glue/xdgmime/xdgmimecache.c

   1 /* -*- mode: C; c-file-style: "gnu" -*- */
   2 /* xdgmimealias.c: Private file.  mmappable caches for mime data
   3  *
   4  * More info can be found at http://www.freedesktop.org/standards/
   5  *
   6  * Copyright (C) 2005  Matthias Clasen <mclasen@redhat.com>
   7  *
   8  * Licensed under the Academic Free License version 2.0
   9  * Or under the following terms:
  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 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  * You should have received a copy of the GNU Lesser General Public
  22  * License along with this library; if not, write to the
  23  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  24  * Boston, MA 02111-1307, USA.
  25  */
  26
  27 #ifdef HAVE_CONFIG_H
  28 #include <config.h>
  29 #endif
  30
  31 #include <stdio.h>
  32 #include <stdlib.h>
  33 #include <string.h>
  34
  35 #include <fcntl.h>
  36 #include <unistd.h>
  37 #include <fnmatch.h>
  38 #include <assert.h>
  39
  40 #include <netinet/in.h> /* for ntohl/ntohs */
  41
  42 #ifdef HAVE_MMAP
  43 #include <sys/mman.h>
  44 #endif
  45
  46 #include <sys/stat.h>
  47 #include <sys/types.h>
  48
  49 #include "xdgmimecache.h"
  50 #include "xdgmimeint.h"
  51
  52 #ifndef MAX
  53 #define MAX(a,b) ((a) > (b) ? (a) : (b))
  54 #endif
  55
  56 #ifndef FALSE
  57 #define FALSE   (0)
  58 #endif
  59
  60 #ifndef TRUE
  61 #define TRUE    (!FALSE)
  62 #endif
  63
  64 #ifndef _O_BINARY
  65 #define _O_BINARY 0
  66 #endif
  67
  68 #ifndef MAP_FAILED
  69 #define MAP_FAILED ((void *) -1)
  70 #endif
  71
  72 #define MAJOR_VERSION 1
  73 #define MINOR_VERSION 0
  74
  75 struct _XdgMimeCache
  76 {
  77   int ref_count;
  78
  79   size_t  size;
  80   char   *buffer;
  81 };
  82
  83 #define GET_UINT16(cache,offset) (ntohs(*(xdg_uint16_t*)((cache) + (offset))))
  84 #define GET_UINT32(cache,offset) (ntohl(*(xdg_uint32_t*)((cache) + (offset))))
  85
  86 XdgMimeCache *
  87 _xdg_mime_cache_ref (XdgMimeCache *cache)
  88 {
  89   cache->ref_count++;
  90   return cache;
  91 }
  92
  93 void
  94 _xdg_mime_cache_unref (XdgMimeCache *cache)
  95 {
  96   cache->ref_count--;
  97
  98   if (cache->ref_count == 0)
  99     {
 100 #ifdef HAVE_MMAP
 101       munmap (cache->buffer, cache->size);
 102 #endif
 103       free (cache);
 104     }
 105 }
 106
 107 XdgMimeCache *
 108 _xdg_mime_cache_new_from_file (const char *file_name)
 109 {
 110   XdgMimeCache *cache = NULL;
 111
 112 #ifdef HAVE_MMAP
 113   int fd = -1;
 114   struct stat st;
 115   char *buffer = NULL;
 116
 117   /* Open the file and map it into memory */
 118   fd = open (file_name, O_RDONLY|_O_BINARY, 0);
 119
 120   if (fd < 0)
 121     return NULL;
 122
 123   if (fstat (fd, &st) < 0 || st.st_size < 4)
 124     goto done;
 125
 126   buffer = (char *) mmap (NULL, st.st_size, PROT_READ, MAP_SHARED, fd, 0);
 127
 128   if (buffer == MAP_FAILED)
 129     goto done;
 130
 131   /* Verify version */
 132   if (GET_UINT16 (buffer, 0) != MAJOR_VERSION ||
 133       GET_UINT16 (buffer, 2) != MINOR_VERSION)
 134     {
 135       munmap (buffer, st.st_size);
 136
 137       goto done;
 138     }
 139
 140   cache = (XdgMimeCache *) malloc (sizeof (XdgMimeCache));
 141   cache->ref_count = 1;
 142   cache->buffer = buffer;
 143   cache->size = st.st_size;
 144
 145  done:
 146   if (fd != -1)
 147     close (fd);
 148
 149 #endif  /* HAVE_MMAP */
 150
 151   return cache;
 152 }
 153
 154 static int
 155 cache_magic_matchlet_compare_to_data (XdgMimeCache *cache,
 156                                       xdg_uint32_t  offset,
 157                                       const void   *data,
 158                                       size_t        len)
