elf/dl-close.c

   1 /* Close a shared object opened by `_dl_open'.
   2    Copyright (C) 1996, 1997, 1998, 1999, 2000 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 <libintl.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <bits/libc-lock.h>
  26 #include <ldsodefs.h>
  27 #include <sys/types.h>
  28 #include <sys/mman.h>
  29
  30
  31 /* Type of the constructor functions.  */
  32 typedef void (*fini_t) (void);
  33
  34
  35 /* During the program run we must not modify the global data of
  36    loaded shared object simultanously in two threads.  Therefore we
  37    protect `dlopen' and `dlclose' in dlclose.c.  */
  38 __libc_lock_define (extern, _dl_load_lock)
  39
  40 void
  41 internal_function
  42 _dl_close (void *_map)
  43 {
  44   struct link_map **list;
  45   struct link_map **rellist;
  46   struct link_map *map = _map;
  47   unsigned int nsearchlist;
  48   unsigned int nrellist;
  49   unsigned int i;
  50
  51   if (map->l_opencount == 0)
  52     _dl_signal_error (0, map->l_name, N_("shared object not open"));
  53
  54   /* Acquire the lock.  */
  55   __libc_lock_lock (_dl_load_lock);
  56
  57   /* Decrement the reference count.  */
  58   if (map->l_opencount > 1 || map->l_type != lt_loaded)
  59     {
  60       /* There are still references to this object.  Do nothing more.  */
  61       --map->l_opencount;
  62       __libc_lock_unlock (_dl_load_lock);
  63       return;
  64     }
  65
  66   list = map->l_searchlist.r_list;
  67   nsearchlist = map->l_searchlist.r_nlist;
  68
  69   rellist = map->l_reldeps;
  70   nrellist = map->l_reldepsact;
  71
  72   /* Call all termination functions at once.  */
  73   for (i = 0; i < nsearchlist; ++i)
  74     {
  75       struct link_map *imap = map->l_initfini[i];
  76       if (imap->l_opencount == 1 && imap->l_type == lt_loaded
  77           && (imap->l_info[DT_FINI] || imap->l_info[DT_FINI_ARRAY])
  78           /* Skip any half-cooked objects that were never initialized.  */
  79           && imap->l_init_called)
  80         {
  81           /* When debugging print a message first.  */
  82           if (__builtin_expect (_dl_debug_impcalls, 0))
  83             _dl_debug_message (1, "\ncalling fini: ", imap->l_name,
  84                                "\n\n", NULL);
  85
  86           /* Call its termination function.  */
  87           if (imap->l_info[DT_FINI_ARRAY] != NULL)
  88             {
  89               ElfW(Addr) *array =
  90                 (ElfW(Addr) *) (imap->l_addr
  91                                 + imap->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
  92               unsigned int sz = (imap->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
  93                                  / sizeof (ElfW(Addr)));
  94               unsigned int cnt;
  95
  96               for (cnt = 0; cnt < sz; ++cnt)
  97                 ((fini_t) (imap->l_addr + array[cnt])) ();
  98             }
  99
 100           /* Next try the old-style destructor.  */
 101           if (imap->l_info[DT_FINI] != NULL)
 102             (*(void (*) (void)) ((void *) imap->l_addr
 103                                  + imap->l_info[DT_FINI]->d_un.d_ptr)) ();
 104         }
 105     }
 106
 107   /* Notify the debugger we are about to remove some loaded objects.  */
 108   _r_debug.r_state = RT_DELETE;
 109   _dl_debug_state ();
 110
 111   /* The search list contains a counted reference to each object it
 112      points to, the 0th elt being MAP itself.  Decrement the reference
 113      counts on all the objects MAP depends on.  */
 114   for (i = 0; i < nsearchlist; ++i)
 115     --list[i]->l_opencount;
 116
 117   /* Check each element of the search list to see if all references to
 118      it are gone.  */
 119   for (i = 0; i < nsearchlist; ++i)
 120     {
 121       struct link_map *imap = list[i];
 122       if (imap->l_opencount == 0 && imap->l_type == lt_loaded)
 123         {
 124           struct libname_list *lnp;
