xserver: Clean up lockfile creation a bit

compositor/xserver-launcher.c

@@ -648,74 +648,96 @@ bind_to_unix_socket(int display)
 	return fd;
 }
 
-int
+static int
-wlsc_xserver_init(struct wlsc_compositor *compositor)
+create_lockfile(int display, char *lockfile, size_t lsize)
 {
-	struct wl_display *display = compositor->wl_display;
+	char pid[16], *end;
-	struct wlsc_xserver *mxs;
-	char lockfile[256], pid[16], *end;
-	pid_t other;
 	int fd, size;
+	pid_t other;
 
-	mxs = malloc(sizeof *mxs);
+	snprintf(lockfile, lsize, "/tmp/.X%d-lock", display);
-	memset(mxs, 0, sizeof *mxs);
+	fd = open(lockfile, O_WRONLY | O_CLOEXEC | O_CREAT | O_EXCL, 0444);
-
-	mxs->process.cleanup = wlsc_xserver_cleanup;
-	mxs->wl_display = display;
-
-	mxs->display = 0;
-	do {
-		snprintf(lockfile, sizeof lockfile,
-			 "/tmp/.X%d-lock", mxs->display);
-		fd = open(lockfile,
-			  O_WRONLY | O_CLOEXEC | O_CREAT | O_EXCL, 0444);
 	if (fd < 0 && errno == EEXIST) {
 		fd = open(lockfile, O_CLOEXEC, O_RDONLY);
 		if (fd < 0 || read(fd, pid, 11) != 11) {
-				fprintf(stderr,
+			fprintf(stderr, "can't read lock file %s: %s\n",
-					"can't read lock file %s: %s\n",
 				lockfile, strerror(errno));
-				mxs->display++;
+			errno = EEXIST;
-				continue;
+			return -1;
 		}
 
 		other = strtol(pid, &end, 0);
 		if (end != pid + 10) {
 			fprintf(stderr, "can't parse lock file %s\n",
 				lockfile);
-				mxs->display++;
+			errno = EEXIST;
-				continue;
+			return -1;
 		}
 
 		if (kill(other, 0) < 0 && errno == ESRCH) {
 			/* stale lock file; unlink and try again */
 			fprintf(stderr,
-					"unlinking stale lock file %s\n",
+				"unlinking stale lock file %s\n", lockfile);
-					lockfile);
 			unlink(lockfile);
-				continue;
+			errno = EAGAIN;
+			return -1;
 		}
 
-			mxs->display++;
+		errno = EEXIST;
-			continue;
+		return -1;
 	} else if (fd < 0) {
 		fprintf(stderr, "failed to create lock file %s: %s\n",
 			lockfile, strerror(errno));
-			free(mxs);
 		return -1;
 	}
 
 	/* Subtle detail: we use the pid of the wayland
 	 * compositor, not the xserver in the lock file. */
 	size = snprintf(pid, sizeof pid, "%10d\n", getpid());
-		write(fd, pid, size);
+	if (write(fd, pid, size) != size) {
+		unlink(lockfile);
 		close(fd);
+		return -1;
+	}
+
+	close(fd);
+
+	return 0;
+}
+
+int
+wlsc_xserver_init(struct wlsc_compositor *compositor)
+{
+	struct wl_display *display = compositor->wl_display;
+	struct wlsc_xserver *mxs;
+	char lockfile[256];
+
+	mxs = malloc(sizeof *mxs);
+	memset(mxs, 0, sizeof *mxs);
+
+	mxs->process.cleanup = wlsc_xserver_cleanup;
+	mxs->wl_display = display;
+
+	mxs->display = 0;
+
+ retry:
+	if (create_lockfile(mxs->display, lockfile, sizeof lockfile) < 0) {
+		if (errno == EAGAIN) {
+			goto retry;
+		} else if (errno == EEXIST) {
+			mxs->display++;
+			goto retry;
+		} else {
+			free(mxs);
+			return -1;
+		}
+	}				
 
 	mxs->abstract_fd = bind_to_abstract_socket(mxs->display);
 	if (mxs->abstract_fd < 0 && errno == EADDRINUSE) {
 		mxs->display++;
 		unlink(lockfile);
-			continue;
+		goto retry;
 	}
 
 	mxs->unix_fd = bind_to_unix_socket(mxs->display);
@@ -726,9 +748,6 @@ wlsc_xserver_init(struct wlsc_compositor *compositor)
 		return -1;
 	}
 
-		break;
-	} while (errno != 0);
-
 	fprintf(stderr, "xserver listening on display :%d\n", mxs->display);
 
 	mxs->loop = wl_display_get_event_loop(display);