src/liblzma/simple/simple_coder.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       simple_coder.c
   4 /// \brief      Wrapper for simple filters
   5 ///
   6 /// Simple filters don't change the size of the data i.e. number of bytes
   7 /// in equals the number of bytes out.
   8 //
   9 //  Copyright (C) 2007 Lasse Collin
  10 //
  11 //  This library is free software; you can redistribute it and/or
  12 //  modify it under the terms of the GNU Lesser General Public
  13 //  License as published by the Free Software Foundation; either
  14 //  version 2.1 of the License, or (at your option) any later version.
  15 //
  16 //  This library is distributed in the hope that it will be useful,
  17 //  but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19 //  Lesser General Public License for more details.
  20 //
  21 ///////////////////////////////////////////////////////////////////////////////
  22
  23 #include "simple_private.h"
  24
  25
  26 /// Copied or encodes/decodes more data to out[]. Checks and updates
  27 /// uncompressed_size when we are the last coder in the chain.
  28 /// If we aren't the last filter in the chain, we don't need to care about
  29 /// uncompressed size, since we don't change it; the next filter in the
  30 /// chain will check it anyway.
  31 static lzma_ret
  32 copy_or_code(lzma_coder *coder, lzma_allocator *allocator,
  33                 const uint8_t *restrict in, size_t *restrict in_pos,
  34                 size_t in_size, uint8_t *restrict out,
  35                 size_t *restrict out_pos, size_t out_size, lzma_action action)
  36 {
  37         assert(!coder->end_was_reached);
  38
  39         if (coder->next.code == NULL) {
  40                 const size_t in_avail = in_size - *in_pos;
  41
  42                 if (coder->is_encoder) {
  43                         if (action == LZMA_FINISH) {
  44                                 // If uncompressed size is known and the
  45                                 // amount of available input doesn't match
  46                                 // the uncompressed size, return an error.
  47                                 if (coder->uncompressed_size
  48                                                 != LZMA_VLI_VALUE_UNKNOWN
  49                                                 && coder->uncompressed_size
  50                                                         != in_avail)
  51                                         return LZMA_DATA_ERROR;
  52
  53                         } else if (coder->uncompressed_size
  54                                         < (lzma_vli)(in_avail)) {
  55                                 // There is too much input available.
  56                                 return LZMA_DATA_ERROR;
  57                         }
  58                 } else {
  59                         // Limit in_size so that we don't copy too much.
  60                         if ((lzma_vli)(in_avail) > coder->uncompressed_size)
  61                                 in_size = *in_pos + (size_t)(
  62                                                 coder->uncompressed_size);
  63                 }
  64
  65                 // Store the old position so we can update uncompressed_size.
  66                 const size_t out_start = *out_pos;
  67
  68                 // Copy the data
  69                 bufcpy(in, in_pos, in_size, out, out_pos, out_size);
  70
  71                 // Update uncompressed_size.
  72                 if (coder->uncompressed_size != LZMA_VLI_VALUE_UNKNOWN)
  73                         coder->uncompressed_size -= *out_pos - out_start;
  74
  75                 // Check if end of stream was reached.
  76                 if (coder->is_encoder) {
  77                         if (action == LZMA_FINISH && *in_pos == in_size)
  78                                 coder->end_was_reached = true;
  79                 } else {
  80                         if (coder->uncompressed_size == 0)
  81                                 coder->end_was_reached = true;
  82                 }
  83
  84         } else {
  85                 // Call the next coder in the chain to provide us some data.
  86                 // We don't care about uncompressed_size here, because
  87                 // the next filter in the chain will do it for us (since
  88                 // we don't change the size of the data).