 159 {
 160   xdg_uint32_t range_start = GET_UINT32 (cache->buffer, offset);
 161   xdg_uint32_t range_length = GET_UINT32 (cache->buffer, offset + 4);
 162   xdg_uint32_t data_length = GET_UINT32 (cache->buffer, offset + 12);
 163   xdg_uint32_t data_offset = GET_UINT32 (cache->buffer, offset + 16);
 164   xdg_uint32_t mask_offset = GET_UINT32 (cache->buffer, offset + 20);
 165
 166   int i, j;
 167
 168   for (i = range_start; i <= range_start + range_length; i++)
 169     {
 170       int valid_matchlet = TRUE;
 171
 172       if (i + data_length > len)
 173         return FALSE;
 174
 175       if (mask_offset)
 176         {
 177           for (j = 0; j < data_length; j++)
 178             {
 179               if ((((unsigned char *)cache->buffer)[data_offset + j] & ((unsigned char *)cache->buffer)[mask_offset + j]) !=
 180                   ((((unsigned char *) data)[j + i]) & ((unsigned char *)cache->buffer)[mask_offset + j]))
 181                 {
 182                   valid_matchlet = FALSE;
 183                   break;
 184                 }
 185             }
 186         }
 187       else
 188         {
 189           for (j = 0; j < data_length; j++)
 190             {
 191               if (((unsigned char *)cache->buffer)[data_offset + j] != ((unsigned char *) data)[j + i])
 192                 {
 193                   valid_matchlet = FALSE;
 194                   break;
 195                 }
 196             }
 197         }
 198
 199       if (valid_matchlet)
 200         return TRUE;
 201     }
 202
 203   return FALSE;
 204 }
 205
 206 static int
 207 cache_magic_matchlet_compare (XdgMimeCache *cache,
 208                               xdg_uint32_t  offset,
 209                               const void   *data,
 210                               size_t        len)
 211 {
 212   xdg_uint32_t n_children = GET_UINT32 (cache->buffer, offset + 24);
 213   xdg_uint32_t child_offset = GET_UINT32 (cache->buffer, offset + 28);
 214
 215   int i;
 216
 217   if (cache_magic_matchlet_compare_to_data (cache, offset, data, len))
 218     {
 219       if (n_children == 0)
 220         return TRUE;
 221
 222       for (i = 0; i < n_children; i++)
 223         {
 224           if (cache_magic_matchlet_compare (cache, child_offset + 32 * i,
 225                                             data, len))
 226             return TRUE;
 227         }
 228     }
 229
 230   return FALSE;
 231 }
 232
 233 static const char *
 234 cache_magic_compare_to_data (XdgMimeCache *cache,
 235                              xdg_uint32_t  offset,
 236                              const void   *data,
 237                              size_t        len,
 238                              int          *prio)
 239 {
 240   xdg_uint32_t priority = GET_UINT32 (cache->buffer, offset);
 241   xdg_uint32_t mimetype_offset = GET_UINT32 (cache->buffer, offset + 4);
 242   xdg_uint32_t n_matchlets = GET_UINT32 (cache->buffer, offset + 8);
 243   xdg_uint32_t matchlet_offset = GET_UINT32 (cache->buffer, offset + 12);
 244
 245   int i;
 246
 247   for (i = 0; i < n_matchlets; i++)
 248     {
 249       if (cache_magic_matchlet_compare (cache, matchlet_offset + i * 32,
 250                                         data, len))
 251         {
 252           *prio = priority;
 253
 254           return cache->buffer + mimetype_offset;
 255         }
 256     }
 257
 258   return NULL;
 259 }
 260
 261 static const char *
 262 cache_magic_lookup_data (XdgMimeCache *cache,
 263                          const void   *data,
 264                          size_t        len,
 265                          int          *prio,
 266                          const char   *mime_types[],
