extensions_manager: Introduce typed callbacks for extensions_manager

This commit introduces a typed virtual table for operations on
extensions_manager, aiming at replacing the legacy pf_control() callback
which is using va_list.

The operations can now be implemented directly by the modules, providing
type safety at every level.

When no operation is provided (i.e., extensions_manager_t.ops is NULL) by a
module implementation, the legacy pf_control will be used instead as a fallback.

include/vlc_extensions.h

@@ -55,6 +55,20 @@ typedef struct extension_t {
     int   i_icondata_size;    /**< Size of that data */
 } extension_t;
 
+struct vlc_extensions_manager_operations {
+    int (*activate)(extensions_manager_t*, extension_t *);
+    int (*deactivate)(extensions_manager_t *, extension_t *);
+    bool (*is_activated)(extensions_manager_t *, extension_t *);
+    bool (*has_menu)(extensions_manager_t *, extension_t *);
+    int (*get_menu)(extensions_manager_t *, extension_t *, char ***, uint16_t **);
+    bool (*trigger_only)(extensions_manager_t *, extension_t *);
+    int (*trigger)(extensions_manager_t *, extension_t *);
+    int (*trigger_menu)(extensions_manager_t *, extension_t *, int);
+    int (*set_input)(extensions_manager_t *, extension_t *, input_item_t *);
+    int (*playing_changed)(extensions_manager_t *, extension_t *, int);
+    int (*meta_changed)(extensions_manager_t *, extension_t *);
+};
+
 /** Extensions manager object */
 struct extensions_manager_t
 {
@@ -67,8 +81,19 @@ struct extensions_manager_t
     DECL_ARRAY(extension_t*) extensions; /**< Array of extension descriptors */
     vlc_mutex_t lock;                  /**< A lock for the extensions array */
 
-    /** Control, see extension_Control */
+    /** Control, see extension_Control
+     *
+     *  Legacy way of implementing callbacks.
+     *  \ref vlc_extensions_manager_operations should be preferred.
+     */
     int (*pf_control)(extensions_manager_t*, int, extension_t *, va_list);
+
+    /**
+     * Implementation of the extension manager operations.
+     *
+     * If NULL all operations will be redirected to \ref extensions_manager_t.pf_control 
+     */
+    const struct vlc_extensions_manager_operations *ops;
 };
 
 /* Control commands */
@@ -88,6 +113,11 @@ enum
     EXTENSION_META_CHANGED,   /**< arg1: extension_t*, arg2 (input_item_t*) */
 };
 
+VLC_API int vlc_extension_VaControl( extensions_manager_t *p_mgr,
+                                       int i_control,
+                                       extension_t *ext,
+                                       va_list args );
+
 /**
  * Control function for extensions.
  * Every GUI -> extension command will go through this function.
@@ -98,7 +128,7 @@ static inline int extension_Control( extensions_manager_t *p_mgr,
 {
     va_list args;
     va_start(args, ext);
-    int i_ret = p_mgr->pf_control(p_mgr, i_control, ext, args);
+    int i_ret = vlc_extension_VaControl(p_mgr, i_control, ext, args);
     va_end( args );
     return i_ret;
 }

src/Makefile.am

@@ -392,6 +392,7 @@ libvlccore_la_SOURCES = \
 	misc/fourcc.c \
 	misc/fourcc_list.h \
 	misc/es_format.c \
+	misc/extensions.c \
 	misc/picture.c \
 	misc/picture.h \
 	misc/picture_fifo.c \

src/libvlccore.sym

@@ -113,6 +113,7 @@ es_format_Init
 es_format_InitFromVideo
 es_format_IsSimilar
 es_format_LogDifferences
+vlc_extension_VaControl
 filter_AddProxyCallbacks
 filter_DelProxyCallbacks
 filter_Blend

src/meson.build

@@ -243,6 +243,7 @@ libvlccore_sources_base = files(
     'misc/fourcc.c',
     'misc/fourcc_list.h',
     'misc/es_format.c',
+    'misc/extensions.c',
     'misc/picture.c',
     'misc/picture.h',
     'misc/picture_fifo.c',

