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///////////////////////////////////////////////////////////////////////////////
//
/// \file alone_decoder.c
/// \brief Decoder for LZMA_Alone 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 "alone_decoder.h"
#include "lzma_decoder.h"
struct lzma_coder_s {
lzma_next_coder next;
enum {
SEQ_PROPERTIES,
SEQ_DICTIONARY_SIZE,
SEQ_UNCOMPRESSED_SIZE,
SEQ_CODER_INIT,
SEQ_CODE,
} sequence;
/// Position in the header fields
size_t pos;
/// Uncompressed size decoded from the header
lzma_vli uncompressed_size;
/// Options decoded from the header needed to initialize
/// the LZMA decoder
lzma_options_lzma options;
};
static lzma_ret
alone_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,
size_t *restrict out_pos, size_t out_size,
lzma_action action)
{
while (*out_pos < out_size
&& (coder->sequence == SEQ_CODE || *in_pos < in_size))
switch (coder->sequence) {
case SEQ_PROPERTIES:
if (lzma_lzma_decode_properties(&coder->options, in[*in_pos]))
return LZMA_FORMAT_ERROR;
coder->sequence = SEQ_DICTIONARY_SIZE;
++*in_pos;
break;
case SEQ_DICTIONARY_SIZE:
coder->options.dictionary_size
|= (size_t)(in[*in_pos]) << (coder->pos * 8);
if (++coder->pos == 4) {
if (coder->options.dictionary_size
< LZMA_DICTIONARY_SIZE_MIN
|| coder->options.dictionary_size
> LZMA_DICTIONARY_SIZE_MAX)
return LZMA_FORMAT_ERROR;
// A hack to ditch tons of false positives: We allow
// only dictionary sizes that are 2^n or 2^n + 2^(n-1).
// LZMA_Alone created only files with 2^n, but accepts
// any dictionary size. If someone complains, this
// will be reconsidered.
uint32_t d = coder->options.dictionary_size - 1;
d |= d >> 2;
d |= d >> 3;
d |= d >> 4;
d |= d >> 8;
d |= d >> 16;
++d;
if (d != coder->options.dictionary_size)
return LZMA_FORMAT_ERROR;
coder->pos = 0;
coder->sequence = SEQ_UNCOMPRESSED_SIZE;
}
++*in_pos;
break;
case SEQ_UNCOMPRESSED_SIZE:
coder->uncompressed_size
|= (lzma_vli)(in[*in_pos]) << (coder->pos * 8);
if (++coder->pos == 8) {
// Another hack to ditch false positives: Assume that
// if the uncompressed size is known, it must be less
// than 256 GiB. Again, if someone complains, this
// will be reconsidered.
if (coder->uncompressed_size != LZMA_VLI_VALUE_UNKNOWN
&& coder->uncompressed_size
>= (LZMA_VLI_C(1) << 38))
return LZMA_FORMAT_ERROR;
coder->pos = 0;
coder->sequence = SEQ_CODER_INIT;
}
++*in_pos;
break;
case SEQ_CODER_INIT: {
// Two is enough because there won't be implicit filters.
lzma_filter_info filters[2] = {
{
.init = &lzma_lzma_decoder_init,
.options = &coder->options,
}, {
.init = NULL,
}
};
const lzma_ret ret = lzma_next_filter_init(&coder->next,
allocator, filters);
if (ret != LZMA_OK)
return ret;
// Use a hack to set the uncompressed size.
lzma_lzma_decoder_uncompressed_size(&coder->next,
coder->uncompressed_size);
coder->sequence = SEQ_CODE;
}
// Fall through
case SEQ_CODE: {
return coder->next.code(coder->next.coder,
allocator, in, in_pos, in_size,
out, out_pos, out_size, action);
}
default:
return LZMA_PROG_ERROR;
}
return LZMA_OK;
}
static void
alone_decoder_end(lzma_coder *coder, lzma_allocator *allocator)
{
lzma_next_coder_end(&coder->next, allocator);
lzma_free(coder, allocator);
return;
}
static lzma_ret
alone_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 = &alone_decode;
next->end = &alone_decoder_end;
next->coder->next = LZMA_NEXT_CODER_INIT;
}
next->coder->sequence = SEQ_PROPERTIES;
next->coder->pos = 0;
next->coder->options.dictionary_size = 0;
next->coder->uncompressed_size = 0;
return LZMA_OK;
}
extern lzma_ret
lzma_alone_decoder_init(lzma_next_coder *next, lzma_allocator *allocator)
{
lzma_next_coder_init0(alone_decoder_init, next, allocator);
}
extern LZMA_API lzma_ret
lzma_alone_decoder(lzma_stream *strm)
{
lzma_next_strm_init0(strm, alone_decoder_init);
strm->internal->supported_actions[LZMA_RUN] = true;
strm->internal->supported_actions[LZMA_SYNC_FLUSH] = true;
return LZMA_OK;
}
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