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fix: Alignment was previously handled incorrectly (#33)

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Chris Hennick 2024-04-23 12:07:30 -07:00
parent c3d9123abf
commit 00378bc6f2
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GPG key ID: DA47AABA4961C509
2 changed files with 23 additions and 12 deletions
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31
src/write.rs
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@ -761,25 +761,36 @@ impl<W: Write + Seek> ZipWriter<W> {
let mut header_end = writer.stream_position()?;
if options.alignment > 1 {
let align = options.alignment as u64;
if header_end % align != 0 {
let pad_length = (align - (header_end + 4) % align) % align;
if pad_length + extra_field_length as u64 > u16::MAX as u64 {
let unaligned_header_bytes = header_end % align;
if unaligned_header_bytes != 0 {
let pad_length = (align - unaligned_header_bytes) as usize;
let Some(new_extra_field_length) =
(pad_length as u16).checked_add(extra_field_length)
else {
let _ = self.abort_file();
return Err(InvalidArchive(
"Extra data field would be larger than allowed after aligning",
));
};
if pad_length >= 4 {
// Add an extra field to the extra_data
let pad_body = vec![0; pad_length - 4];
writer.write_all(b"za").map_err(ZipError::from)?; // 0x617a
writer
.write_u16::<LittleEndian>(pad_body.len() as u16)
.map_err(ZipError::from)?;
writer.write_all(&pad_body).map_err(ZipError::from)?;
} else {
// extra_data padding is too small for an extra field header, so pad with
// zeroes
let pad = vec![0; pad_length];
writer.write_all(&pad).map_err(ZipError::from)?;
}
let pad = vec![0; pad_length as usize];
writer.write_all(b"za").map_err(ZipError::from)?; // 0x617a
writer
.write_u16::<LittleEndian>(pad.len() as u16)
.map_err(ZipError::from)?;
writer.write_all(&pad).map_err(ZipError::from)?;
header_end = writer.stream_position()?;
// Update extra field length in local file header.
writer.seek(SeekFrom::Start(file.header_start + 28))?;
writer.write_u16::<LittleEndian>(pad_length as u16 + extra_field_length)?;
writer.write_u16::<LittleEndian>(new_extra_field_length)?;
writer.seek(SeekFrom::Start(header_end))?;
debug_assert_eq!(header_end % align, 0);
}