From 7a5d3c4d3bf8c2f21fcec65182f1563f4c857408 Mon Sep 17 00:00:00 2001
From: sghctoma <sghctoma@gmail.com>
Date: Fri, 7 Sep 2018 16:37:25 +0200
Subject: [PATCH] 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 | 34 +++++++++-----------------------
 backend/session/direct-ipc.c     | 10 ++++++----
 2 files changed, 15 insertions(+), 29 deletions(-)

diff --git a/backend/session/direct-freebsd.c b/backend/session/direct-freebsd.c
index 7784296b..cecfb0c1 100644
--- a/backend/session/direct-freebsd.c
+++ b/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;
-	if (fstat(fd, &st) < 0) {
-		wlr_log_errno(WLR_ERROR, "Stat failed");
-		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) {
+	int ev;
+	struct drm_version dv = {0};
+	if (ioctl(fd, DRM_IOCTL_VERSION, &dv) == 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 (name != NULL && strncmp(name, "drm/", 4) == 0) {
+			if (ioctl(dev->fd, DRM_IOCTL_VERSION, &dv) == 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 (name != NULL && strncmp(name, "drm/", 4) == 0) {
+			if (ioctl(dev->fd, DRM_IOCTL_VERSION, &dv) == 0) {
 				direct_ipc_setmaster(session->sock, dev->fd);
 			}
 		}
diff --git a/backend/session/direct-ipc.c b/backend/session/direct-ipc.c
index 99ffcb1b..302b639e 100644
--- a/backend/session/direct-ipc.c
+++ b/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) &&
-				strncmp(msg.path, "/dev/input/event", 16)) {
-
+			int ev;
+			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