src/liblzma/common/auto_decoder.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       auto_decoder.c
   4 /// \brief      Autodetect between .xz, .lzma (LZMA_Alone), and .lz (lzip)
   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 #ifdef HAVE_LZIP_DECODER
  16 #       include "lzip_decoder.h"
  17 #endif
  18
  19
  20 typedef struct {
  21         /// .xz Stream decoder, LZMA_Alone decoder, or lzip decoder
  22         lzma_next_coder next;
  23
  24         uint64_t memlimit;
  25         uint32_t flags;
  26
  27         enum {
  28                 SEQ_INIT,
  29                 SEQ_CODE,
  30                 SEQ_FINISH,
  31         } sequence;
  32 } lzma_auto_coder;
  33
  34
  35 static lzma_ret
  36 auto_decode(void *coder_ptr, const lzma_allocator *allocator,
  37                 const uint8_t *restrict in, size_t *restrict in_pos,
  38                 size_t in_size, uint8_t *restrict out,
  39                 size_t *restrict out_pos, size_t out_size, lzma_action action)
  40 {
  41         lzma_auto_coder *coder = coder_ptr;
  42
  43         switch (coder->sequence) {
  44         case SEQ_INIT:
  45                 if (*in_pos >= in_size)
  46                         return LZMA_OK;
  47
  48                 // Update the sequence now, because we want to continue from
  49                 // SEQ_CODE even if we return some LZMA_*_CHECK.
  50                 coder->sequence = SEQ_CODE;
  51
  52                 // Detect the file format. .xz files start with 0xFD which
  53                 // cannot be the first byte of .lzma (LZMA_Alone) format.
  54                 // The .lz format starts with 0x4C which could be the
  55                 // first byte of a .lzma file but luckily it would mean
  56                 // lc/lp/pb being 4/3/1 which liblzma doesn't support because
  57                 // lc + lp > 4. So using just 0x4C to detect .lz is OK here.
  58                 if (in[*in_pos] == 0xFD) {
  59                         return_if_error(lzma_stream_decoder_init(
  60                                         &coder->next, allocator,
  61                                         coder->memlimit, coder->flags));
  62 #ifdef HAVE_LZIP_DECODER
  63                 } else if (in[*in_pos] == 0x4C) {
  64                         return_if_error(lzma_lzip_decoder_init(
  65                                         &coder->next, allocator,
  66                                         coder->memlimit, coder->flags));
  67 #endif
  68                 } else {
  69                         return_if_error(lzma_alone_decoder_init(&coder->next,
  70                                         allocator, coder->memlimit, true));
  71
  72                         // If the application wants to know about missing
  73                         // integrity check or about the check in general, we
  74                         // need to handle it here, because LZMA_Alone decoder
  75                         // doesn't accept any flags.
  76                         if (coder->flags & LZMA_TELL_NO_CHECK)
  77                                 return LZMA_NO_CHECK;
  78
  79                         if (coder->flags & LZMA_TELL_ANY_CHECK)
  80                                 return LZMA_GET_CHECK;
  81                 }
  82
  83         // Fall through
  84
  85         case SEQ_CODE: {
  86                 const lzma_ret ret = coder->next.code(
  87                                 coder->next.coder, allocator,
  88                                 in, in_pos, in_size,
  89                                 out, out_pos, out_size, action);
  90                 if (ret != LZMA_STREAM_END
  91                                 || (coder->flags & LZMA_CONCATENATED) == 0)
  92                         return ret;
  93
  94                 coder->sequence = SEQ_FINISH;
  95         }
  96
  97         // Fall through
  98
  99         case SEQ_FINISH:
 100                 // When LZMA_CONCATENATED was used and we were decoding
 101                 // a LZMA_Alone file, we need to check that there is no
 102                 // trailing garbage and wait for LZMA_FINISH.
 103                 if (*in_pos < in_size)
 104                         return LZMA_DATA_ERROR;
 105
 106                 return action == LZMA_FINISH ? LZMA_STREAM_END : LZMA_OK;
 107
 108         default:
 109                 assert(0);
 110                 return LZMA_PROG_ERROR;
 111         }
 112 }
 113
 114
 115 static void
 116 auto_decoder_end(void *coder_ptr, const lzma_allocator *allocator)
 117 {
 118         lzma_auto_coder *coder = coder_ptr;
 119         lzma_next_end(&coder->next, allocator);
 120         lzma_free(coder, allocator);
 121         return;
 122 }
 123
 124
 125 static lzma_check
 126 auto_decoder_get_check(const void *coder_ptr)
 127 {
 128         const lzma_auto_coder *coder = coder_ptr;
 129
 130         // It is LZMA_Alone if get_check is NULL.
 131         return coder->next.get_check == NULL ? LZMA_CHECK_NONE
 132                         : coder->next.get_check(coder->next.coder);
 133 }
 134
 135
 136 static lzma_ret
 137 auto_decoder_memconfig(void *coder_ptr, uint64_t *memusage,
 138                 uint64_t *old_memlimit, uint64_t new_memlimit)
 139 {
 140         lzma_auto_coder *coder = coder_ptr;
 141
 142         lzma_ret ret;
 143
 144         if (coder->next.memconfig != NULL) {
 145                 ret = coder->next.memconfig(coder->next.coder,
 146                                 memusage, old_memlimit, new_memlimit);
 147                 assert(*old_memlimit == coder->memlimit);
 148         } else {
 149                 // No coder is configured yet. Use the base value as
 150                 // the current memory usage.
 151                 *memusage = LZMA_MEMUSAGE_BASE;
 152                 *old_memlimit = coder->memlimit;
 153
 154                 ret = LZMA_OK;
 155                 if (new_memlimit != 0 && new_memlimit < *memusage)
 156                         ret = LZMA_MEMLIMIT_ERROR;
 157         }
 158
 159         if (ret == LZMA_OK && new_memlimit != 0)
 160                 coder->memlimit = new_memlimit;
 161
 162         return ret;
 163 }
 164
 165
 166 static lzma_ret
 167 auto_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
 168                 uint64_t memlimit, uint32_t flags)
 169 {
 170         lzma_next_coder_init(&auto_decoder_init, next, allocator);
 171
 172         if (flags & ~LZMA_SUPPORTED_FLAGS)
 173                 return LZMA_OPTIONS_ERROR;
 174
 175         lzma_auto_coder *coder = next->coder;
 176         if (coder == NULL) {
 177                 coder = lzma_alloc(sizeof(lzma_auto_coder), allocator);
 178                 if (coder == NULL)
 179                         return LZMA_MEM_ERROR;
 180
 181                 next->coder = coder;
 182                 next->code = &auto_decode;
 183                 next->end = &auto_decoder_end;
 184                 next->get_check = &auto_decoder_get_check;
 185                 next->memconfig = &auto_decoder_memconfig;
 186                 coder->next = LZMA_NEXT_CODER_INIT;
 187         }
 188
 189         coder->memlimit = my_max(1, memlimit);
 190         coder->flags = flags;
 191         coder->sequence = SEQ_INIT;
 192
 193         return LZMA_OK;
 194 }
 195
 196
 197 extern LZMA_API(lzma_ret)
 198 lzma_auto_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags)
 199 {
 200         lzma_next_strm_init(auto_decoder_init, strm, memlimit, flags);
 201
 202         strm->internal->supported_actions[LZMA_RUN] = true;
 203         strm->internal->supported_actions[LZMA_FINISH] = true;
 204
 205         return LZMA_OK;
 206 }