plugins: Let plugins fill GeanyPlugin::callbacks instead of passing their own pointer

This is easier to handle if we decide to add callbacks. Since we can
zero-initialize callbacks before passing it to the plugin we can be certain as
to which callbacks the plugin knew about when it was compiled. This is exactly
the same method used for GeanyPlugin::info already and easier than inspecting
the API version.

src/plugindata.h

@@ -237,12 +237,15 @@ GeanyData;
 
 #define geany			geany_data	/**< Simple macro for @c geany_data that reduces typing. */
 
+typedef struct GeanyPluginFuncs GeanyPluginFuncs;
+
 /** Basic information for the plugin and identification.
  * @see geany_plugin. */
 typedef struct GeanyPlugin
 {
 	PluginInfo	*info;	/**< Fields set in plugin_set_info(). */
 	GeanyData	*geany_data;	/**< Pointer to global GeanyData intance */
+	GeanyPluginFuncs *funcs;	/**< Functions implemented by the plugin, set in geany_load_module() */
 
 	struct GeanyPluginPrivate *priv;	/* private */
 }
@@ -287,7 +290,7 @@ gboolean geany_load_module(GeanyPlugin *plugin);
  *
  * @since 1.26 (API 225)
  **/
-typedef struct GeanyPluginFuncs
+struct GeanyPluginFuncs
 {
 	/** Array of plugin-provided signal handlers @see PluginCallback */
 	PluginCallback *callbacks;
@@ -299,11 +302,10 @@ typedef struct GeanyPluginFuncs
 	void        (*help)      (GeanyPlugin *plugin, gpointer pdata);
 	/** Called when the plugin is disabled or when Geany exits (must not be @c NULL) */
 	void        (*cleanup)   (GeanyPlugin *plugin, gpointer pdata);
-}
-GeanyPluginFuncs;
+};
 
 gboolean geany_plugin_register(GeanyPlugin *plugin, gint api_version, gint min_api_version,
-                               gint abi_version, GeanyPluginFuncs *cbs, gpointer pdata);
+                               gint abi_version, gpointer pdata);
 
 /** Convinience macro to register a plugin.
  *
@@ -311,9 +313,9 @@ gboolean geany_plugin_register(GeanyPlugin *plugin, gint api_version, gint min_a
  *
  * @since 1.26 (API 225)
  **/
-#define GEANY_PLUGIN_REGISTER(plugin, min_api_version) \
+#define GEANY_PLUGIN_REGISTER(plugin, min_api_version, pdata) \
 	geany_plugin_register((plugin), GEANY_API_VERSION, \
-	                      (min_api_version), GEANY_ABI_VERSION)
+	                      (min_api_version), GEANY_ABI_VERSION, pdata)
 
 /* Deprecated aliases */
 #ifndef GEANY_DISABLE_DEPRECATED

src/plugins.c

@@ -261,7 +261,12 @@ static gint cmp_plugin_names(gconstpointer a, gconstpointer b)
 /** Register a plugin to Geany.
  *
  * The plugin will show up in the plugin manager. The user can interact with
- * it based on the callbacks it provides and installed GUI elements.
+ * it based on the functions it provides and installed GUI elements.
+ *
+ * You must initialize the info and funcs fields of @ref GeanyPlugin
+ * appropriately prior to calling this, otherwise registration will fail. For
+ * info at least a valid name must be set (possibly localized). For funcs,
+ * at least init() and cleanup() functions must be implemented and set.
  *
  * The return value must be checked. It may be FALSE if the plugin failed to register which can
  * mainly happen for two reasons (future Geany versions may add new failure conditions):
@@ -275,7 +280,6 @@ static gint cmp_plugin_names(gconstpointer a, gconstpointer b)
  * @param api_version The API version the plugin is compiled against (pass GEANY_API_VERSION)
  * @param min_api_version The minimum API version required by the plugin
  * @param abi_version The exact ABI version the plugin is compiled against (pass GEANY_ABI_VERSION)
- * @param cbs A statically allocated @ref GeanyPluginFuncs structure filled with callbacks
  * @param pdata A data pointer to store plugin-specific data, will be passed to the plugin's callbacks
  *
  * @return TRUE if the plugin was successfully registered. Otherwise FALSE.
@@ -285,9 +289,10 @@ static gint cmp_plugin_names(gconstpointer a, gconstpointer b)
  **/
 GEANY_API_SYMBOL
 gboolean geany_plugin_register(GeanyPlugin *plugin, gint api_version, gint min_api_version,
-                               gint abi_version, GeanyPluginFuncs *cbs, gpointer pdata)
+                               gint abi_version, gpointer pdata)
 {
 	Plugin *p;
+	GeanyPluginFuncs *cbs = plugin->funcs;
 
 	g_return_val_if_fail(plugin != NULL, FALSE);
 
@@ -295,19 +300,12 @@ gboolean geany_plugin_register(GeanyPlugin *plugin, gint api_version, gint min_a
 	/* Prevent registering incompatible plugins. */
 	if (! plugin_check_version(p, PLUGIN_VERSION_CODE(api_version, abi_version)))
 		return FALSE;
-	/* If it ever becomes necessary we can save the api version in Plugin
-	 * and apply compat code on a per-plugin basis, because we learn about
-	 * the requested API version here. Also if we add to GeanyPluginFuncs then
-	 * we have to inspect the plugin's api so that we don't misinterpret
-	 * function pointers the plugin doesn't know anything about. */
-	p->cbs.n = *cbs;
-	p->cb_data = pdata;
 
 	/* Only init and cleanup callbacks are truly mandatory. */
 	if (! cbs->init || ! cbs->cleanup)
 	{
 		geany_debug("Plugin '%s' has no %s function - ignoring plugin!",
-				cbs->init ? "cleanup" : "init", g_module_name(p->module));
+				 g_module_name(p->module), cbs->init ? "cleanup" : "init");
 	}
 	else
 	{
@@ -317,6 +315,10 @@ gboolean geany_plugin_register(GeanyPlugin *plugin, gint api_version, gint min_a
 			p->flags = LOADED_OK;
 	}
 
+	/* If it ever becomes necessary we can save the api version in Plugin
+	 * and apply compat code on a per-plugin basis, because we learn about
+	 * the requested API version here. For now it's not necessary. */
+
 	return PLUGIN_LOADED_OK(p);
 }
 
@@ -487,8 +489,9 @@ plugin_new(const gchar *fname, gboolean load_plugin, gboolean add_to_list)
 	plugin->filename = g_strdup(fname);
 	plugin->public.geany_data = &geany_data;
 	plugin->public.priv = plugin;
-	/* Fields of plugin->info must to be initialized by the plugin */
+	/* Fields of plugin->info/funcs must to be initialized by the plugin */
 	plugin->public.info = &plugin->info;
+	plugin->public.funcs = &plugin->cbs.n;
 
 	g_module_symbol(module, "geany_load_module", (void *) &p_geany_load_module);
 	if (p_geany_load_module)