swaybar: add skeleton dbus code to tray

swaybar/tray/tray.c

@@ -1,19 +1,48 @@
 #include <cairo.h>
 #include <stdint.h>
 #include <stdlib.h>
+#include <string.h>
 #include "swaybar/bar.h"
 #include "swaybar/tray/tray.h"
 #include "log.h"
 
 struct swaybar_tray *create_tray(struct swaybar *bar) {
 	wlr_log(WLR_DEBUG, "Initializing tray");
-	return NULL;
+
+	sd_bus *bus;
+	int ret = sd_bus_open_user(&bus);
+	if (ret < 0) {
+		wlr_log(WLR_ERROR, "Failed to connect to user bus: %s", strerror(-ret));
+		return NULL;
+	}
+
+	struct swaybar_tray *tray = calloc(1, sizeof(struct swaybar_tray));
+	if (!tray) {
+		return NULL;
+	}
+	tray->bar = bar;
+	tray->bus = bus;
+	tray->fd = sd_bus_get_fd(tray->bus);
+	return tray;
 }
 
 void destroy_tray(struct swaybar_tray *tray) {
+	if (!tray) {
+		return;
+	}
+	sd_bus_flush_close_unref(tray->bus);
+	free(tray);
 }
 
 void tray_in(int fd, short mask, void *data) {
+	sd_bus *bus = data;
+	int ret;
+	while ((ret = sd_bus_process(bus, NULL)) > 0) {
+		// This space intentionally left blank
+	}
+	if (ret < 0) {
+		wlr_log(WLR_ERROR, "Failed to process bus: %s", strerror(-ret));
+	}
 }
 
 uint32_t render_tray(cairo_t *cairo, struct swaybar_output *output, double *x) {