| /////////////////////////////////////////////////////////////////////////////// |
| // |
| /// \file block_decoder.c |
| /// \brief Decodes .lzma Blocks |
| // |
| // 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 "block_decoder.h" |
| #include "filter_decoder.h" |
| #include "check.h" |
| |
| |
| struct lzma_coder_s { |
| enum { |
| SEQ_CODE, |
| SEQ_PADDING, |
| SEQ_CHECK, |
| } sequence; |
| |
| /// The filters in the chain; initialized with lzma_raw_decoder_init(). |
| lzma_next_coder next; |
| |
| /// Decoding options; we also write Compressed Size and Uncompressed |
| /// Size back to this structure when the encoding has been finished. |
| lzma_block *options; |
| |
| /// Compressed Size calculated while encoding |
| lzma_vli compressed_size; |
| |
| /// Uncompressed Size calculated while encoding |
| lzma_vli uncompressed_size; |
| |
| /// Maximum allowed Compressed Size; this takes into account the |
| /// size of the Block Header and Check fields when Compressed Size |
| /// is unknown. |
| lzma_vli compressed_limit; |
| |
| /// Position when reading the Check field |
| size_t check_pos; |
| |
| /// Check of the uncompressed data |
| lzma_check_state check; |
| }; |
| |
| |
| static inline bool |
| update_size(lzma_vli *size, lzma_vli add, lzma_vli limit) |
| { |
| if (limit > LZMA_VLI_VALUE_MAX) |
| limit = LZMA_VLI_VALUE_MAX; |
| |
| if (limit < *size || limit - *size < add) |
| return true; |
| |
| *size += add; |
| |
| return false; |
| } |
| |
| |
| static inline bool |
| is_size_valid(lzma_vli size, lzma_vli reference) |
| { |
| return reference == LZMA_VLI_VALUE_UNKNOWN || reference == size; |
| } |
| |
| |
| static lzma_ret |
| block_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) |
| { |
| switch (coder->sequence) { |
| case SEQ_CODE: { |
| const size_t in_start = *in_pos; |
| const size_t out_start = *out_pos; |
| |
| const lzma_ret ret = coder->next.code(coder->next.coder, |
| allocator, in, in_pos, in_size, |
| out, out_pos, out_size, action); |
| |
| const size_t in_used = *in_pos - in_start; |
| const size_t out_used = *out_pos - out_start; |
| |
| // NOTE: We compare to compressed_limit here, which prevents |
| // the total size of the Block growing past LZMA_VLI_VALUE_MAX. |
| if (update_size(&coder->compressed_size, in_used, |
| coder->compressed_limit) |
| || update_size(&coder->uncompressed_size, |
| out_used, |
| coder->options->uncompressed_size)) |
| return LZMA_DATA_ERROR; |
| |
| lzma_check_update(&coder->check, coder->options->check, |
| out + out_start, out_used); |
| |
| if (ret != LZMA_STREAM_END) |
| return ret; |
| |
| coder->sequence = SEQ_PADDING; |
| } |
| |
| // Fall through |
| |
| case SEQ_PADDING: |
| // Compressed Data is padded to a multiple of four bytes. |
| while (coder->compressed_size & 3) { |
| if (*in_pos >= in_size) |
| return LZMA_OK; |
| |
| if (in[(*in_pos)++] != 0x00) |
| return LZMA_DATA_ERROR; |
| |
| if (update_size(&coder->compressed_size, 1, |
| coder->compressed_limit)) |
| return LZMA_DATA_ERROR; |
| } |
| |
| // Compressed and Uncompressed Sizes are now at their final |
| // values. Verify that they match the values given to us. |
| if (!is_size_valid(coder->compressed_size, |
| coder->options->compressed_size) |
| || !is_size_valid(coder->uncompressed_size, |
| coder->options->uncompressed_size)) |
| return LZMA_DATA_ERROR; |
| |
| // Copy the values into coder->options. The caller |
