liblzma: Add .lz support to lzma_auto_decoder().

Thanks to Michał Górny for the original patch.
This commit is contained in:
Lasse Collin 2022-10-08 00:29:20 +03:00
parent 0538db038f
commit 034086e1ae
4 changed files with 47 additions and 11 deletions

View File

@ -700,11 +700,13 @@ extern LZMA_API(lzma_ret) lzma_stream_decoder_mt(
/**
* \brief Decode .xz Streams and .lzma files with autodetection
* \brief Decode .xz, .lzma, and .lz (lzip) files with autodetection
*
* This decoder autodetects between the .xz and .lzma file formats, and
* calls lzma_stream_decoder() or lzma_alone_decoder() once the type
* of the input file has been detected.
* This decoder autodetects between the .xz, .lzma, and .lz file formats,
* and calls lzma_stream_decoder(), lzma_alone_decoder(), or
* lzma_lzip_decoder() once the type of the input file has been detected.
*
* Support for .lz was added in 5.4.0.
*
* If the flag LZMA_CONCATENATED is used and the input is a .lzma file:
* For historical reasons concatenated .lzma files aren't supported.

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@ -97,6 +97,7 @@ endif
if COND_LZIP_DECODER
liblzma_la_SOURCES += \
common/lzip_decoder.c
common/lzip_decoder.c \
common/lzip_decoder.h
endif
endif

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@ -1,7 +1,7 @@
///////////////////////////////////////////////////////////////////////////////
//
/// \file auto_decoder.c
/// \brief Autodetect between .xz Stream and .lzma (LZMA_Alone) formats
/// \brief Autodetect between .xz, .lzma (LZMA_Alone), and .lz (lzip)
//
// Author: Lasse Collin
//
@ -12,10 +12,13 @@
#include "stream_decoder.h"
#include "alone_decoder.h"
#ifdef HAVE_LZIP_DECODER
# include "lzip_decoder.h"
#endif
typedef struct {
/// Stream decoder or LZMA_Alone decoder
/// .xz Stream decoder, LZMA_Alone decoder, or lzip decoder
lzma_next_coder next;
uint64_t memlimit;
@ -46,14 +49,22 @@ auto_decode(void *coder_ptr, const lzma_allocator *allocator,
// SEQ_CODE even if we return some LZMA_*_CHECK.
coder->sequence = SEQ_CODE;
// Detect the file format. For now this is simple, since if
// it doesn't start with 0xFD (the first magic byte of the
// new format), it has to be LZMA_Alone, or something that
// we don't support at all.
// Detect the file format. .xz files start with 0xFD which
// cannot be the first byte of .lzma (LZMA_Alone) format.
// The .lz format starts with 0x4C which could be the
// first byte of a .lzma file but luckily it would mean
// lc/lp/pb being 4/3/1 which liblzma doesn't support because
// lc + lp > 4. So using just 0x4C to detect .lz is OK here.
if (in[*in_pos] == 0xFD) {
return_if_error(lzma_stream_decoder_init(
&coder->next, allocator,
coder->memlimit, coder->flags));
#ifdef HAVE_LZIP_DECODER
} else if (in[*in_pos] == 0x4C) {
return_if_error(lzma_lzip_decoder_init(
&coder->next, allocator,
coder->memlimit, coder->flags));
#endif
} else {
return_if_error(lzma_alone_decoder_init(&coder->next,
allocator, coder->memlimit, true));

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@ -0,0 +1,22 @@
///////////////////////////////////////////////////////////////////////////////
//
/// \file lzip_decoder.h
/// \brief Decodes .lz (lzip) files
//
// Author: Michał Górny
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#ifndef LZMA_LZIP_DECODER_H
#define LZMA_LZIP_DECODER_H
#include "common.h"
extern lzma_ret lzma_lzip_decoder_init(
lzma_next_coder *next, const lzma_allocator *allocator,
uint64_t memlimit, uint32_t flags);
#endif