elf/dl-close.c

   1 /* Close a shared object opened by `_dl_open'.
   2    Copyright (C) 1996, 1997, 1998, 1999 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 Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <assert.h>
  21 #include <dlfcn.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <bits/libc-lock.h>
  25 #include <elf/ldsodefs.h>
  26 #include <sys/types.h>
  27 #include <sys/mman.h>
  28
  29
  30 /* During the program run we must not modify the global data of
  31    loaded shared object simultanously in two threads.  Therefore we
  32    protect `dlopen' and `dlclose' in dlclose.c.  */
  33 __libc_lock_define (extern, _dl_load_lock)
  34
  35 #define LOSE(s) _dl_signal_error (0, map->l_name, s)
  36
  37 void
  38 internal_function
  39 _dl_close (void *_map)
  40 {
  41   struct link_map **list;
  42   struct link_map *map = _map;
  43   unsigned nsearchlist;
  44   unsigned int i;
  45
  46   if (map->l_opencount == 0)
  47     LOSE ("shared object not open");
  48
  49   /* Acquire the lock.  */
  50   __libc_lock_lock (_dl_load_lock);
  51
  52   /* Decrement the reference count.  */
  53   if (map->l_opencount > 1 || map->l_type != lt_loaded)
  54     {
  55       /* There are still references to this object.  Do nothing more.  */
  56       --map->l_opencount;
  57       __libc_lock_unlock (_dl_load_lock);
  58       return;
  59     }
  60
  61   list = map->l_searchlist.r_list;
  62   nsearchlist = map->l_searchlist.r_nlist;
  63
  64   /* Call all termination functions at once.  */
  65   for (i = 0; i < nsearchlist; ++i)
  66     {
  67       struct link_map *imap = list[i];
  68       if (imap->l_opencount == 1 && imap->l_type == lt_loaded
  69           && imap->l_info[DT_FINI]
  70           /* Skip any half-cooked objects that were never initialized.  */
  71           && imap->l_init_called)
  72         {
  73           /* When debugging print a message first.  */
  74           if (_dl_debug_impcalls)
  75             _dl_debug_message (1, "\ncalling fini: ", imap->l_name,
  76                                "\n\n", NULL);
  77           /* Call its termination function.  */
  78           (*(void (*) (void)) ((void *) imap->l_addr
  79                                + imap->l_info[DT_FINI]->d_un.d_ptr)) ();
  80         }
  81     }
  82
  83   /* Notify the debugger we are about to remove some loaded objects.  */
  84   _r_debug.r_state = RT_DELETE;
  85   _dl_debug_state ();
  86
  87   /* The search list contains a counted reference to each object it
  88      points to, the 0th elt being MAP itself.  Decrement the reference
  89      counts on all the objects MAP depends on.  */
  90   for (i = 0; i < nsearchlist; ++i)
  91     --list[i]->l_opencount;
  92
  93   /* Check each element of the search list to see if all references to
  94      it are gone.  */
  95   for (i = 0; i < nsearchlist; ++i)
  96     {
  97       struct link_map *imap = list[i];
  98       if (imap->l_opencount == 0 && imap->l_type == lt_loaded)
  99         {
 100           struct libname_list *lnp;
 101
 102           /* That was the last reference, and this was a dlopen-loaded
 103              object.  We can unmap it.  */
 104           if (imap->l_global)
 105             {
 106               /* This object is in the global scope list.  Remove it.  */
 107               int cnt = _dl_main_searchlist->r_nlist;
 108
 109               do
 110                 --cnt;
 111               while (_dl_main_searchlist->r_list[cnt] != imap);
 112
 113               /* The object was already correctly registered.  */
 114               while (++cnt < _dl_main_searchlist->r_nlist)
 115                 _dl_main_searchlist->r_list[cnt - 1]
 116                   = _dl_main_searchlist->r_list[cnt];
 117
 118               --_dl_main_searchlist->r_nlist;
 119             }
 120
 121           /* We can unmap all the maps at once.  We determined the
 122              start address and length when we loaded the object and
 123              the `munmap' call does the rest.  */
 124           __munmap ((void *) imap->l_map_start,
 125                     imap->l_map_end - imap->l_map_start);
 126
 127           /* Finally, unlink the data structure and free it.  */
 128 #ifdef PIC
 129           /* We will unlink the first object only if this is a statically
 130              linked program.  */
 131           assert (imap->l_prev != NULL);
 132           imap->l_prev->l_next = imap->l_next;
 133 #else
 134           if (imap->l_prev != NULL)
 135             imap->l_prev->l_next = imap->l_next;
 136           else
 137             _dl_loaded = imap->l_next;
 138 #endif
 139           if (imap->l_next)
 140             imap->l_next->l_prev = imap->l_prev;
 141
 142           if (imap->l_versions != NULL)
 143             free (imap->l_versions);
 144           if (imap->l_origin != NULL && imap->l_origin != (char *) -1)
 145             free ((char *) imap->l_origin);
 146
 147           /* This name always is allocated.  */
 148           free (imap->l_name);
 149           /* Remove the list with all the names of the shared object.  */
 150           lnp = imap->l_libname;
 151           do
 152             {
 153               struct libname_list *this = lnp;
 154               lnp = lnp->next;
 155               free (this);
 156             }
 157           while (lnp != NULL);
 158
 159           /* Remove the searchlists.  */
 160           if (imap->l_searchlist.r_duplist != imap->l_searchlist.r_list)
 161             {
 162               /* If a r_list exists there always also is a r_duplist.  */
 163               assert (imap->l_searchlist.r_list != NULL);
 164               free (imap->l_searchlist.r_duplist);
 165             }
 166           if (imap != map && imap->l_searchlist.r_list != NULL)
 167             free (imap->l_searchlist.r_list);
 168
 169           if (imap->l_phdr_allocated)
 170             free ((void *) imap->l_phdr);
 171
 172           free (imap);
 173         }
 174     }
 175
 176   free (list);
 177
 178   if (_dl_global_scope_alloc != 0
 179       && _dl_main_searchlist->r_nlist == _dl_initial_searchlist.r_nlist)
 180     {
 181       /* All object dynamically loaded by the program are unloaded.  Free
 182          the memory allocated for the global scope variable.  */
 183       struct link_map **old = _dl_main_searchlist->r_list;
 184
 185       /* Put the old map in.  */
 186       _dl_main_searchlist->r_list = _dl_initial_searchlist.r_list;
 187       /* Signal that the original map is used.  */
 188       _dl_global_scope_alloc = 0;
 189
 190       /* Now free the old map.  */
 191       free (old);
 192     }
 193
 194   /* Notify the debugger those objects are finalized and gone.  */
 195   _r_debug.r_state = RT_CONSISTENT;
 196   _dl_debug_state ();
 197
 198   /* Release the lock.  */
 199   __libc_lock_unlock (_dl_load_lock);
 200 }