iconv/gconv_cache.c

   1 /* Cache handling for iconv modules.
   2    Copyright (C) 2001-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 2001.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <dlfcn.h>
  21 #include <errno.h>
  22 #include <fcntl.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <sys/mman.h>
  27 #include <sys/stat.h>
  28
  29 #include <gconv_int.h>
  30 #include <iconvconfig.h>
  31 #include <not-cancel.h>
  32
  33 #include "../intl/hash-string.h"
  34
  35 static void *gconv_cache;
  36 static size_t cache_size;
  37 static int cache_malloced;
  38
  39
  40 void *
  41 __gconv_get_cache (void)
  42 {
  43   return gconv_cache;
  44 }
  45
  46
  47 int
  48 internal_function
  49 __gconv_load_cache (void)
  50 {
  51   int fd;
  52   struct stat64 st;
  53   struct gconvcache_header *header;
  54
  55   /* We cannot use the cache if the GCONV_PATH environment variable is
  56      set.  */
  57   __gconv_path_envvar = getenv ("GCONV_PATH");
  58   if (__gconv_path_envvar != NULL)
  59     return -1;
  60
  61   /* See whether the cache file exists.  */
  62   fd = __open_nocancel (GCONV_MODULES_CACHE, O_RDONLY, 0);
  63   if (__builtin_expect (fd, 0) == -1)
  64     /* Not available.  */
  65     return -1;
  66
  67   /* Get information about the file.  */
  68   if (__builtin_expect (__fxstat64 (_STAT_VER, fd, &st), 0) < 0
  69       /* We do not have to start looking at the file if it cannot contain
  70          at least the cache header.  */
  71       || (size_t) st.st_size < sizeof (struct gconvcache_header))
  72     {
  73     close_and_exit:
  74       __close_nocancel_nostatus (fd);
  75       return -1;
  76     }
  77
  78   /* Make the file content available.  */
  79   cache_size = st.st_size;
  80 #ifdef _POSIX_MAPPED_FILES
  81   gconv_cache = __mmap (NULL, cache_size, PROT_READ, MAP_SHARED, fd, 0);
  82   if (__glibc_unlikely (gconv_cache == MAP_FAILED))
  83 #endif
  84     {
  85       size_t already_read;
  86
  87       gconv_cache = malloc (cache_size);
  88       if (gconv_cache == NULL)
  89         goto close_and_exit;
  90
  91       already_read = 0;
  92       do
  93         {
  94           ssize_t n = __read (fd, (char *) gconv_cache + already_read,
  95                               cache_size - already_read);
  96           if (__builtin_expect (n, 0) == -1)
  97             {
  98               free (gconv_cache);
  99               gconv_cache = NULL;
 100               goto close_and_exit;
 101             }
 102
 103           already_read += n;
 104         }
 105       while (already_read < cache_size);
 106
 107       cache_malloced = 1;
 108     }
 109
 110   /* We don't need the file descriptor anymore.  */
 111   __close_nocancel_nostatus (fd);
 112
 113   /* Check the consistency.  */
 114   header = (struct gconvcache_header *) gconv_cache;
 115   if (__builtin_expect (header->magic, GCONVCACHE_MAGIC) != GCONVCACHE_MAGIC
 116       || __builtin_expect (header->string_offset >= cache_size, 0)
 117       || __builtin_expect (header->hash_offset >= cache_size, 0)
 118       || __builtin_expect (header->hash_size == 0, 0)
 119       || __builtin_expect ((header->hash_offset
 120                             + header->hash_size * sizeof (struct hash_entry))
 121                            > cache_size, 0)
 122       || __builtin_expect (header->module_offset >= cache_size, 0)
 123       || __builtin_expect (header->otherconv_offset > cache_size, 0))
 124     {
 125       if (cache_malloced)
 126         {
 127           free (gconv_cache);
 128           cache_malloced = 0;
 129         }
 130 #ifdef _POSIX_MAPPED_FILES
 131       else
 132         __munmap (gconv_cache, cache_size);
 133 #endif
 134       gconv_cache = NULL;
 135
 136       return -1;
 137     }
 138
 139   /* That worked.  */
 140   return 0;
 141 }
 142
 143
 144 static int
 145 internal_function