src/misc/extensions.c

@@ -0,0 +1,113 @@
+/*****************************************************************************
+ * extensions.c
+ *****************************************************************************
+ * Copyright (C) 2024 VideoLabs
+ *
+ * Authors: Vikram Kangotra <vikramkangotra8055@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <assert.h>
+
+#include <vlc_common.h>
+#include <vlc_extensions.h>
+
+int vlc_extension_VaControl( extensions_manager_t *p_mgr,
+                         int i_control,
+                         extension_t *ext,
+                         va_list args )
+{
+    if (p_mgr->ops == NULL)
+        return p_mgr->pf_control(p_mgr, i_control, ext, args);
+
+    switch (i_control) {
+        case EXTENSION_ACTIVATE:
+            if (p_mgr->ops->activate != NULL)
+                return p_mgr->ops->activate(p_mgr, ext);
+            return VLC_EGENERIC;
+        case EXTENSION_DEACTIVATE:
+            if (p_mgr->ops->deactivate != NULL)
+                return p_mgr->ops->deactivate(p_mgr, ext);
+            return VLC_EGENERIC;
+        case EXTENSION_IS_ACTIVATED:
+        {
+            bool *is_activated = va_arg(args, bool *);
+            if (p_mgr->ops->is_activated != NULL)
+                *is_activated = p_mgr->ops->is_activated(p_mgr, ext);
+            else
+                *is_activated = false;
+            return VLC_SUCCESS;
+        }
+        case EXTENSION_HAS_MENU:
+        {
+            bool *has_menu = va_arg(args, bool *);
+            if (p_mgr->ops->has_menu != NULL)
+                *has_menu = p_mgr->ops->has_menu(p_mgr, ext);
+            else
+                *has_menu = false;
+            return VLC_SUCCESS;
+        }
+        case EXTENSION_GET_MENU:
+            if (p_mgr->ops->get_menu != NULL) {
+                char ***pppsz_titles = va_arg(args, char ***);
+                uint16_t **ppi_ids = va_arg(args, uint16_t **);
+                return p_mgr->ops->get_menu(p_mgr, ext, pppsz_titles, ppi_ids);
+            }
+            return VLC_EGENERIC;
+        case EXTENSION_TRIGGER_ONLY: 
+        {
+            bool *p_trigger_only = va_arg(args, bool *);
+            if (p_mgr->ops->trigger_only != NULL)
+                *p_trigger_only = p_mgr->ops->trigger_only(p_mgr, ext);
+            else
+                *p_trigger_only = false;
+            return VLC_SUCCESS;
+        }
+        case EXTENSION_TRIGGER:
+            if (p_mgr->ops->trigger != NULL)
+                return p_mgr->ops->trigger(p_mgr, ext);
+            return VLC_EGENERIC;
+        case EXTENSION_TRIGGER_MENU:
+            if (p_mgr->ops->trigger_menu != NULL) {
+                int i = va_arg(args, int);
+                return p_mgr->ops->trigger_menu(p_mgr, ext, i);
+            }
+            return VLC_EGENERIC;
+        case EXTENSION_SET_INPUT:
+            if (p_mgr->ops->set_input != NULL) {
+                input_item_t *p_item = va_arg(args, input_item_t *);
+                return p_mgr->ops->set_input(p_mgr, ext, p_item);
+            }
+            return VLC_EGENERIC;
+        case EXTENSION_PLAYING_CHANGED:
+            if (p_mgr->ops->playing_changed != NULL) {
+                int i = va_arg(args, int);
+                return p_mgr->ops->playing_changed(p_mgr, ext, i);
+            }
+            return VLC_EGENERIC;
+        case EXTENSION_META_CHANGED:
+            if (p_mgr->ops->meta_changed != NULL)
+                return p_mgr->ops->meta_changed(p_mgr, ext);
+            return VLC_EGENERIC;
+        default:
+            vlc_assert_unreachable();
+    }
+}
+