plugin: add hooks to disable internal features

Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/1249>

src/evdev.h

@@ -36,6 +36,7 @@
 
 #include "evdev-frame.h"
 #include "filter.h"
+#include "libinput-feature.h"
 #include "libinput-private.h"
 #include "linux/input.h"
 #include "quirks.h"
@@ -352,6 +353,9 @@ struct evdev_dispatch_interface {
 	void (*left_handed_toggle)(struct evdev_dispatch *dispatch,
 				   struct evdev_device *device,
 				   bool left_handed_enabled);
+
+	void (*disable_feature)(struct evdev_dispatch *dispatch,
+				enum libinput_feature feature);
 };
 
 enum evdev_dispatch_type {
@@ -389,6 +393,14 @@ evdev_libinput_context(const struct evdev_device *device)
 	return device->base.seat->libinput;
 }
 
+static inline void
+evdev_device_disable_feature(struct evdev_device *device, enum libinput_feature feature)
+{
+	if (device->dispatch && device->dispatch->interface &&
+	    device->dispatch->interface->disable_feature)
+		device->dispatch->interface->disable_feature(device->dispatch, feature);
+}
+
 static inline bool
 evdev_device_has_model_quirk(struct evdev_device *device, enum quirk model_quirk)
 {

src/libinput-feature.h

@@ -0,0 +1,26 @@
+/*
+ * Copyright © 2025 Red Hat, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#pragma once
+
+enum libinput_feature { LIBINPUT_FEATURE_BUTTON_DEBOUNCING = 1, _LIBINPUT_N_FEATURES };

src/libinput-plugin-system.h

@@ -34,6 +34,7 @@
 #include "evdev-frame.h"
 #include "libinput.h"
 
+enum libinput_feature;
 struct libinput;
 struct libinput_plugin;
 
@@ -95,3 +96,9 @@ void
 libinput_plugin_system_notify_evdev_frame(struct libinput_plugin_system *system,
 					  struct libinput_device *device,
 					  struct evdev_frame *frame);
+
+void
+libinput_plugin_system_notify_device_feature_disabled(
+	struct libinput_plugin_system *system,
+	struct libinput_device *device,
+	enum libinput_feature feature);

src/libinput-plugin.c

@@ -30,12 +30,14 @@
 
 #include "evdev-frame.h"
 #include "evdev-plugin.h"
+#include "libinput-feature.h"
 #include "libinput-plugin-button-debounce.h"
 #include "libinput-plugin-lua.h"
 #include "libinput-plugin-mouse-wheel-lowres.h"
 #include "libinput-plugin-mouse-wheel.h"
 #include "libinput-plugin-mtdev.h"
 #include "libinput-plugin-private.h"
+#include "libinput-plugin-system.h"
 #include "libinput-plugin-tablet-double-tool.h"
 #include "libinput-plugin-tablet-eraser-button.h"
 #include "libinput-plugin-tablet-forced-tool.h"
@@ -208,6 +210,22 @@ libinput_plugin_enable_evdev_usage(struct libinput_plugin *plugin,
 	evdev_mask_set_usage(plugin->mask, evdev_usage_from(usage));
 }
 
+void
+libinput_plugin_disable_device_feature(struct libinput_plugin *plugin,
+				       struct libinput_device *device,
+				       enum libinput_feature feature)
+{
+	struct libinput *libinput = plugin->libinput;
+
+	/* During device-added, only some plugins are loaded so this notifies
+	 * some of the plugins. All plugins are notified once device-added is
+	 * complete.  */
+	libinput_plugin_system_notify_device_feature_disabled(&libinput->plugin_system,
+							      device,
+							      feature);
+	bitmask_set_bit(&device->disabled_features, feature);
+}
+
 struct plugin_queued_event {
 	struct list link;
 	struct evdev_frame *frame;      /* owns a ref */
@@ -501,6 +519,21 @@ libinput_plugin_system_notify_device_added(struct libinput_plugin_system *system
 		libinput_plugin_notify_device_added(plugin, device);
 	}
 	libinput_plugin_system_drop_unregistered_plugins(system);
+
+	/* Now that we added all our devices in all our plugins, notify
+	 * all plugins about disabled features. Some plugins may get
+	 * this notification twice but they should be able to handle that
+	 * case.
+	 */
+	enum libinput_feature feature = _LIBINPUT_N_FEATURES;
+
+	while (--feature > 0) {
+		if (bitmask_bit_is_set(device->disabled_features, feature)) {
+			libinput_plugin_system_notify_device_feature_disabled(system,
+									      device,
+									      feature);
+		}
+	}
 }
 
 void
@@ -538,6 +571,22 @@ libinput_plugin_system_notify_tablet_tool_configured(
 	libinput_plugin_system_drop_unregistered_plugins(system);
 }
 
