src/posix/plugin.c

   1 /*****************************************************************************
   2  * plugin.c : Low-level dynamic library handling
   3  *****************************************************************************
   4  * Copyright (C) 2001-2007 VLC authors and VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Sam Hocevar <sam@zoy.org>
   8  *          Ethan C. Baldridge <BaldridgeE@cadmus.com>
   9  *          Hans-Peter Jansen <hpj@urpla.net>
  10  *          Gildas Bazin <gbazin@videolan.org>
  11  *
  12  * This program is free software; you can redistribute it and/or modify it
  13  * under the terms of the GNU Lesser General Public License as published by
  14  * the Free Software Foundation; either version 2.1 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  20  * GNU Lesser General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Lesser General Public License
  23  * along with this program; if not, write to the Free Software Foundation,
  24  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  25  *****************************************************************************/
  26
  27 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #include <vlc_common.h>
  32 #include "modules/modules.h"
  33
  34 #include <sys/types.h>
  35 #include <dlfcn.h>
  36
  37 #ifdef HAVE_VALGRIND_VALGRIND_H
  38 # include <valgrind/valgrind.h>
  39 #endif
  40
  41 /**
  42  * Load a dynamically linked library using a system dependent method.
  43  *
  44  * \param p_this vlc object
  45  * \param path library file
  46  * \param p_handle the module handle returned
  47  * \return 0 on success as well as the module handle.
  48  */
  49 int module_Load (vlc_object_t *p_this, const char *path,
  50                  module_handle_t *p_handle, bool lazy)
  51 {
  52 #if defined (RTLD_NOW)
  53     const int flags = lazy ? RTLD_LAZY : RTLD_NOW;
  54 #elif defined (DL_LAZY)
  55     const int flags = DL_LAZY;
  56 #else
  57     const int flags = 0;
  58 #endif
  59
  60     module_handle_t handle = dlopen (path, flags);
  61     if( handle == NULL )
  62     {
  63         msg_Warn( p_this, "cannot load module `%s' (%s)", path, dlerror() );
  64         return -1;
  65     }
  66     *p_handle = handle;
  67     return 0;
  68 }
  69
  70 /**
  71  * CloseModule: unload a dynamic library
  72  *
  73  * This function unloads a previously opened dynamically linked library
  74  * using a system dependent method. No return value is taken in consideration,
  75  * since some libraries sometimes refuse to close properly.
  76  * \param handle handle of the library
  77  * \return nothing
  78  */
  79 void module_Unload( module_handle_t handle )
  80 {
  81 #if !defined(__SANITIZE_ADDRESS__)
  82 #ifdef HAVE_VALGRIND_VALGRIND_H
  83     if( RUNNING_ON_VALGRIND > 0 )
  84         return; /* do not dlclose() so that we get proper stack traces */
  85 #endif
  86     dlclose( handle );
  87 #else
  88     (void) handle;
  89 #endif
  90 }
  91
  92 /**
  93  * Looks up a symbol from a dynamically loaded library
  94  *
  95  * This function queries a loaded library for a symbol specified in a
  96  * string, and returns a pointer to it. We don't check for dlerror() or
  97  * similar functions, since we want a non-NULL symbol anyway.
  98  *
  99  * @param handle handle to the module
 100  * @param psz_function function name
 101  * @return NULL on error, or the address of the symbol
 102  */
 103 void *module_Lookup( module_handle_t handle, const char *psz_function )
 104 {
 105     return dlsym( handle, psz_function );
 106 }