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         const struct compressor_ops *ops;
  85         u64 size;
  86
  87         if (!compressor_ctype_valid(ctype))
  88                 return 0;
  89
  90         if (max_block_size == 0)
  91                 return 0;
  92
  93         ops = compressor_ops[ctype];
  94
  95         if (compression_level == 0)
  96                 compression_level = default_compression_levels[ctype];
  97         if (compression_level == 0)
  98                 compression_level = DEFAULT_COMPRESSION_LEVEL;
  99
 100         if (ops->get_needed_memory) {
 101                 size = ops->get_needed_memory(max_block_size, compression_level);
 102
 103                 /* 0 is never valid and indicates an invalid max_block_size.  */
 104                 if (size == 0)
 105                         return 0;
 106         } else {
 107                 size = 0;
 108         }
 109         return size + sizeof(struct wimlib_compressor);
 110 }
 111
 112 WIMLIBAPI int
 113 wimlib_create_compressor(enum wimlib_compression_type ctype,
 114                          size_t max_block_size,
 115                          unsigned int compression_level,
 116                          struct wimlib_compressor **c_ret)
 117 {
 118         struct wimlib_compressor *c;
 119
 120         if (!compressor_ctype_valid(ctype))
 121                 return WIMLIB_ERR_INVALID_COMPRESSION_TYPE;
 122
 123         if (c_ret == NULL)
 124                 return WIMLIB_ERR_INVALID_PARAM;
 125
 126         if (max_block_size == 0)
 127                 return WIMLIB_ERR_INVALID_PARAM;
 128
 129         c = MALLOC(sizeof(*c));
 130         if (c == NULL)
 131                 return WIMLIB_ERR_NOMEM;
 132         c->ops = compressor_ops[ctype];
 133         c->private = NULL;
 134         c->ctype = ctype;
 135         c->max_block_size = max_block_size;
 136         if (c->ops->create_compressor) {
 137                 int ret;
 138
 139                 if (compression_level == 0)
 140                         compression_level = default_compression_levels[ctype];
 141                 if (compression_level == 0)
 142                         compression_level = DEFAULT_COMPRESSION_LEVEL;
 143
 144                 ret = c->ops->create_compressor(max_block_size,
 145                                                 compression_level,
 146                                                 &c->private);
 147                 if (ret) {
 148                         FREE(c);
 149                         return ret;
 150                 }
 151         }
 152         *c_ret = c;
 153         return 0;
 154 }
 155
 156 WIMLIBAPI size_t
 157 wimlib_compress(const void *uncompressed_data, size_t uncompressed_size,
 158                 void *compressed_data, size_t compressed_size_avail,
 159                 struct wimlib_compressor *c)
 160 {
 161         size_t compressed_size;
 162
 163         if (unlikely(uncompressed_size == 0 || uncompressed_size > c->max_block_size))
 164                 return 0;
 165
 166         compressed_size = c->ops->compress(uncompressed_data,
 167                                            uncompressed_size,
 168                                            compressed_data,
 169                                            compressed_size_avail,
 170                                            c->private);
 171
 172         /* (Optional) Verify that we really get the same thing back when
 173          * decompressing.  Should always be the case, unless there's a bug.  */
 174 #ifdef ENABLE_VERIFY_COMPRESSION
 175         if (compressed_size != 0) {
 176                 struct wimlib_decompressor *d;
 177                 int res;
 178                 u8 *buf;
 179
 180                 buf = MALLOC(uncompressed_size);
 181                 if (!buf) {
 182                         WARNING("Unable to verify results of %s compression "
 183                                 "(can't allocate buffer)",
 184                                 wimlib_get_compression_type_string(c->ctype));
 185                         return 0;
 186                 }
 187
 188                 res = wimlib_create_decompressor(c->ctype,
 189                                                  c->max_block_size, &d);
 190                 if (res) {
 191                         WARNING("Unable to verify results of %s compression "
 192                                 "(can't create decompressor)",
 193                                 wimlib_get_compression_type_string(c->ctype));
 194                         FREE(buf);
 195                         return 0;
 196                 }
 197
 198                 res = wimlib_decompress(compressed_data, compressed_size,
 199                                         buf, uncompressed_size, d);
 200                 wimlib_free_decompressor(d);
 201                 if (res) {
 202                         ERROR("Failed to decompress our %s-compressed data",
 203                               wimlib_get_compression_type_string(c->ctype));
 204                         FREE(buf);
 205                         abort();
 206                 }
 207
 208                 res = memcmp(uncompressed_data, buf, uncompressed_size);
 209                 FREE(buf);
 210
 211                 if (res) {
 212                         ERROR("Our %s-compressed data did not decompress "
 213                               "to original",
 214                               wimlib_get_compression_type_string(c->ctype));
 215                         abort();
 216                 }
 217         }
 218 #endif /* ENABLE_VERIFY_COMPRESSION */
 219
 220         return compressed_size;
 221 }
 222
 223 WIMLIBAPI void
 224 wimlib_free_compressor(struct wimlib_compressor *c)
 225 {
 226         if (c) {
 227                 if (c->ops->free_compressor)
 228                         c->ops->free_compressor(c->private);
 229                 FREE(c);
 230         }
 231 }