Merge branch 'jorth/display-upgrade' into 'main'

protocol: add wl_display_upgrade global

See merge request wayland/wayland!534

protocol/wayland.xml

@@ -28,10 +28,14 @@
     SOFTWARE.
   </copyright>
 
-  <interface name="wl_display" version="1">
+  <interface name="wl_display" version="2">
     <description summary="core global object">
       The core global object.  This is a special singleton object.  It
       is used for internal Wayland protocol features.
+
+      This interface guarantees that the semantics of requests of this interface
+      are unaffected by the minor version of this interface. The semantics of
+      events may change and new events may be added.
     </description>
 
     <request name="sync">
@@ -110,7 +114,7 @@
     </event>
   </interface>
 
-  <interface name="wl_registry" version="1">
+  <interface name="wl_registry" version="2">
     <description summary="global registry object">
       The singleton global registry object.  The server has a number of
       global objects that are available to all clients.  These objects
@@ -132,6 +136,10 @@
       request.  This creates a client-side handle that lets the object
       emit events to the client and lets the client invoke requests on
       the object.
+
+      This interface guarantees that the semantics of the messages of this
+      interface are unaffected by the minor version of this interface; and that
+      no new events will be added to any minor version of this interface.
     </description>
 
     <request name="bind">
@@ -171,6 +179,14 @@
       </description>
       <arg name="name" type="uint" summary="numeric name of the global object"/>
     </event>
+
+    <!-- Version 2 additions -->
+
+    <request name="release" type="destructor" since="2">
+      <description summary="destroys this registry">
+        Objects created from this registry are not affected by this request.
+      </description>
+    </request>
   </interface>
 
   <interface name="wl_callback" version="1" frozen="true">
@@ -3362,4 +3378,56 @@
     </request>
   </interface>
 
+  <interface name="wl_display_upgrade" version="2">
+    <description summary="wayland upgrade object">
+      This global allows the IPC library to upgrade the version of the
+      wl_display object.
+
+      This global must not be bound more than once over the lifetime of the
+      connection, otherwise the already_bound error is emitted.
+
+      This global should only be bound by the IPC library because the IPC
+      library must be aware of the version of the wl_display object.
+
+      A compositor that advertises this global must also advertise the wl_fixes
+      global.
+    </description>
+
+    <enum name="error">
+      <description summary="wl_display_upgrade error values">
+        These errors can be emitted in response to wl_display_upgrade requests.
+      </description>
+      <entry name="already_bound" value="0"
+             summary="the wl_display_upgrade global was bound more than once"/>
+      <entry name="has_objects" value="1"
+             summary="objects other than wl_display and this object exist"/>
+      <entry name="out_of_bounds" value="2"
+             summary="the version requested by the upgrade request is out of bounds"/>
+    </enum>
+
+    <event name="max_version">
+      <description summary="the version supported by the compositor">
+        This event informs the client of the maximum wl_display version
+        supported by the compositor. It is sent immediately after this global
+        has been bound. The version is guaranteed to be at least 1.
+      </description>
+      <arg name="version" type="uint" summary="the version"/>
+    </event>
+
+    <request name="upgrade" type="destructor">
+      <description summary="upgrade the wl_display version">
+        Negotiates an upgrade of the version of the wl_display object.
+
+        At the time of the request, no objects other than the wl_display and
+        this object must exist, otherwise the has_objects error is emitted. In
+        particular, the client must use wl_fixes to destroy the registry from
+        which this object was created.
+
+        The version must be at least 1 and must not be larger than the version
+        sent in the version event, otherwise the out_of_bounds error is emitted.
+      </description>
+      <arg name="version" type="uint" summary="the version"/>
+    </request>
+  </interface>
+
 </protocol>

src/wayland-client-core.h

@@ -245,6 +245,9 @@ wl_display_connect_to_fd(int fd);
 void
 wl_display_disconnect(struct wl_display *display);
 
+void
+wl_display_upgrade(struct wl_display *display);
+
 int
 wl_display_get_fd(struct wl_display *display);
 

src/wayland-client.c

@@ -1405,6 +1405,84 @@ wl_display_disconnect(struct wl_display *display)
 	free(display);
 }
 
