elf/dl-close.c

   1 /* Close a shared object opened by `_dl_open'.
   2    Copyright (C) 1996-2001, 2002 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <assert.h>
  21 #include <dlfcn.h>
  22 #include <libintl.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <bits/libc-lock.h>
  27 #include <ldsodefs.h>
  28 #include <sys/types.h>
  29 #include <sys/mman.h>
  30
  31
  32 /* Type of the constructor functions.  */
  33 typedef void (*fini_t) (void);
  34
  35
  36 #ifdef USE_TLS
  37 /* Returns true we an non-empty was found.  */
  38 static bool
  39 remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp)
  40 {
  41   if (idx - disp >= listp->len)
  42     {
  43       /* There must be a next entry.  Otherwise would the index be wrong.  */
  44       assert (listp->next != NULL);
  45
  46       if (remove_slotinfo (idx, listp->next, disp + listp->len))
  47         return true;
  48
  49       /* No non-empty entry.  Search from the end of this elements
  50          slotinfo array.  */
  51       idx = disp + listp->len;
  52     }
  53   else
  54     {
  55       struct link_map *old_map = listp->slotinfo[idx - disp].map;
  56       assert (old_map != NULL);
  57
  58       /* Mark the entry as unused.  */
  59       listp->slotinfo[idx - disp].gen = GL(dl_tls_generation) + 1;
  60       listp->slotinfo[idx - disp].map = NULL;
  61
  62       /* If this is not the last currently used entry no need to look
  63          further.  */
  64       if (old_map->l_tls_modid != GL(dl_tls_max_dtv_idx))
  65         return true;
  66
  67       assert (old_map->l_tls_modid == GL(dl_tls_max_dtv_idx));
  68     }
  69
  70   while (idx - disp > disp == 0 ? 1 + GL(dl_tls_static_nelem) : 0)
  71     {
  72       --idx;
  73
  74       if (listp->slotinfo[idx - disp].map != NULL)
  75         {
  76           /* Found a new last used index.  */
  77           GL(dl_tls_max_dtv_idx) = idx;
  78           return true;
  79         }
  80     }
  81
  82   /* No non-entry in this list element.  */
  83   return false;
  84 }
  85 #endif
  86
  87
  88 void
  89 internal_function
  90 _dl_close (void *_map)
  91 {
  92   struct reldep_list
  93   {
  94     struct link_map **rellist;
  95     unsigned int nrellist;
  96     struct reldep_list *next;
  97   } *reldeps = NULL;
  98   struct link_map **list;
  99   struct link_map *map = _map;
 100   unsigned int i;
 101   unsigned int *new_opencount;
 102 #ifdef USE_TLS
 103   bool any_tls = false;
 104 #endif
 105
 106   /* First see whether we can remove the object at all.  */
 107   if (__builtin_expect (map->l_flags_1 & DF_1_NODELETE, 0)
 108       && map->l_init_called)
 109     /* Nope.  Do nothing.  */
 110     return;
 111
 112   if (__builtin_expect (map->l_opencount, 1) == 0)
 113     _dl_signal_error (0, map->l_name, NULL, N_("shared object not open"));
 114
 115   /* Acquire the lock.  */
 116   __libc_lock_lock_recursive (GL(dl_load_lock));
 117
 118   /* Decrement the reference count.  */
 119   if (map->l_opencount > 1 || map->l_type != lt_loaded)
 120     {
 121       /* There are still references to this object.  Do nothing more.  */
 122       if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_FILES, 0))
 123         _dl_debug_printf ("\nclosing file=%s; opencount == %u\n",
 124                           map->l_name, map->l_opencount);
 125
 126       /* One decrement the object itself, not the dependencies.  */
 127       --map->l_opencount;
 128
 129       __libc_lock_unlock_recursive (GL(dl_load_lock));
 130       return;
 131     }
 132
