1use crate::read::{self, Error, ReadError as _};
2use crate::{endian, CompressedFileRange, CompressionFormat, ReadRef, U32Bytes};
3
4// Attempt to parse the the CompressedFileRange for a section using the GNU-style
5// inline compression header format. This is used by the Go compiler in Mach-O files
6// as well as by the GNU linker in some ELF files.
7pub(super) fn compressed_file_range<'data, R: ReadRef<'data>>(
8 file_data: R,
9 section_offset: u64,
10 section_size: u64,
11) -> read::Result<CompressedFileRange> {
12 let mut offset = section_offset;
13 // Assume ZLIB-style uncompressed data is no more than 4GB to avoid accidentally
14 // huge allocations. This also reduces the chance of accidentally matching on a
15 // .debug_str that happens to start with "ZLIB".
16 let header = file_data
17 .read_bytes(&mut offset, 8)
18 .read_error("GNU compressed section is too short")?;
19 if header != b"ZLIB\0\0\0\0" {
20 return Err(Error("Invalid GNU compressed section header"));
21 }
22 let uncompressed_size = file_data
23 .read::<U32Bytes<_>>(&mut offset)
24 .read_error("GNU compressed section is too short")?
25 .get(endian::BigEndian)
26 .into();
27 let compressed_size = section_size
28 .checked_sub(offset - section_offset)
29 .read_error("GNU compressed section is too short")?;
30 Ok(CompressedFileRange {
31 format: CompressionFormat::Zlib,
32 offset,
33 compressed_size,
34 uncompressed_size,
35 })
36}
37