wimlib.net Git - wimlib/blob - src/compress.c

   1 /*
   2  * compress.c
   3  *
   4  * Generic functions for compression, wrapping around actual compression
   5  * implementations.
   6  */
   7
   8 /*
   9  * Copyright (C) 2013, 2014 Eric Biggers
  10  *
  11  * This file is free software; you can redistribute it and/or modify it under
  12  * the terms of the GNU Lesser General Public License as published by the Free
  13  * Software Foundation; either version 3 of the License, or (at your option) any
  14  * later version.
  15  *
  16  * This file is distributed in the hope that it will be useful, but WITHOUT
  17  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  18  * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
  19  * details.
  20  *
  21  * You should have received a copy of the GNU Lesser General Public License
  22  * along with this file; if not, see http://www.gnu.org/licenses/.
  23  */
  24
  25 #ifdef HAVE_CONFIG_H
  26 #  include "config.h"
  27 #endif
  28
  29 #include <stdlib.h>
  30 #include <string.h>
  31
  32 #include "wimlib.h"
  33 #include "wimlib/error.h"
  34 #include "wimlib/compressor_ops.h"
  35 #include "wimlib/util.h"
  36
  37 struct wimlib_compressor {
  38         const struct compressor_ops *ops;
  39         void *private;
  40         enum wimlib_compression_type ctype;
  41         size_t max_block_size;
  42 };
  43
  44 static const struct compressor_ops *compressor_ops[] = {
  45         [WIMLIB_COMPRESSION_TYPE_XPRESS] = &xpress_compressor_ops,
  46         [WIMLIB_COMPRESSION_TYPE_LZX]    = &lzx_compressor_ops,
  47         [WIMLIB_COMPRESSION_TYPE_LZMS]   = &lzms_compressor_ops,
  48 };
  49
  50 /* Scale: 10 = low, 50 = medium, 100 = high */
  51
  52 #define DEFAULT_COMPRESSION_LEVEL 50
  53
  54 static unsigned int default_compression_levels[ARRAY_LEN(compressor_ops)];
  55
  56 static bool
  57 compressor_ctype_valid(int ctype)
  58 {
  59         return (ctype >= 0 &&
  60                 ctype < ARRAY_LEN(compressor_ops) &&
  61                 compressor_ops[ctype] != NULL);
  62 }
  63
  64 WIMLIBAPI int
  65 wimlib_set_default_compression_level(int ctype, unsigned int compression_level)
  66 {
  67         if (ctype == -1) {
  68                 for (int i = 0; i < ARRAY_LEN(default_compression_levels); i++)
  69                         default_compression_levels[i] = compression_level;
  70         } else {
  71                 if (!compressor_ctype_valid(ctype))
  72                         return WIMLIB_ERR_INVALID_COMPRESSION_TYPE;
  73
  74                 default_compression_levels[ctype] = compression_level;
  75         }
  76         return 0;
  77 }
  78
  79 WIMLIBAPI u64
  80 wimlib_get_compressor_needed_memory(enum wimlib_compression_type ctype,
  81                                     size_t max_block_size,
  82                                     unsigned int compression_level)
  83 {
  84         bool destructive;
  85         const struct compressor_ops *ops;
  86         u64 size;
  87
  88         destructive = (compression_level & WIMLIB_COMPRESSOR_FLAG_DESTRUCTIVE);
  89         compression_level &= ~WIMLIB_COMPRESSOR_FLAG_DESTRUCTIVE;
  90
  91         if (!compressor_ctype_valid(ctype))
  92                 return 0;
  93
  94         if (compression_level > 0xFFFFFF)
  95                 return 0;
  96
  97         if (max_block_size == 0)
  98                 return 0;
  99
 100         ops = compressor_ops[ctype];
 101
 102         if (compression_level == 0)
 103                 compression_level = default_compression_levels[ctype];
 104         if (compression_level == 0)
 105                 compression_level = DEFAULT_COMPRESSION_LEVEL;
 106
 107         if (ops->get_needed_memory) {
 108                 size = ops->get_needed_memory(max_block_size, compression_level,
 109                                               destructive);
 110
 111                 /* 0 is never valid and indicates an invalid max_block_size.  */
 112                 if (size == 0)
 113                         return 0;
 114         } else {
 115                 size = 0;
 116         }
 117         return size + sizeof(struct wimlib_compressor);
 118 }
 119
 120 WIMLIBAPI int
 121 wimlib_create_compressor(enum wimlib_compression_type ctype,
 122                          size_t max_block_size,
 123                          unsigned int compression_level,
 124                          struct wimlib_compressor **c_ret)
 125 {
 126         bool destructive;
 127         struct wimlib_compressor *c;
 128
 129         destructive = (compression_level & WIMLIB_COMPRESSOR_FLAG_DESTRUCTIVE);
 130         compression_level &= ~WIMLIB_COMPRESSOR_FLAG_DESTRUCTIVE;
 131
 132         if (!compressor_ctype_valid(ctype))
