X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=lzma%2Fcommon%2Fstream_decoder.c;fp=lzma%2Fcommon%2Fstream_decoder.c;h=3ab938c9f1426d7421a8c5d52b299cad33614b4c;hb=32b8a6b26ed8843828e03e505d2256960bda0980;hp=0000000000000000000000000000000000000000;hpb=d48fc23a4bcf8ca3c406d6e8c8a6f8c6b0fa2f1e;p=zpackage diff --git a/lzma/common/stream_decoder.c b/lzma/common/stream_decoder.c new file mode 100644 index 0000000..3ab938c --- /dev/null +++ b/lzma/common/stream_decoder.c @@ -0,0 +1,462 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file stream_decoder.c +/// \brief Decodes .xz Streams +// +// Author: Lasse Collin +// +// This file has been put into the public domain. +// You can do whatever you want with this file. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "stream_decoder.h" +#include "block_decoder.h" + + +struct lzma_coder_s { + enum { + SEQ_STREAM_HEADER, + SEQ_BLOCK_HEADER, + SEQ_BLOCK, + SEQ_INDEX, + SEQ_STREAM_FOOTER, + SEQ_STREAM_PADDING, + } 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_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; + + /// Memory usage limit + uint64_t memlimit; + + /// Amount of memory actually needed (only an estimate) + uint64_t memusage; + + /// If true, LZMA_NO_CHECK is returned if the Stream has + /// no integrity check. + bool tell_no_check; + + /// If true, LZMA_UNSUPPORTED_CHECK is returned if the Stream has + /// an integrity check that isn't supported by this liblzma build. + bool tell_unsupported_check; + + /// If true, LZMA_GET_CHECK is returned after decoding Stream Header. + bool tell_any_check; + + /// If true, we will tell the Block decoder to skip calculating + /// and verifying the integrity check. + bool ignore_check; + + /// If true, we will decode concatenated Streams that possibly have + /// Stream Padding between or after them. LZMA_STREAM_END is returned + /// once the application isn't giving us any new input, and we aren't + /// in the middle of a Stream, and possible Stream Padding is a + /// multiple of four bytes. + bool concatenated; + + /// When decoding concatenated Streams, this is true as long as we + /// are decoding the first Stream. This is needed to avoid misleading + /// LZMA_FORMAT_ERROR in case the later Streams don't have valid magic + /// bytes. + bool first_stream; + + /// Write position in buffer[] and position in Stream Padding + size_t 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_decoder_reset(lzma_coder *coder, const lzma_allocator *allocator) +{ + // Initialize the Index hash used to verify the Index. + coder->index_hash = lzma_index_hash_init(coder->index_hash, allocator); + if (coder->index_hash == NULL) + return LZMA_MEM_ERROR; + + // Reset the rest of the variables. + coder->sequence = SEQ_STREAM_HEADER; + coder->pos = 0; + + return LZMA_OK; +} + + +static lzma_ret +stream_decode(lzma_coder *coder, const 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 (true) + switch (coder->sequence) { + case SEQ_STREAM_HEADER: { + // Copy the Stream Header to the internal buffer. + lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos, + LZMA_STREAM_HEADER_SIZE); + + // Return if we didn't get the whole Stream Header yet. + if (coder->pos < LZMA_STREAM_HEADER_SIZE) + return LZMA_OK; + + coder->pos = 0; + + // Decode the Stream Header. + const lzma_ret ret = lzma_stream_header_decode( + &coder->stream_flags, coder->buffer); + if (ret != LZMA_OK) + return ret == LZMA_FORMAT_ERROR && !coder->first_stream + ? LZMA_DATA_ERROR : ret; + + // If we are decoding concatenated Streams, and the later + // Streams have invalid Header Magic Bytes, we give + // LZMA_DATA_ERROR instead of LZMA_FORMAT_ERROR. + coder->first_stream = false; + + // 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_*_CHECK below, we want + // to continue from Block Header decoding. + coder->sequence = SEQ_BLOCK_HEADER; + + // Detect if there's no integrity check or if it is + // unsupported if those were requested by the application. + if (coder->tell_no_check && coder->stream_flags.check + == LZMA_CHECK_NONE) + return LZMA_NO_CHECK; + + if (coder->tell_unsupported_check + && !lzma_check_is_supported( + coder->stream_flags.check)) + return LZMA_UNSUPPORTED_CHECK; + + if (coder->tell_any_check) + return LZMA_GET_CHECK; + } + + // Fall through + + case SEQ_BLOCK_HEADER: { + if (*in_pos >= in_size) + return LZMA_OK; + + if (coder->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. + lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos, + coder->block_options.header_size); + + // Return if we didn't get the whole Block Header yet. + if (coder->pos < coder->block_options.header_size) + return LZMA_OK; + + coder->pos = 0; + + // Version 1 is needed to support the .ignore_check option. + coder->block_options.version = 1; + + // 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_filter filters[LZMA_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)); + + // If LZMA_IGNORE_CHECK was used, this flag needs to be set. + // It has to be set after lzma_block_header_decode() because + // it always resets this to false. + coder->block_options.ignore_check = coder->ignore_check; + + // Check the memory