = "time2", since = "1.8.0")]
+impl Add<Duration> for Instant {
+    type Output = Instant;
+
+    /// # Panics
+    ///
+    /// This function may panic if the resulting point in time cannot be represented by the
+    /// underlying data structure. See [`Instant::checked_add`] for a version without panic.
+    fn add(self, other: Duration) -> Instant {
+        self.checked_add(other).expect("overflow when adding duration to instant")
+    }
+}
+
+#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
+impl AddAssign<Duration> for Instant {
+    fn add_assign(&mut self, other: Duration) {
+        *self = *self + other;
+    }
+}
+
+#[stable(feature = "time2", since = "1.8.0")]
+impl Sub<Duration> for Instant {
+    type Output = Instant;
+
+    fn sub(self, other: Duration) -> Instant {
+        self.checked_sub(other).expect("overflow when subtracting duration from instant")
+    }
+}
+
+#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
+impl SubAssign<Duration> for Instant {
+    fn sub_assign(&mut self, other: Duration) {
+        *self = *self - other;
+    }
+}
+
+#[stable(feature = "time2", since = "1.8.0")]
+impl Sub<Instant> for Instant {
+    type Output = Duration;
+
+    /// Returns the amount of time elapsed from another instant to this one,
+    /// or zero duration if that instant is later than this one.
+    ///
+    /// # Panics
+    ///
+    /// Previous Rust versions panicked when `other` was later than `self`. Currently this
+    /// method saturates. Future versions may reintroduce the panic in some circumstances.
+    /// See [Monotonicity].
+    ///
+    /// [Monotonicity]: Instant#monotonicity
+    fn sub(self, other: Instant) -> Duration {
+        self.duration_since(other)
+    }
+}
+
+#[stable(feature = "time2", since = "1.8.0")]
+impl fmt::Debug for Instant {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+impl SystemTime {
+    /// An anchor in time which can be used to create new `SystemTime` instances or
+    /// learn about where in time a `SystemTime` lies.
+    //
+    // NOTE! this documentation is duplicated, here and in std::time::UNIX_EPOCH.
+    // The two copies are not quite identical, because of the difference in naming.
+    ///
+    /// This constant is defined to be "1970-01-01 00:00:00 UTC" on all systems with
+    /// respect to the system clock. Using `duration_since` on an existing
+    /// `SystemTime` instance can tell how far away from this point in time a
+    /// measurement lies, and using `UNIX_EPOCH + duration` can be used to create a
+    /// `SystemTime` instance to represent another fixed point in time.
+    ///
+    /// `duration_since(UNIX_EPOCH).unwrap().as_secs()` returns
+    /// the number of non-leap seconds since the start of 1970 UTC.
+    /// This is a POSIX `time_t` (as a `u64`),
+    /// and is the same time representation as used in many Internet protocols.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::time::SystemTime;
+    ///
+    /// match SystemTime::now().duration_since(SystemTime::UNIX_EPOCH) {
+    ///     Ok(n) => println!("1970-01-01 00:00:00 UTC was {} seconds ago!", n.as_secs()),
+    ///     Err(_) => panic!("SystemTime before UNIX EPOCH!"),
+    /// }
+    /// ```
+    #[stable(feature = "assoc_unix_epoch", since = "1.28.0")]
+    pub const UNIX_EPOCH: SystemTime = UNIX_EPOCH;
+
+    /// Represents the maximum value representable by [`SystemTime`] on this platform.
+    ///
+    /// This value differs a lot between platforms, but it is always the case
+    /// that any positive addition of a [`Duration`], whose value is greater
+    /// than or equal to the time precision of the operating system, to
+    /// [`SystemTime::MAX`] will fail.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// #![feature(time_systemtime_limits)]
+    /// use std::time::{Duration, SystemTime};
+    ///
+    /// // Adding zero will change nothing.
+    /// assert_eq!(SystemTime::MAX.checked_add(Duration::ZERO), Some(SystemTime::MAX));
+    ///
+    /// // But adding just one second will already fail ...
+    /// //
+    /// // Keep in mind that this in fact may succeed, if the Duration is
+    /// // smaller than the time precision of the operating system, which
+    /// // happens to be 1ns on most operating systems, with Windows being the
+    /// // notable exception by using 100ns, hence why this example uses 1s.
+    /// assert_eq!(SystemTime::MAX.checked_add(Duration::new(1, 0)), None);
+    ///
+    /// // Utilize this for saturating arithmetic to improve error handling.
+    /// // In this case, we will use a certificate with a timestamp in the
+    /// // future as a practical example.
+    /// let configured_offset = Duration::from_secs(60 * 60 * 24);
+    /// let valid_after =
+    ///     SystemTime::now()
+    ///         .checked_add(configured_offset)
+    ///         .unwrap_or(SystemTime::MAX);
+    /// ```
+    #[unstable(feature = "time_systemtime_limits", issue = "149067")]
+    pub const MAX: SystemTime = SystemTime(time::SystemTime::MAX);
+
+    /// Represents the minimum value representable by [`SystemTime`] on this platform.
+    ///
+    /// This value differs a lot between platforms, but it is always the case
+    /// that any positive subtraction of a [`Duration`] from, whose value is
+    /// greater than or equal to the time precision of the operating system, to
+    /// [`SystemTime::MIN`] will fail.
+    ///
+    /// Depending on the platform, this may be either less than or equal to
+    /// [`SystemTime::UNIX_EPOCH`], depending on whether the operating system
+    /// supports the representation of timestamps before the Unix epoch or not.
+    /// However, it is always guaranteed that a [`SystemTime::UNIX_EPOCH`] fits
+    /// between a [`SystemTime::MIN`] and [`SystemTime::MAX`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(time_systemtime_limits)]
