2 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
3 * 2000 Wim Taymans <wtay@chello.be>
5 * gstplugin.c: Plugin subsystem for loading elements, types, and libs
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Library General Public
9 * License as published by the Free Software Foundation; either
10 * version 2 of the License, or (at your option) any later version.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Library General Public License for more details.
17 * You should have received a copy of the GNU Library General Public
18 * License along with this library; if not, write to the
19 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 * Boston, MA 02111-1307, USA.
25 * @short_description: Container for features loaded from a shared object module
26 * @see_also: #GstPluginFeature, #GstElementFactory
28 * GStreamer is extensible, so #GstElement instances can be loaded at runtime.
29 * A plugin system can provide one or more of the basic
30 * <application>GStreamer</application> #GstPluginFeature subclasses.
32 * A plugin should export a symbol <symbol>gst_plugin_desc</symbol> that is a
33 * struct of type #GstPluginDesc.
34 * the plugin loader will check the version of the core library the plugin was
35 * linked against and will create a new #GstPlugin. It will then call the
36 * #GstPluginInitFunc function that was provided in the
37 * <symbol>gst_plugin_desc</symbol>.
39 * Once you have a handle to a #GstPlugin (e.g. from the #GstRegistryPool), you
40 * can add any object that subclasses #GstPluginFeature.
42 * Use gst_plugin_find_feature() and gst_plugin_get_feature_list() to find
43 * features in a plugin.
45 * Usually plugins are always automaticlly loaded so you don't need to call
46 * gst_plugin_load() explicitly to bring it into memory. There are options to
47 * statically link plugins to an app or even use GStreamer without a plugin
48 * repository in which case gst_plugin_load() can be needed to bring the plugin
55 #include <glib/gstdio.h>
56 #include <sys/types.h>
66 #include "gst_private.h"
70 #define GST_CAT_DEFAULT GST_CAT_PLUGIN_LOADING
72 static GList *_gst_plugin_static = NULL;
73 static gboolean _gst_plugin_inited;
75 /* static variables for segfault handling of plugin loading */
76 static char *_gst_plugin_fault_handler_filename = NULL;
79 static gboolean _gst_plugin_fault_handler_is_setup = FALSE;
82 /* list of valid licenses.
83 * One of these must be specified or the plugin won't be loaded
84 * Contact gstreamer-devel@lists.sourceforge.net if your license should be
87 * GPL: http://www.gnu.org/copyleft/gpl.html
88 * LGPL: http://www.gnu.org/copyleft/lesser.html
89 * QPL: http://www.trolltech.com/licenses/qpl.html
90 * MPL: http://www.opensource.org/licenses/mozilla1.1.php
91 * MIT/X11: http://www.opensource.org/licenses/mit-license.php
92 * 3-clause BSD: http://www.opensource.org/licenses/bsd-license.php
94 static const gchar *valid_licenses[] = {
95 "LGPL", /* GNU Lesser General Public License */
96 "GPL", /* GNU General Public License */
97 "QPL", /* Trolltech Qt Public License */
98 "GPL/QPL", /* Combi-license of GPL + QPL */
99 "MPL", /* MPL 1.1 license */
100 "BSD", /* 3-clause BSD license */
101 "MIT/X11", /* MIT/X11 license */
102 "Proprietary", /* Proprietary license */
103 GST_LICENSE_UNKNOWN, /* some other license */
107 static GstPlugin *gst_plugin_register_func (GstPlugin * plugin,
108 GstPluginDesc * desc);
109 static void gst_plugin_desc_copy (GstPluginDesc * dest,
110 const GstPluginDesc * src);
111 static void gst_plugin_desc_free (GstPluginDesc * desc);
114 G_DEFINE_TYPE (GstPlugin, gst_plugin, GST_TYPE_OBJECT);
117 gst_plugin_init (GstPlugin * plugin)
119 /* do nothing, needed because of G_DEFINE_TYPE */
123 gst_plugin_finalize (GObject * object)
125 GstPlugin *plugin = GST_PLUGIN_CAST (object);
126 GstRegistry *registry = gst_registry_get_default ();
129 GST_DEBUG ("finalizing plugin %p", plugin);
130 for (g = registry->plugins; g; g = g->next) {
131 if (g->data == (gpointer) plugin) {
132 g_warning ("removing plugin that is still in registry");
135 g_free (plugin->filename);
136 g_free (plugin->basename);
137 gst_plugin_desc_free (&plugin->desc);
139 G_OBJECT_CLASS (gst_plugin_parent_class)->finalize (object);
143 gst_plugin_class_init (GstPluginClass * klass)
145 G_OBJECT_CLASS (klass)->finalize = GST_DEBUG_FUNCPTR (gst_plugin_finalize);
149 gst_plugin_error_quark (void)
151 static GQuark quark = 0;
154 quark = g_quark_from_static_string ("gst_plugin_error");
158 /* this function can be called in the GCC constructor extension, before
159 * the _gst_plugin_initialize() was called. In that case, we store the
160 * plugin description in a list to initialize it when we open the main
162 * When the main module is known, we can register the plugin right away.
