Add a small part of the real rust std

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/mod.rs

@@ -0,0 +1,24 @@
+pub mod env;
+pub mod os_str;
+
+/// 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::bstr::ByteStr;
+use alloc::collections::TryReserveError;
+use crate::rc::Rc;
+use alloc::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};
+    }
+}