+    /// use std::time::{Duration, SystemTime};
+    ///
+    /// // Subtracting zero will change nothing.
+    /// assert_eq!(SystemTime::MIN.checked_sub(Duration::ZERO), Some(SystemTime::MIN));
+    ///
+    /// // But subtracting just one second will already fail.
+    /// //
+    /// // Keep in mind that this in fact may succeed, if the Duration is
+    /// // smaller than the time precision of the operating system, which
+    /// // happens to be 1ns on most operating systems, with Windows being the
+    /// // notable exception by using 100ns, hence why this example uses 1s.
+    /// assert_eq!(SystemTime::MIN.checked_sub(Duration::new(1, 0)), None);
+    ///
+    /// // Utilize this for saturating arithmetic to improve error handling.
+    /// // In this case, we will use a cache expiry as a practical example.
+    /// let configured_expiry = Duration::from_secs(60 * 3);
+    /// let expiry_threshold =
+    ///     SystemTime::now()
+    ///         .checked_sub(configured_expiry)
+    ///         .unwrap_or(SystemTime::MIN);
+    /// ```
+    #[unstable(feature = "time_systemtime_limits", issue = "149067")]
+    pub const MIN: SystemTime = SystemTime(time::SystemTime::MIN);
+
+    /// Returns the system time corresponding to "now".
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::time::SystemTime;
+    ///
+    /// let sys_time = SystemTime::now();
+    /// ```
+    #[must_use]
+    #[stable(feature = "time2", since = "1.8.0")]
+    pub fn now() -> SystemTime {
+        SystemTime(time::SystemTime::now())
+    }
+
+    /// Returns the amount of time elapsed from an earlier point in time.
+    ///
+    /// This function may fail because measurements taken earlier are not
+    /// guaranteed to always be before later measurements (due to anomalies such
+    /// as the system clock being adjusted either forwards or backwards).
+    /// [`Instant`] can be used to measure elapsed time without this risk of failure.
+    ///
+    /// If successful, <code>[Ok]\([Duration])</code> is returned where the duration represents
+    /// the amount of time elapsed from the specified measurement to this one.
+    ///
+    /// Returns an [`Err`] if `earlier` is later than `self`, and the error
+    /// contains how far from `self` the time is.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::time::SystemTime;
+    ///
+    /// let sys_time = SystemTime::now();
+    /// let new_sys_time = SystemTime::now();
+    /// let difference = new_sys_time.duration_since(sys_time)
+    ///     .expect("Clock may have gone backwards");
+    /// println!("{difference:?}");
+    /// ```
+    #[stable(feature = "time2", since = "1.8.0")]
+    pub fn duration_since(&self, earlier: SystemTime) -> Result<Duration, SystemTimeError> {
+        self.0.sub_time(&earlier.0).map_err(SystemTimeError)
+    }
+
+    /// Returns the difference from this system time to the
+    /// current clock time.
+    ///
+    /// This function may fail as the underlying system clock is susceptible to
+    /// drift and updates (e.g., the system clock could go backwards), so this
+    /// function might not always succeed. If successful, <code>[Ok]\([Duration])</code> is
+    /// returned where the duration represents the amount of time elapsed from
+    /// this time measurement to the current time.
+    ///
+    /// To measure elapsed time reliably, use [`Instant`] instead.
+    ///
+    /// Returns an [`Err`] if `self` is later than the current system time, and
+    /// the error contains how far from the current system time `self` is.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::thread::sleep;
+    /// use std::time::{Duration, SystemTime};
+    ///
+    /// let sys_time = SystemTime::now();
+    /// let one_sec = Duration::from_secs(1);
+    /// sleep(one_sec);
+    /// assert!(sys_time.elapsed().unwrap() >= one_sec);
+    /// ```
+    #[stable(feature = "time2", since = "1.8.0")]
+    pub fn elapsed(&self) -> Result<Duration, SystemTimeError> {
+        SystemTime::now().duration_since(*self)
+    }
+
+    /// Returns `Some(t)` where `t` is the time `self + duration` if `t` can be represented as
+    /// `SystemTime` (which means it's inside the bounds of the underlying data structure), `None`
+    /// otherwise.
+    ///
+    /// In the case that the `duration` is smaller than the time precision of the operating
+    /// system, `Some(self)` will be returned.
+    #[stable(feature = "time_checked_add", since = "1.34.0")]
+    pub fn checked_add(&self, duration: Duration) -> Option<SystemTime> {
+        self.0.checked_add_duration(&duration).map(SystemTime)
+    }
+
+    /// Returns `Some(t)` where `t` is the time `self - duration` if `t` can be represented as
+    /// `SystemTime` (which means it's inside the bounds of the underlying data structure), `None`
+    /// otherwise.
+    ///
+    /// In the case that the `duration` is smaller than the time precision of the operating
+    /// system, `Some(self)` will be returned.
+    #[stable(feature = "time_checked_add", since = "1.34.0")]
+    pub fn checked_sub(&self, duration: Duration) -> Option<SystemTime> {
+        self.0.checked_sub_duration(&duration).map(SystemTime)
+    }
+
+    /// Saturating [`SystemTime`] addition, computing `self + duration`,
+    /// returning [`SystemTime::MAX`] if overflow occurred.
+    ///
+    /// In the case that the `duration` is smaller than the time precision of
+    /// the operating system, `self` will be returned.
+    #[unstable(feature = "time_saturating_systemtime", issue = "151199")]
+    pub fn saturating_add(&self, duration: Duration) -> SystemTime {
+        self.checked_add(duration).unwrap_or(SystemTime::MAX)
+    }
+
+    /// Saturating [`SystemTime`] subtraction, computing `self - duration`,