 146 find_module_idx (const char *str, size_t *idxp)
 147 {
 148   unsigned int idx;
 149   unsigned int hval;
 150   unsigned int hval2;
 151   const struct gconvcache_header *header;
 152   const char *strtab;
 153   const struct hash_entry *hashtab;
 154   unsigned int limit;
 155
 156   header = (const struct gconvcache_header *) gconv_cache;
 157   strtab = (char *) gconv_cache + header->string_offset;
 158   hashtab = (struct hash_entry *) ((char *) gconv_cache
 159                                    + header->hash_offset);
 160
 161   hval = __hash_string (str);
 162   idx = hval % header->hash_size;
 163   hval2 = 1 + hval % (header->hash_size - 2);
 164
 165   limit = cache_size - header->string_offset;
 166   while (hashtab[idx].string_offset != 0)
 167     if (hashtab[idx].string_offset < limit
 168         && strcmp (str, strtab + hashtab[idx].string_offset) == 0)
 169       {
 170         *idxp = hashtab[idx].module_idx;
 171         return 0;
 172       }
 173     else
 174       if ((idx += hval2) >= header->hash_size)
 175         idx -= header->hash_size;
 176
 177   /* Nothing found.  */
 178   return -1;
 179 }
 180
 181
 182 #ifndef STATIC_GCONV
 183 static int
 184 internal_function
 185 find_module (const char *directory, const char *filename,
 186              struct __gconv_step *result)
 187 {
 188   size_t dirlen = strlen (directory);
 189   size_t fnamelen = strlen (filename) + 1;
 190   char fullname[dirlen + fnamelen];
 191   int status = __GCONV_NOCONV;
 192
 193   memcpy (__mempcpy (fullname, directory, dirlen), filename, fnamelen);
 194
 195   result->__shlib_handle = __gconv_find_shlib (fullname);
 196   if (result->__shlib_handle != NULL)
 197     {
 198       status = __GCONV_OK;
 199
 200       result->__modname = NULL;
 201       result->__fct = result->__shlib_handle->fct;
 202       result->__init_fct = result->__shlib_handle->init_fct;
 203       result->__end_fct = result->__shlib_handle->end_fct;
 204
 205       /* These settings can be overridden by the init function.  */
 206       result->__btowc_fct = NULL;
 207       result->__data = NULL;
 208
 209       /* Call the init function.  */
 210       if (result->__init_fct != NULL)
 211         {
 212           __gconv_init_fct init_fct = result->__init_fct;
 213 #ifdef PTR_DEMANGLE
 214           PTR_DEMANGLE (init_fct);
 215 #endif
 216           status = DL_CALL_FCT (init_fct, (result));
 217
 218 #ifdef PTR_MANGLE
 219           if (result->__btowc_fct != NULL)
 220             PTR_MANGLE (result->__btowc_fct);
 221 #endif
 222         }
 223     }
 224
 225   return status;
 226 }
 227 #endif
 228
 229
 230 int
 231 internal_function
 232 __gconv_compare_alias_cache (const char *name1, const char *name2, int *result)
 233 {
 234   size_t name1_idx;
 235   size_t name2_idx;
 236
 237   if (gconv_cache == NULL)
 238     return -1;
 239
 240   if (find_module_idx (name1, &name1_idx) != 0
 241       || find_module_idx (name2, &name2_idx) != 0)
 242     *result = strcmp (name1, name2);
 243   else
 244     *result = (int) (name1_idx - name2_idx);
 245
 246   return 0;
 247 }
 248
 249
 250 int
 251 internal_function
 252 __gconv_lookup_cache (const char *toset, const char *fromset,
 253                       struct __gconv_step **handle, size_t *nsteps, int flags)
 254 {
 255   const struct gconvcache_header *header;
 256   const char *strtab;
 257   size_t fromidx;
 258   size_t toidx;
 259   const struct module_entry *modtab;
 260   const struct module_entry *from_module;
 261   const struct module_entry *to_module;
 262   struct __gconv_step *result;
 263
 264   if (gconv_cache == NULL)
 265     /* We have no cache available.  */
 266     return __GCONV_NODB;
 267
 268   header = (const struct gconvcache_header *) gconv_cache;
 269   strtab = (char *) gconv_cache + header->string_offset;
 270   modtab = (const struct module_entry *) ((char *) gconv_cache
