Add a mode to ensure a server is not already running.

tools/xdisplaycheck/xdisplaycheck.cc

Index: tools/xdisplaycheck/xdisplaycheck.cc
===================================================================
--- tools/xdisplaycheck/xdisplaycheck.cc	(revision 135379)
+++ tools/xdisplaycheck/xdisplaycheck.cc	(working copy)
@@ -12,6 +12,7 @@
 
 #include <errno.h>
 #include <stdio.h>
+#include <string.h>
 #include <time.h>
 #include <X11/Xlib.h>
 
@@ -34,8 +35,18 @@
 }
 
 int main(int argc, char* argv[]) {
+  Display* display = NULL;
+  if (argv[1] && strcmp(argv[1], "--noserver")==0) {

[cmp, 2012/05/18 20:05:24]

spaces around ==

[Peter Mayo, 2012/05/18 20:25:44]

Done.

+    display = XOpenDisplay(NULL);
+    if (display) {
+      fprintf(stderr, "Found unexpected connectable display %s\n",
+              XDisplayName(NULL));
+    }
+    // Use upside down logic to resemble previous behaviour.

[cmp, 2012/05/18 20:05:24]

can you change this comment to be more explicit about the case you're returning
on?  (for example 'previous behavior' won't be clear later to others looking at
the code, 'upside down logic' is not clear to me.)

[Peter Mayo, 2012/05/18 20:25:44]

Better?

+    return !display;
+  }
+
   int kNumTries = 78;  // 78*77/2 * 10 = 30s of waiting
-  Display* display = NULL;
   int tries;
   for (tries = 0; tries < kNumTries; ++tries) {
     display = XOpenDisplay(NULL);