Add `dbus_get_prop_async` utility

This drastically reduces the amount of boilerplate needed to get a
property from a bus object.

4 files changed, 137 insertions, 293 deletions

diff --git a/include/swaybar/tray/dbus.h b/include/swaybar/tray/dbus.h
index 51754464..125ce96f 100644
--- a/include/swaybar/tray/dbus.h
+++ b/include/swaybar/tray/dbus.h
@@ -12,6 +12,23 @@ extern DBusConnection *conn;
 bool dbus_message_iter_check_signature(DBusMessageIter *iter, const char *sig);
 
 /**
+ * Fetches the property and calls `callback` with a message iter pointing it.
+ * Performs error handling and signature checking.
+ *
+ * Returns: true if message is successfully sent (will not necessarily arrive)
+ * and false otherwise
+ *
+ * NOTE: `expected_signature` must remain valid until the message reply is
+ * received, please only use 'static signatures.
+ */
+bool dbus_get_prop_async(const char *destination,
+		const char *path,
+		const char *iface,
+		const char *prop,
+		const char *expected_signature,
+		void(*callback)(DBusMessageIter *iter, void *data),
+		void *data);
+/**
  * Should be called in main loop to dispatch events
  */
 void dispatch_dbus();
diff --git a/swaybar/tray/dbus.c b/swaybar/tray/dbus.c
index 46a1c807..4439fb83 100644
--- a/swaybar/tray/dbus.c
+++ b/swaybar/tray/dbus.c
@@ -136,7 +136,58 @@ static void dispatch_status(DBusConnection *connection, DBusDispatchStatus new_s
 	}
 }
 
-/* Public functions below */
+struct async_prop_data {
+	char const *sig;
+	void(*callback)(DBusMessageIter *, void *);
+	void *usr_data;
+};
+
+static void get_prop_callback(DBusPendingCall *pending, void *_data) {
+	struct async_prop_data *data = _data;
+
+	DBusMessage *reply = dbus_pending_call_steal_reply(pending);
+
+	if (!reply) {
+		sway_log(L_INFO, "Got no icon name reply from item");
+		goto bail;
+	}
+
+	if (dbus_message_get_type(reply) == DBUS_MESSAGE_TYPE_ERROR) {
+		char *msg;
+
+		dbus_message_get_args(reply, NULL,
+				DBUS_TYPE_STRING, &msg,
+				DBUS_TYPE_INVALID);
+
+		sway_log(L_INFO, "Failure to get property: %s", msg);
+		goto bail;
+	}
+
+	DBusMessageIter iter;
+	DBusMessageIter variant;
+
+	dbus_message_iter_init(reply, &iter);
+	if (dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_VARIANT) {
+		sway_log(L_ERROR, "Property relpy type incorrect");
+		goto bail;
+	}
+	dbus_message_iter_recurse(&iter, &variant);
+
+	if (!dbus_message_iter_check_signature(&variant, data->sig)) {
+		sway_log(L_INFO, "Property returned has incorrect signatue.");
+		goto bail;
+	}
+
+	data->callback(&variant, data->usr_data);
+
+bail:
+	if (reply) {
+		dbus_message_unref(reply);
+	}
+	dbus_pending_call_unref(pending);
+}
+
+/* Public functions below -- see header for docs*/
 
 bool dbus_message_iter_check_signature(DBusMessageIter *iter, const char *sig) {
 	char *msg_sig = dbus_message_iter_get_signature(iter);
@@ -145,6 +196,43 @@ bool dbus_message_iter_check_signature(DBusMessageIter *iter, const char *sig) {
 	return (result == 0);
 }
 
