src/liblzma/common/alone_decoder.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       alone_decoder.c
   4 /// \brief      Decoder for LZMA_Alone files
   5 //
   6 //  Copyright (C) 2007 Lasse Collin
   7 //
   8 //  This library is free software; you can redistribute it and/or
   9 //  modify it under the terms of the GNU Lesser General Public
  10 //  License as published by the Free Software Foundation; either
  11 //  version 2.1 of the License, or (at your option) any later version.
  12 //
  13 //  This library is distributed in the hope that it will be useful,
  14 //  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 //  Lesser General Public License for more details.
  17 //
  18 ///////////////////////////////////////////////////////////////////////////////
  19
  20 #include "alone_decoder.h"
  21 #include "lzma_decoder.h"
  22 #include "lz_decoder.h"
  23
  24
  25 struct lzma_coder_s {
  26         lzma_next_coder next;
  27
  28         enum {
  29                 SEQ_PROPERTIES,
  30                 SEQ_DICTIONARY_SIZE,
  31                 SEQ_UNCOMPRESSED_SIZE,
  32                 SEQ_CODER_INIT,
  33                 SEQ_CODE,
  34         } sequence;
  35
  36         /// Position in the header fields
  37         size_t pos;
  38
  39         /// Uncompressed size decoded from the header
  40         lzma_vli uncompressed_size;
  41
  42         /// Memory usage limit
  43         uint64_t memlimit;
  44
  45         /// Options decoded from the header needed to initialize
  46         /// the LZMA decoder
  47         lzma_options_lzma options;
  48 };
  49
  50
  51 static lzma_ret
  52 alone_decode(lzma_coder *coder,
  53                 lzma_allocator *allocator lzma_attribute((unused)),
  54                 const uint8_t *restrict in, size_t *restrict in_pos,
  55                 size_t in_size, uint8_t *restrict out,
  56                 size_t *restrict out_pos, size_t out_size,
  57                 lzma_action action)
  58 {
  59         while (*out_pos < out_size
  60                         && (coder->sequence == SEQ_CODE || *in_pos < in_size))
  61         switch (coder->sequence) {
  62         case SEQ_PROPERTIES:
  63                 if (lzma_lzma_lclppb_decode(&coder->options, in[*in_pos]))
  64                         return LZMA_FORMAT_ERROR;
  65
  66                 coder->sequence = SEQ_DICTIONARY_SIZE;
  67                 ++*in_pos;
  68                 break;
  69
  70         case SEQ_DICTIONARY_SIZE:
  71                 coder->options.dictionary_size
  72                                 |= (size_t)(in[*in_pos]) << (coder->pos * 8);
  73
  74                 if (++coder->pos == 4) {
  75                         if (coder->options.dictionary_size
  76                                         > LZMA_DICTIONARY_SIZE_MAX)
  77                                 return LZMA_FORMAT_ERROR;
  78
  79                         // A hack to ditch tons of false positives: We allow
  80                         // only dictionary sizes that are 2^n or 2^n + 2^(n-1).
  81                         // LZMA_Alone created only files with 2^n, but accepts
  82                         // any dictionary size. If someone complains, this
  83                         // will be reconsidered.
  84                         uint32_t d = coder->options.dictionary_size - 1;
  85                         d |= d >> 2;
  86                         d |= d >> 3;
  87                         d |= d >> 4;
  88                         d |= d >> 8;
  89                         d |= d >> 16;
  90                         ++d;
  91
  92                         if (d != coder->options.dictionary_size)
  93                                 return LZMA_FORMAT_ERROR;
  94
  95                         coder->pos = 0;
  96                         coder->sequence = SEQ_UNCOMPRESSED_SIZE;
  97                 }
  98
  99                 ++*in_pos;
 100                 break;
 101
 102         case SEQ_UNCOMPRESSED_SIZE:
 103                 coder->uncompressed_size
 104                                 |= (lzma_vli)(in[*in_pos]) << (coder->pos * 8);
 105
 106                 if (++coder->pos == 8) {
 107                         // Another hack to ditch false positives: Assume that
 108                         // if the uncompressed size is known, it must be less
 109                         // than 256 GiB. Again, if someone complains, this
 110                         // will be reconsidered.