 267                          int           n_mime_types)
 268 {
 269   xdg_uint32_t list_offset;
 270   xdg_uint32_t n_entries;
 271   xdg_uint32_t offset;
 272
 273   int j, n;
 274
 275   *prio = 0;
 276
 277   list_offset = GET_UINT32 (cache->buffer, 24);
 278   n_entries = GET_UINT32 (cache->buffer, list_offset);
 279   offset = GET_UINT32 (cache->buffer, list_offset + 8);
 280
 281   for (j = 0; j < n_entries; j++)
 282     {
 283       const char *match;
 284
 285       match = cache_magic_compare_to_data (cache, offset + 16 * j,
 286                                            data, len, prio);
 287       if (match)
 288         return match;
 289       else
 290         {
 291           xdg_uint32_t mimetype_offset;
 292           const char *non_match;
 293
 294           mimetype_offset = GET_UINT32 (cache->buffer, offset + 16 * j + 4);
 295           non_match = cache->buffer + mimetype_offset;
 296
 297           for (n = 0; n < n_mime_types; n++)
 298             {
 299               if (mime_types[n] &&
 300                   xdg_mime_mime_type_equal (mime_types[n], non_match))
 301                 mime_types[n] = NULL;
 302             }
 303         }
 304     }
 305
 306   return NULL;
 307 }
 308
 309 static const char *
 310 cache_alias_lookup (const char *alias)
 311 {
 312   const char *ptr;
 313   int i, min, max, mid, cmp;
 314
 315   for (i = 0; _caches[i]; i++)
 316     {
 317       XdgMimeCache *cache = _caches[i];
 318       xdg_uint32_t list_offset = GET_UINT32 (cache->buffer, 4);
 319       xdg_uint32_t n_entries = GET_UINT32 (cache->buffer, list_offset);
 320       xdg_uint32_t offset;
 321
 322       min = 0;
 323       max = n_entries - 1;
 324       while (max >= min)
 325         {
 326           mid = (min + max) / 2;
 327
 328           offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * mid);
 329           ptr = cache->buffer + offset;
 330           cmp = strcmp (ptr, alias);
 331
 332           if (cmp < 0)
 333             min = mid + 1;
 334           else if (cmp > 0)
 335             max = mid - 1;
 336           else
 337             {
 338               offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * mid + 4);
 339               return cache->buffer + offset;
 340             }
 341         }
 342     }
 343
 344   return NULL;
 345 }
 346
 347 static int
 348 cache_glob_lookup_literal (const char *file_name,
 349                            const char *mime_types[],
 350                            int         n_mime_types)
 351 {
 352   const char *ptr;
 353   int i, min, max, mid, cmp;
 354
 355   for (i = 0; _caches[i]; i++)
 356     {
 357       XdgMimeCache *cache = _caches[i];
 358       xdg_uint32_t list_offset = GET_UINT32 (cache->buffer, 12);
 359       xdg_uint32_t n_entries = GET_UINT32 (cache->buffer, list_offset);
 360       xdg_uint32_t offset;
 361
 362       min = 0;
 363       max = n_entries - 1;
 364       while (max >= min)
 365         {
 366           mid = (min + max) / 2;
 367
 368           offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * mid);
 369           ptr = cache->buffer + offset;
 370           cmp = strcmp (ptr, file_name);
 371
 372           if (cmp < 0)
 373             min = mid + 1;
 374           else if (cmp > 0)
 375             max = mid - 1;
 376           else
 377             {
 378               offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * mid + 4);
 379               mime_types[0] = (const char *)(cache->buffer + offset);
 380
 381               return 1;
 382             }
 383         }
 384     }
 385
 386   return 0;
 387 }
 388
 389 static int
 390 cache_glob_lookup_fnmatch (const char *file_name,
 391                            const char *mime_types[],