+void
+libinput_plugin_system_notify_device_feature_disabled(
+	struct libinput_plugin_system *system,
+	struct libinput_device *device,
+	enum libinput_feature feature)
+{
+	libinput_device_disable_feature(device, feature);
+
+	struct libinput_plugin *plugin;
+	list_for_each_safe(plugin, &system->plugins, link) {
+		if (plugin->interface->feature_disabled)
+			plugin->interface->feature_disabled(plugin, device, feature);
+	}
+	libinput_plugin_system_drop_unregistered_plugins(system);
+}
+
 static void
 libinput_plugin_process_frame(struct libinput_plugin *plugin,
 			      struct libinput_device *device,

src/libinput-plugin.h

@@ -39,6 +39,7 @@ struct libinput_device;
 struct libinput_tablet_tool;
 struct libinput_plugin;
 enum libinput_log_priority;
+enum libinput_feature;
 
 #define plugin_log_debug(p_, ...) plugin_log_msg((p_), LIBINPUT_LOG_PRIORITY_DEBUG, __VA_ARGS__)
 #define plugin_log_info(p_, ...) plugin_log_msg((p_), LIBINPUT_LOG_PRIORITY_INFO, __VA_ARGS__)
@@ -107,6 +108,14 @@ struct libinput_plugin_interface {
 	 */
 	void (*tool_configured)(struct libinput_plugin *plugin,
 				struct libinput_tablet_tool *tool);
+
+	/**
+	 * Notification that the given feature was disabled on
+	 * the given device.
+	 */
+	void (*feature_disabled)(struct libinput_plugin *plugin,
+				 struct libinput_device *device,
+				 enum libinput_feature feature);
 };
 
 /**
@@ -159,6 +168,11 @@ libinput_plugin_enable_device_event_frame(struct libinput_plugin *plugin,
 					  struct libinput_device *device,
 					  bool enable);
 
+void
+libinput_plugin_disable_device_feature(struct libinput_plugin *plugin,
+				       struct libinput_device *device,
+				       enum libinput_feature feature);
+
 /**
  * Mask this plugin's evdev_frame function to be called only
  * if the frame **contains** the given evdev usage. Plugins

src/libinput-private.h

@@ -35,6 +35,7 @@
 #include <libwacom/libwacom.h>
 #endif
 
+#include "util-bits.h"
 #include "util-newtype.h"
 
 #include "libinput-log.h"
@@ -528,6 +529,11 @@ struct libinput_device {
 	struct libinput_device_config config;
 
 	bitmask_t plugin_frame_callbacks;
+	/**
+	 * Lua plugins see the device before our internal
+	 * plugins do any calls need to be cached.
+	 */
+	bitmask_t disabled_features;
 
 	void (*inject_evdev_frame)(struct libinput_device *device,
 				   struct evdev_frame *frame);
@@ -724,6 +730,10 @@ libinput_device_init(struct libinput_device *device, struct libinput_seat *seat)
 bool
 libinput_device_has_model_quirk(struct libinput_device *device, enum quirk model_quirk);
 
+void
+libinput_device_disable_feature(struct libinput_device *device,
+				enum libinput_feature feature);
+
 struct libinput_device_group *
 libinput_device_group_create(struct libinput *libinput, const char *identifier);
 

src/libinput.c

@@ -38,6 +38,7 @@
 #include "util-libinput.h"
 
 #include "evdev.h"
+#include "libinput-feature.h"
 #include "libinput-private.h"
 #include "libinput.h"
 #include "quirks.h"
@@ -2166,6 +2167,13 @@ libinput_device_unref(struct libinput_device *device)
 	return device;
 }
 
+void
+libinput_device_disable_feature(struct libinput_device *device,
+				enum libinput_feature feature)
+{
+	evdev_device_disable_feature((struct evdev_device *)device, feature);
+}
+
 LIBINPUT_EXPORT int
 libinput_get_fd(struct libinput *libinput)
 {