165 _gst_plugin_register_static (GstPluginDesc * desc)
167 if (!_gst_plugin_inited) {
169 GST_LOG ("queueing static plugin \"%s\" for loading later on",
171 _gst_plugin_static = g_list_prepend (_gst_plugin_static, desc);
176 GST_LOG ("attempting to load static plugin \"%s\" now...", desc->name);
177 plugin = g_object_new (GST_TYPE_PLUGIN, NULL);
178 if (gst_plugin_register_func (plugin, desc)) {
180 GST_INFO ("loaded static plugin \"%s\"", desc->name);
181 gst_default_registry_add_plugin (plugin);
187 _gst_plugin_initialize (void)
189 _gst_plugin_inited = TRUE;
191 /* now register all static plugins */
192 g_list_foreach (_gst_plugin_static, (GFunc) _gst_plugin_register_static,
196 /* this function could be extended to check if the plugin license matches the
197 * applications license (would require the app to register its license somehow).
198 * We'll wait for someone who's interested in it to code it :)
201 gst_plugin_check_license (const gchar * license)
203 const gchar **check_license = valid_licenses;
205 g_assert (check_license);
207 while (*check_license) {
208 if (strcmp (license, *check_license) == 0)
216 gst_plugin_check_version (gint major, gint minor)
218 /* return NULL if the major and minor version numbers are not compatible */
220 if (major != GST_VERSION_MAJOR || minor != GST_VERSION_MINOR)
227 gst_plugin_register_func (GstPlugin * plugin, GstPluginDesc * desc)
229 if (!gst_plugin_check_version (desc->major_version, desc->minor_version)) {
231 GST_WARNING ("plugin \"%s\" has incompatible version, not loading",
236 if (!desc->license || !desc->description || !desc->source ||
237 !desc->package || !desc->origin) {
239 GST_WARNING ("plugin \"%s\" has incorrect GstPluginDesc, not loading",
244 if (!gst_plugin_check_license (desc->license)) {
246 GST_WARNING ("plugin \"%s\" has invalid license \"%s\", not loading",
247 plugin->filename, desc->license);
252 GST_LOG ("plugin \"%s\" looks good", GST_STR_NULL (plugin->filename));
254 gst_plugin_desc_copy (&plugin->desc, desc);
256 if (!((desc->plugin_init) (plugin))) {
258 GST_WARNING ("plugin \"%s\" failed to initialise", plugin->filename);
259 plugin->module = NULL;
264 GST_LOG ("plugin \"%s\" initialised", GST_STR_NULL (plugin->filename));
269 #ifdef HAVE_SIGACTION
270 static struct sigaction oldaction;
273 * _gst_plugin_fault_handler_restore:
274 * segfault handler restorer
277 _gst_plugin_fault_handler_restore (void)
279 if (!_gst_plugin_fault_handler_is_setup)
282 _gst_plugin_fault_handler_is_setup = FALSE;
284 sigaction (SIGSEGV, &oldaction, NULL);
288 * _gst_plugin_fault_handler_sighandler:
289 * segfault handler implementation
292 _gst_plugin_fault_handler_sighandler (int signum)
294 /* We need to restore the fault handler or we'll keep getting it */
295 _gst_plugin_fault_handler_restore ();
299 g_print ("\nERROR: ");
300 g_print ("Caught a segmentation fault while loading plugin file:\n");
301 g_print ("%s\n\n", _gst_plugin_fault_handler_filename);
302 g_print ("Please either:\n");
303 g_print ("- remove it and restart.\n");
304 g_print ("- run with --gst-disable-segtrap and debug.\n");
308 g_print ("Caught unhandled signal on plugin loading\n");
314 * _gst_plugin_fault_handler_setup:
