elf/dl-close.c

   1 /* Close a shared object opened by `_dl_open'.
   2    Copyright (C) 1996, 1997, 1998 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 (struct link_map *map)
  40 {
  41   struct link_map **list;
  42   unsigned nsearchlist;
  43   unsigned int i;
  44
  45   if (map->l_opencount == 0)
  46     LOSE ("shared object not open");
  47
  48   /* Acquire the lock.  */
  49   __libc_lock_lock (_dl_load_lock);
  50
  51   /* Decrement the reference count.  */
  52   if (map->l_opencount > 1 || map->l_type != lt_loaded)
  53     {
  54       /* There are still references to this object.  Do nothing more.  */
  55       --map->l_opencount;
  56       __libc_lock_unlock (_dl_load_lock);
  57       return;
  58     }
  59
  60   list = map->l_searchlist.r_list;
  61   nsearchlist = map->l_searchlist.r_nlist;
  62
  63   /* Call all termination functions at once.  */
  64   for (i = 0; i < nsearchlist; ++i)
  65     {
  66       struct link_map *imap = list[i];
  67       if (imap->l_opencount == 1 && imap->l_type == lt_loaded
  68           && imap->l_info[DT_FINI]
  69           /* Skip any half-cooked objects that were never initialized.  */
  70           && imap->l_init_called)
  71         {
  72           /* When debugging print a message first.  */
  73           if (_dl_debug_impcalls)
  74             _dl_debug_message (1, "\ncalling fini: ", imap->l_name,
  75                                "\n\n", NULL);
  76           /* Call its termination function.  */
  77           (*(void (*) (void)) ((void *) imap->l_addr
  78                                + imap->l_info[DT_FINI]->d_un.d_ptr)) ();
  79         }
  80     }
  81
  82   /* Notify the debugger we are about to remove some loaded objects.  */
  83   _r_debug.r_state = RT_DELETE;
  84   _dl_debug_state ();
  85
  86   /* The search list contains a counted reference to each object it
  87      points to, the 0th elt being MAP itself.  Decrement the reference
  88      counts on all the objects MAP depends on.  */
  89   for (i = 0; i < nsearchlist; ++i)
  90     --list[i]->l_opencount;
  91
  92   /* Check each element of the search list to see if all references to
  93      it are gone.  */
  94   for (i = 0; i < nsearchlist; ++i)
  95     {
  96       struct link_map *imap = list[i];
  97       if (imap->l_opencount == 0 && imap->l_type == lt_loaded)
  98         {
  99           struct libname_list *lnp;
 100
 101           /* That was the last reference, and this was a dlopen-loaded
 102              object.  We can unmap it.  */
 103           if (imap->l_global)
 104             {
 105               /* This object is in the global scope list.  Remove it.  */
 106               unsigned int cnt = _dl_main_searchlist->r_nlist;
 107
 108               do
 109                 --cnt;
 110               while (_dl_main_searchlist->r_list[cnt] != imap);
 111               while (cnt < _dl_main_searchlist->r_nlist)
 112                 {
 113                   _dl_main_searchlist->r_list[0]
 114                     = _dl_main_searchlist->r_list[1];
 115                   ++cnt;
 116                 }
 117               --_dl_main_searchlist->r_nlist;
 118               if (_dl_main_searchlist->r_nlist
 119                   == _dl_initial_searchlist.r_nlist)
 120                 {
 121                   /* All object dynamically loaded by the program are
 122                      unloaded.  Free the memory allocated for the global
 123                      scope variable.  */
 124                   struct link_map **old = _dl_main_searchlist->r_list;
 125
 126                   /* Put the old map in.  */
 127                   _dl_main_searchlist->r_list = _dl_initial_searchlist.r_list;
 128                   /* Signal that the old map is used.  */
 129                   _dl_global_scope_alloc = 0;
 130
 131                   /* Now free the old map.  */
 132                   free (old);
 133                 }
 134             }
 135
 136           /* We can unmap all the maps at once.  We determined the
 137              start address and length when we loaded the object and
 138              the `munmap' call does the rest.  */
 139           __munmap ((void *) imap->l_map_start,
 140                     imap->l_map_end - imap->l_map_start);
 141
 142           /* Finally, unlink the data structure and free it.  */
 143 #ifdef PIC
 144           /* We will unlink the first object only if this is a statically
 145              linked program.  */
 146           assert (imap->l_prev != NULL);
 147           imap->l_prev->l_next = imap->l_next;
 148 #else
 149           if (imap->l_prev != NULL)
 150             imap->l_prev->l_next = imap->l_next;
 151           else
 152             _dl_loaded = imap->l_next;
 153 #endif
 154           if (imap->l_next)
 155             imap->l_next->l_prev = imap->l_prev;
 156
 157           if (imap->l_versions != NULL)
 158             free (imap->l_versions);
 159           if (imap->l_origin != NULL && imap->l_origin != (char *) -1)
 160             free ((char *) imap->l_origin);
 161
 162           /* This name always is allocated.  */
 163           free (imap->l_name);
 164           /* Remove the list with all the names of the shared object.  */
 165           lnp = imap->l_libname;
 166           do
 167             {
 168               struct libname_list *this = lnp;
 169               lnp = lnp->next;
 170               free (this);
 171             }
 172           while (lnp != NULL);
 173
 174           /* Remove the searchlists.  */
 175           if (imap->l_searchlist.r_duplist != imap->l_searchlist.r_list)
 176             {
 177               /* If a r_list exists there always also is a r_duplist.  */
 178               assert (imap->l_searchlist.r_list != NULL);
 179               free (imap->l_searchlist.r_duplist);
 180             }
 181           if (imap != map && imap->l_searchlist.r_list != NULL)
 182             free (imap->l_searchlist.r_list);
 183
 184           free (imap);
 185         }
 186     }
 187
 188   free (list);
 189
 190   /* Notify the debugger those objects are finalized and gone.  */
 191   _r_debug.r_state = RT_CONSISTENT;
 192   _dl_debug_state ();
 193
 194   /* Release the lock.  */
 195   __libc_lock_unlock (_dl_load_lock);
 196 }