 133                 return WIMLIB_ERR_INVALID_COMPRESSION_TYPE;
 134
 135         if (compression_level > 0xFFFFFF)
 136                 return WIMLIB_ERR_INVALID_PARAM;
 137
 138         if (c_ret == NULL)
 139                 return WIMLIB_ERR_INVALID_PARAM;
 140
 141         if (max_block_size == 0)
 142                 return WIMLIB_ERR_INVALID_PARAM;
 143
 144         c = MALLOC(sizeof(*c));
 145         if (c == NULL)
 146                 return WIMLIB_ERR_NOMEM;
 147         c->ops = compressor_ops[ctype];
 148         c->private = NULL;
 149         c->ctype = ctype;
 150         c->max_block_size = max_block_size;
 151         if (c->ops->create_compressor) {
 152                 int ret;
 153
 154                 if (compression_level == 0)
 155                         compression_level = default_compression_levels[ctype];
 156                 if (compression_level == 0)
 157                         compression_level = DEFAULT_COMPRESSION_LEVEL;
 158
 159                 ret = c->ops->create_compressor(max_block_size,
 160                                                 compression_level,
 161                                                 destructive,
 162                                                 &c->private);
 163                 if (ret) {
 164                         FREE(c);
 165                         return ret;
 166                 }
 167         }
 168         *c_ret = c;
 169         return 0;
 170 }
 171
 172 WIMLIBAPI size_t
 173 wimlib_compress(const void *uncompressed_data, size_t uncompressed_size,
 174                 void *compressed_data, size_t compressed_size_avail,
 175                 struct wimlib_compressor *c)
 176 {
 177         size_t compressed_size;
 178
 179         if (unlikely(uncompressed_size == 0 || uncompressed_size > c->max_block_size))
 180                 return 0;
 181
 182         compressed_size = c->ops->compress(uncompressed_data,
 183                                            uncompressed_size,
 184                                            compressed_data,
 185                                            compressed_size_avail,
 186                                            c->private);
 187
 188         /* (Optional) Verify that we really get the same thing back when
 189          * decompressing.  Should always be the case, unless there's a bug.  */
 190 #ifdef ENABLE_VERIFY_COMPRESSION
 191         if (compressed_size != 0) {
 192                 struct wimlib_decompressor *d;
 193                 int res;
 194                 u8 *buf;
 195
 196                 buf = MALLOC(uncompressed_size);
 197                 if (!buf) {
 198                         WARNING("Unable to verify results of %s compression "
 199                                 "(can't allocate buffer)",
 200                                 wimlib_get_compression_type_string(c->ctype));
 201                         return 0;
 202                 }
 203
 204                 res = wimlib_create_decompressor(c->ctype,
 205                                                  c->max_block_size, &d);
 206                 if (res) {
 207                         WARNING("Unable to verify results of %s compression "
 208                                 "(can't create decompressor)",
 209                                 wimlib_get_compression_type_string(c->ctype));
 210                         FREE(buf);
 211                         return 0;
 212                 }
 213
 214                 res = wimlib_decompress(compressed_data, compressed_size,
 215                                         buf, uncompressed_size, d);
 216                 wimlib_free_decompressor(d);
 217                 if (res) {
 218                         ERROR("Failed to decompress our %s-compressed data",
 219                               wimlib_get_compression_type_string(c->ctype));
 220                         FREE(buf);
 221                         abort();
 222                 }
 223
 224                 res = memcmp(uncompressed_data, buf, uncompressed_size);
 225                 FREE(buf);
 226
 227                 if (res) {
 228                         ERROR("Our %s-compressed data did not decompress "
 229                               "to original",
 230                               wimlib_get_compression_type_string(c->ctype));
 231                         abort();
 232                 }
 233         }
 234 #endif /* ENABLE_VERIFY_COMPRESSION */
 235
 236         return compressed_size;
 237 }
 238
 239 WIMLIBAPI void
 240 wimlib_free_compressor(struct wimlib_compressor *c)
 241 {
 242         if (c) {
 243                 if (c->ops->free_compressor)
 244                         c->ops->free_compressor(c->private);
 245                 FREE(c);
 246         }
 247 }