backend/x11: Check for xinput extension

README.md

@@ -62,6 +62,7 @@ If you choose to enable X11 support:
 * xcb
 * xcb-composite
 * xcb-xfixes
+* xcb-xinput
 * xcb-image
 * xcb-render
 * x11-xcb

backend/x11/backend.c

@@ -12,6 +12,7 @@
 #include <X11/Xlib-xcb.h>
 #include <wayland-server.h>
 #include <xcb/xcb.h>
+#include <xcb/xinput.h>
 #if WLR_HAS_XCB_XKB
 #include <xcb/xkb.h>
 #endif
@@ -74,6 +75,12 @@ static void handle_x11_event(struct wlr_x11_backend *x11,
 		}
 		break;
 	}
+	case XCB_GE_GENERIC: {
+		xcb_ge_generic_event_t *ev = (xcb_ge_generic_event_t *)event;
+		if (ev->extension == x11->xinput_opcode) {
+			handle_x11_xinput_event(x11, ev);
+		}
+	}
 	}
 }
 
@@ -259,6 +266,26 @@ struct wlr_backend *wlr_x11_backend_create(struct wl_display *display,
 		}
 	}
 
+	const xcb_query_extension_reply_t *ext =
+		xcb_get_extension_data(x11->xcb, &xcb_input_id);
+	if (!ext || !ext->present) {
+		wlr_log(WLR_ERROR, "X11 does not support Xinput extension");
+		goto error_display;
+	}
+	x11->xinput_opcode = ext->major_opcode;
+
+	xcb_input_xi_query_version_cookie_t xi_cookie =
+		xcb_input_xi_query_version(x11->xcb, 2, 0);
+	xcb_input_xi_query_version_reply_t *xi_reply =
+		xcb_input_xi_query_version_reply(x11->xcb, xi_cookie, NULL);
+
+	if (!xi_reply || xi_reply->major_version < 2) {
+		wlr_log(WLR_ERROR, "X11 does not support required Xinput version");
+		free(xi_reply);
+		goto error_display;
+	}
+	free(xi_reply);
+
 	int fd = xcb_get_file_descriptor(x11->xcb);
 	struct wl_event_loop *ev = wl_display_get_event_loop(display);
 	uint32_t events = WL_EVENT_READABLE | WL_EVENT_ERROR | WL_EVENT_HANGUP;

backend/x11/meson.build

@@ -1,7 +1,8 @@
 x11_libs = []
 x11_required = [
-	'xcb',
 	'x11-xcb',
+	'xcb',
+	'xcb-xinput',
 ]
 x11_optional = [
 	'xcb-xkb',

include/backend/x11.h

@@ -67,6 +67,8 @@ struct wlr_x11_backend {
 	// A blank cursor
 	xcb_cursor_t cursor;
 
+	uint8_t xinput_opcode;
+
 #if WLR_HAS_XCB_XKB
 	bool xkb_supported;
 	uint8_t xkb_base_event;