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Treat non-existent data blocks as all zeroes

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This commit is contained in:
pjht 2024-09-16 13:50:13 -05:00
parent e55ad22620
commit 9326191911
Signed by: pjht
GPG Key ID: CA239FC6934E6F3A
1 changed files with 36 additions and 31 deletions
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67
src/ext2/file.rs
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@ -54,42 +54,47 @@ impl File {
let start_block = (pos / self.block_size as u64) as u32;
let offset = (pos % self.block_size as u64) as usize;
let length = core::cmp::min(bytes_to_end, buf.len() as u64);
let _ = fs
.reader
.read_block_offset(
self.inode
.log_to_phys_block(&fs, start_block)
.ok_or_else(|| io::Error::new(io::ErrorKind::UnexpectedEof, "EOF reached"))?,
offset as u32,
)?
.read(buf)?;
if let Some(phys_block) = self.inode.log_to_phys_block(fs, start_block) {
let _ = fs
.reader
.read_block_offset(phys_block, offset as u32)?
.read(buf)?;
} else {
let buf_len = buf.len();
buf[..usize::min(self.block_size, buf_len)].fill(0);
}
let mut remaining_bytes = length.saturating_sub((self.block_size - offset) as u64);
let mut block = start_block + 1;
while remaining_bytes != 0 {
let mut chunk_start_block = self
.inode
.log_to_phys_block(&fs, block)
.ok_or_else(|| io::Error::new(io::ErrorKind::UnexpectedEof, "EOF reached"))?;
let mut chunk_num_blocks = 1;
block += 1;
loop {
if (chunk_num_blocks as usize * self.block_size) as u64 >= remaining_bytes {
break;
}
let Some(phys_block) = self.inode.log_to_phys_block(&fs, block) else {
break;
};
if phys_block != chunk_start_block + chunk_num_blocks {
break;
}
chunk_num_blocks += 1;
if let Some(chunk_start_block) = self.inode.log_to_phys_block(fs, block) {
let mut chunk_num_blocks = 1;
block += 1;
loop {
if (chunk_num_blocks as usize * self.block_size) as u64 >= remaining_bytes {
break;
}
let Some(phys_block) = self.inode.log_to_phys_block(fs, block) else {
break;
};
if phys_block != chunk_start_block + chunk_num_blocks {
break;
}
chunk_num_blocks += 1;
block += 1;
}
let _ = fs
.reader
.read_blocks(chunk_start_block, chunk_num_blocks as usize)?
.read(&mut buf[((length - remaining_bytes) as usize)..])?;
remaining_bytes = remaining_bytes
.saturating_sub((self.block_size * chunk_num_blocks as usize) as u64);
} else {
let tmp = &mut buf[((length - remaining_bytes) as usize)..];
let tmp_len = tmp.len();
tmp[..usize::min(self.block_size, tmp_len)].fill(0);
remaining_bytes = remaining_bytes.saturating_sub(1024);
}
let _ = fs
.reader
.read_blocks(chunk_start_block, chunk_num_blocks as usize)?
.read(&mut buf[((length - remaining_bytes) as usize)..])?;
remaining_bytes = remaining_bytes.saturating_sub((self.block_size * chunk_num_blocks as usize) as u64);
}
Ok((length - remaining_bytes) as usize)
}