  89                 const lzma_ret ret = coder->next.code(
  90                                 coder->next.coder, allocator,
  91                                 in, in_pos, in_size,
  92                                 out, out_pos, out_size, action);
  93
  94                 if (ret == LZMA_STREAM_END) {
  95                         assert(!coder->is_encoder
  96                                         || action == LZMA_FINISH);
  97                         coder->end_was_reached = true;
  98
  99                 } else if (ret != LZMA_OK) {
 100                         return ret;
 101                 }
 102         }
 103
 104         return LZMA_OK;
 105 }
 106
 107
 108 static size_t
 109 call_filter(lzma_coder *coder, uint8_t *buffer, size_t size)
 110 {
 111         const size_t filtered = coder->filter(coder->simple,
 112                         coder->now_pos, coder->is_encoder,
 113                         buffer, size);
 114         coder->now_pos += filtered;
 115         return filtered;
 116 }
 117
 118
 119 static lzma_ret
 120 simple_code(lzma_coder *coder, lzma_allocator *allocator,
 121                 const uint8_t *restrict in, size_t *restrict in_pos,
 122                 size_t in_size, uint8_t *restrict out,
 123                 size_t *restrict out_pos, size_t out_size, lzma_action action)
 124 {
 125         // Flush already filtered data from coder->buffer[] to out[].
 126         if (coder->pos < coder->filtered) {
 127                 bufcpy(coder->buffer, &coder->pos, coder->filtered,
 128                                 out, out_pos, out_size);
 129
 130                 // If we couldn't flush all the filtered data, return to
 131                 // application immediatelly.
 132                 if (coder->pos < coder->filtered)
 133                         return LZMA_OK;
 134
 135                 if (coder->end_was_reached) {
 136                         assert(coder->filtered == coder->size);
 137                         return LZMA_STREAM_END;
 138                 }
 139         }
 140
 141         // If we get here, there is no filtered data left in the buffer.
 142         coder->filtered = 0;
 143
 144         assert(!coder->end_was_reached);
 145
 146         // If there is more output space left than there is unfiltered data
 147         // in coder->buffer[], flush coder->buffer[] to out[], and copy/code
 148         // more data to out[] hopefully filling it completely. Then filter
 149         // the data in out[]. This step is where most of the data gets
 150         // filtered if the buffer sizes used by the application are reasonable.
 151         const size_t out_avail = out_size - *out_pos;
 152         const size_t buf_avail = coder->size - coder->pos;
 153         if (out_avail > buf_avail) {
 154                 // Store the old position so that we know from which byte
 155                 // to start filtering.
 156                 const size_t out_start = *out_pos;
 157
 158                 // Flush data from coder->buffer[] to out[], but don't reset
 159                 // coder->pos and coder->size yet. This way the coder can be
 160                 // restarted if the next filter in the chain returns e.g.
 161                 // LZMA_MEM_ERROR.
 162                 memcpy(out + *out_pos, coder->buffer + coder->pos, buf_avail);
 163                 *out_pos += buf_avail;
 164
 165                 // Copy/Encode/Decode more data to out[].
 166                 {
 167                         const lzma_ret ret = copy_or_code(coder, allocator,
 168                                         in, in_pos, in_size,
 169                                         out, out_pos, out_size, action);
 170                         assert(ret != LZMA_STREAM_END);
 171                         if (ret != LZMA_OK)
 172                                 return ret;
 173                 }
 174
 175                 // Filter out[].
 176                 const size_t size = *out_pos - out_start;
 177                 const size_t filtered = call_filter(
 178                                 coder, out + out_start, size);
 179
 180                 const size_t unfiltered = size - filtered;
 181                 assert(unfiltered <= coder->allocated / 2);
 182
 183                 // Now we can update coder->pos and coder->size, because
 184                 // the next coder in the chain (if any) was successful.
 185                 coder->pos = 0;
 186                 coder->size = unfiltered;
 187
 188                 if (coder->end_was_reached) {
 189                         // The last byte has been copied to out[] already.
 190                         // They are left as is.
 191                         coder->size = 0;
 192
 193                 } else if (unfiltered > 0) {
 194                         // There is unfiltered data left in out[]. Copy it to
 195                         // coder->buffer[] and rewind *out_pos appropriately.