 392                            int         n_mime_types)
 393 {
 394   const char *mime_type;
 395   const char *ptr;
 396
 397   int i, j, n;
 398
 399   n = 0;
 400   for (i = 0; _caches[i]; i++)
 401     {
 402       XdgMimeCache *cache = _caches[i];
 403
 404       xdg_uint32_t list_offset = GET_UINT32 (cache->buffer, 20);
 405       xdg_uint32_t n_entries = GET_UINT32 (cache->buffer, list_offset);
 406
 407       for (j = 0; j < n_entries && n < n_mime_types; j++)
 408         {
 409           xdg_uint32_t offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * j);
 410           xdg_uint32_t mimetype_offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * j + 4);
 411           ptr = cache->buffer + offset;
 412           mime_type = cache->buffer + mimetype_offset;
 413
 414           /* FIXME: Not UTF-8 safe */
 415           if (fnmatch (ptr, file_name, 0) == 0)
 416             mime_types[n++] = mime_type;
 417         }
 418
 419       if (n > 0)
 420         return n;
 421     }
 422
 423   return 0;
 424 }
 425
 426 static int
 427 cache_glob_node_lookup_suffix (XdgMimeCache *cache,
 428                                xdg_uint32_t  n_entries,
 429                                xdg_uint32_t  offset,
 430                                const char   *suffix,
 431                                int           ignore_case,
 432                                const char   *mime_types[],
 433                                int           n_mime_types)
 434 {
 435   xdg_unichar_t character;
 436   xdg_unichar_t match_char;
 437   xdg_uint32_t mimetype_offset;
 438   xdg_uint32_t n_children;
 439   xdg_uint32_t child_offset;
 440
 441   int min, max, mid, n, i;
 442
 443   character = _xdg_utf8_to_ucs4 (suffix);
 444   if (ignore_case)
 445     character = _xdg_ucs4_to_lower (character);
 446
 447   min = 0;
 448   max = n_entries - 1;
 449   while (max >= min)
 450     {
 451       mid = (min + max) /  2;
 452
 453       match_char = GET_UINT32 (cache->buffer, offset + 16 * mid);
 454
 455       if (match_char < character)
 456         min = mid + 1;
 457       else if (match_char > character)
 458         max = mid - 1;
 459       else
 460         {
 461           suffix = _xdg_utf8_next_char (suffix);
 462           if (*suffix == '\0')
 463             {
 464               mimetype_offset = GET_UINT32 (cache->buffer, offset + 16 * mid + 4);
 465               n = 0;
 466               mime_types[n++] = cache->buffer + mimetype_offset;
 467
 468               n_children = GET_UINT32 (cache->buffer, offset + 16 * mid + 8);
 469               child_offset = GET_UINT32 (cache->buffer, offset + 16 * mid + 12);
 470               i = 0;
 471               while (n < n_mime_types && i < n_children)
 472                 {
 473                   match_char = GET_UINT32 (cache->buffer, child_offset + 16 * i);
 474                   mimetype_offset = GET_UINT32 (cache->buffer, offset + 16 * i + 4);
 475                   if (match_char != 0)
 476                     break;
 477
 478                   mime_types[n++] = cache->buffer + mimetype_offset;
 479                   i++;
 480                 }
 481
 482               return n;
 483             }
 484           else
 485             {
 486               n_children = GET_UINT32 (cache->buffer, offset + 16 * mid + 8);
 487               child_offset = GET_UINT32 (cache->buffer, offset + 16 * mid + 12);
 488
 489               return cache_glob_node_lookup_suffix (cache,
 490                                                     n_children, child_offset,
 491                                                     suffix, ignore_case,
 492                                                     mime_types,