+    /// returning [`SystemTime::MIN`] if overflow occurred.
+    ///
+    /// In the case that the `duration` is smaller than the time precision of
+    /// the operating system, `self` will be returned.
+    #[unstable(feature = "time_saturating_systemtime", issue = "151199")]
+    pub fn saturating_sub(&self, duration: Duration) -> SystemTime {
+        self.checked_sub(duration).unwrap_or(SystemTime::MIN)
+    }
+
+    /// Saturating computation of time elapsed from an earlier point in time,
+    /// returning [`Duration::ZERO`] in the case that `earlier` is later or
+    /// equal to `self`.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// #![feature(time_saturating_systemtime)]
+    /// use std::time::{Duration, SystemTime};
+    ///
+    /// let now = SystemTime::now();
+    /// let prev = now.saturating_sub(Duration::new(1, 0));
+    ///
+    /// // now - prev should return non-zero.
+    /// assert_eq!(now.saturating_duration_since(prev), Duration::new(1, 0));
+    /// assert!(now.duration_since(prev).is_ok());
+    ///
+    /// // prev - now should return zero (and fail with the non-saturating).
+    /// assert_eq!(prev.saturating_duration_since(now), Duration::ZERO);
+    /// assert!(prev.duration_since(now).is_err());
+    ///
+    /// // now - now should return zero (and work with the non-saturating).
+    /// assert_eq!(now.saturating_duration_since(now), Duration::ZERO);
+    /// assert!(now.duration_since(now).is_ok());
+    /// ```
+    #[unstable(feature = "time_saturating_systemtime", issue = "151199")]
+    pub fn saturating_duration_since(&self, earlier: SystemTime) -> Duration {
+        self.duration_since(earlier).unwrap_or(Duration::ZERO)
+    }
+}
+
+#[stable(feature = "time2", since = "1.8.0")]
+impl Add<Duration> for SystemTime {
+    type Output = SystemTime;
+
+    /// # Panics
+    ///
+    /// This function may panic if the resulting point in time cannot be represented by the
+    /// underlying data structure. See [`SystemTime::checked_add`] for a version without panic.
+    fn add(self, dur: Duration) -> SystemTime {
+        self.checked_add(dur).expect("overflow when adding duration to instant")
+    }
+}
+
+#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
+impl AddAssign<Duration> for SystemTime {
+    fn add_assign(&mut self, other: Duration) {
+        *self = *self + other;
+    }
+}
+
+#[stable(feature = "time2", since = "1.8.0")]
+impl Sub<Duration> for SystemTime {
+    type Output = SystemTime;
+
+    fn sub(self, dur: Duration) -> SystemTime {
+        self.checked_sub(dur).expect("overflow when subtracting duration from instant")
+    }
+}
+
+#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
+impl SubAssign<Duration> for SystemTime {
+    fn sub_assign(&mut self, other: Duration) {
+        *self = *self - other;
+    }
+}
+
+#[stable(feature = "time2", since = "1.8.0")]
+impl fmt::Debug for SystemTime {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+/// An anchor in time which can be used to create new `SystemTime` instances or
+/// learn about where in time a `SystemTime` lies.
+//
+// NOTE! this documentation is duplicated, here and in SystemTime::UNIX_EPOCH.
+// The two copies are not quite identical, because of the difference in naming.
+///
+/// This constant is defined to be "1970-01-01 00:00:00 UTC" on all systems with
+/// respect to the system clock. Using `duration_since` on an existing
+/// [`SystemTime`] instance can tell how far away from this point in time a
+/// measurement lies, and using `UNIX_EPOCH + duration` can be used to create a
+/// [`SystemTime`] instance to represent another fixed point in time.
+///
+/// `duration_since(UNIX_EPOCH).unwrap().as_secs()` returns
+/// the number of non-leap seconds since the start of 1970 UTC.
+/// This is a POSIX `time_t` (as a `u64`),
+/// and is the same time representation as used in many Internet protocols.
+///
+/// # Examples
+///
+/// ```no_run
+/// use std::time::{SystemTime, UNIX_EPOCH};
+///
+/// match SystemTime::now().duration_since(UNIX_EPOCH) {
+///     Ok(n) => println!("1970-01-01 00:00:00 UTC was {} seconds ago!", n.as_secs()),
+///     Err(_) => panic!("SystemTime before UNIX EPOCH!"),
+/// }
+/// ```
+#[stable(feature = "time2", since = "1.8.0")]
+pub const UNIX_EPOCH: SystemTime = SystemTime(time::UNIX_EPOCH);
+
+impl SystemTimeError {
+    /// Returns the positive duration which represents how far forward the
+    /// second system time was from the first.
+    ///
+    /// A `SystemTimeError` is returned from the [`SystemTime::duration_since`]
+    /// and [`SystemTime::elapsed`] methods whenever the second system time
+    /// represents a point later in time than the `self` of the method call.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::thread::sleep;
+    /// use std::time::{Duration, SystemTime};
+    ///
+    /// let sys_time = SystemTime::now();
+    /// sleep(Duration::from_secs(1));
+    /// let new_sys_time = SystemTime::now();
+    /// match sys_time.duration_since(new_sys_time) {
+    ///     Ok(_) => {}
+    ///     Err(e) => println!("SystemTimeError difference: {:?}", e.duration()),
+    /// }
+    /// ```
+    #[must_use]
+    #[stable(feature = "time2", since = "1.8.0")]
+    pub fn duration(&self) -> Duration {
+        self.0
+    }
+}
+
+#[stable(feature = "time2", since = "1.8.0")]
+impl Error for SystemTimeError {}
+
+#[stable(feature = "time2", since = "1.8.0")]
+impl fmt::Display for SystemTimeError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "second time provided was later than self")
+    }
+}
+
+impl FromInner<time::SystemTime> for SystemTime {
+    fn from_inner(time: time::SystemTime) -> SystemTime {
+        SystemTime(time)
+    }
+}
+
+impl IntoInner<time::SystemTime> for SystemTime {
+    fn into_inner(self) -> time::SystemTime {
+        self.0
+    }
+}

