elf/dl-version.c

   1 /* Handle symbol and library versioning.
   2    Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    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    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <elf.h>
  22 #include <errno.h>
  23 #include <libintl.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <ldsodefs.h>
  27 #include <stdio-common/_itoa.h>
  28
  29 #include <assert.h>
  30
  31
  32 #ifndef VERSYMIDX
  33 # define VERSYMIDX(tag) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (tag))
  34 #endif
  35
  36
  37 #define make_string(string, rest...) \
  38   ({                                                                          \
  39     const char *all[] = { string, ## rest };                                  \
  40     size_t len, cnt;                                                          \
  41     char *result, *cp;                                                        \
  42                                                                               \
  43     len = 1;                                                                  \
  44     for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt)                \
  45       len += strlen (all[cnt]);                                               \
  46                                                                               \
  47     cp = result = alloca (len);                                               \
  48     for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt)                \
  49       cp = __stpcpy (cp, all[cnt]);                                           \
  50                                                                               \
  51     result;                                                                   \
  52   })
  53
  54
  55 static inline struct link_map *
  56 find_needed (const char *name, struct link_map *map)
  57 {
  58   struct link_map *tmap;
  59   unsigned int n;
  60
  61   for (tmap = _dl_loaded; tmap != NULL; tmap = tmap->l_next)
  62     if (_dl_name_match_p (name, tmap))
  63       return tmap;
  64
  65   /* The required object is not in the global scope, look to see if it is
  66      a dependency of the current object.  */
  67   for (n = 0; n < map->l_searchlist.r_nlist; n++)
  68     if (_dl_name_match_p (name, map->l_searchlist.r_list[n]))
  69       return map->l_searchlist.r_list[n];
  70
  71   /* Should never happen.  */
  72   return NULL;
  73 }
  74
  75
  76 static int
  77 internal_function
  78 match_symbol (const char *name, ElfW(Word) hash, const char *string,
  79               struct link_map *map, int verbose, int weak)
  80 {
  81   const char *strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
  82   ElfW(Addr) def_offset;
  83   ElfW(Verdef) *def;
  84
  85   /* Display information about what we are doing while debugging.  */
  86   if (__builtin_expect (_dl_debug_versions, 0))
  87     _dl_debug_message (1, "checking for version `", string, "' in file ",
  88                        map->l_name[0] ? map->l_name : _dl_argv[0],
  89                        " required by file ", name, "\n", NULL);
  90
  91   if (__builtin_expect (map->l_info[VERSYMIDX (DT_VERDEF)] == NULL, 0))
  92     {
  93       /* The file has no symbol versioning.  I.e., the dependent
  94          object was linked against another version of this file.  We
  95          only print a message if verbose output is requested.  */
  96       if (verbose)
  97         /* XXX We cannot translate the messages.  */
  98         _dl_signal_cerror (0, map->l_name,
  99                            make_string ("\
 100 no version information available (required by ",
 101                                         name, ")"));
 102       return 0;
 103     }
 104
 105   def_offset = map->l_info[VERSYMIDX (DT_VERDEF)]->d_un.d_ptr;
 106   assert (def_offset != 0);
 107
 108   def = (ElfW(Verdef) *) ((char *) map->l_addr + def_offset);
 109   while (1)
 110     {
 111       /* Currently the version number of the definition entry is 1.
