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 16 static bool 17 stream_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 29 extern LZMA_API(lzma_ret) 30 lzma_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 56 extern LZMA_API(lzma_ret) 57 lzma_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