+bool dbus_get_prop_async(const char *destination,
+		const char *path, const char *iface,
+		const char *prop, const char *expected_signature,
+		void(*callback)(DBusMessageIter *, void *), void *usr_data) {
+	struct async_prop_data *data = malloc(sizeof(struct async_prop_data));
+	if (!data) {
+		return false;
+	}
+	DBusPendingCall *pending;
+	DBusMessage *message = dbus_message_new_method_call(
+			destination, path,
+			"org.freedesktop.DBus.Properties",
+			"Get");
+
+	dbus_message_append_args(message,
+			DBUS_TYPE_STRING, &iface,
+			DBUS_TYPE_STRING, &prop,
+			DBUS_TYPE_INVALID);
+
+	bool status =
+		dbus_connection_send_with_reply(conn, message, &pending, -1);
+
+	dbus_message_unref(message);
+
+	if (!(pending || status)) {
+		sway_log(L_ERROR, "Could not get property");
+		return false;
+	}
+
+	data->sig = expected_signature;
+	data->callback = callback;
+	data->usr_data = usr_data;
+	dbus_pending_call_set_notify(pending, get_prop_callback, data, free);
+
+	return true;
+}
+
 void dispatch_dbus() {
 	if (!should_dispatch || !conn) {
 		return;
diff --git a/swaybar/tray/sni.c b/swaybar/tray/sni.c
index 401a0091..200422da 100644
--- a/swaybar/tray/sni.c
+++ b/swaybar/tray/sni.c
@@ -14,6 +14,9 @@
 #include "client/cairo.h"
 #include "log.h"
 
+static const char *KDE_IFACE = "org.kde.StatusNotifierItem";
+static const char *FD_IFACE = "org.freedesktop.StatusNotifierItem";
+
 // Not sure what this is but cairo needs it.
 static const cairo_user_data_key_t cairo_user_data_key;
 
@@ -38,57 +41,19 @@ void sni_icon_ref_free(struct sni_icon_ref *sni_ref) {
 }
 
 /* Gets the pixmap of an icon */
-static void reply_icon(DBusPendingCall *pending, void *_data) {
+static void reply_icon(DBusMessageIter *iter /* a(iiay) */, void *_data) {
 	struct StatusNotifierItem *item = _data;
 
-	DBusMessage *reply = dbus_pending_call_steal_reply(pending);
-
-	if (!reply) {
-		sway_log(L_ERROR, "Did not get reply");
-		goto bail;
-	}
-
-	int message_type = dbus_message_get_type(reply);
-
-	if (message_type == DBUS_MESSAGE_TYPE_ERROR) {
-		char *msg;
-
-		dbus_message_get_args(reply, NULL,
-				DBUS_TYPE_STRING, &msg,
-				DBUS_TYPE_INVALID);
-
-		sway_log(L_ERROR, "Message is error: %s", msg);
-		goto bail;
-	}
-
-	DBusMessageIter iter;
-	DBusMessageIter variant; /* v[a(iiay)] */
-	DBusMessageIter array; /* a(iiay) */
 	DBusMessageIter d_struct; /* (iiay) */
 	DBusMessageIter icon; /* ay */
 
-	dbus_message_iter_init(reply, &iter);
-
-	// Each if here checks the types above before recursing
-	if (dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_VARIANT) {
-		sway_log(L_ERROR, "Icon relpy type incorrect");
-		goto bail;
-	}
-	dbus_message_iter_recurse(&iter, &variant);
-
-	if (dbus_message_iter_check_signature(&variant, "a(iiay)")) {
-		sway_log(L_ERROR, "Icon relpy type incorrect");
-		goto bail;
-	}
-
-	if (dbus_message_iter_get_element_count(&variant) == 0) {
+	if (dbus_message_iter_get_element_count(iter) == 0) {
 		// Can't recurse if there are no items
 		sway_log(L_INFO, "Item has no icon");
-		goto bail;
+		return;
 	}
-	dbus_message_iter_recurse(&variant, &array);
 
-	dbus_message_iter_recurse(&array, &d_struct);
+	dbus_message_iter_recurse(iter, &d_struct);
 
 	int width;
 	dbus_message_iter_get_basic(&d_struct, &width);
@@ -102,13 +67,13 @@ static void reply_icon(DBusPendingCall *pending, void *_data) {
 
 	if (!len) {
 		sway_log(L_ERROR, "No icon data");
-		goto bail;
+		return;
 	}
 
 	// Also implies len % 4 == 0, useful below
 	if (len != width * height * 4) {
 		sway_log(L_ERROR, "Incorrect array size passed");
-		goto bail;
+		return;
 	}
 
 	dbus_message_iter_recurse(&d_struct, &icon);
@@ -117,7 +82,7 @@ static void reply_icon(DBusPendingCall *pending, void *_data) {
 	// FIXME support a variable stride
 	// (works on my machine though for all tested widths)
 	if (!sway_assert(stride == width * 4, "Stride must be equal to byte length")) {
-		goto bail;
+		return;
 	}
 