ilm.ld

@@ -5,7 +5,7 @@ OUTPUT_ARCH(riscv)
 ENTRY(_start)
 
 MEMORY {
-    RAM (wxa) : ORIGIN = 0x80000000, LENGTH = 128M
+    RAM (wxa) : ORIGIN = 0x80000000, LENGTH = 512M
 }
 
 SECTIONS {

justfile

@@ -2,6 +2,7 @@ release := ""
 qemu_flags := ""
 cargo_flags := "" + if release != "" { "--release" } else { "" }
 bin_path := if release != "" { "target/riscv64/release" } else { "target/riscv64/debug" }
+rust_src := `rustc --print sysroot` / "lib/rustlib/src/rust/library/std/src"
 
 default: run
 
@@ -12,6 +13,67 @@ mount_filesystem:
 sync_filesystem:
     sync
 
+cp_std path:
+    @echo "Copying {{ path }}"
+    @mkdir {{ "crates/std/src" / parent_directory(path) }} -p
+    @cp {{ rust_src / path }} {{ "crates/std/src" / path }}
+    @sed -i -f patches.sed {{ "crates/std/src" / path }}
+
+insert_target line path:
+    @sed -i '{{ line }}a \target_os = "survos",' {{ "crates/std/src" / path }}
+
+update_std:
+    @# Not copied : sys/mod.rs, io.rs, error.rs, thread.rs, sync.rs
+    # @just cp_std "process.rs"
+    # @just cp_std "fs.rs"
+    @just cp_std "time.rs"
+    @just cp_std "hash/mod.rs"
+    @just cp_std "hash/random.rs"
+    @just cp_std "num/mod.rs"
+    @just cp_std "ffi/c_str.rs"
+    @just cp_std "ffi/mod.rs"
+    @just cp_std "ffi/os_str.rs"
+    @just cp_std "ffi/os_str/tests.rs"
+    @just cp_std "thread/local.rs"
+    @just cp_std "sys/exit.rs"
+    @just cp_std "sys/env_consts.rs"
+    @just cp_std "sys/configure_builtins.rs"
+    @just cp_std "sys/cmath.rs"
+    @just cp_std "sys/sync/condvar/mod.rs"
+    @just cp_std "sys/sync/condvar/no_threads.rs"
+    @just cp_std "sys/sync/mutex/mod.rs"
+    @just cp_std "sys/sync/mutex/no_threads.rs"
+    @just cp_std "sys/sync/once/mod.rs"
+    @just cp_std "sys/sync/once/no_threads.rs"
+    @just cp_std "sys/sync/rwlock/mod.rs"
+    @just cp_std "sys/sync/rwlock/no_threads.rs"
+    @just cp_std "sys/thread/mod.rs"
+    @just cp_std "sys/thread/unsupported.rs"
+    @just cp_std "sys/thread_local/no_threads.rs"
+    @just cp_std "sys/thread_local/os.rs"
+    @just cp_std "sys/time/mod.rs"
+    @just cp_std "sys/time/unsupported.rs"
+    @just cp_std "sys/random/mod.rs"
+    @just cp_std "sys/random/unsupported.rs"
+    @just cp_std "sys/env/mod.rs"
+    @just cp_std "sys/env/common.rs"
+    @just cp_std "sys/env/unsupported.rs"
+    @just cp_std "sys/os_str/mod.rs"
+    @just cp_std "sys/os_str/bytes.rs"
+    @just cp_std "sys/os_str/bytes/tests.rs"
+    @just cp_std "sys/path/mod.rs"
+    @just cp_std "sys/fs/mod.rs"
+    @just cp_std "sys/fs/common.rs"
+    @just cp_std "sys/fs/unsupported.rs"
+    @just insert_target 108 "sys/random/mod.rs"
+    @just insert_target 125 "sys/random/mod.rs"
+    @# Copied but edited for the moment
+    # @just cp_std "sys/thread_local/mod.rs"
+    # @just cp_std "sys/alloc/mod.rs"
+    # @just cp_std "alloc.rs"
+    # @just cp_std "path.rs"
+    # @just cp_std "sys/path/unix.rs"
+
 build_user_prog prog:
     RUSTFLAGS="-C relocation-model=pic -C link-arg=-Tuser.ld -C link-arg=-pie" cargo b {{ cargo_flags }} --package {{ prog }}
     riscv64-elf-strip {{ bin_path / prog }}
@@ -34,8 +96,8 @@ qemu := f"qemu-system-riscv64 \
     -device bochs-display \
     -device virtio-keyboard-pci \
     -device virtio-mouse-pci \
-    -device loader,file=disk.img,addr=0x90000000 \
+    -device loader,file=disk.img,addr=0xA0000000 \
-    -bios none -m 512M {{qemu_flags}}"
+    -bios none -m 1024M {{qemu_flags}}"
 
 # -trace \"virtio*\"
 # -d guest_errors,unimp,int"

patches.sed

@@ -0,0 +1,9 @@
+s|crate::bstr::ByteStr|alloc_crate::bstr::ByteStr|g
+s|crate::collections::TryReserveError|alloc_crate::collections::TryReserveError|g
+s|crate::sync::Arc|alloc_crate::sync::Arc|g
+s|alloc::ffi|alloc_crate::ffi|g
+s|alloc::slice::Join|alloc_crate::slice::Join|g
+# /target_os = "xous",/a \    target_os = "survos",
+
+# Ajouter d'autres modifications facilement ici :
+# s|ancien_texte|nouveau_texte|g

riscv64.json

@@ -6,7 +6,7 @@
     "target-endian": "little",
     "target-pointer-width": 64,
     "arch": "riscv64",
-    "os": "none",
+    "os": "survos",
     "vendor": "unknown",
     "env": "",
     "features": "+i,+m,+a,+zicsr",

src/drivers.rs

@@ -0,0 +1,2 @@
+pub mod keyboard;
+pub mod mouse;

src/drivers/keyboard.rs

@@ -0,0 +1,67 @@
+use crate::{
+    keymap::{KeyType, ModifierType, map_keycode},
+    tty::TTY0,
+    virtio::{
+        Virtqueue,
+        input::{EventCodeValue, VirtioInputEvent, VirtioPciDriver},
+    },
+    virtual_fs::{FILE_SYSTEM, VirtualFileSystem},
+};
+
+#[derive(Debug, Clone, Copy, Default)]
+pub struct KeyboardState {
+    // ctrl_modifier: bool,
+    pub shift_modifier: bool,
+    pub alt_gr_modifier: bool,
+}
+
+impl KeyboardState {
+    pub const fn new() -> Self {
+        Self {
+            // ctrl_modifier: false,
+            shift_modifier: false,
+            alt_gr_modifier: false,
+        }
+    }
+}
+
+static mut KBD_QUEUE: Virtqueue = unsafe { core::mem::zeroed() };
+pub static mut KBD_DRIVER: VirtioPciDriver<KeyboardState> = unsafe {
+    VirtioPciDriver::new(
+        |state, event| {
+            let mut kbd_buffer = FILE_SYSTEM.open("/dev/input/keyboard".as_ref()).unwrap();
+            kbd_buffer
+                .write(core::mem::transmute::<
+                    &VirtioInputEvent,
+                    &[u8; size_of::<VirtioInputEvent>()],
+                >(event))
+                .unwrap();
+
+            if event.is_key() {
+                let event = event.as_key_event();
+                #[allow(clippy::single_match)]
+                match map_keycode(event.code, state) {
+                    KeyType::Ascii(c) if event.value == EventCodeValue::Pressed => {
+                        let mut buf = [0; 4];
+                        let to_send = c.encode_utf8(&mut buf);
+                        for c in to_send.as_bytes() {
+                            TTY0.buffer.borrow_mut().push(*c);
+                        }
+                    }
+                    KeyType::Modifier(ModifierType::Shift) => {
+                        state.shift_modifier = !state.shift_modifier;
+                    }
+                    KeyType::Modifier(ModifierType::AltGr) => {
+                        state.alt_gr_modifier = !state.alt_gr_modifier;
+                    }
+                    _ => {}
+                }
+                // println!("event: {:#?}", event);
+            } else {
+                // println!("key pressed, {:#?}", event);
+            }
+        },
+        KeyboardState::new(),
+        &mut KBD_QUEUE,
+    )
+};

src/drivers/mouse.rs

@@ -0,0 +1,38 @@
+use crate::{
+    cursor::{clear_cursor, draw_cursor},
+    vga::Vga,
+    virtio::{self, Virtqueue, input::VirtioPciDriver},
+};
+
+pub static mut MOUSE_POSITION: (u16, u16) = (0, 0);
+
+static mut MOUSE_QUEUE: Virtqueue = unsafe { core::mem::zeroed() };
+pub static mut MOUSE_DRIVER: VirtioPciDriver<()> = unsafe {
+    VirtioPciDriver::new(
+        |_, event| {
+            if event.is_relative() {
+                let event = event.as_relative_event();
+
+                clear_cursor(&mut Vga, MOUSE_POSITION.0, MOUSE_POSITION.1);
+
+                match event.code {
+                    virtio::input::EventCodeRelative::X => {
+                        MOUSE_POSITION.0 = (MOUSE_POSITION.0 as i32 + event.value) as u16
+                    }
+                    virtio::input::EventCodeRelative::Y => {
+                        MOUSE_POSITION.1 = (MOUSE_POSITION.1 as i32 + event.value) as u16
+                    }
+                    _ => {}
+                }
+
+                draw_cursor(&mut Vga, MOUSE_POSITION.0, MOUSE_POSITION.1);
+
+                // println!("mouse moved relatively, {:#?}", event);
+            } else {
+                // println!("mouse moved, {:#?}", event);
+            }
+        },
+        (),
+        &mut MOUSE_QUEUE,
+    )
+};

src/fs.rs

@@ -12,7 +12,7 @@ use io::{IoBase, Read, Seek, Write};
 
 use crate::virtual_fs::{VirtualFileSystem, VirtualNode};
 
