dlfcn/dlvsym.c

   1 /* Look up a versioned symbol in a shared object loaded by `dlopen'.
   2    Copyright (C) 1995-2000, 2004 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 Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <dlfcn.h>
  21 #include <stddef.h>
  22
  23 #include <ldsodefs.h>
  24
  25 struct dlvsym_args
  26 {
  27   /* The arguments to dlvsym_doit.  */
  28   void *handle;
  29   const char *name;
  30   const char *version;
  31   void *who;
  32
  33   /* The return values of dlvsym_doit.  */
  34   void *sym;
  35 };
  36
  37
  38 static void
  39 dlvsym_doit (void *a)
  40 {
  41   struct dlvsym_args *args = (struct dlvsym_args *)a;
  42
  43   args->sym = _dl_vsym (args->handle, args->name, args->version, args->who);
  44 }
  45
  46 void *
  47 __dlvsym (void *handle, const char *name, const char *version_str)
  48 {
  49   struct dlvsym_args args;
  50
  51   args.handle = handle;
  52   args.name = name;
  53   args.who = RETURN_ADDRESS (0);
  54   args.version = version_str;
  55
  56   /* Protect against concurrent loads and unloads.  */
  57   __rtld_lock_lock_recursive (GL(dl_load_lock));
  58
  59   void *result = (_dlerror_run (dlvsym_doit, &args) ? NULL : args.sym);
  60
  61   __rtld_lock_unlock_recursive (GL(dl_load_lock));
  62
  63   return result;
  64 }
  65 weak_alias (__dlvsym, dlvsym)