wlr-output-management: Implement version 3 release requests

Head/mode resources older than version 3 and lacking a release request
are intentionally leaked as this is the only way to fix the race.

Implements: https://gitlab.freedesktop.org/wlroots/wlr-protocols/-/merge_requests/114

2 files changed, 63 insertions, 21 deletions

diff --git a/protocol/wlr-output-management-unstable-v1.xml b/protocol/wlr-output-management-unstable-v1.xml
index cadc45fb..3568e04c 100644
--- a/protocol/wlr-output-management-unstable-v1.xml
+++ b/protocol/wlr-output-management-unstable-v1.xml
@@ -39,7 +39,7 @@
     interface version number is reset.
   </description>
 
-  <interface name="zwlr_output_manager_v1" version="2">
+  <interface name="zwlr_output_manager_v1" version="3">
     <description summary="output device configuration manager">
       This interface is a manager that allows reading and writing the current
       output device configuration.
@@ -115,7 +115,7 @@
       </description>
     </request>
 
-    <event name="finished">
+    <event name="finished" type="destructor">
       <description summary="the compositor has finished with the manager">
         This event indicates that the compositor is done sending manager events.
         The compositor will destroy the object immediately after sending this
@@ -125,7 +125,7 @@
     </event>
   </interface>
 
-  <interface name="zwlr_output_head_v1" version="2">
+  <interface name="zwlr_output_head_v1" version="3">
     <description summary="output device">
       A head is an output device. The difference between a wl_output object and
       a head is that heads are advertised even if they are turned off. A head
@@ -251,14 +251,15 @@
     </event>
 
     <event name="finished">
-      <description summary="the head has been destroyed">
-        The compositor will destroy the object immediately after sending this
-        event, so it will become invalid and the client should release any
-        resources associated with it.
+      <description summary="the head has disappeared">
+        This event indicates that the head is no longer available. The head
+        object becomes inert. Clients should send a destroy request and release
+        any resources associated with it.
       </description>
     </event>
 
     <!-- Version 2 additions -->
+
     <event name="make" since="2">
       <description summary="head manufacturer">
         This event describes the manufacturer of the head.
@@ -328,9 +329,18 @@
       </description>
       <arg name="serial_number" type="string"/>
     </event>
+
+    <!-- Version 3 additions -->
+
+    <request name="release" type="destructor" since="3">
+      <description summary="destroy the head object">
+        This request indicates that the client will no longer use this head
+        object.
+      </description>
+    </request>
   </interface>
 
-  <interface name="zwlr_output_mode_v1" version="2">
+  <interface name="zwlr_output_mode_v1" version="3">
     <description summary="output mode">
       This object describes an output mode.
 
@@ -368,15 +378,24 @@
     </event>
 
     <event name="finished">
-      <description summary="the mode has been destroyed">
-        The compositor will destroy the object immediately after sending this
-        event, so it will become invalid and the client should release any
-        resources associated with it.
+      <description summary="the mode has disappeared">
+        This event indicates that the mode is no longer available. The mode
+        object becomes inert. Clients should send a destroy request and release
+        any resources associated with it.
       </description>
     </event>
+
+    <!-- Version 3 additions -->
+
+    <request name="release" type="destructor" since="3">
+      <description summary="destroy the mode object">
+        This request indicates that the client will no longer use this mode
+        object.
+      </description>
+    </request>
   </interface>
 
-  <interface name="zwlr_output_configuration_v1" version="2">
+  <interface name="zwlr_output_configuration_v1" version="3">
     <description summary="output configuration">
       This object is used by the client to describe a full output configuration.
 
