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Defer parsing of local file header

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This commit is contained in:
Sam Rijs 2018-11-06 23:13:20 +11:00
parent 493424e93d
commit 9e8747872b
1 changed files with 16 additions and 23 deletions
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39
src/read.rs
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@ -282,15 +282,28 @@ impl<R: Read+io::Seek> ZipArchive<R>
pub fn by_index<'a>(&'a mut self, file_number: usize) -> ZipResult<ZipFile<'a>>
{
if file_number >= self.files.len() { return Err(ZipError::FileNotFound); }
let ref data = self.files[file_number];
let pos = data.data_start;
let ref mut data = self.files[file_number];
if data.encrypted
{
return unsupported_zip_error("Encrypted files are not supported")
}
self.reader.seek(io::SeekFrom::Start(pos))?;
// Parse local header
self.reader.seek(io::SeekFrom::Start(data.header_start))?;
let signature = self.reader.read_u32::<LittleEndian>()?;
if signature != spec::LOCAL_FILE_HEADER_SIGNATURE
{
return Err(ZipError::InvalidArchive("Invalid local file header"))
}
self.reader.seek(io::SeekFrom::Current(22))?;
let file_name_length = self.reader.read_u16::<LittleEndian>()? as u64;
let extra_field_length = self.reader.read_u16::<LittleEndian>()? as u64;
let magic_and_header = 4 + 22 + 2 + 2;
data.data_start = data.header_start + magic_and_header + file_name_length + extra_field_length;
self.reader.seek(io::SeekFrom::Start(data.data_start))?;
let limit_reader = (self.reader.by_ref() as &mut Read).take(data.compressed_size);
Ok(ZipFile { reader: make_reader(data.compression_method, data.crc32, limit_reader)?, data: Cow::Borrowed(data) })
@ -374,26 +387,6 @@ fn central_header_to_zip_file<R: Read+io::Seek>(reader: &mut R, archive_offset:
// Account for shifted zip offsets.
result.header_start += archive_offset;
// Remember end of central header
let return_position = reader.seek(io::SeekFrom::Current(0))?;
// Parse local header
reader.seek(io::SeekFrom::Start(result.header_start))?;
let signature = reader.read_u32::<LittleEndian>()?;
if signature != spec::LOCAL_FILE_HEADER_SIGNATURE
{
return Err(ZipError::InvalidArchive("Invalid local file header"))
}
reader.seek(io::SeekFrom::Current(22))?;
let file_name_length = reader.read_u16::<LittleEndian>()? as u64;
let extra_field_length = reader.read_u16::<LittleEndian>()? as u64;
let magic_and_header = 4 + 22 + 2 + 2;
result.data_start = result.header_start + magic_and_header + file_name_length + extra_field_length;
// Go back after the central header
reader.seek(io::SeekFrom::Start(return_position))?;
Ok(result)
}