-const DISK_ADDR: *const u8 = 0x9000_0000 as *const _;
+const DISK_ADDR: *const u8 = 0xA000_0000 as *const _;
 
 #[derive(Debug)]
 /// Simple disk backend that reads from a fixed memory region.

src/interrupt.rs

@@ -9,9 +9,9 @@ use log::info;
 use shared::syscall::SysCall;
 
 use crate::{
-    KBD_DRIVER, MOUSE_DRIVER,
     boot::sbi::{ExtensionID, TimerFunctionID},
     clear_csr,
+    drivers::{keyboard::KBD_DRIVER, mouse::MOUSE_DRIVER},
     process::{ExecutionContext, exit_process, sleep},
     read_csr,
     riscv::{disable_interrupt, dump_cpu},
@@ -160,6 +160,15 @@ unsafe extern "C" fn supervisor_trap_handler(
 
                         unsafe { (*interrupt_state).a[0] = fd as u64 };
                     }
+                    SysCall::Close => {
+                        let fd = a1;
+
+                        let mut scheduler = SCHEDULER.lock();
+                        let current_process = scheduler.get_current_process();
+                        let mut vnode = current_process.fd_table[fd as usize].take().unwrap();
+
+                        vnode.close();
+                    }
                     SysCall::Write => {
                         let fd = a1;
                         let buf =
@@ -168,7 +177,8 @@ unsafe extern "C" fn supervisor_trap_handler(
                         let mut scheduler = SCHEDULER.lock();
                         let current_process = scheduler.get_current_process();
                         let vnode = current_process.fd_table[fd as usize].as_mut().unwrap();
-                        vnode.write(buf).unwrap();
+                        let res = vnode.write(buf).unwrap();
+                        unsafe { (*interrupt_state).a[0] = res as u64 };
                     }
                     SysCall::Read => {
                         let fd = a1;
@@ -182,6 +192,8 @@ unsafe extern "C" fn supervisor_trap_handler(
                         if res == 0 && !buf.is_empty() {
                             loop_syscall(interrupt_state);
                             scheduler.schedule(&mut interrupt_state);
+                        } else {
+                            unsafe { (*interrupt_state).a[0] = res as u64 };
                         }
                     }
                     SysCall::Seek => {
@@ -197,6 +209,17 @@ unsafe extern "C" fn supervisor_trap_handler(
                         let vnode = current_process.fd_table[fd as usize].as_mut().unwrap();
                         vnode.seek(seek).unwrap();
                     }
+                    SysCall::Spawn => {
+                        let path = unsafe { str::from_raw_parts(a1 as *const u8, a2 as usize) };
+                        let mut scheduler = SCHEDULER.lock();
+                        scheduler.create_process_from_file(path, 0, core::ptr::null());
+                    }
+                    SysCall::ExecVE => {
+                        // let path = unsafe { str::from_raw_parts(a1 as *const u8, a2 as usize) };
+                        // let mut scheduler = SCHEDULER.lock();
+                        // scheduler.create_process_from_file(path, &[]);
+                        unimplemented!("ExecVE is not implemented")
+                    }
                     SysCall::Alloc => {
                         let layout = Layout::from_size_align(a1 as usize, a2 as usize).unwrap();
                         // Allocate memory and put the pointer in a0

src/keymap.rs

@@ -1,4 +1,4 @@
-use crate::KeyboardState;
+use crate::drivers::keyboard::KeyboardState;
 
 #[derive(Debug, Clone, Copy)]
 #[derive_const(PartialEq, Eq)]

src/main.rs

@@ -12,7 +12,8 @@
     arbitrary_self_types_pointers,
     derive_const,
     const_cmp,
-    const_trait_impl
+    const_trait_impl,
+    trait_alias
 )]
 
 use core::sync::atomic::AtomicBool;
@@ -22,20 +23,15 @@ use embedded_alloc::LlffHeap as Heap;
 use log::info;
 
 use crate::{
-    cursor::{clear_cursor, draw_cursor},
+    drivers::{keyboard::KBD_DRIVER, mouse::MOUSE_DRIVER},
     io::init_log,
-    keymap::{KeyType, ModifierType, map_keycode},
+    pci::scan_virtio_devices,
-    pci::{PciDeviceIterator, scan_virtio_devices},
     riscv::enable_supervisor_interrupt,
     scheduler::{SCHEDULER, idle},
-    tty::TTY0,
     user::{proc2, test},
     vga::Vga,
-    virtio::{
+    virtio::input::init_plic_pci,
-        Virtqueue,
+    virtual_fs::init_file_system,
-        input::{EventCodeValue, VirtioInputEvent, VirtioPciDriver, init_plic_pci},
-    },
-    virtual_fs::{FILE_SYSTEM, VirtualFileSystem, init_file_system},
 };
 
 extern crate alloc;
@@ -44,6 +40,7 @@ mod critical_section;
 mod cursor;
 mod data_structures;
 mod draw;
+mod drivers;
 mod fs;
 mod interrupt;
 mod io;
@@ -75,97 +72,6 @@ const _: () = assert!(core::mem::size_of::<usize>() == core::mem::size_of::<u64>
 #[cfg(not(target_endian = "little"))]
 compile_error! {"This kernel implementation assume endianness is little-endian. Some memory access like PCI could not work in big-endian."}
 