 133   list = map->l_initfini;
 134
 135   /* Compute the new l_opencount values.  */
 136   i = map->l_searchlist.r_nlist;
 137   if (__builtin_expect (i == 0, 0))
 138     /* This can happen if we handle relocation dependencies for an
 139        object which wasn't loaded directly.  */
 140     for (i = 1; list[i] != NULL; ++i)
 141       ;
 142
 143   new_opencount = (unsigned int *) alloca (i * sizeof (unsigned int));
 144
 145   for (i = 0; list[i] != NULL; ++i)
 146     {
 147       list[i]->l_idx = i;
 148       new_opencount[i] = list[i]->l_opencount;
 149     }
 150   --new_opencount[0];
 151   for (i = 1; list[i] != NULL; ++i)
 152     if ((! (list[i]->l_flags_1 & DF_1_NODELETE) || ! list[i]->l_init_called)
 153         /* Decrement counter.  */
 154         && --new_opencount[i] == 0
 155         /* Test whether this object was also loaded directly.  */
 156         && list[i]->l_searchlist.r_list != NULL)
 157       {
 158         /* In this case we have the decrement all the dependencies of
 159            this object.  They are all in MAP's dependency list.  */
 160         unsigned int j;
 161         struct link_map **dep_list = list[i]->l_searchlist.r_list;
 162
 163         for (j = 1; j < list[i]->l_searchlist.r_nlist; ++j)
 164           if (! (dep_list[j]->l_flags_1 & DF_1_NODELETE)
 165               || ! dep_list[j]->l_init_called)
 166             {
 167               assert (dep_list[j]->l_idx < map->l_searchlist.r_nlist);
 168               --new_opencount[dep_list[j]->l_idx];
 169             }
 170       }
 171   assert (new_opencount[0] == 0);
 172
 173   /* Call all termination functions at once.  */
 174   for (i = 0; list[i] != NULL; ++i)
 175     {
 176       struct link_map *imap = list[i];
 177       if (new_opencount[i] == 0 && imap->l_type == lt_loaded
 178           && (imap->l_info[DT_FINI] || imap->l_info[DT_FINI_ARRAY])
 179           && (! (imap->l_flags_1 & DF_1_NODELETE) || ! imap->l_init_called)
 180           /* Skip any half-cooked objects that were never initialized.  */
 181           && imap->l_init_called)
 182         {
 183           /* When debugging print a message first.  */
 184           if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
 185             _dl_debug_printf ("\ncalling fini: %s\n\n", imap->l_name);
 186
 187           /* Call its termination function.  */
 188           if (imap->l_info[DT_FINI_ARRAY] != NULL)
 189             {
 190               ElfW(Addr) *array =
 191                 (ElfW(Addr) *) (imap->l_addr
 192                                 + imap->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
 193               unsigned int sz = (imap->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
 194                                  / sizeof (ElfW(Addr)));
 195               unsigned int cnt;
 196
 197               for (cnt = 0; cnt < sz; ++cnt)
 198                 ((fini_t) (imap->l_addr + array[cnt])) ();
 199             }
 200
 201           /* Next try the old-style destructor.  */
 202           if (imap->l_info[DT_FINI] != NULL)
 203             (*(void (*) (void)) DL_DT_FINI_ADDRESS
 204               (imap, (void *) imap->l_addr
 205                      + imap->l_info[DT_FINI]->d_un.d_ptr)) ();
 206         }
 207       else if (new_opencount[i] != 0 && imap->l_type == lt_loaded)
 208         {
 209           /* The object is still used.  But the object we are unloading
 210              right now is responsible for loading it and therefore we
 211              have the search list of the current object in its scope.