@@ -494,7 +513,7 @@
     </request>
   </interface>
 
-  <interface name="zwlr_output_configuration_head_v1" version="2">
+  <interface name="zwlr_output_configuration_head_v1" version="3">
     <description summary="head configuration">
       This object is used by the client to update a single head's configuration.
 
diff --git a/types/wlr_output_management_v1.c b/types/wlr_output_management_v1.c
index 64eff211..f7ac5dcf 100644
--- a/types/wlr_output_management_v1.c
+++ b/types/wlr_output_management_v1.c
@@ -5,7 +5,7 @@
 #include <wlr/util/log.h>
 #include "wlr-output-management-unstable-v1-protocol.h"
 
-#define OUTPUT_MANAGER_VERSION 2
+#define OUTPUT_MANAGER_VERSION 3
 
 enum {
 	HEAD_STATE_ENABLED = 1 << 0,
@@ -27,6 +27,7 @@ static struct wlr_output_head_v1 *head_from_resource(
 	return wl_resource_get_user_data(resource);
 }
 
+// Can return NULL if the mode is inert
 static struct wlr_output_mode *mode_from_resource(
 		struct wl_resource *resource) {
 	assert(wl_resource_instance_of(resource,
@@ -41,11 +42,15 @@ static void head_destroy(struct wlr_output_head_v1 *head) {
 	struct wl_resource *resource, *tmp;
 	wl_resource_for_each_safe(resource, tmp, &head->mode_resources) {
 		zwlr_output_mode_v1_send_finished(resource);
-		wl_resource_destroy(resource);
+		wl_list_remove(wl_resource_get_link(resource));
+		wl_list_init(wl_resource_get_link(resource));
+		wl_resource_set_user_data(resource, NULL);
 	}
 	wl_resource_for_each_safe(resource, tmp, &head->resources) {
 		zwlr_output_head_v1_send_finished(resource);
-		wl_resource_destroy(resource);
+		wl_list_remove(wl_resource_get_link(resource));
+		wl_list_init(wl_resource_get_link(resource));
+		wl_resource_set_user_data(resource, NULL);
 	}
 	wl_list_remove(&head->link);
 	wl_list_remove(&head->output_destroy.link);
@@ -648,10 +653,19 @@ static void send_mode_state(struct wl_resource *mode_resource,
 	}
 }
 
-static void mode_handle_resource_destroy(struct wl_resource *resource) {
+static void output_mode_handle_resource_destroy(struct wl_resource *resource) {
 	wl_list_remove(wl_resource_get_link(resource));
 }
 
+static void output_mode_handle_release(struct wl_client *client,
+		struct wl_resource *resource) {
+	wl_resource_destroy(resource);
+}
+
+static const struct zwlr_output_mode_v1_interface output_mode_impl = {
+	.release = output_mode_handle_release,
+};
+
 static struct wl_resource *head_send_mode(struct wlr_output_head_v1 *head,
 		struct wl_resource *head_resource, struct wlr_output_mode *mode) {
 	struct wl_client *client = wl_resource_get_client(head_resource);
@@ -662,8 +676,8 @@ static struct wl_resource *head_send_mode(struct wlr_output_head_v1 *head,
 		wl_resource_post_no_memory(head_resource);
 		return NULL;
 	}
-	wl_resource_set_implementation(mode_resource, NULL, mode,
-		mode_handle_resource_destroy);
+	wl_resource_set_implementation(mode_resource, &output_mode_impl, mode,
+		output_mode_handle_resource_destroy);
 	wl_list_insert(&head->mode_resources, wl_resource_get_link(mode_resource));
 
 	zwlr_output_head_v1_send_mode(head_resource, mode_resource);
@@ -739,6 +753,15 @@ static void head_handle_resource_destroy(struct wl_resource *resource) {
 	wl_list_remove(wl_resource_get_link(resource));
 }
 
+static void head_handle_release(struct wl_client *client,
+		struct wl_resource *resource) {
+	wl_resource_destroy(resource);
+}
+
+static const struct zwlr_output_head_v1_interface head_impl = {
+	.release = head_handle_release,
+};
+
 static void manager_send_head(struct wlr_output_manager_v1 *manager,
 		struct wlr_output_head_v1 *head, struct wl_resource *manager_resource) {
 	struct wlr_output *output = head->state.output;
@@ -751,7 +774,7 @@ static void manager_send_head(struct wlr_output_manager_v1 *manager,
 		wl_resource_post_no_memory(manager_resource);
 		return;
 	}
-	wl_resource_set_implementation(head_resource, NULL, head,
+	wl_resource_set_implementation(head_resource, &head_impl, head,
 		head_handle_resource_destroy);
 	wl_list_insert(&head->resources, wl_resource_get_link(head_resource));