move i3 sync code into sync_respond (for following commits)

Makefile.am

@@ -562,6 +562,7 @@ i3_SOURCES = \
 	src/sd-daemon.c \
 	src/sighandler.c \
 	src/startup.c \
+	src/sync.c \
 	src/tree.c \
 	src/util.c \
 	src/version.c \

include/all.h

@@ -82,4 +82,5 @@
 #include "fake_outputs.h"
 #include "display_version.h"
 #include "restore_layout.h"
+#include "sync.h"
 #include "main.h"

include/sync.h

@@ -0,0 +1,14 @@
+/*
+ * vim:ts=4:sw=4:expandtab
+ *
+ * i3 - an improved dynamic tiling window manager
+ * © 2009 Michael Stapelberg and contributors (see also: LICENSE)
+ *
+ * sync.c: i3 sync protocol: https://i3wm.org/docs/testsuite.html#i3_sync
+ *
+ */
+#pragma once
+
+#include <xcb/xcb.h>
+
+void sync_respond(xcb_window_t window, uint32_t rnd);

src/handlers.c

@@ -800,21 +800,7 @@ static void handle_client_message(xcb_client_message_event_t *event) {
     } else if (event->type == A_I3_SYNC) {
         xcb_window_t window = event->data.data32[0];
         uint32_t rnd = event->data.data32[1];
-        DLOG("[i3 sync protocol] Sending random value %d back to X11 window 0x%08x\n", rnd, window);
-
-        void *reply = scalloc(32, 1);
-        xcb_client_message_event_t *ev = reply;
-
-        ev->response_type = XCB_CLIENT_MESSAGE;
-        ev->window = window;
-        ev->type = A_I3_SYNC;
-        ev->format = 32;
-        ev->data.data32[0] = window;
-        ev->data.data32[1] = rnd;
-
-        xcb_send_event(conn, false, window, XCB_EVENT_MASK_NO_EVENT, (char *)ev);
-        xcb_flush(conn);
-        free(reply);
+        sync_respond(window, rnd);
     } else if (event->type == A__NET_REQUEST_FRAME_EXTENTS) {
         /*
          * A client can request an estimate for the frame size which the window

src/sync.c

@@ -0,0 +1,28 @@
+/*
+ * vim:ts=4:sw=4:expandtab
+ *
+ * i3 - an improved dynamic tiling window manager
+ * © 2009 Michael Stapelberg and contributors (see also: LICENSE)
+ *
+ * sync.c: i3 sync protocol: https://i3wm.org/docs/testsuite.html#i3_sync
+ *
+ */
+#include "all.h"
+
+void sync_respond(xcb_window_t window, uint32_t rnd) {
+    DLOG("[i3 sync protocol] Sending random value %d back to X11 window 0x%08x\n", rnd, window);
+
+    void *reply = scalloc(32, 1);
+    xcb_client_message_event_t *ev = reply;
+
+    ev->response_type = XCB_CLIENT_MESSAGE;
+    ev->window = window;
+    ev->type = A_I3_SYNC;
+    ev->format = 32;
+    ev->data.data32[0] = window;
+    ev->data.data32[1] = rnd;
+
+    xcb_send_event(conn, false, window, XCB_EVENT_MASK_NO_EVENT, (char *)ev);
+    xcb_flush(conn);
+    free(reply);
+}