elf/dlsym.c

   1 /* dlsym -- Look up a symbol in a shared object loaded by `dlopen'.
   2 Copyright (C) 1995 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 <stddef.h>
  21 #include <link.h>
  22 #include <dlfcn.h>
  23 #include <setjmp.h>
  24
  25
  26 void *
  27 dlsym (void *handle, const char *name)
  28 {
  29   struct link_map *map = handle;
  30   struct link_map *real_next;
  31   Elf32_Addr loadbase;
  32   const Elf32_Sym *ref = NULL;
  33   int lose;
  34   void doit (void)
  35     {
  36       loadbase = _dl_lookup_symbol (name, &ref, map, map->l_name, 1);
  37     }
  38
  39   /* Confine the symbol scope to just this map.  */
  40   real_next = map->l_next;
  41   map->l_next = NULL;
  42   lose = _dlerror_run (doit);
  43   map->l_next = real_next;
  44
  45   return lose ? NULL : (void *) (loadbase + ref->st_value);
  46 }