[Android] Add partial output to TimeoutError raised in cmd_helper.

build/android/pylib/cmd_helper.py

 # 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.
 
 """A wrapper for subprocess to make calling shell commands easier."""
 
 import logging
 import os
 import pipes
 import select
@@ skipping 142 matching lines @@
   if stderr:
     logging.critical(stderr)
   if len(stdout) > 4096:
     logging.debug('Truncated output:')
   logging.debug(stdout[:4096])
   return (pipe.returncode, stdout)
 
 
 class TimeoutError(Exception):
   """Module-specific timeout exception."""
-  pass
+
+  def __init__(self, output=None):
+    super(TimeoutError, self).__init__()
+    self._output = output
+
+  @property
+  def output(self):
+    return self._output
 
 
 def _IterProcessStdout(process, timeout=None, buffer_size=4096,
                        poll_interval=1):
   assert fcntl, 'fcntl module is required'
   try:
     # Enable non-blocking reads from the child's stdout.
     child_fd = process.stdout.fileno()
     fl = fcntl.fcntl(child_fd, fcntl.F_GETFL)
     fcntl.fcntl(child_fd, fcntl.F_SETFL, fl | os.O_NONBLOCK)
 
     end_time = (time.time() + timeout) if timeout else None
     while True:
       if end_time and time.time() > end_time:
-        raise TimeoutError
+        raise TimeoutError()
       read_fds, _, _ = select.select([child_fd], [], [], poll_interval)
       if child_fd in read_fds:
         data = os.read(child_fd, buffer_size)
         if not data:
           break
         yield data
       if process.poll() is not None:
         break
   finally:
     try:
@@ skipping 20 matching lines @@
     logfile: Optional file-like object that will receive output from the
       command as it is running.
 
   Returns:
     The 2-tuple (exit code, output).
   """
   _ValidateAndLogCommand(args, cwd, shell)
   output = StringIO.StringIO()
   process = Popen(args, cwd=cwd, shell=shell, stdout=subprocess.PIPE,
                   stderr=subprocess.STDOUT)
-  for data in _IterProcessStdout(process, timeout=timeout):
-    if logfile:
-      logfile.write(data)
-    output.write(data)
+  try:
+    for data in _IterProcessStdout(process, timeout=timeout):
+      if logfile:
+        logfile.write(data)
+      output.write(data)
+  except TimeoutError:
+    raise TimeoutError(output.getvalue())
+
   return process.returncode, output.getvalue()
 
 
 def IterCmdOutputLines(args, timeout=None, cwd=None, shell=False,
                        check_status=True):
   """Executes a subprocess and continuously yields lines from its output.
 
   Args:
     args: List of arguments to the program, the program to execute is the first
       element.
@@ skipping 19 matching lines @@
     buffer_output += data
     has_incomplete_line = buffer_output[-1] not in '\r\n'
     lines = buffer_output.splitlines()
     buffer_output = lines.pop() if has_incomplete_line else ''
     for line in lines:
       yield line
   if buffer_output:
     yield buffer_output
   if check_status and process.returncode:
     raise subprocess.CalledProcessError(process.returncode, cmd)