rust-fatfs/src/fs.rs

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use std::io::prelude::*;
use std::io;
use std::str;
use std::io::{Error, ErrorKind, SeekFrom};
use byteorder::{LittleEndian, ReadBytesExt};
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use file::FatFile;
// FAT implementation based on:
// http://wiki.osdev.org/FAT
// https://www.win.tue.nl/~aeb/linux/fs/fat/fat-1.html
#[derive(Debug, Copy, Clone, PartialEq)]
pub enum FatType {
Fat12, Fat16, Fat32, ExFat
}
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#[allow(dead_code)]
pub struct FatFileSystem<T: Read+Seek> {
pub(crate) rdr: T,
pub(crate) fat_type: FatType,
pub(crate) boot: FatBootRecord,
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first_fat_sector: u32,
pub(crate) first_data_sector: u32,
pub(crate) root_dir_sectors: u32,
}
#[allow(dead_code)]
#[derive(Default, Debug)]
pub(crate) struct FatBiosParameterBlock {
bytes_per_sector: u16,
sectors_per_cluster: u8,
reserved_sector_count: u16,
table_count: u8,
root_entry_count: u16,
total_sectors_16: u16,
media_type: u8,
table_size_16: u16,
sectors_per_track: u16,
head_side_count: u16,
hidden_sector_count: u32,
total_sectors_32: u32,
// Extended BIOS Parameter Block
table_size_32: u32,
extended_flags: u16,
fat_version: u16,
root_cluster: u32,
fat_info: u16,
backup_bs_sector: u16,
reserved_0: [u8; 12],
drive_num: u8,
reserved_1: u8,
ext_sig: u8,
volume_id: u32,
volume_label: [u8; 11],
fat_type_label: [u8; 8],
}
#[allow(dead_code)]
pub(crate) struct FatBootRecord {
bootjmp: [u8; 3],
oem_name: [u8; 8],
bpb: FatBiosParameterBlock,
boot_code: [u8; 448],
boot_sig: [u8; 2],
}
impl Default for FatBootRecord {
fn default() -> FatBootRecord {
FatBootRecord {
bootjmp: Default::default(),
oem_name: Default::default(),
bpb: Default::default(),
boot_code: [0; 448],
boot_sig: Default::default(),
}
}
}
impl<T: Read+Seek> FatFileSystem<T> {
fn fat_type_from_clusters(total_clusters: u32) -> FatType {
if total_clusters < 4085 {
FatType::Fat12
} else if total_clusters < 65525 {
FatType::Fat16
} else if total_clusters < 268435445 {
FatType::Fat32
} else {
FatType::ExFat
}
}
pub fn new(rdr: &mut T) -> io::Result<FatFileSystem<&mut T>> {
let boot = FatFileSystem::<T>::read_boot_record(rdr)?;
if boot.boot_sig != [0x55, 0xAA] {
return Err(Error::new(ErrorKind::Other, "invalid signature"));
}
let total_sectors = if boot.bpb.total_sectors_16 == 0 { boot.bpb.total_sectors_32 } else { boot.bpb.total_sectors_16 as u32 };
let table_size = if boot.bpb.table_size_16 == 0 { boot.bpb.table_size_32 } else { boot.bpb.table_size_16 as u32 };
let root_dir_sectors = ((boot.bpb.root_entry_count * 32) + (boot.bpb.bytes_per_sector - 1)) / (boot.bpb.bytes_per_sector);
let first_data_sector = boot.bpb.reserved_sector_count as u32 + (boot.bpb.table_count as u32 * table_size) + root_dir_sectors as u32;
let first_fat_sector = boot.bpb.reserved_sector_count as u32;
let data_sectors = total_sectors - (boot.bpb.reserved_sector_count as u32 + (boot.bpb.table_count as u32 * table_size) + root_dir_sectors as u32);
let total_clusters = data_sectors / boot.bpb.sectors_per_cluster as u32;
let fat_type = FatFileSystem::<T>::fat_type_from_clusters(total_clusters);
{
let oem_name_str = str::from_utf8(&boot.oem_name).unwrap().trim_right();
let volume_label_str = str::from_utf8(&boot.bpb.volume_label).unwrap().trim_right();
let fat_type_label_str = str::from_utf8(&boot.bpb.fat_type_label).unwrap().trim_right();