usage limit. + const uint64_t memusage = lzma_raw_decoder_memusage(filters); + lzma_ret ret; + + if (memusage == UINT64_MAX) { + // One or more unknown Filter IDs. + ret = LZMA_OPTIONS_ERROR; + } else { + // Now we can set coder->memusage since we know that + // the filter chain is valid. We don't want + // lzma_memusage() to return UINT64_MAX in case of + // invalid filter chain. + coder->memusage = memusage; + + if (memusage > coder->memlimit) { + // The chain would need too much memory. + ret = LZMA_MEMLIMIT_ERROR; + } else { + // Memory usage is OK. + // Initialize the Block decoder. + 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_FILTERS_MAX; ++i) + lzma_free(filters[i].options, allocator); + + coder->block_options.filters = NULL; + + // Check if memory usage calculation and Block enocoder + // initialization succeeded. + if (ret != LZMA_OK) + return ret; + + coder->sequence = SEQ_BLOCK; + } + + // Fall through + + case SEQ_BLOCK: { + const 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_unpadded_size( + &coder->block_options), + coder->block_options.uncompressed_size)); + + coder->sequence = SEQ_BLOCK_HEADER; + break; + } + + case SEQ_INDEX: { + // If we don't have any input, don't call + // lzma_index_hash_decode() since it would return + // LZMA_BUF_ERROR, which we must not do here. + if (*in_pos >= in_size) + return LZMA_OK; + + // 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; + } + + // Fall through + + case SEQ_STREAM_FOOTER: { + // Copy the Stream Footer to the internal buffer. + lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos, + LZMA_STREAM_HEADER_SIZE); + + // Return if we didn't get the whole Stream Footer yet. + if (coder->pos < LZMA_STREAM_HEADER_SIZE) + return LZMA_OK; + + coder->pos = 0; + + // Decode the Stream Footer. The decoder gives + // LZMA_FORMAT_ERROR if the magic bytes don't match, + // so convert that return code to LZMA_DATA_ERROR. + lzma_stream_flags footer_flags; + const lzma_ret ret = lzma_stream_footer_decode( + &footer_flags, coder->buffer); + if (ret != LZMA_OK) + return ret == LZMA_FORMAT_ERROR + ? LZMA_DATA_ERROR : ret; + + // 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. + return_if_error(lzma_stream_flags_compare( + &coder->stream_flags, &footer_flags)); + + if (!coder->concatenated) + return LZMA_STREAM_END; + + coder->sequence = SEQ_STREAM_PADDING; + } + + // Fall through + + case SEQ_STREAM_PADDING: + assert(coder->concatenated); + + // Skip over possible Stream Padding. + while (true) { + if (*in_pos >= in_size) { + // Unless LZMA_FINISH was used, we cannot + // know if there's more input coming later. + if (action != LZMA_FINISH) + return LZMA_OK; + + // Stream Padding must be a multiple of + // four bytes. + return coder->pos == 0 + ? LZMA_STREAM_END + : LZMA_DATA_ERROR; + } + + // If the byte is not zero, it probably indicates + // beginning of a new Stream (or the file is corrupt). + if (in[*in_pos] != 0x00) + break; + + ++*in_pos; + coder->pos = (coder->pos + 1) & 3; + } + + // Stream Padding must be a multiple of four bytes (empty + // Stream Padding is OK). + if (coder->pos != 0) { + ++*in_pos; + return LZMA_DATA_ERROR; + } + + // Prepare to decode the next Stream. + return_if_error(stream_decoder_reset(coder, allocator)); + break; + + default: + assert(0); + return LZMA_PROG_ERROR; + } + + // Never reached +} + + +static void +stream_decoder_end(lzma_coder *coder, const lzma_allocator *allocator) +{ + lzma_next_end(&coder->block_decoder, allocator); + lzma_index_hash_end(coder->index_hash, allocator); + lzma_free(coder, allocator); + return; +} + + +static lzma_check +stream_decoder_get_check(const lzma_coder *coder) +{ + return coder->stream_flags.check; +} + + +static lzma_ret +stream_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_stream_decoder_init( + lzma_next_coder *next, const lzma_allocator *allocator, + uint64_t memlimit, uint32_t flags) +{ + lzma_next_coder_init(&lzma_stream_decoder_init, next, allocator); + + if (memlimit == 0) + return LZMA_PROG_ERROR; + + if (flags & ~LZMA_SUPPORTED_FLAGS) + return LZMA_OPTIONS_ERROR; + + 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->get_check = &stream_decoder_get_check; + next->memconfig = &stream_decoder_memconfig; + + next->coder->block_decoder = LZMA_NEXT_CODER_INIT; + next->coder->index_hash = NULL; + } + + next->coder->memlimit = memlimit; + next->coder->memusage = LZMA_MEMUSAGE_BASE; + next->coder->tell_no_check = (flags & LZMA_TELL_NO_CHECK) != 0; + next->coder->tell_unsupported_check + = (flags & LZMA_TELL_UNSUPPORTED_CHECK) != 0; + next->coder->tell_any_check = (flags & LZMA_TELL_ANY_CHECK) != 0; + next->coder->ignore_check = (flags & LZMA_IGNORE_CHECK) != 0; + next->coder->concatenated = (flags & LZMA_CONCATENATED) != 0; + next->coder->first_stream = true; + + return stream_decoder_reset(next->coder, allocator); +} + + +extern LZMA_API(lzma_ret) +lzma_stream_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags) +{ + lzma_next_strm_init(lzma_stream_decoder_init, strm, memlimit, flags); + + strm->internal->supported_actions[LZMA_RUN] = true; + strm->internal->supported_actions[LZMA_FINISH] = true; + + return LZMA_OK; +}