 125
 126           /* That was the last reference, and this was a dlopen-loaded
 127              object.  We can unmap it.  */
 128           if (imap->l_global)
 129             {
 130               /* This object is in the global scope list.  Remove it.  */
 131               int cnt = _dl_main_searchlist->r_nlist;
 132
 133               do
 134                 --cnt;
 135               while (_dl_main_searchlist->r_list[cnt] != imap);
 136
 137               /* The object was already correctly registered.  */
 138               while (++cnt < _dl_main_searchlist->r_nlist)
 139                 _dl_main_searchlist->r_list[cnt - 1]
 140                   = _dl_main_searchlist->r_list[cnt];
 141
 142               --_dl_main_searchlist->r_nlist;
 143             }
 144
 145           /* We can unmap all the maps at once.  We determined the
 146              start address and length when we loaded the object and
 147              the `munmap' call does the rest.  */
 148           __munmap ((void *) imap->l_map_start,
 149                     imap->l_map_end - imap->l_map_start);
 150
 151           /* Finally, unlink the data structure and free it.  */
 152 #ifdef SHARED
 153           /* We will unlink the first object only if this is a statically
 154              linked program.  */
 155           assert (imap->l_prev != NULL);
 156           imap->l_prev->l_next = imap->l_next;
 157 #else
 158           if (imap->l_prev != NULL)
 159             imap->l_prev->l_next = imap->l_next;
 160           else
 161             _dl_loaded = imap->l_next;
 162 #endif
 163           if (imap->l_next)
 164             imap->l_next->l_prev = imap->l_prev;
 165
 166           if (imap->l_versions != NULL)
 167             free (imap->l_versions);
 168           if (imap->l_origin != NULL && imap->l_origin != (char *) -1)
 169             free ((char *) imap->l_origin);
 170
 171           /* This name always is allocated.  */
 172           free (imap->l_name);
 173           /* Remove the list with all the names of the shared object.  */
 174           lnp = imap->l_libname;
 175           do
 176             {
 177               struct libname_list *this = lnp;
 178               lnp = lnp->next;
 179               free (this);
 180             }
 181           while (lnp != NULL);
 182
 183           /* Remove the searchlists.  */
 184           if (imap != map)
 185             {
 186             if (imap->l_searchlist.r_list != NULL)
 187               free (imap->l_searchlist.r_list);
 188             else if (imap->l_initfini != NULL)
 189               free (imap->l_initfini);
 190             }
 191
 192           if (imap->l_phdr_allocated)
 193             free ((void *) imap->l_phdr);
 194
 195           free (imap);
 196         }
 197     }
 198
 199   /* Now we can perhaps also remove the modules for which we had
 200      dependencies because of symbol lookup.  */
 201   if (rellist != NULL)
 202     {
 203       while (nrellist-- > 0)
 204         _dl_close (rellist[nrellist]);
 205
 206       free (rellist);
 207     }
 208
 209   free (list);
 210
 211   if (_dl_global_scope_alloc != 0
 212       && _dl_main_searchlist->r_nlist == _dl_initial_searchlist.r_nlist)
 213     {
 214       /* All object dynamically loaded by the program are unloaded.  Free
 215          the memory allocated for the global scope variable.  */
 216       struct link_map **old = _dl_main_searchlist->r_list;
 217
 218       /* Put the old map in.  */
 219       _dl_main_searchlist->r_list = _dl_initial_searchlist.r_list;
 220       /* Signal that the original map is used.  */
 221       _dl_global_scope_alloc = 0;
 222
 223       /* Now free the old map.  */
 224       free (old);
 225     }
 226
 227   /* Notify the debugger those objects are finalized and gone.  */
 228   _r_debug.r_state = RT_CONSISTENT;
 229   _dl_debug_state ();
 230
 231   /* Release the lock.  */
 232   __libc_lock_unlock (_dl_load_lock);
 233 }