 	// Data is by reference, no need to free
@@ -127,7 +92,7 @@ static void reply_icon(DBusPendingCall *pending, void *_data) {
 	uint8_t *image_data = malloc(stride * height);
 	if (!image_data) {
 		sway_log(L_ERROR, "Could not allocate memory for icon");
-		goto bail;
+		return;
 	}
 
 	// Transform from network byte order to host byte order
@@ -155,97 +120,22 @@ static void reply_icon(DBusPendingCall *pending, void *_data) {
 		item->dirty = true;
 		dirty = true;
 
-		dbus_message_unref(reply);
-		dbus_pending_call_unref(pending);
 		return;
 	} else {
 		sway_log(L_ERROR, "Could not create image surface");
 		free(image_data);
 	}
 
-bail:
-	if (reply) {
-		dbus_message_unref(reply);
-	}
-	dbus_pending_call_unref(pending);
 	sway_log(L_ERROR, "Could not get icon from item");
 	return;
 }
-static void send_icon_msg(struct StatusNotifierItem *item) {
-	DBusPendingCall *pending;
-	DBusMessage *message = dbus_message_new_method_call(
-			item->name,
-			item->object_path,
-			"org.freedesktop.DBus.Properties",
-			"Get");
-	const char *iface;
-	if (item->kde_special_snowflake) {
-		iface = "org.kde.StatusNotifierItem";
-	} else {
-		iface = "org.freedesktop.StatusNotifierItem";
-	}
-	const char *prop = "IconPixmap";
-
-	dbus_message_append_args(message,
-			DBUS_TYPE_STRING, &iface,
-			DBUS_TYPE_STRING, &prop,
-			DBUS_TYPE_INVALID);
-
-	bool status =
-		dbus_connection_send_with_reply(conn, message, &pending, -1);
-
-	dbus_message_unref(message);
-
-	if (!(pending || status)) {
-		sway_log(L_ERROR, "Could not get item icon");
-		return;
-	}
-
-	dbus_pending_call_set_notify(pending, reply_icon, item, NULL);
-}
 
 /* Get an icon by its name */
-static void reply_icon_name(DBusPendingCall *pending, void *_data) {
+static void reply_icon_name(DBusMessageIter *iter, void *_data) {
 	struct StatusNotifierItem *item = _data;
 
-	DBusMessage *reply = dbus_pending_call_steal_reply(pending);
-
-	if (!reply) {
-		sway_log(L_INFO, "Got no icon name reply from item");
-		goto bail;
-	}
-
-	int message_type = dbus_message_get_type(reply);
-
-	if (message_type == DBUS_MESSAGE_TYPE_ERROR) {
-		char *msg;
-
-		dbus_message_get_args(reply, NULL,
-				DBUS_TYPE_STRING, &msg,
-				DBUS_TYPE_INVALID);
-
-		sway_log(L_INFO, "Could not get icon name: %s", msg);
-		goto bail;
-	}
-
-	DBusMessageIter iter; /* v[s] */
-	DBusMessageIter variant; /* s */
-
-	dbus_message_iter_init(reply, &iter);
-	if (dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_VARIANT) {
-		sway_log(L_ERROR, "Icon name relpy type incorrect");
-		goto bail;
-	}
-	dbus_message_iter_recurse(&iter, &variant);
-
-
-	if (dbus_message_iter_get_arg_type(&variant) != DBUS_TYPE_STRING) {
-		sway_log(L_ERROR, "Icon name relpy type incorrect");
-		goto bail;
-	}
-
 	char *icon_name;
-	dbus_message_iter_get_basic(&variant, &icon_name);
+	dbus_message_iter_get_basic(iter, &icon_name);
 
 	cairo_surface_t *image = find_icon(icon_name, 256);
 
@@ -259,55 +149,19 @@ static void reply_icon_name(DBusPendingCall *pending, void *_data) {
 		item->dirty = true;
 		dirty = true;
 
-		dbus_message_unref(reply);
-		dbus_pending_call_unref(pending);
 		return;
 	}
 
