1 /////////////////////////////////////////////////////////////////////////////// 2 // 3 /// \file auto_decoder.c 4 /// \brief Autodetect between .xz Stream and .lzma (LZMA_Alone) formats 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_decoder.h" 14 #include "alone_decoder.h" 15 16 17 struct lzma_coder_s { 18 /// Stream decoder or LZMA_Alone decoder 19 lzma_next_coder next; 20 21 uint64_t memlimit; 22 uint32_t flags; 23 24 enum { 25 SEQ_INIT, 26 SEQ_CODE, 27 SEQ_FINISH, 28 } sequence; 29 }; 30 31 32 static lzma_ret 33 auto_decode(lzma_coder *coder, const lzma_allocator *allocator, 34 const uint8_t *restrict in, size_t *restrict in_pos, 35 size_t in_size, uint8_t *restrict out, 36 size_t *restrict out_pos, size_t out_size, lzma_action action) 37 { 38 switch (coder->sequence) { 39 case SEQ_INIT: 40 if (*in_pos >= in_size) 41 return LZMA_OK; 42 43 // Update the sequence now, because we want to continue from 44 // SEQ_CODE even if we return some LZMA_*_CHECK. 45 coder->sequence = SEQ_CODE; 46 47 // Detect the file format. For now this is simple, since if 48 // it doesn't start with 0xFD (the first magic byte of the 49 // new format), it has to be LZMA_Alone, or something that 50 // we don't support at all. 51 if (in[*in_pos] == 0xFD) { 52 return_if_error(lzma_stream_decoder_init( 53 &coder->next, allocator, 54 coder->memlimit, coder->flags)); 55 } else { 56 return_if_error(lzma_alone_decoder_init(&coder->next, 57 allocator, coder->memlimit, true)); 58 59 // If the application wants to know about missing 60 // integrity check or about the check in general, we 61 // need to handle it here, because LZMA_Alone decoder 62 // doesn't accept any flags. 63 if (coder->flags & LZMA_TELL_NO_CHECK) 64 return LZMA_NO_CHECK; 65 66 if (coder->flags & LZMA_TELL_ANY_CHECK) 67 return LZMA_GET_CHECK; 68 } 69 70 // Fall through 71 72 case SEQ_CODE: { 73 const lzma_ret ret = coder->next.code( 74 coder->next.coder, allocator, 75 in, in_pos, in_size, 76 out, out_pos, out_size, action); 77 if (ret != LZMA_STREAM_END 78 || (coder->flags & LZMA_CONCATENATED) == 0) 79 return ret; 80 81 coder->sequence = SEQ_FINISH; 82 } 83 84 // Fall through 85 86 case SEQ_FINISH: 87 // When LZMA_DECODE_CONCATENATED was used and we were decoding 88 // LZMA_Alone file, we need to check check that there is no 89 // trailing garbage and wait for LZMA_FINISH. 90 if (*in_pos < in_size) 91 return LZMA_DATA_ERROR; 92 93 return action == LZMA_FINISH ? LZMA_STREAM_END : LZMA_OK; 94 95 default: 96 assert(0); 97 return LZMA_PROG_ERROR; 98 } 99 } 100 101 102 static void 103 auto_decoder_end(lzma_coder *coder, const lzma_allocator *allocator) 104 { 105 lzma_next_end(&coder->next, allocator); 106 lzma_free(coder, allocator); 107 return; 108 } 109 110 111 static lzma_check 112 auto_decoder_get_check(const lzma_coder *coder) 113 { 114 // It is LZMA_Alone if get_check is NULL. 115 return coder->next.get_check == NULL ? LZMA_CHECK_NONE 116 : coder->next.get_check(coder->next.coder); 117 } 118 119 120 static lzma_ret 121 auto_decoder_memconfig(lzma_coder *coder, uint64_t *memusage, 122 uint64_t *old_memlimit, uint64_t new_memlimit) 123 { 124 lzma_ret ret; 125 126 if (coder->next.memconfig != NULL) { 127 ret = coder->next.memconfig(coder->next.coder, 128 memusage, old_memlimit, new_memlimit); 129 assert(*old_memlimit == coder->memlimit); 130 } else { 131 // No coder is configured yet. Use the base value as 132 // the current memory usage. 133 *memusage = LZMA_MEMUSAGE_BASE; 134 *old_memlimit = coder->memlimit; 135 ret = LZMA_OK; 136 } 137 138 if (ret == LZMA_OK && new_memlimit != 0) 139 coder->memlimit = new_memlimit; 140 141 return ret; 142 } 143 144 145 static lzma_ret 146 auto_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator, 147 uint64_t memlimit, uint32_t flags) 148 { 149 lzma_next_coder_init(&auto_decoder_init, next, allocator); 150 151 if (memlimit == 0) 152 return LZMA_PROG_ERROR; 153 154 if (flags & ~LZMA_SUPPORTED_FLAGS) 155 return LZMA_OPTIONS_ERROR; 156 157 if (next->coder == NULL) { 158 next->coder = lzma_alloc(sizeof(lzma_coder), allocator); 159 if (next->coder == NULL) 160 return LZMA_MEM_ERROR; 161 162 next->code = &auto_decode; 163 next->end = &auto_decoder_end; 164 next->get_check = &auto_decoder_get_check; 165 next->memconfig = &auto_decoder_memconfig; 166 next->coder->next = LZMA_NEXT_CODER_INIT; 167 } 168 169 next->coder->memlimit = memlimit; 170 next->coder->flags = flags; 171 next->coder->sequence = SEQ_INIT; 172 173 return LZMA_OK; 174 } 175 176 177 extern LZMA_API(lzma_ret) 178 lzma_auto_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags) 179 { 180 lzma_next_strm_init(auto_decoder_init, strm, memlimit, flags); 181 182 strm->internal->supported_actions[LZMA_RUN] = true; 183 strm->internal->supported_actions[LZMA_FINISH] = true; 184 185 return LZMA_OK; 186 } 187