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   /* Notify the debugger we are about to remove some loaded objects.  */
  45   _r_debug.r_state = RT_DELETE;
  46   _dl_debug_state ();
  47
  48   list = map->l_searchlist;
  49
  50   /* The search list contains a counted reference to each object it
  51      points to, the 0th elt being MAP itself.  Decrement the reference
  52      counts on all the objects MAP depends on.  */
  53   for (i = 1; i < map->l_nsearchlist; ++i)
  54     --list[i]->l_opencount;
  55
  56   /* Clear the search list so it doesn't get freed while we are still
  57      using it.  We have cached it in LIST and will free it when
  58      finished.  */
  59   map->l_searchlist = NULL;
  60
  61   /* Check each element of the search list to see if all references to
  62      it are gone.  */
  63   for (i = 0; i < map->l_nsearchlist; ++i)
  64     {
  65       struct link_map *map = list[i];
  66       if (map->l_opencount == 0 && map->l_type == lt_loaded)
  67         {
  68           /* That was the last reference, and this was a dlopen-loaded
  69              object.  We can unmap it.  */
  70           const ElfW(Phdr) *ph;
  71
  72           if (map->l_info[DT_FINI])
  73             /* Call its termination function.  */
  74             (*(void (*) (void)) ((void *) map->l_addr +
  75                                  map->l_info[DT_FINI]->d_un.d_ptr)) ();
  76
  77           if (map->l_global)
  78             {
  79               /* This object is in the global scope list.  Remove it.  */
  80               struct link_map **tail = _dl_global_scope_end;
  81               do
  82                 --tail;
  83               while (*tail != map);
  84               --_dl_global_scope_end;
  85               memcpy (tail, tail + 1, _dl_global_scope_end - tail);
  86               _dl_global_scope_end[0] = NULL;
  87               _dl_global_scope_end[1] = NULL;
  88             }
  89
  90           /* Unmap the segments.  */
  91           for (ph = map->l_phdr; ph < &map->l_phdr[map->l_phnum]; ++ph)
  92             if (ph->p_type == PT_LOAD)
  93               {
  94                 ElfW(Addr) mapstart = ph->p_vaddr & ~(ph->p_align - 1);
  95                 ElfW(Addr) mapend = ((ph->p_vaddr + ph->p_memsz
  96                                       + ph->p_align - 1)
  97                                      & ~(ph->p_align - 1));
  98                 __munmap ((caddr_t) mapstart, mapend - mapstart);
  99               }
 100
 101           /* Finally, unlink the data structure and free it.  */
 102           map->l_prev->l_next = map->l_next;
 103           if (map->l_next)
 104             map->l_next->l_prev = map->l_prev;
 105           if (map->l_searchlist)
 106             free (map->l_searchlist);
 107           free (map);
 108         }
 109     }
 110
 111   free (list);
 112
 113   /* Notify the debugger those objects are finalized and gone.  */
 114   _r_debug.r_state = RT_CONSISTENT;
 115   _dl_debug_state ();
 116 }