forked from M-Labs/rust-fatfs
Read FSInfo sector on mount and use it during cluster allocation
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parent
0e6b0a07a4
commit
4793d20977
70
src/fs.rs
70
src/fs.rs
@ -4,7 +4,7 @@ use io::prelude::*;
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use io::{Error, ErrorKind, SeekFrom};
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use io::{Error, ErrorKind, SeekFrom};
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use io;
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use io;
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use byteorder::LittleEndian;
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use byteorder::LittleEndian;
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use byteorder_ext::ReadBytesExt;
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use byteorder_ext::{ReadBytesExt, WriteBytesExt};
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use file::File;
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use file::File;
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use dir::{DirRawStream, Dir};
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use dir::{DirRawStream, Dir};
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@ -205,6 +205,57 @@ impl Default for BootRecord {
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}
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}
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}
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}
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struct FsInfoSector {
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#[allow(dead_code)]
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free_cluster_count: u32,
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next_free_cluster: u32,
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}
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impl FsInfoSector {
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const LEAD_SIG: u32 = 0x41615252;
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const STRUC_SIG: u32 = 0x61417272;
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const TRAIL_SIG: u32 = 0xAA550000;
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fn deserialize(rdr: &mut Read) -> io::Result<FsInfoSector> {
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let lead_sig = rdr.read_u32::<LittleEndian>()?;
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if lead_sig != Self::LEAD_SIG {
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return Err(Error::new(ErrorKind::Other, "invalid lead_sig in FsInfo sector"));
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}
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let mut reserved = [0u8; 480];
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rdr.read_exact(&mut reserved)?;
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let struc_sig = rdr.read_u32::<LittleEndian>()?;
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if struc_sig != Self::STRUC_SIG {
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return Err(Error::new(ErrorKind::Other, "invalid struc_sig in FsInfo sector"));
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}
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let free_cluster_count = rdr.read_u32::<LittleEndian>()?;
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let next_free_cluster = rdr.read_u32::<LittleEndian>()?;
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let mut reserved2 = [0u8; 12];
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rdr.read_exact(&mut reserved2)?;
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let trail_sig = rdr.read_u32::<LittleEndian>()?;
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if trail_sig != Self::TRAIL_SIG {
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return Err(Error::new(ErrorKind::Other, "invalid trail_sig in FsInfo sector"));
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}
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Ok(FsInfoSector {
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free_cluster_count, next_free_cluster
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})
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}
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// TODO: save modified FsInfo secton on unmount
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#[allow(dead_code)]
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fn serialize(&self, wrt: &mut Write) -> io::Result<()> {
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wrt.write_u32::<LittleEndian>(Self::LEAD_SIG)?;
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let reserved = [0u8; 480];
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wrt.write(&reserved)?;
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wrt.write_u32::<LittleEndian>(Self::STRUC_SIG)?;
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wrt.write_u32::<LittleEndian>(self.free_cluster_count)?;
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wrt.write_u32::<LittleEndian>(self.next_free_cluster)?;
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let reserved2 = [0u8; 12];
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wrt.write(&reserved2)?;
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wrt.write_u32::<LittleEndian>(Self::TRAIL_SIG)?;
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Ok(())
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}
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}
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/// FAT filesystem options.
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/// FAT filesystem options.
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#[derive(Debug, Clone, Copy)]
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#[derive(Debug, Clone, Copy)]
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pub struct FsOptions {
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pub struct FsOptions {
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@ -235,6 +286,7 @@ pub struct FileSystem<'a> {
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bpb: BiosParameterBlock,
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bpb: BiosParameterBlock,
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first_data_sector: u32,
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first_data_sector: u32,
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root_dir_sectors: u32,
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root_dir_sectors: u32,
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fs_info: Option<FsInfoSector>,
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}
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}
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impl <'a> FileSystem<'a> {
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impl <'a> FileSystem<'a> {
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@ -272,6 +324,13 @@ impl <'a> FileSystem<'a> {
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let total_clusters = data_sectors / bpb.sectors_per_cluster as u32;
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let total_clusters = data_sectors / bpb.sectors_per_cluster as u32;
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let fat_type = FatType::from_clusters(total_clusters);
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let fat_type = FatType::from_clusters(total_clusters);
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let fs_info = if fat_type == FatType::Fat32 {
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disk.seek(SeekFrom::Start(bpb.fs_info_sector as u64 * 512))?;
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Some(FsInfoSector::deserialize(disk)?)
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} else {
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None
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};
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Ok(FileSystem {
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Ok(FileSystem {
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disk: RefCell::new(disk),
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disk: RefCell::new(disk),
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options,
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options,
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@ -279,6 +338,7 @@ impl <'a> FileSystem<'a> {
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bpb: bpb,
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bpb: bpb,
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first_data_sector,
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first_data_sector,
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root_dir_sectors,
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root_dir_sectors,
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fs_info,
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})
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})
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}
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}
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@ -354,8 +414,12 @@ impl <'a> FileSystem<'a> {
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}
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}
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pub(crate) fn alloc_cluster(&self, prev_cluster: Option<u32>) -> io::Result<u32> {
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pub(crate) fn alloc_cluster(&self, prev_cluster: Option<u32>) -> io::Result<u32> {
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let mut disk_slice = self.fat_slice();
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let hint = match self.fs_info {
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alloc_cluster(&mut disk_slice, self.fat_type, prev_cluster)
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Some(ref info) => Some(info.next_free_cluster),
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None => None,
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};
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let mut fat = self.fat_slice();
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alloc_cluster(&mut fat, self.fat_type, prev_cluster, hint)
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}
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}
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pub fn read_status_flags(&self) -> io::Result<FsStatusFlags> {
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pub fn read_status_flags(&self) -> io::Result<FsStatusFlags> {
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@ -61,8 +61,8 @@ fn find_free_cluster(fat: &mut ReadSeek, fat_type: FatType, cluster: u32) -> io:
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}
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}
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}
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}
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pub(crate) fn alloc_cluster(fat: &mut DiskSlice, fat_type: FatType, prev_cluster: Option<u32>) -> io::Result<u32> {
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pub(crate) fn alloc_cluster(fat: &mut DiskSlice, fat_type: FatType, prev_cluster: Option<u32>, hint: Option<u32>) -> io::Result<u32> {
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let new_cluster = find_free_cluster(fat, fat_type, 2)?;
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let new_cluster = find_free_cluster(fat, fat_type, hint.unwrap_or(2))?;
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write_fat(fat, fat_type, new_cluster, FatValue::EndOfChain)?;
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write_fat(fat, fat_type, new_cluster, FatValue::EndOfChain)?;
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match prev_cluster {
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match prev_cluster {
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Some(n) => write_fat(fat, fat_type, n, FatValue::Data(new_cluster))?,
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Some(n) => write_fat(fat, fat_type, n, FatValue::Data(new_cluster))?,
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