 271                                           + header->module_offset);
 272
 273   if (find_module_idx (fromset, &fromidx) != 0
 274       || (header->module_offset + (fromidx + 1) * sizeof (struct module_entry)
 275           > cache_size))
 276     return __GCONV_NOCONV;
 277   from_module = &modtab[fromidx];
 278
 279   if (find_module_idx (toset, &toidx) != 0
 280       || (header->module_offset + (toidx + 1) * sizeof (struct module_entry)
 281           > cache_size))
 282     return __GCONV_NOCONV;
 283   to_module = &modtab[toidx];
 284
 285   /* Avoid copy-only transformations if the user requests.   */
 286   if (__builtin_expect (flags & GCONV_AVOID_NOCONV, 0) && fromidx == toidx)
 287     return __GCONV_NULCONV;
 288
 289   /* If there are special conversions available examine them first.  */
 290   if (fromidx != 0 && toidx != 0
 291       && __builtin_expect (from_module->extra_offset, 0) != 0)
 292     {
 293       /* Search through the list to see whether there is a module
 294          matching the destination character set.  */
 295       const struct extra_entry *extra;
 296
 297       /* Note the -1.  This is due to the offset added in iconvconfig.
 298          See there for more explanations.  */
 299       extra = (const struct extra_entry *) ((char *) gconv_cache
 300                                             + header->otherconv_offset
 301                                             + from_module->extra_offset - 1);
 302       while (extra->module_cnt != 0
 303              && extra->module[extra->module_cnt - 1].outname_offset != toidx)
 304         extra = (const struct extra_entry *) ((char *) extra
 305                                               + sizeof (struct extra_entry)
 306                                               + (extra->module_cnt
 307                                                  * sizeof (struct extra_entry_module)));
 308
 309       if (extra->module_cnt != 0)
 310         {
 311           /* Use the extra module.  First determine how many steps.  */
 312           char *fromname;
 313           int idx;
 314
 315           *nsteps = extra->module_cnt;
 316           *handle = result =
 317             (struct __gconv_step *) malloc (extra->module_cnt
 318                                             * sizeof (struct __gconv_step));
 319           if (result == NULL)
 320             return __GCONV_NOMEM;
 321
 322           fromname = (char *) strtab + from_module->canonname_offset;
 323           idx = 0;
 324           do
 325             {
 326               result[idx].__from_name = fromname;
 327               fromname = result[idx].__to_name =
 328                 (char *) strtab + modtab[extra->module[idx].outname_offset].canonname_offset;
 329
 330               result[idx].__counter = 1;
 331               result[idx].__data = NULL;
 332
 333 #ifndef STATIC_GCONV
 334               if (strtab[extra->module[idx].dir_offset] != '\0')
 335                 {
 336                   /* Load the module, return handle for it.  */
 337                   int res;
 338
 339                   res = find_module (strtab + extra->module[idx].dir_offset,
 340                                      strtab + extra->module[idx].name_offset,
 341                                      &result[idx]);
 342                   if (__builtin_expect (res, __GCONV_OK) != __GCONV_OK)
 343                     {
 344                       /* Something went wrong.  */
 345                       free (result);
 346                       goto try_internal;
 347                     }
 348                 }
 349               else
 350 #endif
 351                 /* It's a builtin transformation.  */
 352                 __gconv_get_builtin_trans (strtab
 353                                            + extra->module[idx].name_offset,
 354                                            &result[idx]);
 355
 356             }