-bail:
-	if (reply) {
-		dbus_message_unref(reply);
-	}
-	dbus_pending_call_unref(pending);
 	// Now try the pixmap
-	send_icon_msg(item);
-	return;
-}
-static void send_icon_name_msg(struct StatusNotifierItem *item) {
-	DBusPendingCall *pending;
-	DBusMessage *message = dbus_message_new_method_call(
-			item->name,
-			item->object_path,
-			"org.freedesktop.DBus.Properties",
-			"Get");
-	const char *iface;
-	if (item->kde_special_snowflake) {
-		iface = "org.kde.StatusNotifierItem";
-	} else {
-		iface = "org.freedesktop.StatusNotifierItem";
-	}
-	const char *prop = "IconName";
-
-	dbus_message_append_args(message,
-			DBUS_TYPE_STRING, &iface,
-			DBUS_TYPE_STRING, &prop,
-			DBUS_TYPE_INVALID);
-
-	bool status =
-		dbus_connection_send_with_reply(conn, message, &pending, -1);
-
-	dbus_message_unref(message);
-
-	if (!(pending || status)) {
-		sway_log(L_ERROR, "Could not get item icon name");
-		return;
-	}
-
-	dbus_pending_call_set_notify(pending, reply_icon_name, item, NULL);
+	dbus_get_prop_async(item->name, item->object_path,
+		(item->kde_special_snowflake ? KDE_IFACE : FD_IFACE),
+		"IconPixmap", "a(iiay)", reply_icon, item);
 }
 
 void get_icon(struct StatusNotifierItem *item) {
-	send_icon_name_msg(item);
+	dbus_get_prop_async(item->name, item->object_path,
+		(item->kde_special_snowflake ? KDE_IFACE : FD_IFACE),
+		"IconName", "s", reply_icon_name, item);
 }
 
 void sni_activate(struct StatusNotifierItem *item, uint32_t x, uint32_t y) {
diff --git a/swaybar/tray/tray.c b/swaybar/tray/tray.c
index f1ecb429..89e7c3e2 100644
--- a/swaybar/tray/tray.c
+++ b/swaybar/tray/tray.c
@@ -38,47 +38,13 @@ static void register_host(char *name) {
 	dbus_message_unref(message);
 }
 
-static void get_items_reply(DBusPendingCall *pending, void *_data) {
-	DBusMessage *reply = dbus_pending_call_steal_reply(pending);
-
-	if (!reply) {
-		sway_log(L_ERROR, "Got no items reply from sni watcher");
-		goto bail;
-	}
-
-	int message_type = dbus_message_get_type(reply);
-
-	if (message_type == DBUS_MESSAGE_TYPE_ERROR) {
-		char *msg;
-
-		dbus_message_get_args(reply, NULL,
-				DBUS_TYPE_STRING, &msg,
-				DBUS_TYPE_INVALID);
-
-		sway_log(L_ERROR, "Message is error: %s", msg);
-		goto bail;
-	}
-
-	DBusMessageIter iter;
-	DBusMessageIter variant;
+static void get_items_reply(DBusMessageIter *iter, void *_data) {
 	DBusMessageIter array;
 
-	dbus_message_iter_init(reply, &iter);
-	if (dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_VARIANT) {
-		sway_log(L_ERROR, "Replyed with wrong type, not v(as)");
-		goto bail;
-	}
-	dbus_message_iter_recurse(&iter, &variant);
-	if (dbus_message_iter_get_arg_type(&variant) != DBUS_TYPE_ARRAY ||
-			dbus_message_iter_get_element_type(&variant) != DBUS_TYPE_STRING) {
-		sway_log(L_ERROR, "Replyed with wrong type, not v(as)");
-		goto bail;
-	}
-
 	// O(n) function, could be faster dynamically reading values
-	int len = dbus_message_iter_get_element_count(&variant);
+	int len = dbus_message_iter_get_element_count(iter);
 
-	dbus_message_iter_recurse(&variant, &array);
+	dbus_message_iter_recurse(iter, &array);
 	for (int i = 0; i < len; i++) {
 		const char *name;
 		dbus_message_iter_get_basic(&array, &name);
@@ -93,52 +59,14 @@ static void get_items_reply(DBusPendingCall *pending, void *_data) {
 			}
 		}
 	}
-
-bail:
-	dbus_message_unref(reply);
-	dbus_pending_call_unref(pending);
-	return;
 }
-static void get_obj_items_reply(DBusPendingCall *pending, void *_data) {
-	DBusMessage *reply = dbus_pending_call_steal_reply(pending);
-
-	if (!reply) {
-		sway_log(L_ERROR, "Got no object path items reply from sni watcher");
-		goto bail;
-	}
-
-	int message_type = dbus_message_get_type(reply);
-
-	if (message_type == DBUS_MESSAGE_TYPE_ERROR) {
-		char *msg;
-
-		dbus_message_get_args(reply, NULL,
-				DBUS_TYPE_STRING, &msg,
-				DBUS_TYPE_INVALID);
-
-		sway_log(L_ERROR, "Message is error: %s", msg);
-		goto bail;
-	}
-
-	DBusMessageIter iter;
-	DBusMessageIter variant;
+static void get_obj_items_reply(DBusMessageIter *iter, void *_data) {
 	DBusMessageIter array;
 	DBusMessageIter dstruct;
 
