X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=lzma%2Fcommon%2Falone_decoder.c;fp=lzma%2Fcommon%2Falone_decoder.c;h=c1360ca1eb7ade2a4f0b4194a80e39d21742e652;hb=32b8a6b26ed8843828e03e505d2256960bda0980;hp=0000000000000000000000000000000000000000;hpb=d48fc23a4bcf8ca3c406d6e8c8a6f8c6b0fa2f1e;p=zpackage diff --git a/lzma/common/alone_decoder.c b/lzma/common/alone_decoder.c new file mode 100644 index 0000000..c1360ca --- /dev/null +++ b/lzma/common/alone_decoder.c @@ -0,0 +1,238 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file alone_decoder.c +/// \brief Decoder for LZMA_Alone files +// +// Author: Lasse Collin +// +// This file has been put into the public domain. +// You can do whatever you want with this file. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "alone_decoder.h" +#include "lzma_decoder.h" +#include "lz_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; + + /// If true, reject files that are unlikely to be .lzma files. + /// If false, more non-.lzma files get accepted and will give + /// LZMA_DATA_ERROR either immediately or after a few output bytes. + bool picky; + + /// Position in the header fields + size_t pos; + + /// Uncompressed size decoded from the header + lzma_vli uncompressed_size; + + /// Memory usage limit + uint64_t memlimit; + + /// Amount of memory actually needed (only an estimate) + uint64_t memusage; + + /// Options decoded from the header needed to initialize + /// the LZMA decoder + lzma_options_lzma options; +}; + + +static lzma_ret +alone_decode(lzma_coder *coder, + const 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_lclppb_decode(&coder->options, in[*in_pos])) + return LZMA_FORMAT_ERROR; + + coder->sequence = SEQ_DICTIONARY_SIZE; + ++*in_pos; + break; + + case SEQ_DICTIONARY_SIZE: + coder->options.dict_size + |= (size_t)(in[*in_pos]) << (coder->pos * 8); + + if (++coder->pos == 4) { + if (coder->picky && coder->options.dict_size + != UINT32_MAX) { + // 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. + uint32_t d = coder->options.dict_size - 1; + d |= d >> 2; + d |= d >> 3; + d |= d >> 4; + d |= d >> 8; + d |= d >> 16; + ++d; + + if (d != coder->options.dict_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); + ++*in_pos; + if (++coder->pos < 8) + break; + + // Another hack to ditch false positives: Assume that + // if the uncompressed size is known, it must be less + // than 256 GiB. + if (coder->picky + && coder->uncompressed_size != LZMA_VLI_UNKNOWN + && coder->uncompressed_size + >= (LZMA_VLI_C(1) << 38)) + return LZMA_FORMAT_ERROR; + + // Calculate the memory usage so that it is ready + // for SEQ_CODER_INIT. + coder->memusage = lzma_lzma_decoder_memusage(&coder->options) + + LZMA_MEMUSAGE_BASE; + + coder->pos = 0; + coder->sequence = SEQ_CODER_INIT; + + // Fall through + + case SEQ_CODER_INIT: { + if (coder->memusage > coder->memlimit) + return LZMA_MEMLIMIT_ERROR; + + 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_lz_decoder_uncompressed(coder->next.coder, + coder->uncompressed_size); + + coder->sequence = SEQ_CODE; + break; + } + + 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, const lzma_allocator *allocator) +{ + lzma_next_end(&coder->next, allocator); + lzma_free(coder, allocator); + return; +} + + +static lzma_ret +alone_decoder_memconfig(lzma_coder *coder, uint64_t *memusage, + uint64_t *old_memlimit, uint64_t new_memlimit) +{ + *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_alone_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator, + uint64_t memlimit, bool picky) +{ + lzma_next_coder_init(&lzma_alone_decoder_init, next, allocator); + + if (memlimit == 0) + return LZMA_PROG_ERROR; + + 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->memconfig = &alone_decoder_memconfig; + next->coder->next = LZMA_NEXT_CODER_INIT; + } + + next->coder->sequence = SEQ_PROPERTIES; + next->coder->picky = picky; + next->coder->pos = 0; + next->coder->options.dict_size = 0; + next->coder->options.preset_dict = NULL; + next->coder->options.preset_dict_size = 0; + next->coder->uncompressed_size = 0; + next->coder->memlimit = memlimit; + next->coder->memusage = LZMA_MEMUSAGE_BASE; + + return LZMA_OK; +} + + +extern LZMA_API(lzma_ret) +lzma_alone_decoder(lzma_stream *strm, uint64_t memlimit) +{ + lzma_next_strm_init(lzma_alone_decoder_init, strm, memlimit, false); + + strm->internal->supported_actions[LZMA_RUN] = true; + strm->internal->supported_actions[LZMA_FINISH] = true; + + return LZMA_OK; +}