 196                         *out_pos -= unfiltered;
 197                         memcpy(coder->buffer, out + *out_pos, unfiltered);
 198                 }
 199         } else if (coder->pos > 0) {
 200                 memmove(coder->buffer, coder->buffer + coder->pos, buf_avail);
 201                 coder->size -= coder->pos;
 202                 coder->pos = 0;
 203         }
 204
 205         assert(coder->pos == 0);
 206
 207         // If coder->buffer[] isn't empty, try to fill it by copying/decoding
 208         // more data. Then filter coder->buffer[] and copy the successfully
 209         // filtered data to out[]. It is probable, that some filtered and
 210         // unfiltered data will be left to coder->buffer[].
 211         if (coder->size > 0) {
 212                 {
 213                         const lzma_ret ret = copy_or_code(coder, allocator,
 214                                         in, in_pos, in_size,
 215                                         coder->buffer, &coder->size,
 216                                         coder->allocated, action);
 217                         assert(ret != LZMA_STREAM_END);
 218                         if (ret != LZMA_OK)
 219                                 return ret;
 220                 }
 221
 222                 coder->filtered = call_filter(
 223                                 coder, coder->buffer, coder->size);
 224
 225                 // Everything is considered to be filtered if coder->buffer[]
 226                 // contains the last bytes of the data.
 227                 if (coder->end_was_reached)
 228                         coder->filtered = coder->size;
 229
 230                 // Flush as much as possible.
 231                 bufcpy(coder->buffer, &coder->pos, coder->filtered,
 232                                 out, out_pos, out_size);
 233         }
 234
 235         // Check if we got everything done.
 236         if (coder->end_was_reached && coder->pos == coder->size)
 237                 return LZMA_STREAM_END;
 238
 239         return LZMA_OK;
 240 }
 241
 242
 243 static void
 244 simple_coder_end(lzma_coder *coder, lzma_allocator *allocator)
 245 {
 246         lzma_next_coder_end(&coder->next, allocator);
 247         lzma_free(coder->simple, allocator);
 248         lzma_free(coder, allocator);
 249         return;
 250 }
 251
 252
 253 extern lzma_ret
 254 lzma_simple_coder_init(lzma_next_coder *next, lzma_allocator *allocator,
 255                 const lzma_filter_info *filters,
 256                 size_t (*filter)(lzma_simple *simple, uint32_t now_pos,
 257                         bool is_encoder, uint8_t *buffer, size_t size),
 258                 size_t simple_size, size_t unfiltered_max, bool is_encoder)
 259 {
 260         // Allocate memory for the lzma_coder structure if needed.
 261         if (next->coder == NULL) {
 262                 // Here we allocate space also for the temporary buffer. We
 263                 // need twice the size of unfiltered_max, because then it
 264                 // is always possible to filter at least unfiltered_max bytes
 265                 // more data in coder->buffer[] if it can be filled completely.
 266                 next->coder = lzma_alloc(sizeof(lzma_coder)
 267                                 + 2 * unfiltered_max, allocator);
 268                 if (next->coder == NULL)
 269                         return LZMA_MEM_ERROR;
 270
 271                 next->code = &simple_code;
 272                 next->end = &simple_coder_end;
 273
 274                 next->coder->next = LZMA_NEXT_CODER_INIT;
 275                 next->coder->filter = filter;
 276                 next->coder->allocated = 2 * unfiltered_max;
 277
 278                 // Allocate memory for filter-specific data structure.
 279                 if (simple_size > 0) {
 280                         next->coder->simple = lzma_alloc(
 281                                         simple_size, allocator);
 282                         if (next->coder->simple == NULL)
 283                                 return LZMA_MEM_ERROR;
 284                 } else {
 285                         next->coder->simple = NULL;
 286                 }
 287         }
 288
 289         if (filters[0].options != NULL) {
 290                 const lzma_options_simple *simple = filters[0].options;
 291                 next->coder->now_pos = simple->start_offset;
 292         } else {
 293                 next->coder->now_pos = 0;
 294         }
 295
 296         // Reset variables.
 297         next->coder->is_encoder = is_encoder;
 298         next->coder->end_was_reached = false;
 299         next->coder->uncompressed_size = filters[0].uncompressed_size;
 300         next->coder->pos = 0;
 301         next->coder->filtered = 0;
 302         next->coder->size = 0;
 303
 304         return lzma_next_filter_init(
 305                         &next->coder->next, allocator, filters + 1);
 306 }