///////////////////////////////////////////////////////////////////////////////
//
/// \file lzip_decoder.c
/// \brief Decodes .lz (lzip) files
//
// Author: Michał Górny
// Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#include "lzip_decoder.h"
#include "lzma_decoder.h"
#include "check.h"
// .lz format version 0 lacks the 64-bit Member size field in the footer.
#define LZIP_V0_FOOTER_SIZE 12
#define LZIP_V1_FOOTER_SIZE 20
#define LZIP_FOOTER_SIZE_MAX LZIP_V1_FOOTER_SIZE
// lc/lp/pb are hardcoded in the .lz format.
#define LZIP_LC 3
#define LZIP_LP 0
#define LZIP_PB 2
typedef struct {
enum {
SEQ_ID_STRING,
SEQ_VERSION,
SEQ_DICT_SIZE,
SEQ_CODER_INIT,
SEQ_LZMA_STREAM,
SEQ_MEMBER_FOOTER,
} sequence;
/// .lz member format version
uint32_t version;
/// CRC32 of the uncompressed data in the .lz member
uint32_t crc32;
/// Uncompressed size of the .lz member
uint64_t uncompressed_size;
/// Compressed size of the .lz member
uint64_t member_size;
/// Memory usage limit
uint64_t memlimit;
/// Amount of memory actually needed
uint64_t memusage;
/// If true, LZMA_GET_CHECK is returned after decoding the header
/// fields. As all files use CRC32 this is redundant but it's
/// implemented anyway since the initialization functions supports
/// all other flags in addition to LZMA_TELL_ANY_CHECK.
bool tell_any_check;
/// If true, we won't calculate or verify the CRC32 of
/// the uncompressed data.
bool ignore_check;
/// If true, we will decode concatenated .lz members and stop if
/// non-.lz data is seen after at least one member has been
/// successfully decoded.
bool concatenated;
/// When decoding concatenated .lz members, this is true as long as
/// we are decoding the first .lz member. This is needed to avoid
/// incorrect LZMA_FORMAT_ERROR in case there is non-.lz data at
/// the end of the file.
bool first_member;
/// Reading position in the header and footer fields
size_t pos;
/// Buffer to hold the .lz footer fields
uint8_t buffer[LZIP_FOOTER_SIZE_MAX];
/// Options decoded from the .lz header that needed to initialize
/// the LZMA1 decoder.
lzma_options_lzma options;
/// LZMA1 decoder
lzma_next_coder lzma_decoder;
} lzma_lzip_coder;
static lzma_ret
lzip_decode(void *coder_ptr, const lzma_allocator *allocator,
const uint8_t *restrict in, size_t *restrict in_pos,
size_t in_size, uint8_t *restrict out,
size_t *restrict out_pos, size_t out_size, lzma_action action)
{
lzma_lzip_coder *coder = coder_ptr;
while (true)
switch (coder->sequence) {
case SEQ_ID_STRING: {
// The "ID string" or magic bytes are "LZIP" in US-ASCII.
const uint8_t lzip_id_string[4] = { 0x4C, 0x5A, 0x49, 0x50 };
while (coder->pos < sizeof(lzip_id_string)) {
if (*in_pos >= in_size) {
// If we are on the 2nd+ concatenated member
// and the input ends before we can read
// the magic bytes, we discard the bytes that
// were already read (up to 3) and finish.
// See the reasoning below.
return !coder->first_member
&& action == LZMA_FINISH
? LZMA_STREAM_END : LZMA_OK;
}
if (in[*in_pos] != lzip_id_string[coder->pos]) {
// The .lz format allows putting non-.lz data
// at the end of the file. If we have seen
// at least one valid .lz member already,
// then we won't consume the byte at *in_pos
// and will return LZMA_STREAM_END. This way
// apps can easily locate and read the non-.lz
// data after the .lz member(s).
//
// NOTE: If the first 1-3 bytes of the non-.lz
// data match the .lz ID string then the first
// 1-3 bytes of the junk will get ignored by
// us. If apps want to properly locate the
// trailing data they must ensure that the
// first byte of their custom data isn't the
// same as the first byte of .lz ID string.
