| /////////////////////////////////////////////////////////////////////////////// |
| // |
| /// \file stream_flags_decoder.c |
| /// \brief Decodes Stream Header and Stream Footer from .lzma files |
| // |
| // 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 "stream_flags_common.h" |
| |
| |
| static bool |
| stream_flags_decode(lzma_stream_flags *options, const uint8_t *in) |
| { |
| // Reserved bits must be unset. |
| if (in[0] != 0x00 || (in[1] & 0xF0)) |
| return true; |
| |
| options->check = in[1] & 0x0F; |
| |
| return false; |
| } |
| |
| |
| extern LZMA_API lzma_ret |
| lzma_stream_header_decode(lzma_stream_flags *options, const uint8_t *in) |
| { |
| // Magic |
| if (memcmp(in, lzma_header_magic, sizeof(lzma_header_magic)) != 0) |
| return LZMA_FORMAT_ERROR; |
| |
| // Verify the CRC32 so we can distinguish between corrupt |
| // and unsupported files. |
| const uint32_t crc = lzma_crc32(in + sizeof(lzma_header_magic), |
| LZMA_STREAM_FLAGS_SIZE, 0); |
| if (crc != integer_read_32(in + sizeof(lzma_header_magic) |
| + LZMA_STREAM_FLAGS_SIZE)) |
| return LZMA_DATA_ERROR; |
| |
| // Stream Flags |
| if (stream_flags_decode(options, in + sizeof(lzma_header_magic))) |
| return LZMA_HEADER_ERROR; |
| |
| // Set Backward Size to indicate unknown value. That way |
| // lzma_stream_flags_equal can be used to compare Stream Header |
| // and Stream Footer while keeping it useful also for comparing |
| // two Stream Footers. |
| options->backward_size = LZMA_VLI_VALUE_UNKNOWN; |
| |
| return LZMA_OK; |
| } |
| |
| |
| extern LZMA_API lzma_ret |
| lzma_stream_footer_decode(lzma_stream_flags *options, const uint8_t *in) |
| { |
| // Magic |
| if (memcmp(in + sizeof(uint32_t) * 2 + LZMA_STREAM_FLAGS_SIZE, |
| lzma_footer_magic, sizeof(lzma_footer_magic)) != 0) |
| return LZMA_FORMAT_ERROR; |
| |
| // CRC32 |
| const uint32_t crc = lzma_crc32(in + sizeof(uint32_t), |
| sizeof(uint32_t) + LZMA_STREAM_FLAGS_SIZE, 0); |
| if (crc != integer_read_32(in)) |
| return LZMA_DATA_ERROR; |
| |
| // Stream Flags |
| if (stream_flags_decode(options, in + sizeof(uint32_t) * 2)) |
| return LZMA_HEADER_ERROR; |
| |
| // Backward Size |
| options->backward_size = integer_read_32(in + sizeof(uint32_t)); |
| options->backward_size = (options->backward_size + 1) * 4; |
| |
| return LZMA_OK; |
| } |