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 "wimlib.h"
  30 #include "wimlib/assert.h"
  31 #include "wimlib/error.h"
  32 #include "wimlib/compressor_ops.h"
  33 #include "wimlib/util.h"
  34
  35 #include <stdlib.h>
  36 #include <string.h>
  37
  38 struct wimlib_compressor {
  39         const struct compressor_ops *ops;
  40         void *private;
  41         enum wimlib_compression_type ctype;
  42         size_t max_block_size;
  43 };
  44
  45 static const struct compressor_ops *compressor_ops[] = {
  46         [WIMLIB_COMPRESSION_TYPE_XPRESS] = &xpress_compressor_ops,
  47         [WIMLIB_COMPRESSION_TYPE_LZX]    = &lzx_compressor_ops,
  48         [WIMLIB_COMPRESSION_TYPE_LZMS]   = &lzms_compressor_ops,
  49 };
  50
  51 /* Scale: 10 = low, 50 = medium, 100 = high */
  52
  53 #define DEFAULT_COMPRESSION_LEVEL 50
  54
  55 static unsigned int default_compression_levels[ARRAY_LEN(compressor_ops)];
  56
  57 static bool
  58 compressor_ctype_valid(int ctype)
  59 {
  60         return (ctype >= 0 &&
  61                 ctype < ARRAY_LEN(compressor_ops) &&
  62                 compressor_ops[ctype] != NULL);
  63 }
  64
  65 WIMLIBAPI int
  66 wimlib_set_default_compression_level(int ctype, unsigned int compression_level)
  67 {
  68         if (ctype == -1) {
  69                 for (int i = 0; i < ARRAY_LEN(default_compression_levels); i++)
  70                         default_compression_levels[i] = compression_level;
  71         } else {
  72                 if (!compressor_ctype_valid(ctype))
  73                         return WIMLIB_ERR_INVALID_COMPRESSION_TYPE;
  74
  75                 default_compression_levels[ctype] = compression_level;
  76         }
  77         return 0;
  78 }
  79
  80 WIMLIBAPI u64
  81 wimlib_get_compressor_needed_memory(enum wimlib_compression_type ctype,
  82                                     size_t max_block_size,
  83                                     unsigned int compression_level)
  84 {
  85         const struct compressor_ops *ops;
  86         u64 size;
  87
  88         if (!compressor_ctype_valid(ctype))
  89                 return 0;
  90
  91         if (max_block_size == 0)
  92                 return 0;
  93
  94         ops = compressor_ops[ctype];
  95
  96         if (compression_level == 0)
  97                 compression_level = default_compression_levels[ctype];
  98         if (compression_level == 0)
  99                 compression_level = DEFAULT_COMPRESSION_LEVEL;
 100
 101         if (ops->get_needed_memory) {
 102                 size = ops->get_needed_memory(max_block_size, compression_level);
 103
 104                 /* 0 is never valid and indicates an invalid max_block_size.  */
 105                 if (size == 0)
 106                         return 0;
 107         } else {
 108                 size = 0;
 109         }
 110         return size + sizeof(struct wimlib_compressor);
 111 }
 112
 113 WIMLIBAPI int
 114 wimlib_create_compressor(enum wimlib_compression_type ctype,
 115                          size_t max_block_size,
 116                          unsigned int compression_level,
 117                          struct wimlib_compressor **c_ret)
 118 {
 119         struct wimlib_compressor *c;
 120
 121         if (!compressor_ctype_valid(ctype))
 122                 return WIMLIB_ERR_INVALID_COMPRESSION_TYPE;
 123
 124         if (c_ret == NULL)
 125                 return WIMLIB_ERR_INVALID_PARAM;
 126
 127         if (max_block_size == 0)
 128                 return WIMLIB_ERR_INVALID_PARAM;
 129
 130         c = MALLOC(sizeof(*c));
 131         if (c == NULL)
 132                 return WIMLIB_ERR_NOMEM;
 133         c->ops = compressor_ops[ctype];
 134         c->private = NULL;
 135         c->ctype = ctype;
 136         c->max_block_size = max_block_size;
 137         if (c->ops->create_compressor) {
 138                 int ret;
 139
 140                 if (compression_level == 0)
 141                         compression_level = default_compression_levels[ctype];
 142                 if (compression_level == 0)
 143                         compression_level = DEFAULT_COMPRESSION_LEVEL;
 144
 145                 ret = c->ops->create_compressor(max_block_size,
 146                                                 compression_level,
 147                                                 &c->private);
 148                 if (ret) {
 149                         FREE(c);
 150                         return ret;
 151                 }
 152         }
 153         *c_ret = c;
 154         return 0;
 155 }
 156
 157 WIMLIBAPI size_t
 158 wimlib_compress(const void *uncompressed_data, size_t uncompressed_size,
 159                 void *compressed_data, size_t compressed_size_avail,
 160                 struct wimlib_compressor *c)
 161 {
 162         size_t compressed_size;
 163
 164         if (unlikely(uncompressed_size == 0 || uncompressed_size > c->max_block_size))
 165                 return 0;
 166
 167         compressed_size = c->ops->compress(uncompressed_data,
 168                                            uncompressed_size,
 169                                            compressed_data,
 170                                            compressed_size_avail,
 171                                            c->private);
 172
 173         /* (Optional) Verify that we really get the same thing back when
 174          * decompressing.  Should always be the case, unless there's a bug.  */
 175 #ifdef ENABLE_VERIFY_COMPRESSION
 176         if (compressed_size != 0) {
 177                 struct wimlib_decompressor *d;
 178                 int res;
 179                 u8 *buf;
 180
 181                 buf = MALLOC(uncompressed_size);
 182                 if (!buf) {
 183                         WARNING("Unable to verify results of %s compression "
 184                                 "(can't allocate buffer)",
 185                                 wimlib_get_compression_type_string(c->ctype));
 186                         return 0;
 187                 }
 188
 189                 res = wimlib_create_decompressor(c->ctype,
 190                                                  c->max_block_size, &d);
 191                 if (res) {
 192                         WARNING("Unable to verify results of %s compression "
 193                                 "(can't create decompressor)",
 194                                 wimlib_get_compression_type_string(c->ctype));
 195                         FREE(buf);
 196                         return 0;
 197                 }
 198
 199                 res = wimlib_decompress(compressed_data, compressed_size,
 200                                         buf, uncompressed_size, d);
 201                 wimlib_free_decompressor(d);
 202                 if (res) {
 203                         ERROR("Failed to decompress our %s-compressed data",
 204                               wimlib_get_compression_type_string(c->ctype));
 205                         FREE(buf);
 206                         abort();
 207                 }
 208
 209                 res = memcmp(uncompressed_data, buf, uncompressed_size);
 210                 FREE(buf);
 211
 212                 if (res) {
 213                         ERROR("Our %s-compressed data did not decompress "
 214                               "to original",
 215                               wimlib_get_compression_type_string(c->ctype));
 216                         abort();
 217                 }
 218         }
 219 #endif /* ENABLE_VERIFY_COMPRESSION */
 220
 221         return compressed_size;
 222 }
 223
 224 WIMLIBAPI void
 225 wimlib_free_compressor(struct wimlib_compressor *c)
 226 {
 227         if (c) {
 228                 if (c->ops->free_compressor)
 229                         c->ops->free_compressor(c->private);
 230                 FREE(c);
 231         }
 232 }