elf/dl-close.c

   1 /* _dl_close -- Close a shared object opened by `_dl_open'.
   2 Copyright (C) 1996 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
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, USA.  */
  19
  20 #include <link.h>
  21 #include <dlfcn.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <sys/types.h>
  25 #include <sys/mman.h>
  26
  27
  28 #define LOSE(s) _dl_signal_error (0, map->l_name, s)
  29
  30 void
  31 _dl_close (struct link_map *map)
  32 {
  33   struct link_map **list;
  34   unsigned int i;
  35
  36   if (map->l_opencount == 0)
  37     LOSE ("shared object not open");
  38
  39   /* Decrement the reference count.  */
  40   if (--map->l_opencount > 0 || map->l_type != lt_loaded)
  41     /* There are still references to this object.  Do nothing more.  */
  42     return;
  43
  44   list = map->l_searchlist;
  45
  46   /* The search list contains a counted reference to each object it
  47      points to, the 0th elt being MAP itself.  Decrement the reference
  48      counts on all the objects MAP depends on.  */
  49   for (i = 1; i < map->l_nsearchlist; ++i)
  50     --list[i]->l_opencount;
  51
  52   /* Clear the search list so it doesn't get freed while we are still
  53      using it.  We have cached it in LIST and will free it when
  54      finished.  */
  55   map->l_searchlist = NULL;
  56
  57   /* Check each element of the search list to see if all references to
  58      it are gone.  */
  59   for (i = 0; i < map->l_nsearchlist; ++i)
  60     {
  61       struct link_map *map = list[i];
  62       if (map->l_opencount == 0 && map->l_type == lt_loaded)
  63         {
  64           /* That was the last reference, and this was a dlopen-loaded
  65              object.  We can unmap it.  */
  66           const ElfW(Phdr) *ph;
  67
  68           if (map->l_info[DT_FINI])
  69             /* Call its termination function.  */
  70             (*(void (*) (void)) ((void *) map->l_addr +
  71                                  map->l_info[DT_FINI]->d_un.d_ptr)) ();
  72
  73           if (map->l_global)
  74             {
  75               /* This object is in the global scope list.  Remove it.  */
  76               struct link_map **tail = _dl_global_scope_end;
  77               do
  78                 --tail;
  79               while (*tail != map);
  80               --_dl_global_scope_end;
  81               memcpy (tail, tail + 1, _dl_global_scope_end - tail);
  82               _dl_global_scope_end[0] = NULL;
  83               _dl_global_scope_end[1] = NULL;
  84             }
  85
  86           /* Unmap the segments.  */
  87           for (ph = map->l_phdr; ph < &map->l_phdr[map->l_phnum]; ++ph)
  88             if (ph->p_type == PT_LOAD)
  89               {
  90                 ElfW(Addr) mapstart = ph->p_vaddr & ~(ph->p_align - 1);
  91                 ElfW(Addr) mapend = ((ph->p_vaddr + ph->p_memsz
  92                                       + ph->p_align - 1)
  93                                      & ~(ph->p_align - 1));
  94                 __munmap ((caddr_t) mapstart, mapend - mapstart);
  95               }
  96
  97           /* Finally, unlink the data structure and free it.  */
  98           map->l_prev->l_next = map->l_next;
  99           if (map->l_next)
 100             map->l_next->l_prev = map->l_prev;
 101           if (map->l_searchlist)
 102             free (map->l_searchlist);
 103           free (map);
 104         }
 105     }
 106
 107   free (list);
 108 }