-#[derive(Debug, Clone, Copy, Default)]
-pub struct KeyboardState {
-    // ctrl_modifier: bool,
-    pub shift_modifier: bool,
-    pub alt_gr_modifier: bool,
-}
-
-impl KeyboardState {
-    pub const fn new() -> Self {
-        Self {
-            // ctrl_modifier: false,
-            shift_modifier: false,
-            alt_gr_modifier: false,
-        }
-    }
-}
-
-static mut KBD_QUEUE: Virtqueue = unsafe { core::mem::zeroed() };
-pub static mut KBD_DRIVER: VirtioPciDriver<KeyboardState> = unsafe {
-    VirtioPciDriver::new(
-        |state, event| {
-            let mut kbd_buffer = FILE_SYSTEM.open("/dev/input/keyboard".as_ref()).unwrap();
-            kbd_buffer
-                .write(core::mem::transmute::<
-                    &VirtioInputEvent,
-                    &[u8; size_of::<VirtioInputEvent>()],
-                >(event))
-                .unwrap();
-
-            if event.is_key() {
-                let event = event.as_key_event();
-                #[allow(clippy::single_match)]
-                match map_keycode(event.code, state) {
-                    KeyType::Ascii(c) if event.value == EventCodeValue::Pressed => {
-                        let mut buf = [0; 4];
-                        let to_send = c.encode_utf8(&mut buf);
-                        for c in to_send.as_bytes() {
-                            TTY0.buffer.borrow_mut().push(*c);
-                        }
-                    }
-                    KeyType::Modifier(ModifierType::Shift) => {
-                        state.shift_modifier = !state.shift_modifier;
-                    }
-                    KeyType::Modifier(ModifierType::AltGr) => {
-                        state.alt_gr_modifier = !state.alt_gr_modifier;
-                    }
-                    _ => {}
-                }
-                println!("event: {:#?}", event);
-            } else {
-                // println!("key pressed, {:#?}", event);
-            }
-        },
-        KeyboardState::new(),
-        &mut KBD_QUEUE,
-    )
-};
-
-pub static mut MOUSE_POSITION: (u16, u16) = (0, 0);
-
-static mut MOUSE_QUEUE: Virtqueue = unsafe { core::mem::zeroed() };
-pub static mut MOUSE_DRIVER: VirtioPciDriver<()> = unsafe {
-    VirtioPciDriver::new(
-        |_, event| {
-            if event.is_relative() {
-                let event = event.as_relative_event();
-
-                clear_cursor(&mut Vga, MOUSE_POSITION.0, MOUSE_POSITION.1);
-
-                match event.code {
-                    virtio::input::EventCodeRelative::X => {
-                        MOUSE_POSITION.0 = (MOUSE_POSITION.0 as i32 + event.value) as u16
-                    }
-                    virtio::input::EventCodeRelative::Y => {
-                        MOUSE_POSITION.1 = (MOUSE_POSITION.1 as i32 + event.value) as u16
-                    }
-                    _ => {}
-                }
-
-                draw_cursor(&mut Vga, MOUSE_POSITION.0, MOUSE_POSITION.1);
-
-                // println!("mouse moved relatively, {:#?}", event);
-            } else {
-                // println!("mouse moved, {:#?}", event);
-            }
-        },
-        (),
-        &mut MOUSE_QUEUE,
-    )
-};
-
 #[unsafe(no_mangle)]
 pub extern "C" fn supervisor_mode_entry() {
     unsafe {
@@ -180,19 +86,20 @@ pub extern "C" fn supervisor_mode_entry() {
     info!("Hello World !");
     // unsafe { Vga.draw_string(10, 10, "Hello World !", Color::WHITE, Color::BLACK) };
 
-    SCHEDULER.lock().create_process(Box::new(test), "proc1");
+    // let binding = Box::leak(Box::new(["coucou".as_bytes()]));
-    SCHEDULER.lock().create_process(Box::new(proc2), "proc2");
+    SCHEDULER
+        .lock()
+        .create_process(Box::new(test), "proc1", 0, core::ptr::null());
+    SCHEDULER
+        .lock()
+        .create_process(Box::new(proc2), "proc2", 0, core::ptr::null());
 
     SCHEDULER
         .lock()
-        .create_process_from_file("/usr/bin/test_pic");
+        .create_process_from_file("/usr/bin/test_pic", 0, core::ptr::null());
 
     enable_supervisor_interrupt();
 
-    for pci in PciDeviceIterator::new() {
-        println!("{:x?}", pci.vendor_and_device_id())
-    }
-
     unsafe {
         let (pci_keyboard, pci_mouse) = scan_virtio_devices();
         let (pci_keyboard, pci_mouse) = (pci_keyboard.unwrap(), pci_mouse.unwrap());
@@ -214,5 +121,5 @@ pub extern "C" fn supervisor_mode_entry() {
         init_plic_pci(pci_keyboard.irq);
         init_plic_pci(pci_mouse.irq);
     }
-    idle();
+    idle(0, core::ptr::null());
 }

src/process.rs

@@ -19,7 +19,6 @@ use crate::{
     riscv::SStatus,
     scheduler::{ACTIVE_PID, SCHEDULER, Scheduler},
     time::elapsed_time_since_startup,
-    tty::TTY0,
     virtual_fs::{FILE_SYSTEM, VirtualFileSystem, VirtualNode},
 };
 
@@ -66,6 +65,9 @@ pub struct ExecutionContext {
     pub mstatus: u64,
 }
 
+pub trait ProcessEntryTrait = Fn(isize, *const *const u8);
+pub type ProcessEntry = dyn ProcessEntryTrait;
+
 /// Represents a process in the system.
 ///
 /// Each process has its own execution context, stack,
@@ -78,13 +80,13 @@ pub struct Process {
     /// Current state of the process.
     pub state: ProcessState,
     /// Optional entry point for the process code.
-    pub entry: Option<Box<dyn Fn()>>,
+    pub entry: Option<Box<ProcessEntry>>,
     /// Wake time for sleeping processes.
     pub wake_time: Duration,
     /// Saved execution context.
     pub ctx: ExecutionContext,
     /// Process stack.
-    pub stack: [u64; STACK_SIZE],
+    pub stack: Box<[u64; STACK_SIZE]>,
     /// File descriptor table.
     pub fd_table: Vec<Option<Box<dyn VirtualNode>>>,
 }
@@ -109,7 +111,7 @@ impl Default for Process {
                 mepc: core::ptr::null(),
                 mstatus: 0,
             },
-            stack: [0; _],
+            stack: unsafe { Box::new_zeroed().assume_init() },
             entry: None,
             fd_table: Vec::new(),
         }
@@ -150,7 +152,12 @@ impl Scheduler {
     /// Attempts to open `path`, load its contents into memory and create a new
     /// kernel process that will execute the loaded binary. Returns the PID of the
     /// created process, or -1 on failure.
-    pub fn create_process_from_file<T: AsRef<Path>>(&mut self, path: T) -> i64 {
+    pub fn create_process_from_file<T: AsRef<Path>>(
+        &mut self,
+        path: T,
+        argc: isize,
+        argv: *const *const u8,
+    ) -> i64 {
         let path = path.as_ref();
         let name = path.as_str();
 