 112          Make sure all we see is this version.  */
 113       if (__builtin_expect (def->vd_version, 1) != 1)
 114         {
 115           char buf[20];
 116           buf[sizeof (buf) - 1] = '\0';
 117           /* XXX We cannot translate the message.  */
 118           _dl_signal_error (0, map->l_name,
 119                             make_string ("unsupported version ",
 120                                          _itoa_word (def->vd_version,
 121                                                      &buf[sizeof (buf) - 1],
 122                                                      10, 0),
 123                                          " of Verdef record"));
 124           return 1;
 125         }
 126
 127       /* Compare the hash values.  */
 128       if (hash == def->vd_hash)
 129         {
 130           ElfW(Verdaux) *aux = (ElfW(Verdaux) *) ((char *) def + def->vd_aux);
 131
 132           /* To be safe, compare the string as well.  */
 133           if (__builtin_expect (strcmp (string, strtab + aux->vda_name), 0)
 134               == 0)
 135             /* Bingo!  */
 136             return 0;
 137         }
 138
 139       /* If no more definitions we failed to find what we want.  */
 140       if (def->vd_next == 0)
 141         break;
 142
 143       /* Next definition.  */
 144       def = (ElfW(Verdef) *) ((char *) def + def->vd_next);
 145     }
 146
 147   /* Symbol not found.  If it was a weak reference it is not fatal.  */
 148   if (__builtin_expect (weak, 1))
 149     {
 150       if (verbose)
 151         /* XXX We cannot translate the message.  */
 152         _dl_signal_cerror (0, map->l_name,
 153                            make_string ("weak version `", string,
 154                                         "' not found (required by ", name,
 155                                         ")"));
 156       return 0;
 157     }
 158
 159   /* XXX We cannot translate the message.  */
 160   _dl_signal_cerror (0, map->l_name,
 161                      make_string ("version `", string,
 162                                   "' not found (required by ", name, ")"));
 163   return 1;
 164 }
 165
 166
 167 int
 168 internal_function
 169 _dl_check_map_versions (struct link_map *map, int verbose, int trace_mode)
 170 {
 171   int result = 0;
 172   const char *strtab;
 173   /* Pointer to section with needed versions.  */
 174   ElfW(Dyn) *dyn;
 175   /* Pointer to dynamic section with definitions.  */
 176   ElfW(Dyn) *def;
 177   /* We need to find out which is the highest version index used
 178     in a dependecy.  */
 179   unsigned int ndx_high = 0;
 180
 181   /* If we don't have a string table, we must be ok.  */
 182   if (map->l_info[DT_STRTAB] == NULL)
 183     return 0;
 184   strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
 185
 186   dyn = map->l_info[VERSYMIDX (DT_VERNEED)];
 187   def = map->l_info[VERSYMIDX (DT_VERDEF)];
 188
 189   if (dyn != NULL)
 190     {
 191       /* This file requires special versions from its dependencies.  */
 192       ElfW(Verneed) *ent = (ElfW(Verneed) *) (map->l_addr + dyn->d_un.d_ptr);
 193
 194       /* Currently the version number of the needed entry is 1.
 195          Make sure all we see is this version.  */
 196       if (__builtin_expect (ent->vn_version, 1) != 1)
 197         {
 198           char buf[20];
 199           buf[sizeof (buf) - 1] = '\0';
 200           /* XXX We cannot translate the message.  */
 201           _dl_signal_error (0, (*map->l_name ? map->l_name : _dl_argv[0]),
 202                             make_string ("unsupported version ",
 203                                          _itoa_word (ent->vn_version,
 204                                                      &buf[sizeof (buf) - 1],
 205                                                      10, 0),
 206                                          " of Verneed record\n"));
 207           return 1;
 208         }
 209
 210       while (1)
 211         {
 212           ElfW(Vernaux) *aux;
 213           struct link_map *needed = find_needed (strtab + ent->vn_file, map);
 214
 215           /* If NEEDED is NULL this means a dependency was not found
 216              and no stub entry was created.  This should never happen.  */
 217           assert (needed != NULL);
 218
 219           /* Make sure this is no stub we created because of a missing
 220              dependency.  */
 221           if (__builtin_expect (! trace_mode, 1)
 222               || ! __builtin_expect (needed->l_faked, 0))
 223             {
 224               /* NEEDED is the map for the file we need.  Now look for the
 225                  dependency symbols.  */
 226               aux = (ElfW(Vernaux) *) ((char *) ent + ent->vn_aux);
 227               while (1)
 228                 {
 229                   /* Match the symbol.  */
 230                   result |= match_symbol ((*map->l_name
 231                                            ? map->l_name : _dl_argv[0]),
 232                                           aux->vna_hash,
 233                                           strtab + aux->vna_name,
 234                                           needed, verbose,
 235                                           aux->vna_flags & VER_FLG_WEAK);
 236
 237                   /* Compare the version index.  */
 238                   if ((unsigned int) (aux->vna_other & 0x7fff) > ndx_high)
 239                     ndx_high = aux->vna_other & 0x7fff;
 240
 241                   if (aux->vna_next == 0)
 242                     /* No more symbols.  */
 243                     break;
 244
 245                   /* Next symbol.  */
 246                   aux = (ElfW(Vernaux) *) ((char *) aux + aux->vna_next);
 247                 }
 248             }
 249
 250           if (ent->vn_next == 0)
 251             /* No more dependencies.  */
 252             break;
 253
 254           /* Next dependency.  */
 255           ent = (ElfW(Verneed) *) ((char *) ent + ent->vn_next);
 256         }
 257     }
 258
 259   /* We also must store the names of the defined versions.  Determine
 260      the maximum index here as well.
