glibc/elf/dl-close.c

/* _dl_close -- Close a shared object opened by `_dl_open'.
Copyright (C) 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.

The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

#include <link.h>
#include <dlfcn.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/mman.h>


#define LOSE(s) _dl_signal_error (0, map->l_name, s)

void
_dl_close (struct link_map *map)
{
  struct link_map **list;
  unsigned int i;

  if (map->l_opencount == 0)
    LOSE ("shared object not open");

  /* Decrement the reference count.  */
  if (--map->l_opencount > 0 || map->l_type != lt_loaded)
    /* There are still references to this object.  Do nothing more.  */
    return;

  list = map->l_searchlist;

  /* The search list contains a counted reference to each object it
     points to, the 0th elt being MAP itself.  Decrement the reference
     counts on all the objects MAP depends on.  */
  for (i = 1; i < map->l_nsearchlist; ++i)
    --list[i]->l_opencount;

  /* Clear the search list so it doesn't get freed while we are still
     using it.  We have cached it in LIST and will free it when
     finished.  */
  map->l_searchlist = NULL;

  /* Check each element of the search list to see if all references to
     it are gone.  */
  for (i = 0; i < map->l_nsearchlist; ++i)
    {
      struct link_map *map = list[i];
      if (map->l_opencount == 0 && map->l_type == lt_loaded)
	{
	  /* That was the last reference, and this was a dlopen-loaded
	     object.  We can unmap it.  */
	  const ElfW(Phdr) *ph;

	  if (map->l_info[DT_FINI])
	    /* Call its termination function.  */
	    (*(void (*) (void)) ((void *) map->l_addr +
				 map->l_info[DT_FINI]->d_un.d_ptr)) ();

	  if (map->l_global)
	    {
	      /* This object is in the global scope list.  Remove it.  */
	      struct link_map **tail = _dl_global_scope_end;
	      do
		--tail;
	      while (*tail != map);
	      --_dl_global_scope_end;
	      memcpy (tail, tail + 1, _dl_global_scope_end - tail);
	      _dl_global_scope_end[0] = NULL;
	      _dl_global_scope_end[1] = NULL;
	    }

	  /* Unmap the segments.  */
	  for (ph = map->l_phdr; ph < &map->l_phdr[map->l_phnum]; ++ph)
	    if (ph->p_type == PT_LOAD)
	      {
		ElfW(Addr) mapstart = ph->p_vaddr & ~(ph->p_align - 1);
		ElfW(Addr) mapend = ((ph->p_vaddr + ph->p_memsz
				      + ph->p_align - 1)
				     & ~(ph->p_align - 1));
		__munmap ((caddr_t) mapstart, mapend - mapstart);
	      }

	  /* Finally, unlink the data structure and free it.  */
	  map->l_prev->l_next = map->l_next;
	  if (map->l_next)
	    map->l_next->l_prev = map->l_prev;
	  if (map->l_searchlist)
	    free (map->l_searchlist);
	  free (map);
	}
    }

  free (list);
}