| // may use this information to construct Index. |
| coder->options->compressed_size = coder->compressed_size; |
| coder->options->uncompressed_size = coder->uncompressed_size; |
| |
| if (coder->options->check == LZMA_CHECK_NONE) |
| return LZMA_STREAM_END; |
| |
| lzma_check_finish(&coder->check, coder->options->check); |
| coder->sequence = SEQ_CHECK; |
| |
| // Fall through |
| |
| case SEQ_CHECK: { |
| const bool chksup = lzma_check_is_supported( |
| coder->options->check); |
| |
| while (*in_pos < in_size) { |
| // coder->check.buffer[] may be uninitialized when |
| // the Check ID is not supported. |
| if (chksup && coder->check.buffer.u8[coder->check_pos] |
| != in[*in_pos]) { |
| ++*in_pos; |
| return LZMA_DATA_ERROR; |
| } |
| |
| ++*in_pos; |
| |
| if (++coder->check_pos == lzma_check_size( |
| coder->options->check)) |
| return LZMA_STREAM_END; |
| } |
| |
| return LZMA_OK; |
| } |
| } |
| |
| return LZMA_PROG_ERROR; |
| } |
| |
| |
| static void |
| block_decoder_end(lzma_coder *coder, lzma_allocator *allocator) |
| { |
| lzma_next_end(&coder->next, allocator); |
| lzma_free(coder, allocator); |
| return; |
| } |
| |
| |
| extern lzma_ret |
| lzma_block_decoder_init(lzma_next_coder *next, lzma_allocator *allocator, |
| lzma_block *options) |
| { |
| lzma_next_coder_init(lzma_block_decoder_init, next, allocator); |
| |
| // While lzma_block_total_size_get() is meant to calculate the Total |
| // Size, it also validates the options excluding the filters. |
| if (lzma_block_total_size_get(options) == 0) |
| return LZMA_PROG_ERROR; |
| |
| // options->check is used for array indexing so we need to know that |
| // it is in the valid range. |
| if ((unsigned)(options->check) > LZMA_CHECK_ID_MAX) |
| return LZMA_PROG_ERROR; |
| |
| // Allocate and initialize *next->coder if needed. |
| if (next->coder == NULL) { |
| next->coder = lzma_alloc(sizeof(lzma_coder), allocator); |
| if (next->coder == NULL) |
| return LZMA_MEM_ERROR; |
| |
| next->code = &block_decode; |
| next->end = &block_decoder_end; |
| next->coder->next = LZMA_NEXT_CODER_INIT; |
| } |
| |
| // Basic initializations |
| next->coder->sequence = SEQ_CODE; |
| next->coder->options = options; |
| next->coder->compressed_size = 0; |
| next->coder->uncompressed_size = 0; |
| |
| // If Compressed Size is not known, we calculate the maximum allowed |
| // value so that Total Size of the Block still is a valid VLI and |
| // a multiple of four. |
| next->coder->compressed_limit |
| = options->compressed_size == LZMA_VLI_VALUE_UNKNOWN |
| ? (LZMA_VLI_VALUE_MAX & ~LZMA_VLI_C(3)) |
| - options->header_size |
| - lzma_check_size(options->check) |
| : options->compressed_size; |
| |
| // Initialize the check. It's caller's problem if the Check ID is not |
| // supported, and the Block decoder cannot verify the Check field. |
| // Caller can test lzma_checks[options->check]. |
| next->coder->check_pos = 0; |
| lzma_check_init(&next->coder->check, options->check); |
| |
| // Initialize the filter chain. |
| return lzma_raw_decoder_init(&next->coder->next, allocator, |
| options->filters); |
| } |
| |
| |
| extern LZMA_API lzma_ret |
| lzma_block_decoder(lzma_stream *strm, lzma_block *options) |
| { |
| lzma_next_strm_init(lzma_block_decoder_init, strm, options); |
| |
| strm->internal->supported_actions[LZMA_RUN] = true; |
| strm->internal->supported_actions[LZMA_FINISH] = true; |
| |
| return LZMA_OK; |
| } |