path: root/elf/dl-open.c

/* Load a shared object at runtime, relocate it, and run its initializer.
   Copyright (C) 1996, 1997, 1998, 1999, 2000 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., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <assert.h>
#include <dlfcn.h>
#include <errno.h>
#include <libintl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>		/* Check whether MAP_COPY is defined.  */
#include <sys/param.h>
#include <bits/libc-lock.h>
#include <ldsodefs.h>
#include <bp-sym.h>

#include <dl-dst.h>
#include <stdio-common/_itoa.h>


extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
				    void (*dl_main) (const ElfW(Phdr) *phdr,
						     ElfW(Word) phnum,
						     ElfW(Addr) *user_entry));
weak_extern (BP_SYM (_dl_sysdep_start))

/* This function is used to unload the cache file if necessary.  */
extern void _dl_unload_cache (void);

extern int __libc_multiple_libcs;	/* Defined in init-first.c.  */

extern int __libc_argc;
extern char **__libc_argv;

extern char **__environ;

extern int _dl_lazy;			/* Do we do lazy relocations?  */

/* Undefine the following for debugging.  */
/* #define SCOPE_DEBUG 1 */
#ifdef SCOPE_DEBUG
static void show_scope (struct link_map *new);
#endif

/* During the program run we must not modify the global data of
   loaded shared object simultanously in two threads.  Therefore we
   protect `_dl_open' and `_dl_close' in dl-close.c.

   This must be a recursive lock since the initializer function of
   the loaded object might as well require a call to this function.
   At this time it is not anymore a problem to modify the tables.  */
__libc_lock_define (extern, _dl_load_lock)

extern size_t _dl_platformlen;

/* We must be carefull not to leave us in an inconsistent state.  Thus we
   catch any error and re-raise it after cleaning up.  */

struct dl_open_args
{
  const char *file;
  int mode;
  const void *caller;
  struct link_map *map;
};

static void
dl_open_worker (void *a)
{
  struct dl_open_args *args = a;
  const char *file = args->file;
  int mode = args->mode;
  struct link_map *new, *l;
  const char *dst;
  int lazy;
  unsigned int i;

  /* Maybe we have to expand a DST.  */
  dst = strchr (file, '$');
  if (dst != NULL)
    {
      const void *caller = args->caller;
      size_t len = strlen (file);
      size_t required;
      struct link_map *call_map;
      char *new_file;

      /* DSTs must not appear in SUID/SGID programs.  */
      if (__libc_enable_secure)
	/* This is an error.  */
	_dl_signal_error (0, "dlopen",
			  N_("DST not allowed in SUID/SGID programs"));

      /* We have to find out from which object the caller is calling.
	 Find the highest-addressed object that ADDRESS is not below.  */
      call_map = NULL;
      for (l = _dl_loaded; l; l = l->l_next)
	if (l->l_addr != 0 /* Make sure we do not currently set this map up
			      in this moment.  */
	    && caller >= (const void *) l->l_map_start
	    && caller < (const void *) l->l_map_end)
	  {
	    /* There must be exactly one DSO for the range of the virtual
	       memory.  Otherwise something is really broken.  */
	    call_map = l;
	    break;
	  }

      if (call_map == NULL)
	/* In this case we assume this is the main application.  */
	call_map = _dl_loaded;

      /* Determine how much space we need.  We have to allocate the
	 memory locally.  */
      required = DL_DST_REQUIRED (call_map, file, len, _dl_dst_count (dst, 0));

      /* Get space for the new file name.  */
      new_file = (char *) alloca (required + 1);

      /* Generate the new file name.  */
      DL_DST_SUBSTITUTE (call_map, file, new_file, 0);

      /* If the substitution failed don't try to load.  */
      if (*new_file == '\0')
	_dl_signal_error (0, "dlopen",
			  N_("empty dynamic string token substitution"));

      /* Now we have a new file name.  */
      file = new_file;
    }

  /* Load the named object.  */
  args->map = new = _dl_map_object (NULL, file, 0, lt_loaded, 0,
				    mode);

  /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
     set and the object is not already loaded.  */
  if (new == NULL)
    {
      assert (mode & RTLD_NOLOAD);
      return;
    }

  if (new->l_searchlist.r_list)
    {
      /* Let the user know about the opencount.  */
      if (__builtin_expect (_dl_debug_files, 0))
	{
	  char buf[20];

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

	  _dl_debug_message (1, "opening file=", new->l_name,<