Add support for saving VM state after test failure

client/common_lib/utils.py

 #
 # Copyright 2008 Google Inc. Released under the GPL v2
 
 import os, pickle, random, re, resource, select, shutil, signal, StringIO
-import socket, struct, subprocess, sys, time, textwrap, urlparse
+import socket, struct, subprocess, sys, time, textwrap, urlparse, platform
 import warnings, smtplib, logging, urllib2
 from threading import Thread, Event
 try:
     import hashlib
 except ImportError:
     import md5, sha
 from autotest_lib.client.common_lib import error, logging_manager
 
 def deprecated(func):
     """This is a decorator which can be used to mark functions as deprecated.
@@ skipping 1685 matching lines @@
             s.close()
 
     # On the 2.6 kernel, calling try_bind() on UDP socket returns the
     # same port over and over. So always try TCP first.
     while True:
         # Ask the OS for an unused port.
         port = try_bind(0, socket.SOCK_STREAM, socket.IPPROTO_TCP)
         # Check if this port is unused on the other protocol.
         if port and try_bind(port, socket.SOCK_DGRAM, socket.IPPROTO_UDP):
             return port
+
+
+def save_vm_state(checkpoint):
+    """Saves the current state of the virtual machine
+
+    This function is a NOOP if the test is not running under a virtual machine
+    with the USB serial port redirected.
+
+    Arguments:
+      checkpoint - Name used to identify this state
+
+    Returns:
+      None
+    """
+    # The QEMU monitor has been redirected to the guest serial port located at
+    # /dev/ttyUSB0. To save the state of the VM, we just send the 'savevm'
+    # command to the serial port.
+    proc = platform.processor()
+    if proc.find('QEMU') >= 0 and os.path.exists('/dev/ttyUSB0'):
+        logging.info('Saving VM state "%s"' % checkpoint)
+        serial = open('/dev/ttyUSB0', 'w')
+        serial.write("savevm %s\r\n" % checkpoint)
+        logging.info('Done saving VM state "%s"' % checkpoint)