backend/libinput/backend.c, backend/session/session.c: implement libdemi support

backend/libinput/backend.c

@@ -96,6 +96,8 @@ static bool backend_start(struct wlr_backend *wlr_backend) {
 #if WLR_HAS_UDEV
 	backend->libinput_context = libinput_udev_create_context(&libinput_impl,
 		backend, backend->session->dev->udev);
+#elif WLR_HAS_DEMI
+	backend->libinput_context = libinput_create_context(&libinput_impl, backend);
 #elif defined(__linux__)
 	backend->libinput_context = libinput_netlink_create_context(&libinput_impl,
 		backend, NETLINK_BITMASK);
@@ -110,6 +112,8 @@ static bool backend_start(struct wlr_backend *wlr_backend) {
 #if WLR_HAS_UDEV
 	if (libinput_udev_assign_seat(backend->libinput_context,
 			backend->session->seat) != 0) {
+#elif WLR_HAS_DEMI
+	if (libinput_assign_seat(backend->libinput_context, backend->session->seat) != 0) {
 #elif defined(__linux__)
 	if (libinput_netlink_assign_seat(backend->libinput_context,
 			backend->session->seat) != 0) {

backend/session/dev_demi.c

@@ -0,0 +1,148 @@
+#define _POSIX_C_SOURCE 200809L
+#include <demi.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <time.h>
+#include <wayland-server-core.h>
+#include <wlr/backend/session.h>
+#include <wlr/config.h>
+#include <wlr/util/log.h>
+#include <xf86drm.h>
+#include "backend/session/session.h"
+#include "backend/session/dev.h"
+#include "backend/session/dev_demi.h"
+#include "util/signal.h"
+
+static bool is_drm_card(const char *devname) {
+	const char prefix[] = DRM_PRIMARY_MINOR_NAME;
+	const char *name = strrchr(devname);
+	name = name ? name + 1 : devname;
+	if (strncmp(name, prefix, strlen(prefix)) != 0) {
+		return false;
+	}
+	for (size_t i = strlen(prefix); name[i] != '\0'; i++) {
+		if (name[i] < '0' || name[i] > '9') {
+			return false;
+		}
+	}
+	return true;
+}
+
+static int handle_event(int fd, uint32_t mask, void *data) {
+	struct wlr_session *session = data;
+
+	struct demi_event event;
+	if (demi_read(fd, &event) == -1) {
+		// TODO log
+		return 1;
+	}
+
+	const char *devname = event.de_devname;
+	enum demi_event_type event_type = event.de_type;
+
+	if (event_type == DEMI_UNKNOWN) {
+		// TODO log
+		return 1;
+	}
+
+	if (!is_drm_card(devname)) {
+		// TODO log
+		return 1;
+	}
+
+	char devnode[sizeof("/dev/") + sizeof(event.de_devname)];
+	snprintf(devnode, sizeof(devnode), "/dev/%s", devname);
+
+	wlr_log(WLR_DEBUG, "kernel event for %s (code %d)", devnode, event_type);
+
+	// TODO https://todo.sr.ht/~kennylevinsen/seatd/1
+	const char *seat = "seat0";
+	if (session->seat[0] != '\0' && strcmp(session->seat, seat) != 0) {
+		return 1;
+	}
+
+	if (event_type == DEMI_ATTACH) {
+		wlr_log(WLR_DEBUG, "DRM device %s added", devnode);
+		struct wlr_session_add_event event = {
+			.path = devnode,
+		};
+		wlr_signal_emit_safe(&session->events.add_drm_card, &event);
+	} else if (event_type == DEMI_CHANGE || event_type == DEMI_DETACH) {
+		struct stat st;
+		// FIXME stat will fail on DEMI_DETACH
+		if (stat(devnode, &st) == -1) {
+			// FIXME fallback to comparing devnode
+			return 1;
+		}
+
+		struct wlr_device *dev;
+		wl_list_for_each(dev, &session->devices, link) {
+			if (dev->dev != st.st_rdev) {
+				continue;
+			}
+
+			if (event_type == DEMI_CHANGE) {
+				wlr_log(WLR_DEBUG, "DRM device %s changed", devnode);
+				// TODO
+				// struct wlr_device_change_event event = {0};
+				// read_udev_change_event(&event, udev_dev);
+				wlr_signal_emit_safe(&dev->events.change, NULL);
+			} else if (event_type == DEMI_DETACH) {
+				wlr_log(WLR_DEBUG, "DRM device %s removed", devnode);
+				wlr_signal_emit_safe(&dev->events.remove, NULL);
+			} else {
+				abort();
+			}
+			break;
+		}
+	}
+
+	return 1;
+}
+
+int dev_init(struct wlr_session *session, struct wl_display *disp) {
+	struct dev *dev = calloc(1, sizeof(*dev));
+	if (!dev) {
+		wlr_log_errno(WLR_ERROR, "Allocation failed");
+		return -1;
+	}
+
+	dev->fd = demi_init(DEMI_CLOEXEC | DEMI_NONBLOCK);
+	if (dev->fd == -1) {
+		wlr_log_errno(WLR_ERROR, "Failed to subscribe to kernel events");
+		goto error_dev;
+	}
+
+	struct wl_event_loop *event_loop = wl_display_get_event_loop(disp);
+
+	dev->event = wl_event_loop_add_fd(event_loop, dev->fd,
+		WL_EVENT_READABLE, handle_event, session);
+	if (!dev->event) {
+		wlr_log_errno(WLR_ERROR, "Failed to create gpu hotplugging event source");
+		goto error_fd;
+	}
+
+	session->dev = dev;
+	return 0;
+
+error_fd:
+	close(dev->fd);
+error_dev:
+	free(dev);
+	return -1;
+}
+
+void dev_finish(struct wlr_session *session) {
+	if (!session) {
+		return;
+	}
+
+	wl_event_source_remove(session->dev->event);
+	close(session->dev->fd);
+	free(session->dev);
+}