// With the liblzma API we cannot rewind the
// input position across calls to lzma_code().
return !coder->first_member
? LZMA_STREAM_END : LZMA_FORMAT_ERROR;
}
++*in_pos;
++coder->pos;
}
coder->pos = 0;
coder->crc32 = 0;
coder->uncompressed_size = 0;
coder->member_size = sizeof(lzip_id_string);
coder->sequence = SEQ_VERSION;
}
// Fall through
case SEQ_VERSION:
if (*in_pos >= in_size)
return LZMA_OK;
coder->version = in[(*in_pos)++];
// We support version 0 and unextended version 1.
if (coder->version > 1)
return LZMA_OPTIONS_ERROR;
++coder->member_size;
coder->sequence = SEQ_DICT_SIZE;
// .lz versions 0 and 1 use CRC32 as the integrity check
// so if the application wanted to know that
// (LZMA_TELL_ANY_CHECK) we can tell it now.
if (coder->tell_any_check)
return LZMA_GET_CHECK;
// Fall through
case SEQ_DICT_SIZE: {
if (*in_pos >= in_size)
return LZMA_OK;
const uint32_t ds = in[(*in_pos)++];
++coder->member_size;
// The five lowest bits are for the base-2 logarithm of
// the dictionary size and the highest three bits are
// the fractional part (0/16 to 7/16) that will be
// substracted to get the final value.
//
// For example, with 0xB5:
// b2log = 21
// fracnum = 5
// dict_size = 2^21 - 2^21 * 5 / 16 = 1408 KiB
const uint32_t b2log = ds & 0x1F;
const uint32_t fracnum = ds >> 5;
// The format versions 0 and 1 allow dictionary size in the
// range [4 KiB, 512 MiB].
if (b2log < 12 || b2log > 29 || (b2log == 12 && fracnum > 0))
return LZMA_DATA_ERROR;
// 2^[b2log] - 2^[b2log] * [fracnum] / 16
// = 2^[b2log] - [fracnum] * 2^([b2log] - 4)
coder->options.dict_size = (UINT32_C(1) << b2log)
- (fracnum << (b2log - 4));
assert(coder->options.dict_size >= 4096);
assert(coder->options.dict_size <= (UINT32_C(512) << 20));
coder->options.preset_dict = NULL;
coder->options.lc = LZIP_LC;
coder->options.lp = LZIP_LP;
coder->options.pb = LZIP_PB;
// Calculate the memory usage.
coder->memusage = lzma_lzma_decoder_memusage(&coder->options)
+ LZMA_MEMUSAGE_BASE;
// Initialization is a separate step because if we return
// LZMA_MEMLIMIT_ERROR we need to be able to restart after
// the memlimit has been increased.
coder->sequence = SEQ_CODER_INIT;
}
// Fall through
case SEQ_CODER_INIT: {
if (coder->memusage > coder->memlimit)
return LZMA_MEMLIMIT_ERROR;
const lzma_filter_info filters[2] = {
{
.id = LZMA_FILTER_LZMA1,
.init = &lzma_lzma_decoder_init,
.options = &coder->options,
}, {
.init = NULL,
}
};
return_if_error(lzma_next_filter_init(&coder->lzma_decoder,
allocator, filters));
coder->crc32 = 0;
coder->sequence = SEQ_LZMA_STREAM;
}
// Fall through
case SEQ_LZMA_STREAM: {
const size_t in_start = *in_pos;
const size_t out_start = *out_pos;
const lzma_ret ret = coder->lzma_decoder.code(
coder->lzma_decoder.coder, allocator,
in, in_pos, in_size, out, out_pos, out_size,
action);
const size_t out_used = *out_pos - out_start;
coder->member_size += *in_pos - in_start;
coder->uncompressed_size += out_used;
// Don't update the CRC32 if the integrity check will be
// ignored or if there was no new output. The latter is
// important in case out == NULL to avoid null pointer + 0
// which is undefined behavior.
if (!coder->ignore_check && out_used > 0)
coder->crc32 = lzma_crc32(out + out_start, out_used,
coder->crc32);
if (ret != LZMA_STREAM_END)
return ret;
coder->sequence = SEQ_MEMBER_FOOTER;
}
// Fall through
case SEQ_MEMBER_FOOTER: {
// The footer of .lz version 0 lacks the Member size field.