315 * sets up the segfault handler
318 _gst_plugin_fault_handler_setup (void)
320 struct sigaction action;
322 /* if asked to leave segfaults alone, just return */
323 if (!gst_segtrap_is_enabled ())
326 if (_gst_plugin_fault_handler_is_setup)
329 _gst_plugin_fault_handler_is_setup = TRUE;
331 memset (&action, 0, sizeof (action));
332 action.sa_handler = _gst_plugin_fault_handler_sighandler;
334 sigaction (SIGSEGV, &action, &oldaction);
338 _gst_plugin_fault_handler_restore (void)
343 _gst_plugin_fault_handler_setup (void)
348 static void _gst_plugin_fault_handler_setup ();
350 static GStaticMutex gst_plugin_loading_mutex = G_STATIC_MUTEX_INIT;
353 * gst_plugin_load_file:
354 * @filename: the plugin filename to load
355 * @error: pointer to a NULL-valued GError
357 * Loads the given plugin and refs it. Caller needs to unref after use.
359 * Returns: a reference to the existing loaded GstPlugin, a reference to the
360 * newly-loaded GstPlugin, or NULL if an error occurred.
363 gst_plugin_load_file (const gchar * filename, GError ** error)
369 struct stat file_status;
370 GstRegistry *registry;
372 g_return_val_if_fail (filename != NULL, NULL);
374 registry = gst_registry_get_default ();
375 g_static_mutex_lock (&gst_plugin_loading_mutex);
377 plugin = gst_registry_lookup (registry, filename);
379 if (plugin->module) {
380 g_static_mutex_unlock (&gst_plugin_loading_mutex);
383 gst_object_unref (plugin);
388 GST_CAT_DEBUG (GST_CAT_PLUGIN_LOADING, "attempt to load plugin \"%s\"",
391 if (g_module_supported () == FALSE) {
392 GST_CAT_DEBUG (GST_CAT_PLUGIN_LOADING, "module loading not supported");
395 GST_PLUGIN_ERROR_MODULE, "Dynamic loading not supported");
399 if (g_stat (filename, &file_status)) {
400 GST_CAT_DEBUG (GST_CAT_PLUGIN_LOADING, "problem accessing file");
403 GST_PLUGIN_ERROR_MODULE, "Problem accessing file %s: %s", filename,
408 module = g_module_open (filename, G_MODULE_BIND_LOCAL);
409 if (module == NULL) {
410 GST_CAT_WARNING (GST_CAT_PLUGIN_LOADING, "module_open failed: %s",
413 GST_PLUGIN_ERROR, GST_PLUGIN_ERROR_MODULE, "Opening module failed: %s",
415 /* If we failed to open the shared object, then it's probably because a
416 * plugin is linked against the wrong libraries. Print out an easy-to-see
417 * message in this case. */
418 g_warning ("Failed to load plugin '%s': %s", filename, g_module_error ());
422 plugin = g_object_new (GST_TYPE_PLUGIN, NULL);
424 plugin->module = module;
425 plugin->filename = g_strdup (filename);
426 plugin->basename = g_path_get_basename (filename);
427 plugin->file_mtime = file_status.st_mtime;
428 plugin->file_size = file_status.st_size;
430 ret = g_module_symbol (module, "gst_plugin_desc", &ptr);
432 GST_DEBUG ("Could not find plugin entry point in \"%s\"", filename);
435 GST_PLUGIN_ERROR_MODULE,
436 "File \"%s\" is not a GStreamer plugin", filename);
437 g_module_close (module);
440 plugin->orig_desc = (GstPluginDesc *) ptr;
442 GST_LOG ("Plugin %p for file \"%s\" prepared, calling entry function...",
445 /* this is where we load the actual .so, so let's trap SIGSEGV */
446 _gst_plugin_fault_handler_setup ();
447 _gst_plugin_fault_handler_filename = plugin->filename;
