diff --git a/btrfs/src/v2/volume.rs b/btrfs/src/v2/volume.rs
index 6196fc7..6c1724c 100644
--- a/btrfs/src/v2/volume.rs
+++ b/btrfs/src/v2/volume.rs
@@ -8,8 +8,8 @@ use scroll::Pread;
use crate::crc32c::calculate_crc32c;
use crate::path::Path;
use crate::structs::{
- Chunk, DirItemEntry, DirItemType, ExtentData, INodeItem, INodeRefEntry, Item, Key, KeyPtr,
- KnownObjectId, ObjectType, RootItem, Stripe, Superblock, TreeItem,
+ Chunk, CompressionType, DirItemEntry, DirItemType, ExtentData, INodeItem, INodeRefEntry, Item,
+ Key, KeyPtr, KnownObjectId, ObjectType, RootItem, Stripe, Superblock, TreeItem,
};
use crate::{Error, Result};
@@ -569,27 +569,50 @@ impl<R: super::Read> Fs<R> {
log::info!("extents: {}", extents.len());
log::info!("{:?}", extents);
for (offset, extent) in extents.into_iter().filter(|(offset, extent)| {
+ // bounds of the current extent
let extent_start = *offset;
let extent_end = extent_start + extent.len();
+ let extent_len = extent.len();
- // length of the entire range to be read
+ // entire range we want to read from the file
let range_len = end.map(|end| end - start);
- // bounds and length of the intersection of the current extent and
- // the entire range to be read
- let start2 = start.min(extent_start);
- let end = end.map(|end| end.max(extent_end)).unwrap_or(extent.len());
- let len = end - start2;
+ // start of the UNION (from lowest bound to highest bound) of the
+ // current extent and the entire range
+ let start = start.min(extent_start);
+ // end of the UNION of the current extent and the entire range
+ let end = end.map(|end| end.max(extent_end));
+ // width of the union o fthe current extent and the entire range
+ let len = end.map(|end| (end - start));
- // check if current extent intersects the range we want to read
- if let Some(range_len) = range_len {
- range_len + range_len < len
+ if let (Some(len), Some(range_len)) = (len, range_len) {
+ // proceed if the widths of the 2 ranges (the range we want to
+ // read, and the current extent) are greater than the width of
+ // the union range:
+ //
+ // In the first example, the 2 ranges overlap, and the width of
+ // the union is smaller than the sum of the widths of the ranges:
+ //
+ // |------range-1------|
+ // |---range-2----|
+ // |-----width-of-union-----|
+ // |-------sum----|-of---widths-------|
+ // |------------width-of-union------------|
+ // |------range-1------|
+ // |---range-2----|
+ //
+ // In this second example, the ranges do not overlap, and the
+ // width of the unions is equal or greater than the sum of the
+ // widths.
+ len < extent_len + range_len
} else {
- start2 < extent_end
+ start < extent_end
}
}) {
+ //
let start = start.saturating_sub(offset);
- let end = end.map(|end| end - offset).unwrap_or(extent.len());
+
+ let end = end.map(|end| end - offset).unwrap_or(start + extent.len());
let len = end - start;
log::info!("reading {}..{:?} from extent.", start, end);
@@ -607,9 +630,10 @@ impl<R: super::Read> Fs<R> {
let range = address
..(address
+ match extent.extent_data1().compression() {
- crate::structs::CompressionType::Zlib
- | crate::structs::CompressionType::Lzo
- | crate::structs::CompressionType::ZStd => extent.size(), // compressed size
+ // compressed size
+ CompressionType::Zlib
+ | CompressionType::Lzo
+ | CompressionType::ZStd => extent.size(),
_ => len,
});
@@ -622,8 +646,8 @@ impl<R: super::Read> Fs<R> {
log::info!("compression: {:?}", extent.header().compression());
let data = match extent.header().compression() {
- crate::structs::CompressionType::None => data,
- crate::structs::CompressionType::Zlib => {
+ CompressionType::None => data,
+ CompressionType::Zlib => {
let mut state = miniz_oxide::inflate::stream::InflateState::new(
miniz_oxide::DataFormat::Zlib,
);
@@ -638,8 +662,6 @@ impl<R: super::Read> Fs<R> {
miniz_oxide::MZFlush::None,
);
- log::info!("inflated: {:?}", result);
-
match result.status.map_err(|_| Error::DecompressionError)? {
miniz_oxide::MZStatus::Ok => {}
miniz_oxide::MZStatus::StreamEnd => break,
@@ -663,10 +685,10 @@ impl<R: super::Read> Fs<R> {
output_data.into()
}
- crate::structs::CompressionType::Lzo => {
+ CompressionType::Lzo => {
todo!()
}
- crate::structs::CompressionType::ZStd => {
+ CompressionType::ZStd => {
todo!()
}
c => {
@@ -675,6 +697,7 @@ impl<R: super::Read> Fs<R> {
}
};
+ // truncate inflated data if needed
contents.extend_from_slice(&data[..len as usize]);
}
diff --git a/btrfs/tests/read_superblock.rs b/btrfs/tests/read_superblock.rs
index ced839b..15f78f7 100644
--- a/btrfs/tests/read_superblock.rs
+++ b/btrfs/tests/read_superblock.rs
@@ -164,7 +164,9 @@ fn find_file_zlib() -> Result<()> {
log::info!("chidlren: {:?}", children);
let cmake_list = fs.get_inode_by_path(b"/quibble/LICENCE")?;
- let file_contents = fs.read_inode_raw(&cmake_list, ..).expect("file contents");
+ let file_contents = fs
+ .read_inode_raw(&cmake_list, ..100)
+ .expect("file contents");
//assert_eq!(&file_contents[..11], b"hello world");
log::info!("license file:");
log::info!("{}", String::from_utf8_lossy(&file_contents));
@@ -207,7 +209,9 @@ fn find_file_zstd() -> Result<()> {
log::info!("chidlren: {:?}", children);
let cmake_list = fs.get_inode_by_path(b"/quibble/LICENCE")?;
- let file_contents = fs.read_inode_raw(&cmake_list, ..).expect("file contents");
+ let file_contents = fs
+ .read_inode_raw(&cmake_list, ..100)
+ .expect("file contents");
assert_eq!(
&file_contents[..52],
b" GNU LESSER GENERAL PUBLIC LICENSE"