backend/session: wire up openbsd support

backend/session/session_openbsd.c

@@ -0,0 +1,41 @@
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include "backend/session/session.h"
+
+struct drm_event_monitor {
+	int fd;
+};
+
+// TODO: use kqueue NOTE_CHANGE mechanism
+struct drm_event_monitor *monitor_drm_events(int *fd) {
+	struct drm_event_monitor *ctx = calloc(1, sizeof(struct drm_event_monitor));
+	if (!ctx) {
+		return NULL;
+	}
+	ctx->fd = open("/dev/null", O_RDONLY);
+	if (ctx->fd == -1) {
+		free(ctx);
+		return NULL;
+	}
+	*fd = ctx->fd;
+	return ctx;
+}
+void drm_event_monitor_free(struct drm_event_monitor *ctx) {
+	close(ctx->fd);
+	free(ctx);
+}
+
+int receive_drm_device(struct drm_event_monitor *ctx,
+		struct drm_event_content *ev) {
+	return -1;
+}
+
+const char *get_device_seat(struct drm_event_monitor *ctx, const char *devnode) {
+	return NULL;
+}
+
+bool is_drm_device_primary(struct drm_event_monitor *ctx, const char *devnode) {
+	return false;
+}