From ae2cdf0fad921e6ac805fcc0366979f3ae177f0d Mon Sep 17 00:00:00 2001
From: Jamie Strandboge <jamie@ubuntu.com>
Date: Tue, 9 Apr 2013 08:31:39 -0500
Subject: [PATCH] Fix two race conditions: 1) make sure that the xpra socket
 exists before trying to attach to it 2) make sure that the client has
 attached before we start the application

The fix for '1' solves a problem when the system is under load and the
one for '2' fixes a problem with firefox starting too soon and not
having system themes applied.

Exercising the 1 week rule. Seth Arnold commented on the added sleeps and I
adjusted one based on his comments and replied to the list that the other is
needed and that this improves the sandbox/xpra code but that there are
limitations with driving xpra.

Acked-By: Jamie Strandboge <jamie@canonical.com>
---
 utils/apparmor/sandbox.py | 45 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 40 insertions(+), 5 deletions(-)

diff --git a/utils/apparmor/sandbox.py b/utils/apparmor/sandbox.py
index 4171ef4f0..dc2d19151 100644
--- a/utils/apparmor/sandbox.py
+++ b/utils/apparmor/sandbox.py
@@ -1,6 +1,6 @@
 # ------------------------------------------------------------------
 #
-#    Copyright (C) 2011-2012 Canonical Ltd.
+#    Copyright (C) 2011-2013 Canonical Ltd.
 #
 #    This program is free software; you can redistribute it and/or
 #    modify it under the terms of version 2 of the GNU General Public
@@ -15,6 +15,7 @@ import os
 import pwd
 import re
 import signal
+import socket
 import sys
 import tempfile
 import time
@@ -605,13 +606,36 @@ EndSection
         self.pids.append(listener_x)
 
         started = False
-        time.sleep(0.5) # FIXME: detect if running
-        for i in range(self.timeout): # 5 seconds to start
+
+        # We need to wait for the xpra socket to exist before attaching
+        fn = os.path.join(os.environ['HOME'], '.xpra', '%s-%s' % \
+                          (socket.gethostname(), self.display.split(':')[1]))
+        for i in range(self.timeout * 2): # up to self.timeout seconds to start
+            if os.path.exists(fn):
+                debug("Found '%s'! Proceeding to attach" % fn)
+                break
+            debug("'%s' doesn't exist yet, waiting" % fn)
+            time.sleep(0.5)
+
+        if not os.path.exists(fn):
+            sys.stdout.flush()
+            self.cleanup()
+            raise AppArmorException("Could not start xpra (try again with -d)")
+
+        for i in range(self.timeout): # Up to self.timeout seconds to start
             rc, out = cmd(['xpra', 'list'])
-            if 'LIVE session at %s' % self.display in out:
+
+            if 'DEAD session at %s' % self.display in out:
+                error("xpra session at '%s' died" % self.display, do_exit=False)
+                break
+
+            search = 'LIVE session at %s' % self.display
+            if search in out:
                 started = True
                 break
-            time.sleep(1)
+            time.sleep(0.5)
+            debug("Could not find '%s' in:\n" % search)
+            debug(out)
 
         if not started:
             sys.stdout.flush()
@@ -638,6 +662,17 @@ EndSection
 
         self.pids.append(listener_attach)
 
+        # Make sure that a client has attached
+        for i in range(self.timeout): # up to self.timeout seconds to attach
+            time.sleep(1)
+            rc, out = cmd (['xpra', 'info', self.display])
+            search = 'clients=1'
+            if search in out:
+                debug("Client successfully attached!")
+                break
+            debug("Could not find '%s' in:\n" % search)
+            debug(out)
+
         msg("TODO: filter '~/.xpra/run-xpra'")