 212              Remove it.  */
 213           struct r_scope_elem **runp = imap->l_scope;
 214
 215           while (*runp != NULL)
 216             if (*runp == &map->l_searchlist)
 217               {
 218                 /* Copy all later elements.  */
 219                 while ((runp[0] = runp[1]) != NULL)
 220                   ++runp;
 221                 break;
 222               }
 223           else
 224             ++runp;
 225         }
 226
 227       /* Store the new l_opencount value.  */
 228       imap->l_opencount = new_opencount[i];
 229       /* Just a sanity check.  */
 230       assert (imap->l_type == lt_loaded || imap->l_opencount > 0);
 231     }
 232
 233   /* Notify the debugger we are about to remove some loaded objects.  */
 234   _r_debug.r_state = RT_DELETE;
 235   _dl_debug_state ();
 236
 237   /* Check each element of the search list to see if all references to
 238      it are gone.  */
 239   for (i = 0; list[i] != NULL; ++i)
 240     {
 241       struct link_map *imap = list[i];
 242       if (imap->l_opencount == 0 && imap->l_type == lt_loaded)
 243         {
 244           struct libname_list *lnp;
 245
 246           /* That was the last reference, and this was a dlopen-loaded
 247              object.  We can unmap it.  */
 248           if (__builtin_expect (imap->l_global, 0))
 249             {
 250               /* This object is in the global scope list.  Remove it.  */
 251               unsigned int cnt = GL(dl_main_searchlist)->r_nlist;
 252
 253               do
 254                 --cnt;
 255               while (GL(dl_main_searchlist)->r_list[cnt] != imap);
 256
 257               /* The object was already correctly registered.  */
 258               while (++cnt < GL(dl_main_searchlist)->r_nlist)
 259                 GL(dl_main_searchlist)->r_list[cnt - 1]
 260                   = GL(dl_main_searchlist)->r_list[cnt];
 261
 262               --GL(dl_main_searchlist)->r_nlist;
 263             }
 264
 265 #ifdef USE_TLS
 266           /* Remove the object from the dtv slotinfo array if it uses
 267              TLS.  */
 268           if (__builtin_expect (imap->l_tls_blocksize > 0, 0))
 269             {
 270               any_tls = true;
 271
 272               if (! remove_slotinfo (imap->l_tls_modid,
 273                                      GL(dl_tls_dtv_slotinfo_list), 0))
 274                 /* All dynamically loaded modules with TLS are unloaded.  */
 275                 GL(dl_tls_max_dtv_idx) = GL(dl_tls_static_nelem);
 276             }
 277 #endif
 278
 279           /* We can unmap all the maps at once.  We determined the
 280              start address and length when we loaded the object and
 281              the `munmap' call does the rest.  */
 282           DL_UNMAP (imap);
 283
 284           /* Finally, unlink the data structure and free it.  */
 285 #ifdef SHARED
 286           /* We will unlink the first object only if this is a statically
 287              linked program.  */
 288           assert (imap->l_prev != NULL);
 289           imap->l_prev->l_next = imap->l_next;
 290 #else
 291           if (imap->l_prev != NULL)
 292             imap->l_prev->l_next = imap->l_next;
 293           else
 294             GL(dl_loaded) = imap->l_next;
 295 #endif
 296           --GL(dl_nloaded);
 297           if (imap->l_next)
 298             imap->l_next->l_prev = imap->l_prev;
 299
 300           if (imap->l_versions != NULL)
 301             free (imap->l_versions);
 302           if (imap->l_origin != NULL && imap->l_origin != (char *) -1)
 303             free ((char *) imap->l_origin);
 304
 305           /* If the object has relocation dependencies save this
 306              information for latter.  */
 307           if (__builtin_expect (imap->l_reldeps != NULL, 0))
 308             {
 309               struct reldep_list *newrel;
 310
 311               newrel = (struct reldep_list *) alloca (sizeof (*reldeps));
 312               newrel->rellist = imap->l_reldeps;
 313               newrel->nrellist = imap->l_reldepsact;
 314               newrel->next = reldeps;
 315
 316               reldeps = newrel;
