///////////////////////////////////////////////////////////////////////////////
//
/// \file stream_decoder.c
/// \brief Decodes .lzma Streams
//
// 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_common.h"
#include "stream_decoder.h"
#include "check.h"
#include "stream_flags_decoder.h"
#include "block_decoder.h"
struct lzma_coder_s {
enum {
SEQ_STREAM_HEADER,
SEQ_BLOCK_HEADER,
SEQ_BLOCK,
SEQ_INDEX,
SEQ_STREAM_FOOTER,
} sequence;
/// Block or Metadata decoder. This takes little memory and the same
/// data structure can be used to decode every Block Header, so it's
/// a good idea to have a separate lzma_next_coder structure for it.
lzma_next_coder block_decoder;
/// Block options decoded by the Block Header decoder and used by
/// the Block decoder.
lzma_options_block block_options;
/// Stream Flags from Stream Header
lzma_stream_flags stream_flags;
/// Index is hashed so that it can be compared to the sizes of Blocks
/// with O(1) memory usage.
lzma_index_hash *index_hash;
/// Write position in buffer[]
size_t buffer_pos;
/// Buffer to hold Stream Header, Block Header, and Stream Footer.
/// Block Header has biggest maximum size.
uint8_t buffer[LZMA_BLOCK_HEADER_SIZE_MAX];
};
static lzma_ret
stream_decode(lzma_coder *coder, 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)
{
// When decoding the actual Block, it may be able to produce more
// output even if we don't give it any new input.
while (*out_pos < out_size && (*in_pos < in_size
|| coder->sequence == SEQ_BLOCK))
switch (coder->sequence) {
case SEQ_STREAM_HEADER: {
// Copy the Stream Header to the internal buffer.
bufcpy(in, in_pos, in_size, coder->buffer, &coder->buffer_pos,
LZMA_STREAM_HEADER_SIZE);
// Return if we didn't get the whole Stream Header yet.
if (coder->buffer_pos < LZMA_STREAM_HEADER_SIZE)
return LZMA_OK;
coder->buffer_pos = 0;
// Decode the Stream Header.
return_if_error(lzma_stream_header_decode(
&coder->stream_flags, coder->buffer));
// Copy the type of the Check so that Block Header and Block
// decoders see it.
coder->block_options.check = coder->stream_flags.check;
// Even if we return LZMA_UNSUPPORTED_CHECK below, we want
// to continue from Block Header decoding.
coder->sequence = SEQ_BLOCK_HEADER;
// Detect if the Check type is supported and give appropriate
// warning if it isn't. We don't warn every time a new Block
// is started.
if (!lzma_available_checks[coder->block_options.check])
return LZMA_UNSUPPORTED_CHECK;
break;
}
case SEQ_BLOCK_HEADER: {
if (coder->buffer_pos == 0) {
// Detect if it's Index.
if (in[*in_pos] == 0x00) {
coder->sequence = SEQ_INDEX;
break;
}
// Calculate the size of the Block Header. Note that
// Block Header decoder wants to see this byte too
// so don't advance *in_pos.
coder->block_options.header_size
= lzma_block_header_size_decode(
in[*in_pos]);
}
// Copy the Block Header to the internal buffer.
bufcpy(in, in_pos, in_size, coder->buffer, &coder->buffer_pos,
coder->block_options.header_size);
// Return if we didn't get the whole Block Header yet.
if (coder->buffer_pos < coder->block_options.header_size)
return LZMA_OK;
coder->buffer_pos = 0;
// Set up a buffer to hold the filter chain. Block Header
// decoder will initialize all members of this array so
// we don't need to do it here.
lzma_options_filter filters[LZMA_BLOCK_FILTERS_MAX + 1];
coder->block_options.filters = filters;
// Decode the Block Header.
return_if_error(lzma_block_header_decode(&coder->block_options,
allocator, coder->buffer));
// Initialize the Block decoder.
const lzma_ret ret = lzma_block_decoder_init(
&coder->block_decoder,
allocator, &coder->block_options);
// Free the allocated filter options since they are needed
// only to initialize the Block decoder.
