glibc/elf/dl-close.c

/* Close a shared object opened by `_dl_open'.
   Copyright (C) 1996,1997,1998,1999,2000,2001 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 Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <assert.h>
#include <dlfcn.h>
#include <libintl.h>
#include <stdlib.h>
#include <string.h>
#include <bits/libc-lock.h>
#include <ldsodefs.h>
#include <sys/types.h>
#include <sys/mman.h>


/* Type of the constructor functions.  */
typedef void (*fini_t) (void);


/* During the program run we must not modify the global data of
   loaded shared object simultanously in two threads.  Therefore we
   protect `dlopen' and `dlclose' in dlclose.c.  */
__libc_lock_define (extern, _dl_load_lock)

void
internal_function
_dl_close (void *_map)
{
  struct reldep_list
  {
    struct link_map **rellist;
    unsigned int nrellist;
    struct reldep_list *next;
  } *reldeps = NULL;
  struct link_map **list;
  struct link_map *map = _map;
  unsigned int i;
  unsigned int *new_opencount;

  /* First see whether we can remove the object at all.  */
  if ((map->l_flags_1 & DF_1_NODELETE) && map->l_init_called)
    /* Nope.  Do nothing.  */
    return;

  if (__builtin_expect (map->l_opencount, 1) == 0)
    _dl_signal_error (0, map->l_name, N_("shared object not open"));

  /* Acquire the lock.  */
  __libc_lock_lock (_dl_load_lock);

  /* Decrement the reference count.  */
  if (map->l_opencount > 1 || map->l_type != lt_loaded)
    {
      /* There are still references to this object.  Do nothing more.  */
      if (__builtin_expect (_dl_debug_mask & DL_DEBUG_FILES, 0))
	{
	  char buf[20];

	  buf[sizeof buf - 1] = '\0';

	  _dl_debug_printf ("\nclosing file=%s; opencount == %u\n",
			    map->l_name, map->l_opencount);
	}

      /* One decrement the object itself, not the dependencies.  */
      --map->l_opencount;

      __libc_lock_unlock (_dl_load_lock);
      return;
    }

  list = map->l_initfini;

  /* Compute the new l_opencount values.  */
  new_opencount = (unsigned int *) alloca (map->l_searchlist.r_nlist
					   * sizeof (unsigned int));
  for (i = 0; list[i] != NULL; ++i)
    {
      list[i]->l_idx = i;
      new_opencount[i] = list[i]->l_opencount;
    }
  --new_opencount[0];
  for (i = 1; list[i] != NULL; ++i)
    if ((! (list[i]->l_flags_1 & DF_1_NODELETE) || ! list[i]->l_init_called)
	/* Decrement counter.  */
	&& --new_opencount[i] == 0
	/* Test whether this object was also loaded directly.  */
	&& list[i]->l_searchlist.r_list != NULL)
      {
	/* In this case we have the decrement all the dependencies of
           this object.  They are all in MAP's dependency list.  */
	unsigned int j;
	struct link_map **dep_list = list[i]->l_searchlist.r_list;

	for (j = 1; j < list[i]->l_searchlist.r_nlist; ++j)
	  if (! (dep_list[j]->l_flags_1 & DF_1_NODELETE)
	      || ! dep_list[j]->l_init_called)
	    {
	      assert (dep_list[j]->l_idx < map->l_searchlist.r_nlist);
	      --new_opencount[dep_list[j]->l_idx];
	    }
      }
  assert (new_opencount[0] == 0);

  /* Call all termination functions at once.  */
  for (i = 0; list[i] != NULL; ++i)
    {
      struct link_map *imap = list[i];
      if (new_opencount[i] == 0 && imap->l_type == lt_loaded
	  && (imap->l_info[DT_FINI] || imap->l_info[DT_FINI_ARRAY])
	  && (! (imap->l_flags_1 & DF_1_NODELETE) || ! imap->l_init_called)
	  /* Skip any half-cooked objects that were never initialized.  */
	  && imap->l_init_called)
	{
	  /* When debugging print a message first.  */
	  if (__builtin_expect (_dl_debug_mask & DL_DEBUG_IMPCALLS, 0))
	    _dl_debug_printf ("\ncalling fini: %s\n\n", imap->l_name);

	  /* Call its termination function.  */
	  if (imap->l_info[DT_FINI_ARRAY] != NULL)
	    {
	      ElfW(Addr) *array =
		(ElfW(Addr) *) (imap->l_addr
				+ imap->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
	      unsigned int sz = (imap->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
				 / sizeof (ElfW(Addr)));
	      unsigned int cnt;

	      for (cnt = 0; cnt < sz; ++cnt)
		((fini_t) (imap->l_addr + array[cnt])) ();
	    }

	  /* Next try the old-style destructor.  */
	  if (imap->l_info[DT_FINI] != NULL)
	    (*(void (*) (void)) DL_DT_FINI_ADDRESS
	      (imap, (void *) imap->l_addr
		     + imap->l_info[DT_FINI]->d_un.d_ptr)) ();
	}