449 GST_LOG ("Plugin %p for file \"%s\" prepared, registering...",
452 if (!gst_plugin_register_func (plugin, plugin->orig_desc)) {
453 /* remove signal handler */
454 _gst_plugin_fault_handler_restore ();
455 GST_DEBUG ("gst_plugin_register_func failed for plugin \"%s\"", filename);
459 GST_PLUGIN_ERROR_MODULE,
460 "File \"%s\" appears to be a GStreamer plugin, but it failed to initialize",
462 g_module_close (module);
466 /* remove signal handler */
467 _gst_plugin_fault_handler_restore ();
468 _gst_plugin_fault_handler_filename = NULL;
469 GST_INFO ("plugin \"%s\" loaded", plugin->filename);
471 gst_object_ref (plugin);
472 gst_default_registry_add_plugin (plugin);
474 g_static_mutex_unlock (&gst_plugin_loading_mutex);
480 gst_object_unref (plugin);
481 g_static_mutex_unlock (&gst_plugin_loading_mutex);
487 gst_plugin_desc_copy (GstPluginDesc * dest, const GstPluginDesc * src)
489 dest->major_version = src->major_version;
490 dest->minor_version = src->minor_version;
491 dest->name = g_intern_string (src->name);
492 /* maybe intern the description too, just for convenience? */
493 dest->description = g_strdup (src->description);
494 dest->plugin_init = src->plugin_init;
495 dest->version = g_intern_string (src->version);
496 dest->license = g_intern_string (src->license);
497 dest->source = g_intern_string (src->source);
498 dest->package = g_intern_string (src->package);
499 dest->origin = g_intern_string (src->origin);
504 gst_plugin_desc_free (GstPluginDesc * desc)
506 g_free (desc->description);
507 memset (desc, 0, sizeof (GstPluginDesc));
511 * gst_plugin_get_name:
512 * @plugin: plugin to get the name of
514 * Get the short name of the plugin
516 * Returns: the name of the plugin
519 gst_plugin_get_name (GstPlugin * plugin)
521 g_return_val_if_fail (plugin != NULL, NULL);
523 return plugin->desc.name;
527 * gst_plugin_get_description:
528 * @plugin: plugin to get long name of
530 * Get the long descriptive name of the plugin
532 * Returns: the long name of the plugin
534 G_CONST_RETURN gchar *
535 gst_plugin_get_description (GstPlugin * plugin)
537 g_return_val_if_fail (plugin != NULL, NULL);
539 return plugin->desc.description;
543 * gst_plugin_get_filename:
544 * @plugin: plugin to get the filename of
546 * get the filename of the plugin
548 * Returns: the filename of the plugin
550 G_CONST_RETURN gchar *
551 gst_plugin_get_filename (GstPlugin * plugin)
553 g_return_val_if_fail (plugin != NULL, NULL);
555 return plugin->filename;
559 * gst_plugin_get_version:
560 * @plugin: plugin to get the version of
562 * get the version of the plugin
564 * Returns: the version of the plugin
566 G_CONST_RETURN gchar *
567 gst_plugin_get_version (GstPlugin * plugin)
569 g_return_val_if_fail (plugin != NULL, NULL);
571 return plugin->desc.version;
575 * gst_plugin_get_license:
576 * @plugin: plugin to get the license of
578 * get the license of the plugin
580 * Returns: the license of the plugin
582 G_CONST_RETURN gchar *
583 gst_plugin_get_license (GstPlugin * plugin)
585 g_return_val_if_fail (plugin != NULL, NULL);
587 return plugin->desc.license;
591 * gst_plugin_get_source:
592 * @plugin: plugin to get the source of
594 * get the source module the plugin belongs to.