 261
 262      XXX We could avoid the loop by just taking the number of definitions
 263      as an upper bound of new indeces.  */
 264   if (def != NULL)
 265     {
 266       ElfW(Verdef) *ent;
 267       ent = (ElfW(Verdef) *) (map->l_addr + def->d_un.d_ptr);
 268       while (1)
 269         {
 270           if ((unsigned int) (ent->vd_ndx & 0x7fff) > ndx_high)
 271             ndx_high = ent->vd_ndx & 0x7fff;
 272
 273           if (ent->vd_next == 0)
 274             /* No more definitions.  */
 275             break;
 276
 277           ent = (ElfW(Verdef) *) ((char *) ent + ent->vd_next);
 278         }
 279     }
 280
 281   if (ndx_high > 0)
 282     {
 283       /* Now we are ready to build the array with the version names
 284          which can be indexed by the version index in the VERSYM
 285          section.  */
 286       map->l_versions = (struct r_found_version *)
 287         calloc (ndx_high + 1, sizeof (*map->l_versions));
 288       if (__builtin_expect (map->l_versions == NULL, 0))
 289         {
 290           _dl_signal_error (ENOMEM, (*map->l_name ? map->l_name : _dl_argv[0]),
 291                             N_("cannot allocate version reference table"));
 292           result = 1;
 293         }
 294       else
 295         {
 296           /* Store the number of available symbols.  */
 297           map->l_nversions = ndx_high + 1;
 298
 299           /* Compute the pointer to the version symbols.  */
 300           map->l_versyms =
 301             (void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]);
 302
 303           if (dyn != NULL)
 304             {
 305               ElfW(Verneed) *ent;
 306               ent = (ElfW(Verneed) *) (map->l_addr + dyn->d_un.d_ptr);
 307               while (1)
 308                 {
 309                   ElfW(Vernaux) *aux;
 310                   aux = (ElfW(Vernaux) *) ((char *) ent + ent->vn_aux);
 311                   while (1)
 312                     {
 313                       ElfW(Half) ndx = aux->vna_other & 0x7fff;
 314                       map->l_versions[ndx].hash = aux->vna_hash;
 315                       map->l_versions[ndx].hidden = aux->vna_other & 0x8000;
 316                       map->l_versions[ndx].name = &strtab[aux->vna_name];
 317                       map->l_versions[ndx].filename = &strtab[ent->vn_file];
 318
 319                       if (aux->vna_next == 0)
 320                         /* No more symbols.  */
 321                         break;
 322
 323                       /* Advance to next symbol.  */
 324                       aux = (ElfW(Vernaux) *) ((char *) aux + aux->vna_next);
 325                     }
 326
 327                   if (ent->vn_next == 0)
 328                     /* No more dependencies.  */
 329                     break;
 330
 331                   /* Advance to next dependency.  */
 332                   ent = (ElfW(Verneed) *) ((char *) ent + ent->vn_next);
 333                 }
 334             }
 335
 336           /* And insert the defined versions.  */
 337           if (def != NULL)
 338             {
 339               ElfW(Verdef) *ent;
 340               ent = (ElfW(Verdef)  *) (map->l_addr + def->d_un.d_ptr);
 341               while (1)
 342                 {
 343                   ElfW(Verdaux) *aux;
 344                   aux = (ElfW(Verdaux) *) ((char *) ent + ent->vd_aux);
 345
 346                   if ((ent->vd_flags & VER_FLG_BASE) == 0)
 347                     {
 348                       /* The name of the base version should not be
 349                          available for matching a versioned symbol.  */
 350                       ElfW(Half) ndx = ent->vd_ndx & 0x7fff;
 351                       map->l_versions[ndx].hash = ent->vd_hash;
 352                       map->l_versions[ndx].name = &strtab[aux->vda_name];
 353                       map->l_versions[ndx].filename = NULL;
 354                     }
 355
 356                   if (ent->vd_next == 0)
 357                     /* No more definitions.  */
 358                     break;
 359
 360                   ent = (ElfW(Verdef) *) ((char *) ent + ent->vd_next);
 361                 }
 362             }
 363         }
 364     }
 365
 366   return result;
 367 }
 368
 369
 370 int
 371 internal_function
 372 _dl_check_all_versions (struct link_map *map, int verbose, int trace_mode)
 373 {
 374   struct link_map *l;
 375   int result = 0;
 376
 377   for (l = map; l != NULL; l = l->l_next)
 378     result |= ! l->l_faked && _dl_check_map_versions (l, verbose, trace_mode);
 379
 380   return result;
 381 }