backend/session/meson.build

@@ -6,17 +6,26 @@ libseat = dependency('libseat',
 wlr_files += files('session.c')
 wlr_deps += libseat
 
-# libudev
+# libudev & libdemi
 
 if get_option('enum-backend') == 'auto'
 	udev = dependency('libudev', required: false)
+	demi = dependency('demi', required: false)
 	if udev.found()
 		wlr_files += files('dev_udev.c')
 		wlr_deps += udev
 		features += { 'udev': true }
+	elif demi.found()
+		wlr_files += files('dev_demi.c')
+		wlr_deps += demi
+		features += { 'demi': true }
 	endif
 elif get_option('enum-backend') == 'udev'
 	wlr_files += files('dev_udev.c')
 	wlr_deps += dependency('libudev')
 	features += { 'udev': true }
+elif get_option('enum-backend') == 'demi'
+	wlr_files += files('dev_demi.c')
+	wlr_deps += dependency('demi')
+	features += { 'demi': true }
 endif

backend/session/session.c

@@ -145,7 +145,7 @@ struct wlr_session *wlr_session_create(struct wl_display *disp) {
 		goto error_open;
 	}
 
-#if WLR_HAS_UDEV
+#if WLR_HAS_UDEV || WLR_HAS_DEMI
 	if (dev_init(session, disp) == -1) {
 		wlr_log(WLR_ERROR, "Failed to initialize dev backend");
 		goto error_session;
@@ -159,7 +159,7 @@ struct wlr_session *wlr_session_create(struct wl_display *disp) {
 
 	return session;
 
-#if WLR_HAS_UDEV
+#if WLR_HAS_UDEV || WLR_HAS_DEMI
 error_session:
 	libseat_session_finish(session);
 #endif
@@ -176,7 +176,7 @@ void wlr_session_destroy(struct wlr_session *session) {
 	wlr_signal_emit_safe(&session->events.destroy, session);
 	wl_list_remove(&session->display_destroy.link);
 
-#if WLR_HAS_UDEV
+#if WLR_HAS_UDEV || WLR_HAS_DEMI
 	dev_finish(session);
 #endif
 

include/wlr/config.h.in

@@ -12,5 +12,6 @@
 #mesondefine WLR_HAS_XWAYLAND
 
 #mesondefine WLR_HAS_UDEV
+#mesondefine WLR_HAS_DEMI
 
 #endif

meson.build

@@ -93,6 +93,7 @@ features = {
 	'gles2-renderer': false,
 	'vulkan-renderer': false,
 	'udev': false,
+	'demi': false,
 }
 internal_features = {
 	'xcb-errors': false,

meson_options.txt

@@ -4,4 +4,4 @@ option('examples', type: 'boolean', value: true, description: 'Build example app
 option('icon_directory', description: 'Location used to look for cursors (default: ${datadir}/icons)', type: 'string', value: '')
 option('renderers', type: 'array', choices: ['auto', 'gles2', 'vulkan'], value: ['auto'], description: 'Select built-in renderers')
 option('backends', type: 'array', choices: ['auto', 'drm', 'libinput', 'x11'], value: ['auto'], description: 'Select built-in backends')
-option('enum-backend', type: 'combo', choices: ['auto', 'disabled', 'udev'], value: 'udev', description: 'Select device enumeration backend')
+option('enum-backend', type: 'combo', choices: ['auto', 'disabled', 'udev', 'demi'], value: 'udev', description: 'Select device enumeration backend')