0ct0pu5/ladybird
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions 2

Ext2FS: Support reading from file holes

Browse source 
It's perfectly valid for ext2 inodes to have blocks with index 0.
It means that no physical block was allocated for that area of an inode
and we should treat it as if it's filled with zeroes.

Fixes #6139.
This commit is contained in:
Andreas Kling 2021-04-10 11:05:19 +02:00
parent b5b38d372c
commit 642b428793
Notes: sideshowbarker 2024-07-18 20:36:04 +09:00
1 changed files with 10 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

16
Kernel/FileSystem/Ext2FileSystem.cpp
View file

@ -896,14 +896,19 @@ ssize_t Ext2FSInode::read_bytes(off_t offset, ssize_t count, UserOrKernelBuffer&
for (auto bi = first_block_logical_index; remaining_count && bi <= last_block_logical_index; bi = bi.value() + 1) {
auto block_index = m_block_list[bi.value()];
VERIFY(block_index.value());
size_t offset_into_block = (bi == first_block_logical_index) ? offset_into_first_block : 0;
size_t num_bytes_to_copy = min((off_t)block_size - offset_into_block, remaining_count);
auto buffer_offset = buffer.offset(nread);
auto result = fs().read_block(block_index, &buffer_offset, num_bytes_to_copy, offset_into_block, allow_cache);
if (result.is_error()) {
dmesgln("Ext2FSInode[{}]::read_bytes(): Failed to read block {} (index {})", identifier(), block_index.value(), bi);
return result.error();
if (block_index.value() == 0) {
// This is a hole, act as if it's filled with zeroes.
if (!buffer_offset.memset(0, num_bytes_to_copy))
return -EFAULT;
} else {
auto result = fs().read_block(block_index, &buffer_offset, num_bytes_to_copy, offset_into_block, allow_cache);
if (result.is_error()) {
dmesgln("Ext2FSInode[{}]::read_bytes(): Failed to read block {} (index {})", identifier(), block_index.value(), bi);
return result.error();
}
}
remaining_count -= num_bytes_to_copy;
nread += num_bytes_to_copy;
@ -1784,5 +1789,4 @@ KResult Ext2FS::prepare_to_unmount() const
m_inode_cache.clear();
return KSuccess;
}
}