      /* Store the new l_opencount value.  */
      imap->l_opencount = new_opencount[i];
      /* Just a sanity check.  */
      assert (imap->l_type == lt_loaded || imap->l_opencount > 0);
    }

  /* Notify the debugger we are about to remove some loaded objects.  */
  _r_debug.r_state = RT_DELETE;
  _dl_debug_state ();

  /* Check each element of the search list to see if all references to
     it are gone.  */
  for (i = 0; list[i] != NULL; ++i)
    {
      struct link_map *imap = list[i];
      if (imap->l_opencount == 0 && imap->l_type == lt_loaded)
	{
	  struct libname_list *lnp;

	  /* That was the last reference, and this was a dlopen-loaded
	     object.  We can unmap it.  */
	  if (__builtin_expect (imap->l_global, 0))
	    {
	      /* This object is in the global scope list.  Remove it.  */
	      unsigned int cnt = _dl_main_searchlist->r_nlist;

	      do
		--cnt;
	      while (_dl_main_searchlist->r_list[cnt] != imap);

	      /* The object was already correctly registered.  */
	      while (++cnt < _dl_main_searchlist->r_nlist)
		_dl_main_searchlist->r_list[cnt - 1]
		  = _dl_main_searchlist->r_list[cnt];

	      --_dl_main_searchlist->r_nlist;
	    }

	  /* We can unmap all the maps at once.  We determined the
	     start address and length when we loaded the object and
	     the `munmap' call does the rest.  */
	  DL_UNMAP (imap);

	  /* Finally, unlink the data structure and free it.  */
#ifdef SHARED
	  /* We will unlink the first object only if this is a statically
	     linked program.  */
	  assert (imap->l_prev != NULL);
	  imap->l_prev->l_next = imap->l_next;
#else
	  if (imap->l_prev != NULL)
	    imap->l_prev->l_next = imap->l_next;
	  else
	    _dl_loaded = imap->l_next;
#endif
	  --_dl_nloaded;
	  if (imap->l_next)
	    imap->l_next->l_prev = imap->l_prev;

	  if (imap->l_versions != NULL)
	    free (imap->l_versions);
	  if (imap->l_origin != NULL && imap->l_origin != (char *) -1)
	    free ((char *) imap->l_origin);

	  /* If the object has relocation dependencies save this
             information for latter.  */
	  if (__builtin_expect (imap->l_reldeps != NULL, 0))
	    {
	      struct reldep_list *newrel;

	      newrel = (struct reldep_list *) alloca (sizeof (*reldeps));
	      newrel->rellist = imap->l_reldeps;
	      newrel->nrellist = imap->l_reldepsact;
	      newrel->next = reldeps;

	      reldeps = newrel;
	    }

	  /* This name always is allocated.  */
	  free (imap->l_name);
	  /* Remove the list with all the names of the shared object.  */
	  lnp = imap->l_libname;
	  do
	    {
	      struct libname_list *this = lnp;
	      lnp = lnp->next;
	      free (this);
	    }
	  while (lnp != NULL);

	  /* Remove the searchlists.  */
	  if (imap != map)
	      free (imap->l_initfini);

	  if (imap->l_phdr_allocated)
	    free ((void *) imap->l_phdr);

	  if (imap->l_rpath_dirs.dirs != (void *) -1)
	    free (imap->l_rpath_dirs.dirs);
	  if (imap->l_runpath_dirs.dirs != (void *) -1)
	    free (imap->l_runpath_dirs.dirs);

	  free (imap);
	}
    }

  /* Notify the debugger those objects are finalized and gone.  */
  _r_debug.r_state = RT_CONSISTENT;
  _dl_debug_state ();

  /* Now we can perhaps also remove the modules for which we had
     dependencies because of symbol lookup.  */
  while (__builtin_expect (reldeps != NULL, 0))
    {
      while (reldeps->nrellist-- > 0)
	_dl_close (reldeps->rellist[reldeps->nrellist]);

      free (reldeps->rellist);

      reldeps = reldeps->next;
    }

  free (list);

  /* Release the lock.  */
  __libc_lock_unlock (_dl_load_lock);
}


static void
free_mem (void)
{
  if (__builtin_expect (_dl_global_scope_alloc, 0) != 0
      && _dl_main_searchlist->r_nlist == _dl_initial_searchlist.r_nlist)
    {
      /* All object dynamically loaded by the program are unloaded.  Free
	 the memory allocated for the global scope variable.  */
      struct link_map **old = _dl_main_searchlist->r_list;

      /* Put the old map in.  */
      _dl_main_searchlist->r_list = _dl_initial_searchlist.r_list;
      /* Signal that the original map is used.  */
      _dl_global_scope_alloc = 0;

      /* Now free the old map.  */
      free (old);
    }
}
text_set_element (__libc_subfreeres, free_mem);