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Add some sanity checks and fix possible issues with partial read when not using read_exact.

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This commit is contained in:
Rafał Harabień 2017-10-10 23:19:44 +02:00
parent d52b0918ca
commit 98ec30589a
1 changed files with 23 additions and 9 deletions
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32
src/fs.rs
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@ -147,9 +147,23 @@ impl <'a> FileSystem<'a> {
bpb.sectors_per_fat_16 = rdr.read_u16::<LittleEndian>()?;
bpb.sectors_per_track = rdr.read_u16::<LittleEndian>()?;
bpb.heads = rdr.read_u16::<LittleEndian>()?;
bpb.hidden_sectors = rdr.read_u32::<LittleEndian>()?; // hidden_sector_count
bpb.hidden_sectors = rdr.read_u32::<LittleEndian>()?;
bpb.total_sectors_32 = rdr.read_u32::<LittleEndian>()?;
// sanity checks
if bpb.bytes_per_sector < 512 {
return Err(Error::new(ErrorKind::Other, "invalid bytes_per_sector value in BPB"));
}
if bpb.sectors_per_cluster < 1 {
return Err(Error::new(ErrorKind::Other, "invalid sectors_per_cluster value in BPB"));
}
if bpb.reserved_sectors < 1 {
return Err(Error::new(ErrorKind::Other, "invalid reserved_sectors value in BPB"));
}
if bpb.fats == 0 {
return Err(Error::new(ErrorKind::Other, "invalid fats value in BPB"));
}
if bpb.sectors_per_fat_16 == 0 {
bpb.sectors_per_fat_32 = rdr.read_u32::<LittleEndian>()?;
bpb.extended_flags = rdr.read_u16::<LittleEndian>()?;
@ -157,20 +171,20 @@ impl <'a> FileSystem<'a> {
bpb.root_dir_first_cluster = rdr.read_u32::<LittleEndian>()?;
bpb.fs_info_sector = rdr.read_u16::<LittleEndian>()?;
bpb.backup_boot_sector = rdr.read_u16::<LittleEndian>()?;
rdr.read(&mut bpb.reserved_0)?;
rdr.read_exact(&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.fs_type_label)?;
rdr.read_exact(&mut bpb.volume_label)?;
rdr.read_exact(&mut bpb.fs_type_label)?;
} 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.fs_type_label)?;
rdr.read_exact(&mut bpb.volume_label)?;
rdr.read_exact(&mut bpb.fs_type_label)?;
}
Ok(bpb)
}
@ -187,8 +201,8 @@ impl <'a> FileSystem<'a> {
fn read_boot_record(rdr: &mut Read) -> io::Result<BootRecord> {
let mut boot: BootRecord = Default::default();
rdr.read(&mut boot.bootjmp)?;
rdr.read(&mut boot.oem_name)?;
rdr.read_exact(&mut boot.bootjmp)?;
rdr.read_exact(&mut boot.oem_name)?;
boot.bpb = Self::read_bpb(rdr)?;
if boot.bpb.sectors_per_fat_16 == 0 {
@ -196,7 +210,7 @@ impl <'a> FileSystem<'a> {
} else {
rdr.read_exact(&mut boot.boot_code[0..448])?;
}
rdr.read(&mut boot.boot_sig)?;
rdr.read_exact(&mut boot.boot_sig)?;
Ok(boot)
}