for (size_t i = 0; i < LZMA_BLOCK_FILTERS_MAX; ++i)
lzma_free(filters[i].options, allocator);
coder->block_options.filters = NULL;
// Check if Block enocoder initialization succeeded. Don't
// warn about unsupported check anymore since we did it
// earlier if it was needed.
if (ret != LZMA_OK && ret != LZMA_UNSUPPORTED_CHECK)
return ret;
coder->sequence = SEQ_BLOCK;
break;
}
case SEQ_BLOCK: {
lzma_ret ret = coder->block_decoder.code(
coder->block_decoder.coder, allocator,
in, in_pos, in_size, out, out_pos, out_size,
action);
if (ret != LZMA_STREAM_END)
return ret;
// Block decoded successfully. Add the new size pair to
// the Index hash.
return_if_error(lzma_index_hash_append(coder->index_hash,
lzma_block_total_size_get(
&coder->block_options),
coder->block_options.uncompressed_size));
coder->sequence = SEQ_BLOCK_HEADER;
break;
}
case SEQ_INDEX: {
// Decode the Index and compare it to the hash calculated
// from the sizes of the Blocks (if any).
const lzma_ret ret = lzma_index_hash_decode(coder->index_hash,
in, in_pos, in_size);
if (ret != LZMA_STREAM_END)
return ret;
coder->sequence = SEQ_STREAM_FOOTER;
break;
}
case SEQ_STREAM_FOOTER:
// Copy the Stream Footer to the internal buffer.
bufcpy(in, in_pos, in_size, coder->buffer, &coder->buffer_pos,
LZMA_STREAM_HEADER_SIZE);
// Return if we didn't get the whole Stream Footer yet.
if (coder->buffer_pos < LZMA_STREAM_HEADER_SIZE)
return LZMA_OK;
// Decode the Stream Footer.
lzma_stream_flags footer_flags;
return_if_error(lzma_stream_footer_decode(
&footer_flags, coder->buffer));
// Check that Index Size stored in the Stream Footer matches
// the real size of the Index field.
if (lzma_index_hash_size(coder->index_hash)
!= footer_flags.backward_size)
return LZMA_DATA_ERROR;
// Compare that the Stream Flags fields are identical in
// both Stream Header and Stream Footer.
if (!lzma_stream_flags_equal(&coder->stream_flags,
&footer_flags))
return LZMA_DATA_ERROR;
return LZMA_STREAM_END;
default:
assert(0);
return LZMA_PROG_ERROR;
}
return LZMA_OK;
}
static void
stream_decoder_end(lzma_coder *coder, lzma_allocator *allocator)
{
lzma_next_coder_end(&coder->block_decoder, allocator);
lzma_index_hash_end(coder->index_hash, allocator);
lzma_free(coder, allocator);
return;
}
static lzma_ret
stream_decoder_init(lzma_next_coder *next, lzma_allocator *allocator)
{
if (next->coder == NULL) {
next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
if (next->coder == NULL)
return LZMA_MEM_ERROR;
next->code = &stream_decode;
next->end = &stream_decoder_end;
next->coder->block_decoder = LZMA_NEXT_CODER_INIT;
next->coder->index_hash = NULL;
}
// Initialize the Index hash used to verify the Index.
next->coder->index_hash = lzma_index_hash_init(
next->coder->index_hash, allocator);
if (next->coder->index_hash == NULL)
return LZMA_MEM_ERROR;
// Reset the rest of the variables.
next->coder->sequence = SEQ_STREAM_HEADER;
next->coder->block_options.filters = NULL;
next->coder->buffer_pos = 0;
return LZMA_OK;
}
extern lzma_ret
lzma_stream_decoder_init(lzma_next_coder *next, lzma_allocator *allocator)
{
lzma_next_coder_init0(stream_decoder_init, next, allocator);
}
extern LZMA_API lzma_ret
lzma_stream_decoder(lzma_stream *strm)
{
lzma_next_strm_init0(strm, stream_decoder_init);
strm->internal->supported_actions[LZMA_RUN] = true;
strm->internal->supported_actions[LZMA_SYNC_FLUSH] = true;
return LZMA_OK;
}
