stream_flags_encoder.c revision 259065
1/////////////////////////////////////////////////////////////////////////////// 2// 3/// \file stream_flags_encoder.c 4/// \brief Encodes Stream Header and Stream Footer for .xz files 5// 6// Author: Lasse Collin 7// 8// This file has been put into the public domain. 9// You can do whatever you want with this file. 10// 11/////////////////////////////////////////////////////////////////////////////// 12 13#include "stream_flags_common.h" 14 15 16static bool 17stream_flags_encode(const lzma_stream_flags *options, uint8_t *out) 18{ 19 if ((unsigned int)(options->check) > LZMA_CHECK_ID_MAX) 20 return true; 21 22 out[0] = 0x00; 23 out[1] = options->check; 24 25 return false; 26} 27 28 29extern LZMA_API(lzma_ret) 30lzma_stream_header_encode(const lzma_stream_flags *options, uint8_t *out) 31{ 32 assert(sizeof(lzma_header_magic) + LZMA_STREAM_FLAGS_SIZE 33 + 4 == LZMA_STREAM_HEADER_SIZE); 34 35 if (options->version != 0) 36 return LZMA_OPTIONS_ERROR; 37 38 // Magic 39 memcpy(out, lzma_header_magic, sizeof(lzma_header_magic)); 40 41 // Stream Flags 42 if (stream_flags_encode(options, out + sizeof(lzma_header_magic))) 43 return LZMA_PROG_ERROR; 44 45 // CRC32 of the Stream Header 46 const uint32_t crc = lzma_crc32(out + sizeof(lzma_header_magic), 47 LZMA_STREAM_FLAGS_SIZE, 0); 48 49 unaligned_write32le(out + sizeof(lzma_header_magic) 50 + LZMA_STREAM_FLAGS_SIZE, crc); 51 52 return LZMA_OK; 53} 54 55 56extern LZMA_API(lzma_ret) 57lzma_stream_footer_encode(const lzma_stream_flags *options, uint8_t *out) 58{ 59 assert(2 * 4 + LZMA_STREAM_FLAGS_SIZE + sizeof(lzma_footer_magic) 60 == LZMA_STREAM_HEADER_SIZE); 61 62 if (options->version != 0) 63 return LZMA_OPTIONS_ERROR; 64 65 // Backward Size 66 if (!is_backward_size_valid(options)) 67 return LZMA_PROG_ERROR; 68 69 unaligned_write32le(out + 4, options->backward_size / 4 - 1); 70 71 // Stream Flags 72 if (stream_flags_encode(options, out + 2 * 4)) 73 return LZMA_PROG_ERROR; 74 75 // CRC32 76 const uint32_t crc = lzma_crc32( 77 out + 4, 4 + LZMA_STREAM_FLAGS_SIZE, 0); 78 79 unaligned_write32le(out, crc); 80 81 // Magic 82 memcpy(out + 2 * 4 + LZMA_STREAM_FLAGS_SIZE, 83 lzma_footer_magic, sizeof(lzma_footer_magic)); 84 85 return LZMA_OK; 86} 87