 111                         if (coder->uncompressed_size != LZMA_VLI_UNKNOWN
 112                                         && coder->uncompressed_size
 113                                                 >= (LZMA_VLI_C(1) << 38))
 114                                 return LZMA_FORMAT_ERROR;
 115
 116                         coder->pos = 0;
 117                         coder->sequence = SEQ_CODER_INIT;
 118                 }
 119
 120                 ++*in_pos;
 121                 break;
 122
 123         case SEQ_CODER_INIT: {
 124                 // FIXME It is unfair that this doesn't add a fixed amount
 125                 // like lzma_memusage_common() does.
 126                 const uint64_t memusage
 127                                 = lzma_lzma_decoder_memusage(&coder->options);
 128
 129                 // Use LZMA_PROG_ERROR since LZMA_Alone decoder cannot be
 130                 // built without LZMA support.
 131                 // FIXME TODO Make the above comment true.
 132                 if (memusage == UINT64_MAX)
 133                         return LZMA_PROG_ERROR;
 134
 135                 if (memusage > coder->memlimit)
 136                         return LZMA_MEMLIMIT_ERROR;
 137
 138                 lzma_filter_info filters[2] = {
 139                         {
 140                                 .init = &lzma_lzma_decoder_init,
 141                                 .options = &coder->options,
 142                         }, {
 143                                 .init = NULL,
 144                         }
 145                 };
 146
 147                 const lzma_ret ret = lzma_next_filter_init(&coder->next,
 148                                 allocator, filters);
 149                 if (ret != LZMA_OK)
 150                         return ret;
 151
 152                 // Use a hack to set the uncompressed size.
 153                 lzma_lz_decoder_uncompressed(coder->next.coder,
 154                                 coder->uncompressed_size);
 155
 156                 coder->sequence = SEQ_CODE;
 157         }
 158
 159         // Fall through
 160
 161         case SEQ_CODE: {
 162                 return coder->next.code(coder->next.coder,
 163                                 allocator, in, in_pos, in_size,
 164                                 out, out_pos, out_size, action);
 165         }
 166
 167         default:
 168                 return LZMA_PROG_ERROR;
 169         }
 170
 171         return LZMA_OK;
 172 }
 173
 174
 175 static void
 176 alone_decoder_end(lzma_coder *coder, lzma_allocator *allocator)
 177 {
 178         lzma_next_end(&coder->next, allocator);
 179         lzma_free(coder, allocator);
 180         return;
 181 }
 182
 183
 184 extern lzma_ret
 185 lzma_alone_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
 186                 uint64_t memlimit)
 187 {
 188         lzma_next_coder_init(lzma_alone_decoder_init, next, allocator);
 189
 190         if (next->coder == NULL) {
 191                 next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
 192                 if (next->coder == NULL)
 193                         return LZMA_MEM_ERROR;
 194
 195                 next->code = &alone_decode;
 196                 next->end = &alone_decoder_end;
 197                 next->coder->next = LZMA_NEXT_CODER_INIT;
 198         }
 199
 200         next->coder->sequence = SEQ_PROPERTIES;
 201         next->coder->pos = 0;
 202         next->coder->options.dictionary_size = 0;
 203         next->coder->uncompressed_size = 0;
 204         next->coder->memlimit = memlimit;
 205
 206         return LZMA_OK;
 207 }
 208
 209
 210 extern LZMA_API lzma_ret
 211 lzma_alone_decoder(lzma_stream *strm, uint64_t memlimit)
 212 {
 213         lzma_next_strm_init(lzma_alone_decoder_init, strm, memlimit);
 214
 215         strm->internal->supported_actions[LZMA_RUN] = true;
 216         strm->internal->supported_actions[LZMA_FINISH] = true;
 217
 218         return LZMA_OK;
 219 }