 493                                                     n_mime_types);
 494             }
 495         }
 496     }
 497
 498   return 0;
 499 }
 500
 501 static int
 502 cache_glob_lookup_suffix (const char *suffix,
 503                           int         ignore_case,
 504                           const char *mime_types[],
 505                           int         n_mime_types)
 506 {
 507   int i, n;
 508
 509   for (i = 0; _caches[i]; i++)
 510     {
 511       XdgMimeCache *cache = _caches[i];
 512
 513       xdg_uint32_t list_offset = GET_UINT32 (cache->buffer, 16);
 514       xdg_uint32_t n_entries = GET_UINT32 (cache->buffer, list_offset);
 515       xdg_uint32_t offset = GET_UINT32 (cache->buffer, list_offset + 4);
 516
 517       n = cache_glob_node_lookup_suffix (cache,
 518                                          n_entries, offset,
 519                                          suffix, ignore_case,
 520                                          mime_types,
 521                                          n_mime_types);
 522       if (n > 0)
 523         return n;
 524     }
 525
 526   return 0;
 527 }
 528
 529 static void
 530 find_stopchars (char *stopchars)
 531 {
 532   int i, j, k, l;
 533
 534   k = 0;
 535   for (i = 0; _caches[i]; i++)
 536     {
 537       XdgMimeCache *cache = _caches[i];
 538
 539       xdg_uint32_t list_offset = GET_UINT32 (cache->buffer, 16);
 540       xdg_uint32_t n_entries = GET_UINT32 (cache->buffer, list_offset);
 541       xdg_uint32_t offset = GET_UINT32 (cache->buffer, list_offset + 4);
 542
 543       for (j = 0; j < n_entries; j++)
 544         {
 545           xdg_uint32_t match_char = GET_UINT32 (cache->buffer, offset);
 546
 547           if (match_char < 128)
 548             {
 549               for (l = 0; l < k; l++)
 550                 if (stopchars[l] == match_char)
 551                   break;
 552               if (l == k)
 553                 {
 554                   stopchars[k] = (char) match_char;
 555                   k++;
 556                 }
 557             }
 558
 559           offset += 16;
 560         }
 561     }
 562
 563   stopchars[k] = '\0';
 564 }
 565
 566 static int
 567 cache_glob_lookup_file_name (const char *file_name,
 568                              const char *mime_types[],
 569                              int         n_mime_types)
 570 {
 571   const char *ptr;
 572   char stopchars[128];
 573   int n;
 574
 575   assert (file_name != NULL);
 576
 577   /* First, check the literals */
 578   n = cache_glob_lookup_literal (file_name, mime_types, n_mime_types);
 579   if (n > 0)
 580     return n;
 581
 582   find_stopchars (stopchars);
 583
 584   /* Next, check suffixes */
 585   ptr = strpbrk (file_name, stopchars);
 586   while (ptr)
 587     {
 588       n = cache_glob_lookup_suffix (ptr, FALSE, mime_types, n_mime_types);
 589       if (n > 0)
 590         return n;
 591
 592       n = cache_glob_lookup_suffix (ptr, TRUE, mime_types, n_mime_types);
 593       if (n > 0)
 594         return n;
 595
 596       ptr = strpbrk (ptr + 1, stopchars);
 597     }
 598
 599   /* Last, try fnmatch */
 600   return cache_glob_lookup_fnmatch (file_name, mime_types, n_mime_types);
 601 }
 602
 603 int
 604 _xdg_mime_cache_get_max_buffer_extents (void)
 605 {
 606   xdg_uint32_t offset;
 607   xdg_uint32_t max_extent;
 608   int i;
 609
 610   max_extent = 0;
 611   for (i = 0; _caches[i]; i++)
 612     {
 613       XdgMimeCache *cache = _caches[i];
 614
 615       offset = GET_UINT32 (cache->buffer, 24);
 616       max_extent = MAX (max_extent, GET_UINT32 (cache->buffer, offset + 4));
 617     }
 618
 619   return max_extent;
 620 }
 621
 622 static const char *
 623 cache_get_mime_type_for_data (const void *data,