@@ -231,25 +238,30 @@ impl Scheduler {
                 // Entry point
                 let entry_va = gelf.entry;
                 let entry_addr = unsafe { base.add((entry_va - min_vaddr) as usize) } as *const u8;
-                let entry_fn =
+                let entry_fn = unsafe {
-                    unsafe { core::mem::transmute::<*const u8, extern "C" fn()>(entry_addr) };
+                    core::mem::transmute::<*const u8, extern "C" fn(isize, *const *const u8)>(
-                let wrapper = Box::new(move || {
+                        entry_addr,
-                    entry_fn();
+                    )
-                });
+                };
+                let wrapper = move |argc, argv| {
+                    entry_fn(argc, argv);
+                };
                 println!("Program loaded at : {:x?}", entry_addr);
-                return self.create_process(wrapper, name);
+                return self.create_process(wrapper, name, argc, argv);
             }
         }
 
         // Fallback: treat the file as a raw binary blob and execute in-place
         let entry_point = unsafe {
-            core::mem::transmute::<*const u8, extern "C" fn()>(Vec::leak(content).as_ptr())
+            core::mem::transmute::<*const u8, extern "C" fn(isize, *const *const u8)>(
+                Vec::leak(content).as_ptr(),
+            )
+        };
+        let wrapper = move |argc, argv| {
+            entry_point(argc, argv);
         };
-        let wrapper = Box::new(move || {
-            entry_point();
-        });
 
-        self.create_process(wrapper, name)
+        self.create_process(wrapper, name, argc, argv)
     }
 
     /// Creates a new process with the specified code and name.
@@ -271,39 +283,48 @@ impl Scheduler {
     ///
     /// The provided `code` function will be executed when the process is first
     /// scheduled. Returns the new PID, or -1 if the process table is full.
-    pub fn create_process<T: Into<String>, F: Fn() + 'static + Send>(
+    pub fn create_process<T: Into<String>, F: ProcessEntryTrait + 'static + Send>(
         &mut self,
-        code: Box<F>,
+        code: F,
         name: T,
+        argc: isize,
+        argv: *const *const u8,
     ) -> i64 {
         // SAFETY: Initializing process in the global table.
         // Access is safe because we verified bounds and found a Dead slot.
         unsafe {
-            self.process_table
+            self.process_table.insert(self.next_pid, Process::default());
-                .insert(self.next_pid, Box::new(Process::default()));
             let process = self.process_table.get_mut(&self.next_pid).unwrap();
 
             // Configure process metadata
             process.pid = self.next_pid as i64;
             process.name = name.into();
             process.state = ProcessState::Activable;
-            process.entry = Some(code);
+            process.entry = Some(Box::new(code));
 
             process.fd_table = Vec::new();
-            FILE_SYSTEM.mount(
+            // FILE_SYSTEM.mount(
-                format!("/proc/{}/0", process.pid).into(),
+            //     format!("/proc/{}/0", process.pid).into(),
-                Box::new(TTY0.clone()),
+            //     Box::new(TTY0.clone()),
-            );
+            // );
             // FD 0
-            process.fd_table.push(Some(
+            process
-                FILE_SYSTEM
+                .fd_table
-                    .open(format!("/proc/{}/0", process.pid).as_ref())
+                .push(Some(FILE_SYSTEM.open("/dev/null".as_ref()).unwrap()));
-                    .unwrap(),
+            // FD 1
-            ));
+            process
+                .fd_table
+                .push(Some(FILE_SYSTEM.open("/dev/null".as_ref()).unwrap()));
+            // FD 2
+            process
+                .fd_table
+                .push(Some(FILE_SYSTEM.open("/dev/null".as_ref()).unwrap()));
 
             // Configure execution context
             // a0 contains the pointer to the function to execute
             process.ctx.a[0] = &raw const *process.entry.as_ref().unwrap_unchecked() as u64;
+            process.ctx.a[1] = argc as u64;
+            process.ctx.a[2] = argv as u64;
 
             // mepc points to process_launcher which will call the function
             process.ctx.mepc = process_launcher as *const _;
@@ -338,10 +359,15 @@ impl Scheduler {
 /// This function is installed into the process `mepc` so that when the new
 /// process is scheduled it will run this launcher which calls the user
 /// function and ensures the process exits cleanly.
-extern "C" fn process_launcher(code: *const Box<dyn Fn()>) {
+#[allow(improper_ctypes_definitions)]
+extern "C" fn process_launcher(
+    code: *const Box<ProcessEntry>,
+    argc: isize,
+    argv: *const *const u8,
+) {
     // SAFETY: The code pointer was initialized in create_process
     // and points to a valid function.
-    unsafe { (*code)() };
+    unsafe { (*code)(argc, argv) };
 
     // If user code didn't exit explicitly, call exit() to clean up the process
     exit();

src/scheduler.rs

@@ -17,7 +17,7 @@ use crate::{
 #[derive(Debug)]
 pub struct Scheduler {
     pub next_pid: u64,
-    pub process_table: BTreeMap<u64, Box<Process>>,
+    pub process_table: BTreeMap<u64, Process>,
 }
 
 pub static ACTIVE_PID: AtomicU64 = AtomicU64::new(0);
@@ -30,7 +30,7 @@ pub static SCHEDULER: Mutex<LazyCell<Scheduler>> = Mutex::new(LazyCell::new(|| S
 /// Idle loop executed when there is no runnable process.
 ///
 /// Uses the `wfi` instruction to yield the CPU while waiting for interrupts.
-pub fn idle() {
+pub fn idle(_argc: isize, _argv: *const *const u8) {
     loop {
         // write_string_temp("idle");
         // info!("idle");
@@ -47,7 +47,7 @@ impl Scheduler {
     /// it as the active process.
     pub fn init(&mut self) {
         info!("scheduler init");
-        self.create_process(Box::new(idle), "idle");
+        self.create_process(Box::new(idle), "idle", 0, core::ptr::null());
         self.process_table.get_mut(&0).unwrap().state = ProcessState::Active;
     }
 
@@ -69,9 +69,7 @@ impl Scheduler {
                 }
             }
 
-            let mut current_process_iter = self
+            let mut current_process_iter = self.process_table.range_mut(prev_pid + 1..);
-                .process_table
-                .range_mut((Bound::Excluded(prev_pid), Bound::Unbounded));
 
             ACTIVE_PID.store(
                 loop {

src/user.rs

@@ -6,14 +6,15 @@ use core::time::Duration;
 
 use shared::syscall::{sleep, write_string_temp};
 
-pub fn test() {
+pub fn test(_argc: isize, _argv: *const *const u8) {
     loop {
+        // write_string_temp(str::from_utf8(_args[0]).unwrap());
         write_string_temp("test");
         sleep(Duration::new(2, 0));
     }
 }
 
