riscv64-kernel/crates/bffs/src/boot_sector.rs

use io::Read;

use crate::io_ext::ReadLeExt;

#[derive(Debug, Clone, Copy)]
pub struct Fat32BootSector {
    // --- Jump + OEM ---
    pub jump_boot: [u8; 3],
    pub oem_name: [u8; 8],

    // --- BPB (BIOS Parameter Block) ---
    pub bytes_per_sector: u16,
    pub sectors_per_cluster: u8,
    pub reserved_sector_count: u16,
    pub num_fats: u8,
    pub root_entry_count: u16,
    pub total_sectors_16: u16,
    pub media: u8,
    pub fat_size_16: u16,
    pub sectors_per_track: u16,
    pub num_heads: u16,
    pub hidden_sectors: u32,
    pub total_sectors_32: u32,

    // --- FAT32 Extended BPB ---
    pub fat_size_32: u32,
    pub ext_flags: u16,
    pub fs_version: u16,
    pub root_cluster: u32,
    pub fs_info: u16,
    pub bk_boot_sec: u16,
    pub reserved: [u8; 12],

    // --- FAT32 Drive Info ---
    pub drive_number: u8,
    pub reserved1: u8,
    pub boot_signature: u8,
    pub volume_id: u32,
    pub volume_label: [u8; 11],
    pub fs_type: [u8; 8],

    // --- Boot code ---
    pub boot_code: [u8; 420],

    // --- Signature ---
    pub boot_sector_signature: u16, // 0xAA55
}

impl core::fmt::Display for Fat32BootSector {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        f.debug_struct("Fat32BootSector")
            .field("jump_boot", &self.jump_boot)
            .field("oem_name", &self.get_oem_name())
            .field("bytes_per_sector", &self.bytes_per_sector)
            .field("sectors_per_cluster", &self.sectors_per_cluster)
            .field("reserved_sector_count", &self.reserved_sector_count)
            .field("num_fats", &self.num_fats)
            .field("root_entry_count", &self.root_entry_count)
            .field("total_sectors_16", &self.total_sectors_16)
            .field("media", &self.media)
            .field("fat_size_16", &self.fat_size_16)
            .field("sectors_per_track", &self.sectors_per_track)
            .field("num_heads", &self.num_heads)
            .field("hidden_sectors", &self.hidden_sectors)
            .field("total_sectors_32", &self.total_sectors_32)
            .field("fat_size_32", &self.fat_size_32)
            .field("ext_flags", &self.ext_flags)
            .field("fs_version", &self.fs_version)
            .field("root_cluster", &self.root_cluster)
            .field("fs_info", &self.fs_info)
            .field("bk_boot_sec", &self.bk_boot_sec)
            .field("reserved", &self.reserved)
            .field("drive_number", &self.drive_number)
            .field("reserved1", &self.reserved1)
            .field("boot_signature", &self.boot_signature)
            .field("volume_id", &self.volume_id)
            .field("volume_label", &self.get_volume_label())
            .field("fs_type", &self.get_fs_type())
            .field("boot_code", &"[_; 420]")
            .field("boot_sector_signature", &self.boot_sector_signature)
            .finish()
    }
}

impl Fat32BootSector {
    pub fn get_oem_name(&self) -> Result<&str, core::str::Utf8Error> {
        str::from_utf8(&self.oem_name)
    }
    pub fn get_volume_label(&self) -> Result<&str, core::str::Utf8Error> {
        str::from_utf8(&self.volume_label)
    }
    pub fn get_fs_type(&self) -> Result<&str, core::str::Utf8Error> {
        str::from_utf8(&self.fs_type)
    }
}

impl Fat32BootSector {
    pub fn deserialize<T: Read>(disk: &mut T) -> Result<Self, io::Error> {
        let mut jump_boot = [0u8; _];
        disk.read_exact(&mut jump_boot)?;
        let mut oem_name = [0u8; _];
        disk.read_exact(&mut oem_name)?;
        let bytes_per_sector = disk.read_u16_le()?;
        let sectors_per_cluster = disk.read_u8()?;
        let reserved_sector_count = disk.read_u16_le()?;
        let num_fats = disk.read_u8()?;
        let root_entry_count = disk.read_u16_le()?;
        let total_sectors_16 = disk.read_u16_le()?;
        let media = disk.read_u8()?;
        let fat_size_16 = disk.read_u16_le()?;
        let sectors_per_track = disk.read_u16_le()?;
        let num_heads = disk.read_u16_le()?;
        let hidden_sectors = disk.read_u32_le()?;
        let total_sectors_32 = disk.read_u32_le()?;
        let fat_size_32 = disk.read_u32_le()?;
        let ext_flags = disk.read_u16_le()?;
        let fs_version = disk.read_u16_le()?;
        let root_cluster = disk.read_u32_le()?;
        let fs_info = disk.read_u16_le()?;
        let bk_boot_sec = disk.read_u16_le()?;
        let mut reserved = [0u8; _];
        disk.read_exact(&mut reserved)?;
        let drive_number = disk.read_u8()?;
        let reserved1 = disk.read_u8()?;
        let boot_signature = disk.read_u8()?;
        let volume_id = disk.read_u32_le()?;
        let mut volume_label = [0u8; _];
        disk.read_exact(&mut volume_label)?;
        let mut fs_type = [0u8; _];
        disk.read_exact(&mut fs_type)?;
        let mut boot_code = [0u8; _];
        disk.read_exact(&mut boot_code)?;
        let boot_sector_signature = disk.read_u16_le()?;

        Ok(Self {
            jump_boot,
            oem_name,
            bytes_per_sector,
            sectors_per_cluster,
            reserved_sector_count,
            num_fats,
            root_entry_count,
            total_sectors_16,
            media,
            fat_size_16,
            sectors_per_track,
            num_heads,
            hidden_sectors,
            total_sectors_32,
            fat_size_32,
            ext_flags,
            fs_version,
            root_cluster,
            fs_info,
            bk_boot_sec,
            reserved,
            drive_number,
            reserved1,
            boot_signature,
            volume_id,
            volume_label,
            fs_type,
            boot_code,
            boot_sector_signature,
        })
    }
}