 624                               size_t      len,
 625                               const char *mime_types[],
 626                               int         n_mime_types)
 627 {
 628   const char *mime_type;
 629   int i, n, priority;
 630
 631   priority = 0;
 632   mime_type = NULL;
 633   for (i = 0; _caches[i]; i++)
 634     {
 635       XdgMimeCache *cache = _caches[i];
 636
 637       int prio;
 638       const char *match;
 639
 640       match = cache_magic_lookup_data (cache, data, len, &prio,
 641                                        mime_types, n_mime_types);
 642       if (prio > priority)
 643         {
 644           priority = prio;
 645           mime_type = match;
 646         }
 647     }
 648
 649   if (priority > 0)
 650     return mime_type;
 651
 652   for (n = 0; n < n_mime_types; n++)
 653     {
 654       if (mime_types[n])
 655         return mime_types[n];
 656     }
 657
 658   return XDG_MIME_TYPE_UNKNOWN;
 659 }
 660
 661 const char *
 662 _xdg_mime_cache_get_mime_type_for_data (const void *data,
 663                                         size_t      len)
 664 {
 665   return cache_get_mime_type_for_data (data, len, NULL, 0);
 666 }
 667
 668 const char *
 669 _xdg_mime_cache_get_mime_type_for_file (const char  *file_name,
 670                                         struct stat *statbuf)
 671 {
 672   const char *mime_type;
 673   const char *mime_types[2];
 674   FILE *file;
 675   unsigned char *data;
 676   int max_extent;
 677   int bytes_read;
 678   struct stat buf;
 679   const char *base_name;
 680   int n;
 681
 682   if (file_name == NULL)
 683     return NULL;
 684
 685   if (! _xdg_utf8_validate (file_name))
 686     return NULL;
 687
 688   base_name = _xdg_get_base_name (file_name);
 689   n = cache_glob_lookup_file_name (base_name, mime_types, 2);
 690
 691   if (n == 1)
 692     return mime_types[0];
 693
 694   if (!statbuf)
 695     {
 696       if (stat (file_name, &buf) != 0)
 697         return XDG_MIME_TYPE_UNKNOWN;
 698
 699       statbuf = &buf;
 700     }
 701
 702   if (!S_ISREG (statbuf->st_mode))
 703     return XDG_MIME_TYPE_UNKNOWN;
 704
 705   /* FIXME: Need to make sure that max_extent isn't totally broken.  This could
 706    * be large and need getting from a stream instead of just reading it all
 707    * in. */
 708   max_extent = _xdg_mime_cache_get_max_buffer_extents ();
 709   data = malloc (max_extent);
 710   if (data == NULL)
 711     return XDG_MIME_TYPE_UNKNOWN;
 712
 713   file = fopen (file_name, "r");
 714   if (file == NULL)
 715     {
 716       free (data);
 717       return XDG_MIME_TYPE_UNKNOWN;
 718     }
 719
 720   bytes_read = fread (data, 1, max_extent, file);
 721   if (ferror (file))
 722     {
 723       free (data);
 724       fclose (file);
 725       return XDG_MIME_TYPE_UNKNOWN;
 726     }
 727
 728   mime_type = cache_get_mime_type_for_data (data, bytes_read,
 729                                             mime_types, n);
 730
 731   free (data);
 732   fclose (file);
 733
 734   return mime_type;
 735 }
 736
 737 const char *
 738 _xdg_mime_cache_get_mime_type_from_file_name (const char *file_name)
 739 {
 740   const char *mime_type;
 741
 742   if (cache_glob_lookup_file_name (file_name, &mime_type, 1))
 743     return mime_type;
 744   else
 745     return XDG_MIME_TYPE_UNKNOWN;
 746 }
 747
 748 #if 1
 749 static int
 750 is_super_type (const char *mime)
 751 {
 752   int length;
 753   const char *type;
 754
 755   length = strlen (mime);
 756   type = &(mime[length - 2]);
 757
 758   if (strcmp (type, "/*") == 0)
 759     return 1;
 760
 761   return 0;
 762 }
 763 #endif
 764
 765 int
 766 _xdg_mime_cache_mime_type_subclass (const char *mime,