 317             }
 318
 319           /* This name always is allocated.  */
 320           free (imap->l_name);
 321           /* Remove the list with all the names of the shared object.  */
 322           lnp = imap->l_libname;
 323           do
 324             {
 325               struct libname_list *this = lnp;
 326               lnp = lnp->next;
 327               if (!this->dont_free)
 328                 free (this);
 329             }
 330           while (lnp != NULL);
 331
 332           /* Remove the searchlists.  */
 333           if (imap != map)
 334               free (imap->l_initfini);
 335
 336           /* Remove the scope array if we allocated it.  */
 337           if (imap->l_scope != imap->l_scope_mem)
 338             free (imap->l_scope);
 339
 340           if (imap->l_phdr_allocated)
 341             free ((void *) imap->l_phdr);
 342
 343           if (imap->l_rpath_dirs.dirs != (void *) -1)
 344             free (imap->l_rpath_dirs.dirs);
 345           if (imap->l_runpath_dirs.dirs != (void *) -1)
 346             free (imap->l_runpath_dirs.dirs);
 347
 348           free (imap);
 349         }
 350     }
 351
 352 #ifdef USE_TLS
 353   /* If we removed any object which uses TLS bumnp the generation
 354      counter.  */
 355   if (any_tls)
 356     if (__builtin_expect (++GL(dl_tls_generation) == 0, 0))
 357       __libc_fatal (gettext ("TLS generation counter wrapped!  Please send report with the 'glibcbug' script."));
 358 #endif
 359
 360   /* Notify the debugger those objects are finalized and gone.  */
 361   _r_debug.r_state = RT_CONSISTENT;
 362   _dl_debug_state ();
 363
 364   /* Now we can perhaps also remove the modules for which we had
 365      dependencies because of symbol lookup.  */
 366   while (__builtin_expect (reldeps != NULL, 0))
 367     {
 368       while (reldeps->nrellist-- > 0)
 369         _dl_close (reldeps->rellist[reldeps->nrellist]);
 370
 371       free (reldeps->rellist);
 372
 373       reldeps = reldeps->next;
 374     }
 375
 376   free (list);
 377
 378   /* Release the lock.  */
 379   __libc_lock_unlock_recursive (GL(dl_load_lock));
 380 }
 381
 382
 383 #ifdef USE_TLS
 384 static bool
 385 free_slotinfo (struct dtv_slotinfo_list *elemp)
 386 {
 387   size_t cnt;
 388
 389   if (elemp == NULL)
 390     /* Nothing here, all is removed (or there never was anything).  */
 391     return true;
 392
 393   if (!free_slotinfo (elemp->next))
 394     /* We cannot free the entry.  */
 395     return false;
 396
 397   /* The least we could do is remove next element (if there was any).  */
 398   elemp->next = NULL;
 399
 400   for (cnt = 0; cnt < elemp->len; ++cnt)
 401     if (elemp->slotinfo[cnt].map != NULL)
 402       /* Still used.  */
 403       return false;
 404
 405   /* We can remove the list element.  */
 406   free (elemp);
 407
 408   return true;
 409 }
 410 #endif
 411
 412
 413 static void
 414 free_mem (void)
 415 {
 416   if (__builtin_expect (GL(dl_global_scope_alloc), 0) != 0
 417       && GL(dl_main_searchlist)->r_nlist == GL(dl_initial_searchlist).r_nlist)
 418     {
 419       /* All object dynamically loaded by the program are unloaded.  Free
 420          the memory allocated for the global scope variable.  */
 421       struct link_map **old = GL(dl_main_searchlist)->r_list;
 422
 423       /* Put the old map in.  */
 424       GL(dl_main_searchlist)->r_list = GL(dl_initial_searchlist).r_list;
 425       /* Signal that the original map is used.  */
 426       GL(dl_global_scope_alloc) = 0;
 427
 428       /* Now free the old map.  */
 429       free (old);
 430     }
 431
 432 #ifdef USE_TLS
 433   /* Free the memory allocated for the dtv slotinfo array.  We can do
 434      this only if all modules which used this memory are unloaded.
 435      Also, the first element of the list does not have to be
 436      deallocated.  It was allocated in the dynamic linker (i.e., with
 437      a different malloc).  */
 438   if (free_slotinfo (GL(dl_tls_dtv_slotinfo_list)->next))
 439     GL(dl_tls_dtv_slotinfo_list)->next = NULL;
 440 #endif
 441 }
 442 text_set_element (__libc_subfreeres, free_mem);