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 #if !defined SHARED && defined IS_IN_libdl
  26
  27 void *
  28 weak_function
  29 dlvsym (void *handle, const char *name, const char *version_str)
  30 {
  31   return __dlvsym (handle, name, version_str, RETURN_ADDRESS (0));
  32 }
  33
  34 #else
  35
  36 struct dlvsym_args
  37 {
  38   /* The arguments to dlvsym_doit.  */
  39   void *handle;
  40   const char *name;
  41   const char *version;
  42   void *who;
  43
  44   /* The return values of dlvsym_doit.  */
  45   void *sym;
  46 };
  47
  48
  49 static void
  50 dlvsym_doit (void *a)
  51 {
  52   struct dlvsym_args *args = (struct dlvsym_args *)a;
  53
  54   args->sym = _dl_vsym (args->handle, args->name, args->version, args->who);
  55 }
  56
  57 void *
  58 __dlvsym (void *handle, const char *name, const char *version_str
  59           DL_CALLER_DECL)
  60 {
  61 # ifdef SHARED
  62   if (__builtin_expect (_dlfcn_hook != NULL, 0))
  63     return _dlfcn_hook->dlvsym (handle, name, version_str, DL_CALLER);
  64 # endif
  65
  66   struct dlvsym_args args;
  67   args.handle = handle;
  68   args.name = name;
  69   args.who = DL_CALLER;
  70   args.version = version_str;
  71
  72   /* Protect against concurrent loads and unloads.  */
  73   __rtld_lock_lock_recursive (GL(dl_load_lock));
  74
  75   void *result = (_dlerror_run (dlvsym_doit, &args) ? NULL : args.sym);
  76
  77   __rtld_lock_unlock_recursive (GL(dl_load_lock));
  78
  79   return result;
  80 }
  81 # ifdef SHARED
  82 weak_alias (__dlvsym, dlvsym)
  83 # endif
  84 #endif