237 lines
5.4 KiB
C
237 lines
5.4 KiB
C
///////////////////////////////////////////////////////////////////////////////
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//
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/// \file alone_decoder.c
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/// \brief Decoder for LZMA_Alone files
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//
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// Author: Lasse Collin
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//
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// This file has been put into the public domain.
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// You can do whatever you want with this file.
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//
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///////////////////////////////////////////////////////////////////////////////
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#include "alone_decoder.h"
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#include "lzma_decoder.h"
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#include "lz_decoder.h"
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struct lzma_coder_s {
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lzma_next_coder next;
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enum {
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SEQ_PROPERTIES,
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SEQ_DICTIONARY_SIZE,
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SEQ_UNCOMPRESSED_SIZE,
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SEQ_CODER_INIT,
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SEQ_CODE,
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} sequence;
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/// If true, reject files that are unlikely to be .lzma files.
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/// If false, more non-.lzma files get accepted and will give
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/// LZMA_DATA_ERROR either immediately or after a few output bytes.
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bool picky;
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/// Position in the header fields
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size_t pos;
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/// Uncompressed size decoded from the header
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lzma_vli uncompressed_size;
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/// Memory usage limit
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uint64_t memlimit;
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/// Amount of memory actually needed (only an estimate)
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uint64_t memusage;
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/// Options decoded from the header needed to initialize
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/// the LZMA decoder
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lzma_options_lzma options;
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};
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static lzma_ret
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alone_decode(lzma_coder *coder,
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lzma_allocator *allocator lzma_attribute((__unused__)),
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const uint8_t *restrict in, size_t *restrict in_pos,
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size_t in_size, uint8_t *restrict out,
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size_t *restrict out_pos, size_t out_size,
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lzma_action action)
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{
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while (*out_pos < out_size
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&& (coder->sequence == SEQ_CODE || *in_pos < in_size))
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switch (coder->sequence) {
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case SEQ_PROPERTIES:
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if (lzma_lzma_lclppb_decode(&coder->options, in[*in_pos]))
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return LZMA_FORMAT_ERROR;
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coder->sequence = SEQ_DICTIONARY_SIZE;
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++*in_pos;
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break;
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case SEQ_DICTIONARY_SIZE:
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coder->options.dict_size
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|= (size_t)(in[*in_pos]) << (coder->pos * 8);
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if (++coder->pos == 4) {
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if (coder->picky && coder->options.dict_size
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!= UINT32_MAX) {
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// A hack to ditch tons of false positives:
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// We allow only dictionary sizes that are
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// 2^n or 2^n + 2^(n-1). LZMA_Alone created
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// only files with 2^n, but accepts any
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// dictionary size.
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uint32_t d = coder->options.dict_size - 1;
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d |= d >> 2;
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d |= d >> 3;
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d |= d >> 4;
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d |= d >> 8;
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d |= d >> 16;
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++d;
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if (d != coder->options.dict_size)
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return LZMA_FORMAT_ERROR;
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}
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coder->pos = 0;
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coder->sequence = SEQ_UNCOMPRESSED_SIZE;
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}
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++*in_pos;
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break;
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case SEQ_UNCOMPRESSED_SIZE:
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coder->uncompressed_size
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|= (lzma_vli)(in[*in_pos]) << (coder->pos * 8);
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++*in_pos;
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if (++coder->pos < 8)
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break;
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// Another hack to ditch false positives: Assume that
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// if the uncompressed size is known, it must be less
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// than 256 GiB.
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if (coder->picky
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&& coder->uncompressed_size != LZMA_VLI_UNKNOWN
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&& coder->uncompressed_size
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>= (LZMA_VLI_C(1) << 38))
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return LZMA_FORMAT_ERROR;
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// Calculate the memory usage so that it is ready
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// for SEQ_CODER_INIT.
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coder->memusage = lzma_lzma_decoder_memusage(&coder->options)
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+ LZMA_MEMUSAGE_BASE;
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coder->pos = 0;
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coder->sequence = SEQ_CODER_INIT;
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// Fall through
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case SEQ_CODER_INIT: {
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lzma_ret ret;
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lzma_filter_info filters[2] = {
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{ 0, &lzma_lzma_decoder_init, &coder->options },
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{ 0, NULL, NULL }
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};
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if (coder->memusage > coder->memlimit)
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return LZMA_MEMLIMIT_ERROR;
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ret = lzma_next_filter_init(&coder->next,
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allocator, filters);
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if (ret != LZMA_OK)
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return ret;
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// Use a hack to set the uncompressed size.
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lzma_lz_decoder_uncompressed(coder->next.coder,
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coder->uncompressed_size);
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coder->sequence = SEQ_CODE;
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break;
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}
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case SEQ_CODE: {
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return coder->next.code(coder->next.coder,
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allocator, in, in_pos, in_size,
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out, out_pos, out_size, action);
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}
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default:
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return LZMA_PROG_ERROR;
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}
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return LZMA_OK;
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}
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static void
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alone_decoder_end(lzma_coder *coder, lzma_allocator *allocator)
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{
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lzma_next_end(&coder->next, allocator);
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lzma_free(coder, allocator);
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return;
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}
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static lzma_ret
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alone_decoder_memconfig(lzma_coder *coder, uint64_t *memusage,
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uint64_t *old_memlimit, uint64_t new_memlimit)
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{
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*memusage = coder->memusage;
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*old_memlimit = coder->memlimit;
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if (new_memlimit != 0) {
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if (new_memlimit < coder->memusage)
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return LZMA_MEMLIMIT_ERROR;
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coder->memlimit = new_memlimit;
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}
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return LZMA_OK;
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}
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extern lzma_ret
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lzma_alone_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
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uint64_t memlimit, bool picky)
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{
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lzma_next_coder_init(&lzma_alone_decoder_init, next, allocator);
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if (memlimit == 0)
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return LZMA_PROG_ERROR;
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if (next->coder == NULL) {
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next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
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if (next->coder == NULL)
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return LZMA_MEM_ERROR;
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next->code = &alone_decode;
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next->end = &alone_decoder_end;
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next->memconfig = &alone_decoder_memconfig;
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next->coder->next = LZMA_NEXT_CODER_INIT;
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}
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next->coder->sequence = SEQ_PROPERTIES;
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next->coder->picky = picky;
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next->coder->pos = 0;
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next->coder->options.dict_size = 0;
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next->coder->options.preset_dict = NULL;
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next->coder->options.preset_dict_size = 0;
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next->coder->uncompressed_size = 0;
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next->coder->memlimit = memlimit;
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next->coder->memusage = LZMA_MEMUSAGE_BASE;
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return LZMA_OK;
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}
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extern LZMA_API(lzma_ret)
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lzma_alone_decoder(lzma_stream *strm, uint64_t memlimit)
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{
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lzma_next_strm_init2(lzma_alone_decoder_init, strm, memlimit, false);
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strm->internal->supported_actions[LZMA_RUN] = true;
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strm->internal->supported_actions[LZMA_FINISH] = true;
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return LZMA_OK;
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}
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