/* * Decode the Compressed Data field from a Block. Update and validate * the observed compressed and uncompressed sizes of the Block so that * they don't exceed the values possibly stored in the Block Header * (validation assumes that no integer overflow occurs, since vli_type * is normally uint64_t). Update the CRC32 if presence of the CRC32 * field was indicated in Stream Header. * * Once the decoding is finished, validate that the observed sizes match * the sizes possibly stored in the Block Header. Update the hash and * Block count, which are later used to validate the Index field. */ static enum xz_ret dec_block(struct xz_dec *s, struct xz_buf *b) { enum xz_ret ret; s->in_start = b->in_pos; s->out_start = b->out_pos; #ifdef XZ_DEC_BCJ if (s->bcj_active) ret = xz_dec_bcj_run(s->bcj, s->lzma2, b); else #endif ret = xz_dec_lzma2_run(s->lzma2, b); s->block.compressed += b->in_pos - s->in_start; s->block.uncompressed += b->out_pos - s->out_start; /* * There is no need to separately check for VLI_UNKNOWN, since * the observed sizes are always smaller than VLI_UNKNOWN. */ if (s->block.compressed > s->block_header.compressed || s->block.uncompressed > s->block_header.uncompressed) return XZ_DATA_ERROR; if (s->has_crc32) GRUB_MD_CRC32->write(s->crc32_context,b->out + s->out_start, b->out_pos - s->out_start); if (ret == XZ_STREAM_END) { if (s->block_header.compressed != VLI_UNKNOWN && s->block_header.compressed != s->block.compressed) return XZ_DATA_ERROR; if (s->block_header.uncompressed != VLI_UNKNOWN && s->block_header.uncompressed != s->block.uncompressed) return XZ_DATA_ERROR; s->block.hash.unpadded += s->block_header.size + s->block.compressed; if (s->has_crc32) s->block.hash.unpadded += 4; s->block.hash.uncompressed += s->block.uncompressed; GRUB_MD_CRC32->write(s->block.hash.crc32_context, (const uint8_t *)&s->block.hash, 2 * sizeof(vli_type)); ++s->block.count; } return ret; }
#ifdef XZ_DEC_BCJ if (s->bcj_active) ret = xz_dec_bcj_run(s->bcj, s->lzma2, b); else #endif ret = xz_dec_lzma2_run(s->lzma2, b);