 767                                     const char *base)
 768 {
 769   const char *umime, *ubase;
 770
 771   int i, j, min, max, med, cmp;
 772
 773   umime = _xdg_mime_cache_unalias_mime_type (mime);
 774   ubase = _xdg_mime_cache_unalias_mime_type (base);
 775
 776   if (strcmp (umime, ubase) == 0)
 777     return 1;
 778
 779   /* We really want to handle text/ * in GtkFileFilter, so we just
 780    * turn on the supertype matching
 781    */
 782 #if 1
 783   /* Handle supertypes */
 784   if (is_super_type (ubase) &&
 785       xdg_mime_media_type_equal (umime, ubase))
 786     return 1;
 787 #endif
 788
 789   /*  Handle special cases text/plain and application/octet-stream */
 790   if (strcmp (ubase, "text/plain") == 0 &&
 791       strncmp (umime, "text/", 5) == 0)
 792     return 1;
 793
 794   if (strcmp (ubase, "application/octet-stream") == 0)
 795     return 1;
 796
 797   for (i = 0; _caches[i]; i++)
 798     {
 799       XdgMimeCache *cache = _caches[i];
 800
 801       xdg_uint32_t list_offset = GET_UINT32 (cache->buffer, 8);
 802       xdg_uint32_t n_entries = GET_UINT32 (cache->buffer, list_offset);
 803       xdg_uint32_t offset, n_parents, parent_offset;
 804
 805       min = 0;
 806       max = n_entries - 1;
 807       while (max >= min)
 808         {
 809           med = (min + max)/2;
 810
 811           offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * med);
 812           cmp = strcmp (cache->buffer + offset, umime);
 813           if (cmp < 0)
 814             min = med + 1;
 815           else if (cmp > 0)
 816             max = med - 1;
 817           else
 818             {
 819               offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * med + 4);
 820               n_parents = GET_UINT32 (cache->buffer, offset);
 821
 822               for (j = 0; j < n_parents; j++)
 823                 {
 824                   parent_offset = GET_UINT32 (cache->buffer, offset + 4 + 4 * j);
 825                   if (_xdg_mime_cache_mime_type_subclass (cache->buffer + parent_offset, ubase))
 826                     return 1;
 827                 }
 828
 829               break;
 830             }
 831         }
 832     }
 833
 834   return 0;
 835 }
 836
 837 const char *
 838 _xdg_mime_cache_unalias_mime_type (const char *mime)
 839 {
 840   const char *lookup;
 841
 842   lookup = cache_alias_lookup (mime);
 843
 844   if (lookup)
 845     return lookup;
 846
 847   return mime;
 848 }
 849
 850 char **
 851 _xdg_mime_cache_list_mime_parents (const char *mime)
 852 {
 853   int i, j, p;
 854   char *all_parents[128]; /* we'll stop at 128 */
 855   char **result;
 856
 857   p = 0;
 858   for (i = 0; _caches[i]; i++)
 859     {
 860       XdgMimeCache *cache = _caches[i];
 861
 862       xdg_uint32_t list_offset = GET_UINT32 (cache->buffer, 8);
 863       xdg_uint32_t n_entries = GET_UINT32 (cache->buffer, list_offset);
 864
 865       for (j = 0; j < n_entries; j++)
 866         {
 867           xdg_uint32_t mimetype_offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * i);
 868           xdg_uint32_t parents_offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * i + 4);
 869
 870           if (strcmp (cache->buffer + mimetype_offset, mime) == 0)
 871             {
 872               xdg_uint32_t n_parents = GET_UINT32 (cache->buffer, parents_offset);
 873
 874               for (j = 0; j < n_parents; j++)
 875                 all_parents[p++] = cache->buffer + parents_offset + 4 + 4 * j;
 876
 877               break;
 878             }
 879         }
 880     }
 881   all_parents[p++] = 0;
 882
 883   result = (char **) malloc (p * sizeof (char *));
 884   memcpy (result, all_parents, p * sizeof (char *));
 885
 886   return result;
 887 }
 888