Use plugin descriptions, which start with the major and minor version numbers, instead of relying on each plugin to c...

Original commit message from CVS:
Use plugin descriptions, which start with the major and minor version
numbers, instead of relying on each plugin to call gst_plugin_new
appropriately, and check the return value, and tidy up if there's a
failure.  This seems to work fine, and factors out some code common to
all plugins.

examples/plugins/example.c

@@ -335,23 +335,17 @@ gst_example_get_arg (GtkObject *object,GtkArg *arg,guint id)
 /* This is the entry into the plugin itself.  When the plugin loads,
  * this function is called to register everything that the plugin provides.
  */
-GstPlugin*
-plugin_init (GModule *module)
+static gboolean
+plugin_init (GModule *module, GstPlugin *plugin)
 {
-  GstPlugin *plugin;
   GstElementFactory *factory;
 
-  /* First we try to create a new Plugin structure. */
-  plugin = gst_plugin_new("example", GST_VERSION_MAJOR, GST_VERSION_MINOR);
-  /* If we get a NULL back, chances are we're already loaded. */
-  g_return_val_if_fail(plugin != NULL, NULL);
-
   /* We need to create an ElementFactory for each element we provide.
    * This consists of the name of the element, the GtkType identifier,
    * and a pointer to the details structure at the top of the file.
    */
   factory = gst_elementfactory_new("example", GST_TYPE_EXAMPLE, &example_details);
-  g_return_val_if_fail(factory != NULL, NULL);
+  g_return_val_if_fail(factory != NULL, FALSE);
 
   /* The pad templates can be easily generated from the factories above,
    * and then added to the list of padtemplates for the elementfactory.
@@ -367,10 +361,27 @@ plugin_init (GModule *module)
   /* The very last thing is to register the elementfactory with the plugin. */
   gst_plugin_add_factory (plugin, factory);
 
-  /* Now we can return the pointer to the newly created Plugin object. */
-  return plugin;
+  /* Now we can return successfully. */
+  return TRUE;
 
   /* At this point, the GStreamer core registers the plugin, its
    * elementfactories, padtemplates, etc., for use in you application.
    */
 }
+
+/* This structure describes the plugin to the system for dynamically loading
+ * plugins, so that the version number and name can be checked in a uniform
+ * way.
+ *
+ * The symbol pointing to this structure is the only symbol looked up when
+ * loading the plugin.
+ */
+GstPluginDesc plugin_desc = {
+  GST_VERSION_MAJOR, /* The major version of the core that this was built with */
+  GST_VERSION_MINOR, /* The minor version of the core that this was built with */
+  "example",         /* The name of the plugin.  This must be unique: plugins with
+		      * the same name will be assumed to be identical, and only
+		      * one will be loaded. */
+  plugin_init        /* Pointer to the initialisation function for the plugin. */
+};
+

gst/autoplug/gststaticautoplug.c

@@ -80,15 +80,11 @@ gst_static_autoplug_class_init(GstStaticAutoplugClass *klass)
 static void gst_static_autoplug_init(GstStaticAutoplug *autoplug) {
 }
 
-GstPlugin*
-plugin_init (GModule *module)
+static gboolean
+plugin_init (GModule *module, GstPlugin *plugin)
 {
-  GstPlugin *plugin;
   GstAutoplugFactory *factory;
 
-  plugin = gst_plugin_new("gststaticautoplug", GST_VERSION_MAJOR, GST_VERSION_MINOR);
-  g_return_val_if_fail(plugin != NULL,NULL);
-
   gst_plugin_set_longname (plugin, "A static autoplugger");
 
   factory = gst_autoplugfactory_new ("static",
@@ -98,9 +94,16 @@ plugin_init (GModule *module)
   if (factory != NULL) {
      gst_plugin_add_autoplugger (plugin, factory);
   }
-  return plugin;
+  return TRUE;
 }
 
+GstPluginDesc plugin_desc = {
+  GST_VERSION_MAJOR,
+  GST_VERSION_MINOR,
+  "gststaticautoplug",
+  plugin_init
+};
+
 static gboolean
 gst_autoplug_can_match (GstElementFactory *src, GstElementFactory *dest)
 {

gst/autoplug/gststaticautoplugrender.c

@@ -80,15 +80,11 @@ gst_static_autoplug_render_class_init(GstStaticAutoplugRenderClass *klass)
 static void gst_static_autoplug_render_init(GstStaticAutoplugRender *autoplug) {
 }
 
-GstPlugin*
-plugin_init (GModule *module)
+static gboolean
+plugin_init (GModule *module, GstPlugin *plugin)
 {
-  GstPlugin *plugin;
   GstAutoplugFactory *factory;
 
