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///////////////////////////////////////////////////////////////////////////////
//
/// \file stream_flags_decoder.c
/// \brief Decodes Stream Header and tail from .lzma files
//
// Copyright (C) 2007 Lasse Collin
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
///////////////////////////////////////////////////////////////////////////////
#include "stream_flags_decoder.h"
#include "stream_common.h"
////////////
// Common //
////////////
struct lzma_coder_s {
enum {
SEQ_HEADER_MAGIC,
SEQ_HEADER_FLAGS,
SEQ_HEADER_CRC32,
SEQ_FOOTER_FLAGS,
SEQ_FOOTER_MAGIC,
} sequence;
size_t pos;
uint32_t crc32;
lzma_stream_flags *options;
};
static void
stream_header_decoder_end(lzma_coder *coder, lzma_allocator *allocator)
{
lzma_free(coder, allocator);
return;
}
static bool
stream_flags_decode(const uint8_t *in, lzma_stream_flags *options)
{
// Reserved bits must be unset.
if (*in & 0xE0)
return true;
options->check = *in & 0x07;
options->has_crc32 = (*in & 0x08) != 0;
options->is_multi = (*in & 0x10) != 0;
return false;
}
////////////
// Header //
////////////
static lzma_ret
stream_header_decode(lzma_coder *coder,
lzma_allocator *allocator lzma_attribute((unused)),
const uint8_t *restrict in, size_t *restrict in_pos,
size_t in_size, uint8_t *restrict out lzma_attribute((unused)),
size_t *restrict out_pos lzma_attribute((unused)),
size_t out_size lzma_attribute((unused)),
lzma_action action lzma_attribute((unused)))
{
while (*in_pos < in_size)
switch (coder->sequence) {
case SEQ_HEADER_MAGIC:
if (in[*in_pos] != lzma_header_magic[coder->pos])
return LZMA_DATA_ERROR;
++*in_pos;
if (++coder->pos == sizeof(lzma_header_magic)) {
coder->pos = 0;
coder->sequence = SEQ_HEADER_FLAGS;
}
break;
case SEQ_HEADER_FLAGS:
if (stream_flags_decode(in + *in_pos, coder->options))
return LZMA_HEADER_ERROR;
coder->crc32 = lzma_crc32(in + *in_pos, 1, 0);
++*in_pos;
coder->sequence = SEQ_HEADER_CRC32;
break;
case SEQ_HEADER_CRC32:
if (in[*in_pos] != ((coder->crc32 >> (coder->pos * 8)) & 0xFF))
return LZMA_DATA_ERROR;
++*in_pos;
if (++coder->pos == 4)
return LZMA_STREAM_END;
break;
default:
return LZMA_PROG_ERROR;
}
return LZMA_OK;
}
static lzma_ret
stream_header_decoder_init(lzma_next_coder *next,
lzma_allocator *allocator, lzma_stream_flags *options)
{
if (options == NULL)
return LZMA_PROG_ERROR;
if (next->coder == NULL) {
next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
if (next->coder == NULL)
return LZMA_MEM_ERROR;
}
// Set the function pointers unconditionally, because they may
// have been pointing to footer decoder too.
next->code = &stream_header_decode;
next->end = &stream_header_decoder_end;
next->coder->sequence = SEQ_HEADER_MAGIC;
next->coder->pos = 0;
next->coder->crc32 = 0;
next->coder->options = options;
return LZMA_OK;
}
extern lzma_ret
lzma_stream_header_decoder_init(lzma_next_coder *next,
lzma_allocator *allocator, lzma_stream_flags *options)
{
lzma_next_coder_init(
stream_header_decoder_init, next, allocator, options);
}
extern LZMA_API lzma_ret
lzma_stream_header_decoder(lzma_stream *strm, lzma_stream_flags *options)
{
lzma_next_strm_init(strm, stream_header_decoder_init, options);
strm->internal->supported_actions[LZMA_RUN] = true;
return LZMA_OK;
}
//////////
// Tail //
//////////
static lzma_ret
stream_tail_decode(lzma_coder *coder,
lzma_allocator *allocator lzma_attribute((unused)),
const uint8_t *restrict in, size_t *restrict in_pos,
size_t in_size, uint8_t *restrict out lzma_attribute((unused)),
size_t *restrict out_pos lzma_attribute((unused)),
size_t out_size lzma_attribute((unused)),
lzma_action action lzma_attribute((unused)))
{
while (*in_pos < in_size)
switch (coder->sequence) {
case SEQ_FOOTER_FLAGS:
if (stream_flags_decode(in + *in_pos, coder->options))
return LZMA_HEADER_ERROR;
++*in_pos;
coder->sequence = SEQ_FOOTER_MAGIC;
break;
case SEQ_FOOTER_MAGIC:
if (in[*in_pos] != lzma_footer_magic[coder->pos])
return LZMA_DATA_ERROR;
++*in_pos;
if (++coder->pos == sizeof(lzma_footer_magic))
return LZMA_STREAM_END;
break;
default:
return LZMA_PROG_ERROR;
}
return LZMA_OK;
}
static lzma_ret
stream_tail_decoder_init(lzma_next_coder *next,
lzma_allocator *allocator, lzma_stream_flags *options)
{
if (options == NULL)
return LZMA_PROG_ERROR;
if (next->coder == NULL) {
next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
if (next->coder == NULL)
return LZMA_MEM_ERROR;
}
// Set the function pointers unconditionally, because they may
// have been pointing to footer decoder too.
next->code = &stream_tail_decode;
next->end = &stream_header_decoder_end;
next->coder->sequence = SEQ_FOOTER_FLAGS;
next->coder->pos = 0;
next->coder->options = options;
return LZMA_OK;
}
extern lzma_ret
lzma_stream_tail_decoder_init(lzma_next_coder *next,
lzma_allocator *allocator, lzma_stream_flags *options)
{
lzma_next_coder_init2(next, allocator, stream_header_decoder_init,
stream_tail_decoder_init, allocator, options);
}
extern LZMA_API lzma_ret
lzma_stream_tail_decoder(lzma_stream *strm, lzma_stream_flags *options)
{
lzma_next_strm_init2(strm, stream_header_decoder_init,
stream_tail_decoder_init, strm->allocator, options);
strm->internal->supported_actions[LZMA_RUN] = true;
return LZMA_OK;
}
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