596 * Returns: the source of the plugin
598 G_CONST_RETURN gchar *
599 gst_plugin_get_source (GstPlugin * plugin)
601 g_return_val_if_fail (plugin != NULL, NULL);
603 return plugin->desc.source;
607 * gst_plugin_get_package:
608 * @plugin: plugin to get the package of
610 * get the package the plugin belongs to.
612 * Returns: the package of the plugin
614 G_CONST_RETURN gchar *
615 gst_plugin_get_package (GstPlugin * plugin)
617 g_return_val_if_fail (plugin != NULL, NULL);
619 return plugin->desc.package;
623 * gst_plugin_get_origin:
624 * @plugin: plugin to get the origin of
626 * get the URL where the plugin comes from
628 * Returns: the origin of the plugin
630 G_CONST_RETURN gchar *
631 gst_plugin_get_origin (GstPlugin * plugin)
633 g_return_val_if_fail (plugin != NULL, NULL);
635 return plugin->desc.origin;
639 * gst_plugin_get_module:
640 * @plugin: plugin to query
642 * Gets the #GModule of the plugin. If the plugin isn't loaded yet, NULL is
645 * Returns: module belonging to the plugin or NULL if the plugin isn't
649 gst_plugin_get_module (GstPlugin * plugin)
651 g_return_val_if_fail (plugin != NULL, NULL);
653 return plugin->module;
657 * gst_plugin_is_loaded:
658 * @plugin: plugin to query
660 * queries if the plugin is loaded into memory
662 * Returns: TRUE is loaded, FALSE otherwise
665 gst_plugin_is_loaded (GstPlugin * plugin)
667 g_return_val_if_fail (plugin != NULL, FALSE);
669 return (plugin->module != NULL || plugin->filename == NULL);
674 * gst_plugin_feature_list:
675 * @plugin: plugin to query
676 * @filter: the filter to use
677 * @first: only return first match
678 * @user_data: user data passed to the filter function
680 * Runs a filter against all plugin features and returns a GList with
681 * the results. If the first flag is set, only the first match is
682 * returned (as a list with a single object).
684 * Returns: a GList of features, g_list_free after use.
687 gst_plugin_feature_filter (GstPlugin * plugin,
688 GstPluginFeatureFilter filter, gboolean first, gpointer user_data)
693 list = gst_filter_run (plugin->features, (GstFilterFunc) filter, first,
695 for (g = list; g; g = g->next) {
696 gst_object_ref (plugin);
704 GstPluginFeatureFilter filter;
712 _feature_filter (GstPlugin * plugin, gpointer user_data)
715 FeatureFilterData *data = (FeatureFilterData *) user_data;
717 result = gst_plugin_feature_filter (plugin, data->filter, data->first,
720 data->result = g_list_concat (data->result, result);
727 * gst_plugin_list_feature_filter:
728 * @list: a #GList of plugins to query
729 * @filter: the filter function to use
730 * @first: only return first match
731 * @user_data: user data passed to the filter function
733 * Runs a filter against all plugin features of the plugins in the given
734 * list and returns a GList with the results.
735 * If the first flag is set, only the first match is
736 * returned (as a list with a single object).
738 * Returns: a GList of features, g_list_free after use.
741 gst_plugin_list_feature_filter (GList * list,
742 GstPluginFeatureFilter filter, gboolean first, gpointer user_data)
744 FeatureFilterData data;
747 data.filter = filter;
749 data.user_data = user_data;
752 result = gst_filter_run (list, (GstFilterFunc) _feature_filter, first, &data);
753 g_list_free (result);
760 * gst_plugin_name_filter:
761 * @plugin: the plugin to check
762 * @name: the name of the plugin
764 * A standard filter that returns TRUE when the plugin is of the
767 * Returns: TRUE if the plugin is of the given name.