+struct upgrade_listener {
+	struct wl_fixes *wl_fixes;
+	struct wl_display_upgrade *wl_display_upgrade;
+	uint32_t version;
+};
+
+static void upgrade_max_version(void *data,
+				struct wl_display_upgrade *wl_display_upgrade,
+				uint32_t version)
+{
+	struct upgrade_listener *listener = data;
+	listener->version = version;
+}
+
+static struct wl_display_upgrade_listener upgrade_upgrade_listener = {
+	.max_version = upgrade_max_version,
+};
+
+static void upgrade_global(void *data, struct wl_registry *wl_registry,
+			   uint32_t name, const char *interface,
+			   uint32_t version)
+{
+	struct upgrade_listener *listener = data;
+	if (!listener->wl_fixes && strcmp(interface, wl_fixes_interface.name) == 0)
+		listener->wl_fixes = wl_registry_bind(wl_registry, name, &wl_fixes_interface, 1);
+	else if (!listener->wl_display_upgrade && strcmp(interface, wl_display_upgrade_interface.name) == 0) {
+		listener->wl_display_upgrade = wl_registry_bind(wl_registry, name, &wl_display_upgrade_interface, 1);
+		wl_display_upgrade_add_listener(listener->wl_display_upgrade, &upgrade_upgrade_listener, data);
+	}
+}
+
+static void upgrade_global_remove(void *data, struct wl_registry *wl_registry,
+				  uint32_t name)
+{
+	// nothing
+}
+
+static struct wl_registry_listener upgrade_registry_listener = {
+	.global = upgrade_global,
+	.global_remove = upgrade_global_remove,
+};
+
+#define min(a, b) ((a) < (b) ? (a) : (b))
+
+/** Upgrade the wl_display version.
+ *
+ * \param display The display context object
+ *
+ * Tries to upgrade the version of the wl_display. After this function returns,
+ * wl_display_get_version can be used to retrieve the new version of the
+ * wl_display.
+ *
+ * This function should be called immediately after creating the display. It
+ * must not be called any later than that or multiple times, otherwise a
+ * protocol error might occur.
+ *
+ * \memberof wl_display
+ */
+WL_EXPORT void
+wl_display_upgrade(struct wl_display *display)
+{
+	struct wl_registry *registry = wl_display_get_registry(display);
+	struct upgrade_listener listener = { };
+	wl_registry_add_listener(registry, &upgrade_registry_listener, &listener);
+	wl_display_roundtrip(display);
+	if (listener.wl_display_upgrade)
+		wl_display_roundtrip(display);
+	if (listener.wl_fixes) {
+		wl_fixes_destroy_registry(listener.wl_fixes, registry);
+		wl_fixes_destroy(listener.wl_fixes);
+	}
+	if (listener.wl_display_upgrade) {
+		uint32_t version = min(listener.version, (uint32_t)wl_display_interface.version);
+		wl_display_upgrade_upgrade(listener.wl_display_upgrade, version);
+		display->proxy.version = version;
+	}
+}
+
 /** Get a display context's file descriptor
  *
  * \param display The display context object

src/wayland-server-core.h

@@ -697,6 +697,9 @@ wl_shm_buffer_create(struct wl_client *client,
 		     uint32_t id, int32_t width, int32_t height,
 		     int32_t stride, uint32_t format);
 
+int
+wl_display_init_upgrade(struct wl_display *display, uint32_t max_version);
+
 void
 wl_log_set_handler_server(wl_log_func_t handler);
 

src/wayland-server.c

@@ -86,6 +86,7 @@ struct wl_client {
 	struct wl_priv_signal resource_created_signal;
 	void *data;
 	wl_user_data_destroy_func_t data_dtor;
+	bool has_upgrade;
 };
 
 struct wl_display {
@@ -113,6 +114,7 @@ struct wl_display {
 	struct wl_event_source *term_source;
 
 	size_t max_buffer_size;
+	uint32_t max_upgrade_version;
 };
 
 struct wl_global {
@@ -1077,8 +1079,15 @@ registry_bind(struct wl_client *client,
 		global->bind(client, global->data, version, id);
 }
 
+static void
+registry_release(struct wl_client *client, struct wl_resource *resource)
+{
+	wl_resource_destroy(resource);
+}
+
 static const struct wl_registry_interface registry_interface = {
-	registry_bind
+	.bind = registry_bind,
+	.release = registry_release,
 };
 
 static void
@@ -1114,7 +1123,7 @@ display_get_registry(struct wl_client *client,
 	struct wl_global *global;
 
 	registry_resource =
-		wl_resource_create(client, &wl_registry_interface, 1, id);
+		wl_resource_create(client, &wl_registry_interface, resource->version, id);
 	if (registry_resource == NULL) {
 		wl_client_post_no_memory(client);
 		return;
@@ -2428,6 +2437,59 @@ wl_client_set_max_buffer_size(struct wl_client *client, size_t max_buffer_size)
 	wl_connection_set_max_buffer_size(client->connection, max_buffer_size);
 }
 
+static void
+upgrade_display(struct wl_client *client, struct wl_resource *resource,
+		uint32_t version)
+{
+	wl_resource_destroy(resource);
+	// TODO: Check that there are no other objects.
+	if (version < 1 || version > client->display->max_upgrade_version) {
+		wl_resource_post_error(resource,
+				       WL_DISPLAY_UPGRADE_ERROR_OUT_OF_BOUNDS,
+				       "version is out of bounds");
+		return;
+	}
+	client->display_resource->version = (int)version;
+}
+
+static struct wl_display_upgrade_interface upgrade_interface = {
+	.upgrade = upgrade_display,
+};
+
+static void
+bind_upgrade(struct wl_client *client, void *data, uint32_t version,
+	     uint32_t id)
+{
+	struct wl_resource *resource;
+	resource = wl_resource_create(client, &wl_display_upgrade_interface,
+				      (int)version, id);
+	if (!resource) {
+		wl_client_post_no_memory(client);
+		return;
+	}
+	if (client->has_upgrade) {
+		wl_resource_post_error(resource,
+				       WL_DISPLAY_UPGRADE_ERROR_ALREADY_BOUND,
+				       "wl_display_upgrade has already been bound");
+		return;
+	}
+	client->has_upgrade = true;
+	wl_display_upgrade_send_max_version(resource,
+					    client->display->max_upgrade_version);
+	wl_resource_set_implementation(resource, &upgrade_interface, NULL, NULL);
+}
+
+WL_EXPORT int
+wl_display_init_upgrade(struct wl_display *display, uint32_t max_version)
+{
+	if (max_version > (uint32_t)wl_display_upgrade_interface.version)
+		max_version = wl_display_upgrade_interface.version;
+	display->max_upgrade_version = max_version;
+	if (!wl_global_create(display, &wl_display_upgrade_interface, 1, NULL, bind_upgrade))
+		return -1;
+	return 0;
+}
+
 /** \cond INTERNAL */
 
 /** Initialize a wl_priv_signal object