Fix SocketServer control EOF handling (#106)

Handle EOF on the control pipe. This sometimes seems to happen in slow
test environments even though neither end of the control pipe got
closed.

Now close them properly, and use the EOF event as notification instead
of this.running and sending a control byte.

Fixes #105

src/umockdev.vala

@@ -1765,12 +1765,9 @@ private class SocketServer {
         if (!this.running)
             return;
 
-        this.running = false;
-
         // wake up the select() in our thread
         debug ("Stopping SocketServer: signalling thread");
-        char b = '1';
-        assert (Posix.write (this.ctrl_w, &b, 1) == 1);
+        Posix.close (this.ctrl_w);
 
         // merely calling remove_all() does not invoke ScriptRunner dtor, so stop manually
         foreach (unowned ScriptRunner r in this.script_runners.get_values())
@@ -1832,7 +1829,14 @@ private class SocketServer {
             if (Posix.FD_ISSET (this.ctrl_r, fds) > 0) {
                 debug ("socket server thread: woken up by control fd");
                 char buf;
-                assert (Posix.read (this.ctrl_r, &buf, 1) == 1);
+                ssize_t r = Posix.read (this.ctrl_r, &buf, 1);
+                if (r == 0) {
+                    /* EOF on ctrl_w, stop */
+                    this.running = false;
+                    Posix.close (this.ctrl_r);
+                } else {
+                    assert (r == 1);
+                }
                 continue;
             }