 357           while (++idx < extra->module_cnt);
 358
 359           return __GCONV_OK;
 360         }
 361     }
 362
 363  try_internal:
 364   /* See whether we can convert via the INTERNAL charset.  */
 365   if ((fromidx != 0 && __builtin_expect (from_module->fromname_offset, 1) == 0)
 366       || (toidx != 0 && __builtin_expect (to_module->toname_offset, 1) == 0)
 367       || (fromidx == 0 && toidx == 0))
 368     /* Not possible.  Nothing we can do.  */
 369     return __GCONV_NOCONV;
 370
 371   /* We will use up to two modules.  Always allocate room for two.  */
 372   result = (struct __gconv_step *) malloc (2 * sizeof (struct __gconv_step));
 373   if (result == NULL)
 374     return __GCONV_NOMEM;
 375
 376   *handle = result;
 377   *nsteps = 0;
 378
 379   /* Generate data structure for conversion to INTERNAL.  */
 380   if (fromidx != 0)
 381     {
 382       result[0].__from_name = (char *) strtab + from_module->canonname_offset;
 383       result[0].__to_name = (char *) "INTERNAL";
 384
 385       result[0].__counter = 1;
 386       result[0].__data = NULL;
 387
 388 #ifndef STATIC_GCONV
 389       if (strtab[from_module->todir_offset] != '\0')
 390         {
 391           /* Load the module, return handle for it.  */
 392           int res = find_module (strtab + from_module->todir_offset,
 393                                  strtab + from_module->toname_offset,
 394                                  &result[0]);
 395           if (__builtin_expect (res, __GCONV_OK) != __GCONV_OK)
 396             {
 397               /* Something went wrong.  */
 398               free (result);
 399               return res;
 400             }
 401         }
 402       else
 403 #endif
 404         /* It's a builtin transformation.  */
 405         __gconv_get_builtin_trans (strtab + from_module->toname_offset,
 406                                    &result[0]);
 407
 408       ++*nsteps;
 409     }
 410
 411   /* Generate data structure for conversion from INTERNAL.  */
 412   if (toidx != 0)
 413     {
 414       int idx = *nsteps;
 415
 416       result[idx].__from_name = (char *) "INTERNAL";
 417       result[idx].__to_name = (char *) strtab + to_module->canonname_offset;
 418
 419       result[idx].__counter = 1;
 420       result[idx].__data = NULL;
 421
 422 #ifndef STATIC_GCONV
 423       if (strtab[to_module->fromdir_offset] != '\0')
 424         {
 425           /* Load the module, return handle for it.  */
 426           int res = find_module (strtab + to_module->fromdir_offset,
 427                                  strtab + to_module->fromname_offset,
 428                                  &result[idx]);
 429           if (__builtin_expect (res, __GCONV_OK) != __GCONV_OK)
 430             {
 431               /* Something went wrong.  */
 432               if (idx != 0)
 433                 __gconv_release_step (&result[0]);
 434               free (result);
 435               return res;
 436             }
 437         }
 438       else
 439 #endif
 440         /* It's a builtin transformation.  */
 441         __gconv_get_builtin_trans (strtab + to_module->fromname_offset,
 442                                    &result[idx]);
 443
 444       ++*nsteps;
 445     }
 446
 447   return __GCONV_OK;
 448 }
 449
 450
 451 /* Free memory allocated for the transformation record.  */
 452 void
 453 internal_function
 454 __gconv_release_cache (struct __gconv_step *steps, size_t nsteps)
 455 {
 456   if (gconv_cache != NULL)
 457     /* The only thing we have to deallocate is the record with the
 458        steps.  */
 459     free (steps);
 460 }
 461
 462
 463 /* Free all resources if necessary.  */
 464 libc_freeres_fn (free_mem)
 465 {
 466   if (cache_malloced)
 467     free (gconv_cache);
 468 #ifdef _POSIX_MAPPED_FILES
 469   else if (gconv_cache != NULL)
 470     __munmap (gconv_cache, cache_size);
 471 #endif
 472 }