[telemetry] Automatic hash file creation and upload to Cloud Storage.

tools/telemetry/telemetry/page/cloud_storage.py

 # Copyright (c) 2013 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.
 
 """Wrappers for gsutil, for basic interaction with Google Cloud Storage."""
 
 import cStringIO
+import hashlib
 import logging
 import os
 import subprocess
 import sys
 import tarfile
 import urllib2
 
 from telemetry.core import util
 
 
 _GSUTIL_URL = 'http://storage.googleapis.com/pub/gsutil.tar.gz'
 _DOWNLOAD_PATH = os.path.join(util.GetTelemetryDir(), 'third_party', 'gsutil')
 
 
+class CloudStorageError(Exception):
+  pass
+
+
 def _DownloadGsutil():
   logging.info('Downloading gsutil')
   response = urllib2.urlopen(_GSUTIL_URL)
   with tarfile.open(fileobj=cStringIO.StringIO(response.read())) as tar_file:
     tar_file.extractall(os.path.dirname(_DOWNLOAD_PATH))
   logging.info('Downloaded gsutil to %s' % _DOWNLOAD_PATH)
 
   return os.path.join(_DOWNLOAD_PATH, 'gsutil')
 
 
@@ skipping 17 matching lines @@
   return _DownloadGsutil()
 
 
 def _RunCommand(args):
   gsutil_path = _FindGsutil()
   gsutil = subprocess.Popen([sys.executable, gsutil_path] + args,
                             stdout=subprocess.PIPE, stderr=subprocess.PIPE)
   stdout, stderr = gsutil.communicate()
 
   if gsutil.returncode:
-    raise Exception(stderr.splitlines()[-1])
+    raise CloudStorageError(stderr.splitlines()[-1])
 
   return stdout
 
 
 def List(bucket):
   stdout = _RunCommand(['ls', 'gs://%s' % bucket])
   return [url.split('/')[-1] for url in stdout.splitlines()]
 
 
 def Delete(bucket, remote_path):
   url = 'gs://%s/%s' % (bucket, remote_path)
   logging.debug('Deleting %s' % url)
   _RunCommand(['rm', url])
 
 
 def Get(bucket, remote_path, local_path):
   url = 'gs://%s/%s' % (bucket, remote_path)
   logging.debug('Downloading %s to %s' % (url, local_path))
   _RunCommand(['cp', url, local_path])
 
 
 def Insert(bucket, remote_path, local_path):
   url = 'gs://%s/%s' % (bucket, remote_path)
   logging.debug('Uploading %s to %s' % (local_path, url))
   _RunCommand(['cp', local_path, url])
+
+
+def GetHash(file_path):
+  sha1 = hashlib.sha1()
+  with open(file_path, 'rb') as f:
+    while True:
+      # Read in 1mb chunks, so it doesn't all have to be loaded into memory.
+      chunk = f.read(1024*1024)
+      if not chunk:
+        break
+      sha1.update(chunk)
+  return sha1.hexdigest()