elf/dl-close.c

   1 /* _dl_close -- Close a shared object opened by `_dl_open'.
   2    Copyright (C) 1996, 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 <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 *imap = list[i];
  66       if (imap->l_opencount == 0 && imap->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           const ElfW(Phdr) *first, *last;
  72           ElfW(Addr) mapstart, mapend;
  73
  74           if (imap->l_info[DT_FINI])
  75             /* Call its termination function.  */
  76             (*(void (*) (void)) ((void *) imap->l_addr
  77                                  + imap->l_info[DT_FINI]->d_un.d_ptr)) ();
  78
  79           if (imap->l_global)
  80             {
  81               /* This object is in the global scope list.  Remove it.  */
  82               struct link_map **tail = _dl_global_scope_end;
  83               do
  84                 --tail;
  85               while (*tail != imap);
  86               --_dl_global_scope_end;
  87               memcpy (tail, tail + 1, _dl_global_scope_end - tail);
  88               _dl_global_scope_end[0] = NULL;
  89               _dl_global_scope_end[1] = NULL;
  90             }
  91
  92           /* We can unmap all the maps at once.  We just have to determine
  93              the length and the `munmap' call does the rest.  */
  94           first = last = NULL;
  95           for (ph = imap->l_phdr; ph < imap->l_phdr + imap->l_phnum; ++ph)
  96             if (ph->p_type == PT_LOAD)
  97               {
  98                 if (first == NULL)
  99                   first = ph;
 100                 last = ph;
 101               }
 102
 103           /* Now we have all the information we need for the unmapping.
 104              See the method used in `_dl_map_object_from_fd'.  */
 105           mapstart = first->p_vaddr & ~(first->p_align - 1);
 106           mapend = last->p_vaddr + last->p_memsz;
 107           __munmap ((caddr_t) (imap->l_addr + mapstart), mapend - mapstart);
 108
 109           /* Finally, unlink the data structure and free it.  */
 110           if (imap->l_prev)
 111             imap->l_prev->l_next = imap->l_next;
 112           if (imap->l_next)
 113             imap->l_next->l_prev = imap->l_prev;
 114           if (imap->l_searchlist)
 115             free (imap->l_searchlist);
 116           free (imap);
 117         }
 118     }
 119
 120   free (list);
 121
 122   /* Notify the debugger those objects are finalized and gone.  */
 123   _r_debug.r_state = RT_CONSISTENT;
 124   _dl_debug_state ();
 125 }