Handle exception writing to Chromoting host's stdin.

remoting/host/linux/linux_me2me_host.py

 #!/usr/bin/python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Virtual Me2Me implementation.  This script runs and manages the processes
 # required for a Virtual Me2Me desktop, which are: X server, X desktop
 # session, and Host process.
 # This script is intended to run continuously as a background daemon
 # process, running under an ordinary (non-root) user account.
@@ skipping 491 matching lines @@
         ParentProcessLogger.instance().release_parent()
 
     signal.signal(signal.SIGUSR1, sigusr1_handler)
     args.append("--signal-parent")
 
     self.host_proc = subprocess.Popen(args, env=self.child_env,
                                       stdin=subprocess.PIPE)
     logging.info(args)
     if not self.host_proc.pid:
       raise Exception("Could not start Chrome Remote Desktop host")
-    self.host_proc.stdin.write(json.dumps(host_config.data))
-    self.host_proc.stdin.close()
+
+    try:
+      self.host_proc.stdin.write(json.dumps(host_config.data))
+      self.host_proc.stdin.flush()
+    except IOError as e:
+      # This can occur in rare situations, for example, if the machine is
+      # heavily loaded and the host process dies quickly (maybe if the X
+      # connection failed), the host process might be gone before this code
+      # writes to the host's stdin. Catch and log the exception, allowing
+      # the process to be retried instead of exiting the script completely.
+      logging.error("Failed writing to host's stdin: " + str(e))
+    finally:
+      self.host_proc.stdin.close()
 
 
 def get_daemon_proc():
   """Checks if there is already an instance of this script running, and returns
   a psutil.Process instance for it.
 
   Returns:
     A Process instance for the existing daemon process, or None if the daemon
     is not running.
   """
@@ skipping 818 matching lines @@
         else:
           logging.info("Host exited with status %s." % os.WEXITSTATUS(status))
       elif os.WIFSIGNALED(status):
         logging.info("Host terminated by signal %s." % os.WTERMSIG(status))
 
 
 if __name__ == "__main__":
   logging.basicConfig(level=logging.DEBUG,
                       format="%(asctime)s:%(levelname)s:%(message)s")
   sys.exit(main())