-pub fn proc2() {
+pub fn proc2(_argc: isize, _argv: *const *const u8) {
     loop {
         write_string_temp("proc2");
         sleep(Duration::new(3, 0));

src/virtio/input.rs

@@ -22,6 +22,7 @@ pub struct VirtioPciDriver<S, F: Fn(&mut S, &VirtioInputEvent) = fn(&mut S, &Vir
 }
 
 #[repr(u16)]
+#[allow(unused)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub enum EventType {
     Sync = 0,
@@ -31,6 +32,7 @@ pub enum EventType {
 }
 
 #[repr(u16)]
+#[allow(unused)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub enum EventCodeRelative {
     X = 0,
@@ -39,6 +41,7 @@ pub enum EventCodeRelative {
 }
 
 #[repr(u16)]
+#[allow(unused)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub enum EventCodeValue {
     Released = 0,

src/virtual_console.rs

@@ -3,7 +3,6 @@ use io::SeekFrom;
 
 use crate::{
     draw::{Color, Draw, FONT_HEIGHT, FONT_WIDTH},
-    println,
     vga::{self, Vga},
     virtual_fs::{self, FILE_SYSTEM, VirtualFileSystem},
 };
@@ -41,7 +40,6 @@ impl VirtualConsole {
     }
 
     pub fn write_char(&mut self, c: char) {
-        println!("char_console: {:?}", c as u64);
         let mut last_cursor = self.cursor;
         match c {
             '\n' => {

src/virtual_fs.rs

@@ -9,6 +9,7 @@ use hashbrown::HashMap;
 use io::{IoBase, Read, Seek, Write};
 
 pub mod keyboard;
+pub mod null;
 pub mod stdin;
 pub mod virtual_stdin;
 
@@ -16,10 +17,12 @@ use crate::{
     fs::Disk,
     tty::TTY0,
     vga::Vga,
-    virtual_fs::{keyboard::KeyboardBuffer, virtual_stdin::VirtualStdin},
+    virtual_fs::{keyboard::KeyboardBuffer, null::Null, virtual_stdin::VirtualStdin},
 };
 
-pub trait VirtualNode: IoBase<Error = ()> + Read + Write + Seek + Debug {}
+pub trait VirtualNode: IoBase<Error = ()> + Read + Write + Seek + Debug {
+    fn close(&mut self) {}
+}
 
 pub trait VirtualFileSystem: Debug {
     fn open(&mut self, path: &Path) -> Result<Box<dyn VirtualNode + '_>, ()>;
@@ -62,6 +65,7 @@ pub unsafe fn init_file_system() {
     unsafe {
         FILE_SYSTEM.mount("/dev/fb0".into(), Box::new(VGAFileSystem));
         FILE_SYSTEM.mount("/dev/tty0".into(), Box::new(TTY0.clone()));
+        FILE_SYSTEM.mount("/dev/null".into(), Box::new(Null));
         FILE_SYSTEM.mount(
             "/dev/input/keyboard".into(),
             Box::new(KeyboardBuffer::new()),

src/virtual_fs/null.rs

@@ -0,0 +1,51 @@
+use alloc::boxed::Box;
+use io::{IoBase, Read, Seek, Write};
+
+use crate::virtual_fs::{VirtualFileSystem, VirtualNode};
+
+#[derive(Debug)]
+pub struct Null;
+
+#[derive(Debug)]
+pub struct NullNode;
+
+impl VirtualFileSystem for Null {
+    fn open(
+        &mut self,
+        path: &bffs::path::Path,
+    ) -> Result<alloc::boxed::Box<dyn crate::virtual_fs::VirtualNode + '_>, ()> {
+        if !path.is_empty() {
+            Err(())
+        } else {
+            Ok(Box::new(NullNode))
+        }
+    }
+}
+
+impl IoBase for NullNode {
+    type Error = ();
+}
+
+impl Read for NullNode {
+    fn read(&mut self, _buf: &mut [u8]) -> Result<usize, Self::Error> {
+        Ok(0)
+    }
+}
+
+impl Seek for NullNode {
+    fn seek(&mut self, _pos: io::SeekFrom) -> Result<u64, Self::Error> {
+        todo!()
+    }
+}
+
+impl Write for NullNode {
+    fn write(&mut self, _buf: &[u8]) -> Result<usize, Self::Error> {
+        todo!()
+    }
+
+    fn flush(&mut self) -> Result<(), Self::Error> {
+        todo!()
+    }
+}
+
+impl VirtualNode for NullNode {}

user/shell/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "shell"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+std = { path = "../../crates/std" }

user/shell/src/main.rs

@@ -0,0 +1,8 @@
+#![feature(custom_std)]
+
+fn main() -> isize {
+    println!(
+        "Hello from PIC program loaded dynamically with custom std and a better justfile, and syscalls ! "
+    );
+    0
+}

user/test_pic/Cargo.toml

@@ -4,4 +4,4 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
-os-std = { path = "../../crates/os-std" }
+std = { path = "../../crates/std" }

user/test_pic/src/main.rs

@@ -1,10 +1,10 @@
-#![no_std]
+#![feature(custom_std)]
-#![no_main]
+#![allow(unused)]
 
-// use core::time::Duration;
+use std::{
-
+    io::{Read, Write, stdin},
-use os_std::syscall;
+    syscall,
-os_std::custom_std_setup! {}
+};
 
 fn main() {
     // let mut input = String::new();
@@ -12,19 +12,13 @@ fn main() {
     // syscall::seek(&mut file, SeekFrom::End(-3));
     // syscall::write(&mut file, &[255; 6400 * 50]);
     // syscall::sleep(Duration::from_secs_f64(2.0));
-    let mut stdin = syscall::open("/dev/tty0");
+    syscall::close(0);
-    let mut file = syscall::open("/dev/tty0");
+    let mut tty = syscall::open("/dev/tty0");
+    syscall::spawn("/usr/bin/shell");
     loop {
         let mut test = [0; 2];
-        syscall::read(&mut stdin, &mut test);
+        let len = stdin().read(&mut test).unwrap();
-        let len = *test.iter().find(|x| **x == 0).unwrap_or(&1) + 1;
+        tty.write_all(str::from_utf8(&test[..len as usize]).unwrap().as_bytes())
-        syscall::write(
+            .unwrap();
-            &mut file,
-            str::from_utf8(&test[..len as usize]).unwrap().as_bytes(),
-        );
     }
-    // println!(
-    //     "Hello from PIC program loaded dynamically with custom std and a better justfile, and syscalls ! {:?}",
-    //     str::from_utf8(&test)
-    // );
 }