-	dbus_message_iter_init(reply, &iter);
-	if (dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_VARIANT) {
-		sway_log(L_ERROR, "Replyed with wrong type, not v(a(os))");
-		goto bail;
-	}
-	dbus_message_iter_recurse(&iter, &variant);
-	if (dbus_message_iter_check_signature(&iter, "a(os)")) {
-		sway_log(L_ERROR, "Replyed with wrong type not a(os)");
-		goto bail;
-	}
-
-	int len = dbus_message_iter_get_element_count(&variant);
+	int len = dbus_message_iter_get_element_count(iter);
 
-	dbus_message_iter_recurse(&variant, &array);
+	dbus_message_iter_recurse(iter, &array);
 	for (int i = 0; i < len; i++) {
 		const char *object_path;
 		const char *unique_name;
@@ -164,10 +92,6 @@ static void get_obj_items_reply(DBusPendingCall *pending, void *_data) {
 			}
 		}
 	}
-
-bail:
-	dbus_message_unref(reply);
-	dbus_pending_call_unref(pending);
 }
 
 static void get_items() {
@@ -176,52 +100,13 @@ static void get_items() {
 	list_free(tray->items);
 	tray->items = create_list();
 
-	DBusPendingCall *pending;
-	DBusMessage *message = dbus_message_new_method_call(
-			"org.freedesktop.StatusNotifierWatcher",
-			"/StatusNotifierWatcher",
-			"org.freedesktop.DBus.Properties",
-			"Get");
-
-	const char *iface = "org.freedesktop.StatusNotifierWatcher";
-	const char *prop = "RegisteredStatusNotifierItems";
-	dbus_message_append_args(message,
-			DBUS_TYPE_STRING, &iface,
-			DBUS_TYPE_STRING, &prop,
-			DBUS_TYPE_INVALID);
-
-	bool status =
-		dbus_connection_send_with_reply(conn, message, &pending, -1);
-	dbus_message_unref(message);
-
-	if (!(pending || status)) {
-		sway_log(L_ERROR, "Could not get items");
-		return;
-	}
-
-	dbus_pending_call_set_notify(pending, get_items_reply, NULL, NULL);
+	dbus_get_prop_async("org.freedesktop.StatusNotifierWatcher",
+		"/StatusNotifierWatcher","org.freedesktop.StatusNotifierWatcher",
+		"RegisteredStatusNotifierItems", "as", get_items_reply, NULL);
 
-	message = dbus_message_new_method_call(
-			"org.freedesktop.StatusNotifierWatcher",
-			"/StatusNotifierWatcher",
-			"org.freedesktop.DBus.Properties",
-			"Get");
-
-	iface = "org.swaywm.LessSuckyStatusNotifierWatcher";
-	prop = "RegisteredObjectPathItems";
-	dbus_message_append_args(message,
-			DBUS_TYPE_STRING, &iface,
-			DBUS_TYPE_STRING, &prop,
-			DBUS_TYPE_INVALID);
-
-	status = dbus_connection_send_with_reply(conn, message, &pending, -1);
-	dbus_message_unref(message);
-
-	if (!(pending || status)) {
-		sway_log(L_ERROR, "Could not get items");
-		return;
-	}
-	dbus_pending_call_set_notify(pending, get_obj_items_reply, NULL, NULL);
+	dbus_get_prop_async("org.freedesktop.StatusNotifierWatcher",
+		"/StatusNotifierWatcher","org.swaywm.LessSuckyStatusNotifierWatcher",
+		"RegisteredObjectPathItems", "a(os)", get_obj_items_reply, NULL);
 }
 
 static DBusHandlerResult signal_handler(DBusConnection *connection,