println!("fat_type {:?}", fat_type);
println!("volume_id {}", boot.bpb.volume_id);
println!("oem_name {}", oem_name_str);
println!("volume_label {}", volume_label_str);
println!("fat_type_label {}", fat_type_label_str);
}
let fs = FatFileSystem {
rdr: rdr,
fat_type: fat_type,
boot: boot,
first_data_sector: first_data_sector,
first_fat_sector: first_fat_sector,
root_dir_sectors: root_dir_sectors as u32,
};
Ok(fs)
}
fn read_bpb(rdr: &mut Read) -> io::Result<FatBiosParameterBlock> {
let mut bpb: FatBiosParameterBlock = Default::default();
bpb.bytes_per_sector = rdr.read_u16::<LittleEndian>()?;
bpb.sectors_per_cluster = rdr.read_u8()?;
bpb.reserved_sector_count = rdr.read_u16::<LittleEndian>()?;
bpb.table_count = rdr.read_u8()?;
bpb.root_entry_count = rdr.read_u16::<LittleEndian>()? ;
bpb.total_sectors_16 = rdr.read_u16::<LittleEndian>()?;
bpb.media_type = rdr.read_u8()?;
bpb.table_size_16 = rdr.read_u16::<LittleEndian>()?;
bpb.sectors_per_track = rdr.read_u16::<LittleEndian>()?;
bpb.head_side_count = rdr.read_u16::<LittleEndian>()?;
bpb.hidden_sector_count = rdr.read_u32::<LittleEndian>()?; // hidden_sector_count
bpb.total_sectors_32 = rdr.read_u32::<LittleEndian>()?;
if bpb.table_size_16 == 0 {
bpb.table_size_32 = rdr.read_u32::<LittleEndian>()?;
bpb.extended_flags = rdr.read_u16::<LittleEndian>()?;
bpb.fat_version = rdr.read_u16::<LittleEndian>()?;
bpb.root_cluster = rdr.read_u32::<LittleEndian>()?;
bpb.fat_info = rdr.read_u16::<LittleEndian>()?;
bpb.backup_bs_sector = rdr.read_u16::<LittleEndian>()?;
rdr.read(&mut bpb.reserved_0)?;
bpb.drive_num = rdr.read_u8()?;
bpb.reserved_1 = rdr.read_u8()?;
bpb.ext_sig = rdr.read_u8()?; // 0x29
bpb.volume_id = rdr.read_u32::<LittleEndian>()?;
rdr.read(&mut bpb.volume_label)?;
rdr.read(&mut bpb.fat_type_label)?;
//bpb.boot_code = Vec::with_capacity(420);
//rdr.read_exact(bpb.boot_code.as_mut_slice())?;
} else {
bpb.drive_num = rdr.read_u8()?;
bpb.reserved_1 = rdr.read_u8()?;
bpb.ext_sig = rdr.read_u8()?; // 0x29
bpb.volume_id = rdr.read_u32::<LittleEndian>()?;
rdr.read(&mut bpb.volume_label)?;
rdr.read(&mut bpb.fat_type_label)?;
//bpb.boot_code = Vec::with_capacity(448);
//rdr.read_exact(bpb.boot_code.as_mut_slice())?;
}
Ok(bpb)
}
fn read_boot_record(rdr: &mut Read) -> io::Result<FatBootRecord> {
let mut boot: FatBootRecord = Default::default();
rdr.read(&mut boot.bootjmp)?;
rdr.read(&mut boot.oem_name)?;
boot.bpb = FatFileSystem::<T>::read_bpb(rdr)?;
if boot.bpb.table_size_16 == 0 {
rdr.read_exact(&mut boot.boot_code[0..420])?;
} else {
rdr.read_exact(&mut boot.boot_code[0..448])?;
}
rdr.read(&mut boot.boot_sig)?;
Ok(boot)
}
pub fn seek_to_sector(&mut self, sector: u64) -> io::Result<()> {
self.rdr.seek(SeekFrom::Start(sector*512))?;
Ok(())
}
pub fn sector_from_cluster(&self, cluster: u32) -> u32 {
((cluster - 2) * self.boot.bpb.sectors_per_cluster as u32) + self.first_data_sector
}
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pub(crate) fn get_root_dir_sector(&self) -> u32 {
match self.fat_type {
FatType::Fat12 | FatType::Fat16 => self.first_data_sector - self.root_dir_sectors,
_ => self.sector_from_cluster(self.boot.bpb.root_cluster)
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}
}
pub fn root_dir(&mut self) -> FatFile {
let first_root_dir_sector = self.get_root_dir_sector();
let root_dir_size = self.root_dir_sectors * self.boot.bpb.bytes_per_sector as u32;
FatFile::new(first_root_dir_sector, root_dir_size)
}
}