-  plugin = gst_plugin_new("gststaticautoplugrender", GST_VERSION_MAJOR, GST_VERSION_MINOR);
-  g_return_val_if_fail(plugin != NULL,NULL);
-
   gst_plugin_set_longname (plugin, "A static autoplugger");
 
   factory = gst_autoplugfactory_new ("staticrender",
@@ -98,9 +94,16 @@ plugin_init (GModule *module)
   if (factory != NULL) {
      gst_plugin_add_autoplugger (plugin, factory);
   }
-  return plugin;
+  return TRUE;
 }
 
+GstPluginDesc plugin_desc = {
+  GST_VERSION_MAJOR,
+  GST_VERSION_MINOR,
+  "gststaticautoplugrender",
+  plugin_init
+};
+
 static gboolean
 gst_autoplug_can_match (GstElementFactory *src, GstElementFactory *dest)
 {

gst/elements/gstelements.c

@@ -67,15 +67,12 @@ static struct _elements_entry _elements[] = {
   { NULL, 0 },
 };
 
-GstPlugin *plugin_init (GModule *module)
+static gboolean
+plugin_init (GModule *module, GstPlugin *plugin)
 {
-  GstPlugin *plugin;
   GstElementFactory *factory;
   gint i = 0;
 
-  plugin = gst_plugin_new("gstelements", GST_VERSION_MAJOR, GST_VERSION_MINOR);
-  g_return_val_if_fail(plugin != NULL,NULL);
-
   gst_plugin_set_longname (plugin, "Standard GST Elements");
 
   while (_elements[i].name) {
@@ -94,5 +91,13 @@ GstPlugin *plugin_init (GModule *module)
 
 //  INFO (GST_INFO_PLUGIN_LOAD,"gstelements: loaded %d standard elements", i);
 
-  return plugin;
+  return TRUE;
 }
+
+GstPluginDesc plugin_desc = {
+  GST_VERSION_MAJOR,
+  GST_VERSION_MINOR,
+  "gstelements",
+  plugin_init
+};
+

gst/gstplugin.c

@@ -348,7 +348,7 @@ gboolean
 gst_plugin_load_absolute (const gchar *name)
 {
   GModule *module;
-  GstPluginInitFunc initfunc;
+  GstPluginDesc *desc;
   GstPlugin *plugin;
   struct stat file_status;
 
@@ -364,10 +364,19 @@ gst_plugin_load_absolute (const gchar *name)
 
   module = g_module_open(name,G_MODULE_BIND_LAZY);
   if (module != NULL) {
-    if (g_module_symbol(module,"plugin_init",(gpointer *)&initfunc)) {
-      GST_INFO (GST_CAT_PLUGIN_LOADING,"loading plugin \"%s\"...",
-           name);
-      if ((plugin = (initfunc)(module))) {
+    if (g_module_symbol(module,"plugin_desc",(gpointer *)&desc)) {
+      GST_INFO (GST_CAT_PLUGIN_LOADING,"loading plugin \"%s\"...", name);
+      plugin = gst_plugin_new(desc->name, desc->major_version, desc->minor_version);
+      if (plugin != NULL) {
+	if (!((desc->plugin_init)(module, plugin))) {
+          GST_INFO (GST_CAT_PLUGIN_LOADING,"plugin \"%s\" failed to initialise",
+             plugin->name);
+	  g_free(plugin);
+	  plugin = NULL;
+	}
+      }
+
+      if (plugin != NULL) {
         GST_INFO (GST_CAT_PLUGIN_LOADING,"plugin \"%s\" loaded: %d elements, %d types",
              plugin->name,plugin->numelements,plugin->numtypes);
         plugin->filename = g_strdup(name);

gst/gstplugin.h

@@ -40,7 +40,7 @@
 
 
 typedef struct _GstPlugin		GstPlugin;
-typedef struct _GstPluginElement	GstPluginElement;
+typedef struct _GstPluginDesc		GstPluginDesc;
 
 struct _GstPlugin {
   gchar *name;			/* name of the plugin */
@@ -57,8 +57,15 @@ struct _GstPlugin {
   gboolean loaded;              /* if the plugin is in memory */
 };
 
+/* Initialiser function: returns TRUE if plugin initialised successfully */
+typedef gboolean (*GstPluginInitFunc) (GModule *module, GstPlugin *plugin);
 
-typedef GstPlugin* (*GstPluginInitFunc) (GModule *module);
+struct _GstPluginDesc {
+  gint major_version; /* major version of core that plugin was compiled for */
+  gint minor_version; /* minor version of core that plugin was compiled for */
+  gchar *name;        /* name of plugin */
+  GstPluginInitFunc plugin_init; /* pointer to plugin_init function */
+};
 
 void			_gst_plugin_initialize		(void);
 

gst/types/gsttypes.c

@@ -28,15 +28,11 @@ GstTypeFactory _factories[] = {
 };
 