770 gst_plugin_name_filter (GstPlugin * plugin, const gchar * name)
772 return (plugin->desc.name && !strcmp (plugin->desc.name, name));
777 * gst_plugin_find_feature:
778 * @plugin: plugin to get the feature from
779 * @name: The name of the feature to find
780 * @type: The type of the feature to find
782 * Find a feature of the given name and type in the given plugin.
784 * Returns: a GstPluginFeature or NULL if the feature was not found.
787 gst_plugin_find_feature (GstPlugin * plugin, const gchar * name, GType type)
790 GstPluginFeature *result = NULL;
791 GstTypeNameData data;
793 g_return_val_if_fail (name != NULL, NULL);
798 walk = gst_filter_run (plugin->features,
799 (GstFilterFunc) gst_plugin_feature_type_name_filter, TRUE, &data);
802 result = GST_PLUGIN_FEATURE (walk->data);
804 gst_object_ref (result);
805 gst_plugin_feature_list_free (walk);
814 gst_plugin_feature_name_filter (GstPluginFeature * feature, const gchar * name)
816 return !strcmp (name, GST_PLUGIN_FEATURE_NAME (feature));
822 * gst_plugin_find_feature_by_name:
823 * @plugin: plugin to get the feature from
824 * @name: The name of the feature to find
826 * Find a feature of the given name in the given plugin.
828 * Returns: a GstPluginFeature or NULL if the feature was not found.
831 gst_plugin_find_feature_by_name (GstPlugin * plugin, const gchar * name)
834 GstPluginFeature *result = NULL;
836 g_return_val_if_fail (name != NULL, NULL);
838 walk = gst_filter_run (plugin->features,
839 (GstFilterFunc) gst_plugin_feature_name_filter, TRUE, (void *) name);
842 result = GST_PLUGIN_FEATURE (walk->data);
844 gst_object_ref (result);
845 gst_plugin_feature_list_free (walk);
853 * gst_plugin_load_by_name:
854 * @name: name of plugin to load
856 * Load the named plugin. Refs the plugin.
858 * Returns: A reference to a loaded plugin, or NULL on error.
861 gst_plugin_load_by_name (const gchar * name)
863 GstPlugin *plugin, *newplugin;
864 GError *error = NULL;
866 GST_DEBUG ("looking up plugin %s in default registry", name);
867 plugin = gst_registry_find_plugin (gst_registry_get_default (), name);
869 GST_DEBUG ("loading plugin %s from file %s", name, plugin->filename);
870 newplugin = gst_plugin_load_file (plugin->filename, &error);
871 gst_object_unref (plugin);
874 GST_WARNING ("load_plugin error: %s", error->message);
875 g_error_free (error);
878 /* newplugin was reffed by load_file */
882 GST_DEBUG ("Could not find plugin %s in registry", name);
888 * @plugin: plugin to load
890 * Loads @plugin. Note that the *return value* is the loaded plugin; @plugin is
891 * untouched. The normal use pattern of this function goes like this:
894 * GstPlugin *loaded_plugin;
895 * loaded_plugin = gst_plugin_load (plugin);
896 * // presumably, we're no longer interested in the potentially-unloaded plugin
897 * gst_object_unref (plugin);
898 * plugin = loaded_plugin;
901 * Returns: A reference to a loaded plugin, or NULL on error.
904 gst_plugin_load (GstPlugin * plugin)
906 GError *error = NULL;
907 GstPlugin *newplugin;
909 if (gst_plugin_is_loaded (plugin)) {
913 if (!(newplugin = gst_plugin_load_file (plugin->filename, &error)))
920 GST_WARNING ("load_plugin error: %s", error->message);
921 g_error_free (error);
927 * gst_plugin_list_free:
928 * @list: list of #GstPlugin
930 * Unrefs each member of @list, then frees the list.
933 gst_plugin_list_free (GList * list)
937 for (g = list; g; g = g->next) {
938 gst_object_unref (GST_PLUGIN_CAST (g->data));