// This is the only difference between version 0 and
// unextended version 1 formats.
const size_t footer_size = coder->version == 0
? LZIP_V0_FOOTER_SIZE
: LZIP_V1_FOOTER_SIZE;
// Copy the CRC32, Data size, and Member size fields to
// the internal buffer.
lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos,
footer_size);
// Return if we didn't get the whole footer yet.
if (coder->pos < footer_size)
return LZMA_OK;
coder->pos = 0;
coder->member_size += footer_size;
// Check that the footer fields match the observed data.
if (!coder->ignore_check
&& coder->crc32 != read32le(&coder->buffer[0]))
return LZMA_DATA_ERROR;
if (coder->uncompressed_size != read64le(&coder->buffer[4]))
return LZMA_DATA_ERROR;
if (coder->version > 0) {
// .lz version 0 has no Member size field.
if (coder->member_size != read64le(&coder->buffer[12]))
return LZMA_DATA_ERROR;
}
// Decoding is finished if we weren't requested to decode
// more than one .lz member.
if (!coder->concatenated)
return LZMA_STREAM_END;
coder->first_member = false;
coder->sequence = SEQ_ID_STRING;
break;
}
default:
assert(0);
return LZMA_PROG_ERROR;
}
// Never reached
}
static void
lzip_decoder_end(void *coder_ptr, const lzma_allocator *allocator)
{
lzma_lzip_coder *coder = coder_ptr;
lzma_next_end(&coder->lzma_decoder, allocator);
lzma_free(coder, allocator);
return;
}
static lzma_check
lzip_decoder_get_check(const void *coder_ptr lzma_attribute((__unused__)))
{
return LZMA_CHECK_CRC32;
}
static lzma_ret
lzip_decoder_memconfig(void *coder_ptr, uint64_t *memusage,
uint64_t *old_memlimit, uint64_t new_memlimit)
{
lzma_lzip_coder *coder = coder_ptr;
*memusage = coder->memusage;
*old_memlimit = coder->memlimit;
if (new_memlimit != 0) {
if (new_memlimit < coder->memusage)
return LZMA_MEMLIMIT_ERROR;
coder->memlimit = new_memlimit;
}
return LZMA_OK;
}
extern lzma_ret
lzma_lzip_decoder_init(
lzma_next_coder *next, const lzma_allocator *allocator,
uint64_t memlimit, uint32_t flags)
{
lzma_next_coder_init(&lzma_lzip_decoder_init, next, allocator);
if (flags & ~LZMA_SUPPORTED_FLAGS)
return LZMA_OPTIONS_ERROR;
lzma_lzip_coder *coder = next->coder;
if (coder == NULL) {
coder = lzma_alloc(sizeof(lzma_lzip_coder), allocator);
if (coder == NULL)
return LZMA_MEM_ERROR;
next->coder = coder;
next->code = &lzip_decode;
next->end = &lzip_decoder_end;
next->get_check = &lzip_decoder_get_check;
next->memconfig = &lzip_decoder_memconfig;
coder->lzma_decoder = LZMA_NEXT_CODER_INIT;
}
coder->sequence = SEQ_ID_STRING;
coder->memlimit = my_max(1, memlimit);
coder->memusage = LZMA_MEMUSAGE_BASE;
coder->tell_any_check = (flags & LZMA_TELL_ANY_CHECK) != 0;
coder->ignore_check = (flags & LZMA_IGNORE_CHECK) != 0;
coder->concatenated = (flags & LZMA_CONCATENATED) != 0;
coder->first_member = true;
coder->pos = 0;
return LZMA_OK;
}
extern LZMA_API(lzma_ret)
lzma_lzip_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags)
{
lzma_next_strm_init(lzma_lzip_decoder_init, strm, memlimit, flags);
strm->internal->supported_actions[LZMA_RUN] = true;
strm->internal->supported_actions[LZMA_FINISH] = true;
return LZMA_OK;
}