 
-GstPlugin*
-plugin_init (GModule *module) 
+static gboolean
+plugin_init (GModule *module, GstPlugin *plugin)
 {
-  GstPlugin *plugin;
   gint i = 0;
 
-  plugin = gst_plugin_new ("gsttypes", GST_VERSION_MAJOR, GST_VERSION_MINOR);
-  g_return_val_if_fail (plugin != NULL,NULL);
-
   while (_factories[i].mime) {
     gst_type_register (&_factories[i]);
     gst_plugin_add_type (plugin, &_factories[i]);
@@ -46,5 +42,12 @@ plugin_init (GModule *module)
 
   //gst_info ("gsttypes: loaded %d standard types\n",i);
 
-  return plugin;
+  return TRUE;
 }
+
+GstPluginDesc plugin_desc = {
+  GST_VERSION_MAJOR,
+  GST_VERSION_MINOR,
+  "gsttypes",
+  plugin_init
+};

plugins/elements/gstelements.c

@@ -67,15 +67,12 @@ static struct _elements_entry _elements[] = {
   { NULL, 0 },
 };
 
-GstPlugin *plugin_init (GModule *module)
+static gboolean
+plugin_init (GModule *module, GstPlugin *plugin)
 {
-  GstPlugin *plugin;
   GstElementFactory *factory;
   gint i = 0;
 
-  plugin = gst_plugin_new("gstelements", GST_VERSION_MAJOR, GST_VERSION_MINOR);
-  g_return_val_if_fail(plugin != NULL,NULL);
-
   gst_plugin_set_longname (plugin, "Standard GST Elements");
 
   while (_elements[i].name) {
@@ -94,5 +91,13 @@ GstPlugin *plugin_init (GModule *module)
 
 //  INFO (GST_INFO_PLUGIN_LOAD,"gstelements: loaded %d standard elements", i);
 
-  return plugin;
+  return TRUE;
 }
+
+GstPluginDesc plugin_desc = {
+  GST_VERSION_MAJOR,
+  GST_VERSION_MINOR,
+  "gstelements",
+  plugin_init
+};
+

tests/old/examples/plugins/example.c

@@ -335,23 +335,17 @@ gst_example_get_arg (GtkObject *object,GtkArg *arg,guint id)
 /* This is the entry into the plugin itself.  When the plugin loads,
  * this function is called to register everything that the plugin provides.
  */
-GstPlugin*
-plugin_init (GModule *module)
+static gboolean
+plugin_init (GModule *module, GstPlugin *plugin)
 {
-  GstPlugin *plugin;
   GstElementFactory *factory;
 
-  /* First we try to create a new Plugin structure. */
-  plugin = gst_plugin_new("example", GST_VERSION_MAJOR, GST_VERSION_MINOR);
-  /* If we get a NULL back, chances are we're already loaded. */
-  g_return_val_if_fail(plugin != NULL, NULL);
-
   /* We need to create an ElementFactory for each element we provide.
    * This consists of the name of the element, the GtkType identifier,
    * and a pointer to the details structure at the top of the file.
    */
   factory = gst_elementfactory_new("example", GST_TYPE_EXAMPLE, &example_details);
-  g_return_val_if_fail(factory != NULL, NULL);
+  g_return_val_if_fail(factory != NULL, FALSE);
 
   /* The pad templates can be easily generated from the factories above,
    * and then added to the list of padtemplates for the elementfactory.
@@ -367,10 +361,27 @@ plugin_init (GModule *module)
   /* The very last thing is to register the elementfactory with the plugin. */
   gst_plugin_add_factory (plugin, factory);
 
-  /* Now we can return the pointer to the newly created Plugin object. */
-  return plugin;
+  /* Now we can return successfully. */
+  return TRUE;
 
   /* At this point, the GStreamer core registers the plugin, its
    * elementfactories, padtemplates, etc., for use in you application.
    */
 }
+
+/* This structure describes the plugin to the system for dynamically loading
+ * plugins, so that the version number and name can be checked in a uniform
+ * way.
+ *
+ * The symbol pointing to this structure is the only symbol looked up when
+ * loading the plugin.
+ */
+GstPluginDesc plugin_desc = {
+  GST_VERSION_MAJOR, /* The major version of the core that this was built with */
+  GST_VERSION_MINOR, /* The minor version of the core that this was built with */
+  "example",         /* The name of the plugin.  This must be unique: plugins with
+		      * the same name will be assumed to be identical, and only
+		      * one will be loaded. */
+  plugin_init        /* Pointer to the initialisation function for the plugin. */
+};
+