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   /* First see whether we can remove the object at all.  */
  52   if (map->l_flags_1 & DF_1_NODELETE)
  53     /* Nope.  Do nothing.  */
  54     return;
  55
  56   if (map->l_opencount == 0)
  57     _dl_signal_error (0, map->l_name, N_("shared object not open"));
  58
  59   /* Acquire the lock.  */
  60   __libc_lock_lock (_dl_load_lock);
  61
  62   /* Decrement the reference count.  */
  63   if (map->l_opencount > 1 || map->l_type != lt_loaded)
  64     {
  65       /* There are still references to this object.  Do nothing more.  */
  66       --map->l_opencount;
  67       __libc_lock_unlock (_dl_load_lock);
  68       return;
  69     }
  70
  71   list = map->l_searchlist.r_list;
  72   nsearchlist = map->l_searchlist.r_nlist;
  73
  74   rellist = map->l_reldeps;
  75   nrellist = map->l_reldepsact;
  76
  77   /* Call all termination functions at once.  */
  78   for (i = 0; i < nsearchlist; ++i)
  79     {
  80       struct link_map *imap = map->l_initfini[i];
  81       if (imap->l_opencount == 1 && imap->l_type == lt_loaded
  82           && (imap->l_info[DT_FINI] || imap->l_info[DT_FINI_ARRAY])
  83           /* Skip any half-cooked objects that were never initialized.  */
  84           && imap->l_init_called)
  85         {
  86           /* When debugging print a message first.  */
  87           if (__builtin_expect (_dl_debug_impcalls, 0))
  88             _dl_debug_message (1, "\ncalling fini: ", imap->l_name,
  89                                "\n\n", NULL);
  90
  91           /* Call its termination function.  */
  92           if (imap->l_info[DT_FINI_ARRAY] != NULL)
  93             {
  94               ElfW(Addr) *array =
  95                 (ElfW(Addr) *) (imap->l_addr
  96                                 + imap->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
  97               unsigned int sz = (imap->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
  98                                  / sizeof (ElfW(Addr)));
  99               unsigned int cnt;
 100
 101               for (cnt = 0; cnt < sz; ++cnt)
 102                 ((fini_t) (imap->l_addr + array[cnt])) ();
 103             }
 104
 105           /* Next try the old-style destructor.  */
 106           if (imap->l_info[DT_FINI] != NULL)
 107             (*(void (*) (void)) ((void *) imap->l_addr
 108                                  + imap->l_info[DT_FINI]->d_un.d_ptr)) ();
 109         }
 110     }
 111
 112   /* Notify the debugger we are about to remove some loaded objects.  */
 113   _r_debug.r_state = RT_DELETE;
 114   _dl_debug_state ();
 115
 116   /* The search list contains a counted reference to each object it
 117      points to, the 0th elt being MAP itself.  Decrement the reference
 118      counts on all the objects MAP depends on.  */
 119   for (i = 0; i < nsearchlist; ++i)
 120     if (! (list[i]->l_flags_1 & DF_1_NODELETE))
 121       --list[i]->l_opencount;
 122
 123   /* Check each element of the search list to see if all references to
 124      it are gone.  */
 125   for (i = 0; i < nsearchlist; ++i)
 126     {
 127       struct link_map *imap = list[i];
 128       if (imap->l_opencount == 0 && imap->l_type == lt_loaded)
 129         {
 130           struct libname_list *lnp;
 131
 132           /* That was the last reference, and this was a dlopen-loaded
 133              object.  We can unmap it.  */
 134           if (imap->l_global)
 135             {
 136               /* This object is in the global scope list.  Remove it.  */
 137               int cnt = _dl_main_searchlist->r_nlist;
 138
 139               do
 140                 --cnt;
 141               while (_dl_main_searchlist->r_list[cnt] != imap);
 142
 143               /* The object was already correctly registered.  */
 144               while (++cnt < _dl_main_searchlist->r_nlist)
 145                 _dl_main_searchlist->r_list[cnt - 1]
 146                   = _dl_main_searchlist->r_list[cnt];
 147
 148               --_dl_main_searchlist->r_nlist;
 149             }
 150
 151           /* We can unmap all the maps at once.  We determined the
 152              start address and length when we loaded the object and
 153              the `munmap' call does the rest.  */
 154           __munmap ((void *) imap->l_map_start,
 155                     imap->l_map_end - imap->l_map_start);
 156
 157           /* Finally, unlink the data structure and free it.  */
 158 #ifdef SHARED
 159           /* We will unlink the first object only if this is a statically
 160              linked program.  */
 161           assert (imap->l_prev != NULL);
 162           imap->l_prev->l_next = imap->l_next;
 163 #else
 164           if (imap->l_prev != NULL)
 165             imap->l_prev->l_next = imap->l_next;
 166           else
 167             _dl_loaded = imap->l_next;
 168 #endif
 169           if (imap->l_next)
 170             imap->l_next->l_prev = imap->l_prev;
 171
 172           if (imap->l_versions != NULL)
 173             free (imap->l_versions);
 174           if (imap->l_origin != NULL && imap->l_origin != (char *) -1)
 175             free ((char *) imap->l_origin);
 176
 177           /* This name always is allocated.  */
 178           free (imap->l_name);
 179           /* Remove the list with all the names of the shared object.  */
 180           lnp = imap->l_libname;
 181           do
 182             {
 183               struct libname_list *this = lnp;
 184               lnp = lnp->next;
 185               free (this);
 186             }
 187           while (lnp != NULL);
 188
 189           /* Remove the searchlists.  */
 190           if (imap != map)
 191             {
 192             if (imap->l_searchlist.r_list != NULL)
 193               free (imap->l_searchlist.r_list);
 194             else if (imap->l_initfini != NULL)
 195               free (imap->l_initfini);
 196             }
 197
 198           if (imap->l_phdr_allocated)
 199             free ((void *) imap->l_phdr);
 200
 201           free (imap);
 202         }
 203     }
 204
 205   /* Now we can perhaps also remove the modules for which we had
 206      dependencies because of symbol lookup.  */
 207   if (rellist != NULL)
 208     {
 209       while (nrellist-- > 0)
 210         _dl_close (rellist[nrellist]);
 211
 212       free (rellist);
 213     }
 214
 215   free (list);
 216
 217   if (_dl_global_scope_alloc != 0
 218       && _dl_main_searchlist->r_nlist == _dl_initial_searchlist.r_nlist)
 219     {
 220       /* All object dynamically loaded by the program are unloaded.  Free
 221          the memory allocated for the global scope variable.  */
 222       struct link_map **old = _dl_main_searchlist->r_list;
 223
 224       /* Put the old map in.  */
 225       _dl_main_searchlist->r_list = _dl_initial_searchlist.r_list;
 226       /* Signal that the original map is used.  */
 227       _dl_global_scope_alloc = 0;
 228
 229       /* Now free the old map.  */
 230       free (old);
 231     }
 232
 233   /* Notify the debugger those objects are finalized and gone.  */
 234   _r_debug.r_state = RT_CONSISTENT;
 235   _dl_debug_state ();
 236
 237   /* Release the lock.  */
 238   __libc_lock_unlock (_dl_load_lock);
 239 }