Implement device type discovery using ioctl calls

This commit implements device type discovery by calling two ioctls
(DRM_IOCTL_VERSION and EVIOCGVERSION) on the device. These iocts are
specific to drm and input devices respectively, therefore we can
determine the device type based on which one returns an error.

backend/session/direct-freebsd.c

@@ -15,6 +15,7 @@
 #include <wayland-server.h>
 #include <wlr/backend/session/interface.h>
 #include <wlr/util/log.h>
+#include <xf86drm.h>
 #include "backend/session/direct-ipc.h"
 #include "util/signal.h"
 
@@ -47,24 +48,11 @@ static int direct_session_open(struct wlr_session *base, const char *path) {
 static void direct_session_close(struct wlr_session *base, int fd) {
 	struct direct_session *session = wl_container_of(base, session, base);
 
-	struct stat st;
+	int ev;
-	if (fstat(fd, &st) < 0) {
+	struct drm_version dv = {0};
-		wlr_log_errno(WLR_ERROR, "Stat failed");
+	if (ioctl(fd, DRM_IOCTL_VERSION, &dv) == 0) {
-		close(fd);
-		return;
-	}
-
-	char *name;
-	name = devname(st.st_rdev, S_IFCHR);
-	if (name == NULL) {
-		wlr_log_errno(WLR_ERROR, "Failed to get device name");
-		close(fd);
-		return;
-	}
-
-	if (strncmp(name, "drm/", 4) == 0) {
 		direct_ipc_dropmaster(session->sock, fd);
-	} else if (strncmp(name, "input/event", 11)) {
+	} else if (ioctl(fd, EVIOCGVERSION, &ev) == 0) {
 		ioctl(fd, EVIOCREVOKE, 0);
 	}
 
@@ -104,16 +92,15 @@ static void direct_session_destroy(struct wlr_session *base) {
 
 static int vt_handler(int signo, void *data) {
 	struct direct_session *session = data;
+	struct drm_version dv = {0};
+	struct wlr_device *dev;
 
 	if (session->base.active) {
 		session->base.active = false;
 		wlr_signal_emit_safe(&session->base.session_signal, session);
 
-		char *name;
-		struct wlr_device *dev;
 		wl_list_for_each(dev, &session->base.devices, link) {
-			name = devname(dev->dev, S_IFCHR);
+			if (ioctl(dev->fd, DRM_IOCTL_VERSION, &dv) == 0) {
-			if (name != NULL && strncmp(name, "drm/", 4) == 0) {
 				direct_ipc_dropmaster(session->sock, dev->fd);
 			}
 		}
@@ -122,11 +109,8 @@ static int vt_handler(int signo, void *data) {
 	} else {
 		ioctl(session->tty_fd, VT_RELDISP, VT_ACKACQ);
 
-		char *name;
-		struct wlr_device *dev;
 		wl_list_for_each(dev, &session->base.devices, link) {
-			name = devname(dev->dev, S_IFCHR);
+			if (ioctl(dev->fd, DRM_IOCTL_VERSION, &dv) == 0) {
-			if (name != NULL && strncmp(name, "drm/", 4) == 0) {
 				direct_ipc_setmaster(session->sock, dev->fd);
 			}
 		}

backend/session/direct-ipc.c

@@ -3,6 +3,7 @@
 #define __BSD_VISIBLE 1
 #define INPUT_MAJOR 0
 #endif
+#include <dev/evdev/input.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
@@ -159,14 +160,15 @@ static void communicate(int sock) {
 				ret = errno;
 			}
 #else
-			if (strncmp(msg.path, "/dev/drm/", 9) &&
+			int ev;
-				strncmp(msg.path, "/dev/input/event", 16)) {
+			struct drm_version dv = {0};
-
+			if (ioctl(fd, EVIOCGVERSION, &ev) == -1 &&
+					ioctl(fd, DRM_IOCTL_VERSION, &dv) == -1) {
 				ret = ENOTSUP;
 				goto error;
 			}
 
-			if (strncmp(msg.path, "/dev/drm/", 9) == 0 && drmSetMaster(fd)) {
+			if (dv.version_major != 0 && drmSetMaster(fd)) {
 				ret = errno;
 			}
 #endif