contrib/xz/src/liblzma/common/auto_decoder.c

   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 typedef struct {
  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 } lzma_auto_coder;
  30
  31
  32 static lzma_ret
  33 auto_decode(void *coder_ptr, 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         lzma_auto_coder *coder = coder_ptr;
  39
  40         switch (coder->sequence) {
  41         case SEQ_INIT:
  42                 if (*in_pos >= in_size)
  43                         return LZMA_OK;
  44
  45                 // Update the sequence now, because we want to continue from
  46                 // SEQ_CODE even if we return some LZMA_*_CHECK.
  47                 coder->sequence = SEQ_CODE;
  48
  49                 // Detect the file format. For now this is simple, since if
  50                 // it doesn't start with 0xFD (the first magic byte of the
  51                 // new format), it has to be LZMA_Alone, or something that
  52                 // we don't support at all.
  53                 if (in[*in_pos] == 0xFD) {
  54                         return_if_error(lzma_stream_decoder_init(
  55                                         &coder->next, allocator,
  56                                         coder->memlimit, coder->flags));
  57                 } else {
  58                         return_if_error(lzma_alone_decoder_init(&coder->next,
  59                                         allocator, coder->memlimit, true));
  60
  61                         // If the application wants to know about missing
  62                         // integrity check or about the check in general, we
  63                         // need to handle it here, because LZMA_Alone decoder
  64                         // doesn't accept any flags.
  65                         if (coder->flags & LZMA_TELL_NO_CHECK)
  66                                 return LZMA_NO_CHECK;
  67
  68                         if (coder->flags & LZMA_TELL_ANY_CHECK)
  69                                 return LZMA_GET_CHECK;
  70                 }
  71
  72         // Fall through
  73
  74         case SEQ_CODE: {
  75                 const lzma_ret ret = coder->next.code(
  76                                 coder->next.coder, allocator,
  77                                 in, in_pos, in_size,
  78                                 out, out_pos, out_size, action);
  79                 if (ret != LZMA_STREAM_END
  80                                 || (coder->flags & LZMA_CONCATENATED) == 0)
  81                         return ret;
  82
  83                 coder->sequence = SEQ_FINISH;
  84         }
  85
  86         // Fall through
  87
  88         case SEQ_FINISH:
  89                 // When LZMA_DECODE_CONCATENATED was used and we were decoding
  90                 // LZMA_Alone file, we need to check check that there is no
  91                 // trailing garbage and wait for LZMA_FINISH.
  92                 if (*in_pos < in_size)
  93                         return LZMA_DATA_ERROR;
  94
  95                 return action == LZMA_FINISH ? LZMA_STREAM_END : LZMA_OK;
  96
  97         default:
  98                 assert(0);
  99                 return LZMA_PROG_ERROR;
 100         }
 101 }
 102
 103
 104 static void
 105 auto_decoder_end(void *coder_ptr, const lzma_allocator *allocator)
 106 {
 107         lzma_auto_coder *coder = coder_ptr;
 108         lzma_next_end(&coder->next, allocator);
 109         lzma_free(coder, allocator);
 110         return;
 111 }
 112
 113
 114 static lzma_check
 115 auto_decoder_get_check(const void *coder_ptr)
 116 {
 117         const lzma_auto_coder *coder = coder_ptr;
 118
 119         // It is LZMA_Alone if get_check is NULL.
 120         return coder->next.get_check == NULL ? LZMA_CHECK_NONE
 121                         : coder->next.get_check(coder->next.coder);
 122 }
 123
 124
 125 static lzma_ret
 126 auto_decoder_memconfig(void *coder_ptr, uint64_t *memusage,
 127                 uint64_t *old_memlimit, uint64_t new_memlimit)
 128 {
 129         lzma_auto_coder *coder = coder_ptr;
 130
 131         lzma_ret ret;
 132
 133         if (coder->next.memconfig != NULL) {
 134                 ret = coder->next.memconfig(coder->next.coder,
 135                                 memusage, old_memlimit, new_memlimit);
 136                 assert(*old_memlimit == coder->memlimit);
 137         } else {
 138                 // No coder is configured yet. Use the base value as
 139                 // the current memory usage.
 140                 *memusage = LZMA_MEMUSAGE_BASE;
 141                 *old_memlimit = coder->memlimit;
 142                 ret = LZMA_OK;
 143         }
 144
 145         if (ret == LZMA_OK && new_memlimit != 0)
 146                 coder->memlimit = new_memlimit;
 147
 148         return ret;
 149 }
 150
 151
 152 static lzma_ret
 153 auto_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
 154                 uint64_t memlimit, uint32_t flags)
 155 {
 156         lzma_next_coder_init(&auto_decoder_init, next, allocator);
 157
 158         if (memlimit == 0)
 159                 return LZMA_PROG_ERROR;
 160
 161         if (flags & ~LZMA_SUPPORTED_FLAGS)
 162                 return LZMA_OPTIONS_ERROR;
 163
 164         lzma_auto_coder *coder = next->coder;
 165         if (coder == NULL) {
 166                 coder = lzma_alloc(sizeof(lzma_auto_coder), allocator);
 167                 if (coder == NULL)
 168                         return LZMA_MEM_ERROR;
 169
 170                 next->coder = coder;
 171                 next->code = &auto_decode;
 172                 next->end = &auto_decoder_end;
 173                 next->get_check = &auto_decoder_get_check;
 174                 next->memconfig = &auto_decoder_memconfig;
 175                 coder->next = LZMA_NEXT_CODER_INIT;
 176         }
 177
 178         coder->memlimit = memlimit;
 179         coder->flags = flags;
 180         coder->sequence = SEQ_INIT;
 181
 182         return LZMA_OK;
 183 }
 184
 185
 186 extern LZMA_API(lzma_ret)
 187 lzma_auto_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags)
 188 {
 189         lzma_next_strm_init(auto_decoder_init, strm, memlimit, flags);
 190
 191         strm->internal->supported_actions[LZMA_RUN] = true;
 192         strm->internal->supported_actions[LZMA_FINISH] = true;
 193
 194         return LZMA_OK;
 195 }