[NaCl SDK] Add keyboard interrupt handlers for python scripts

native_client_sdk/src/build_tools/sdk_tools/download.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.
 
 import hashlib
 import os
 import sys
 # when pylint runs the third_party module is the one from depot_tools
 # pylint: disable=E0611
 from third_party import fancy_urllib
 import urllib2
 
 
 SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
 
 
 def UrlOpen(url):
   request = fancy_urllib.FancyRequest(url)
   ca_certs = os.path.join(SCRIPT_DIR, 'cacerts.txt')
   request.set_ssl_info(ca_certs=ca_certs)
   url_opener = urllib2.build_opener(
       fancy_urllib.FancyProxyHandler(),
       fancy_urllib.FancyRedirectHandler(),
       fancy_urllib.FancyHTTPSHandler())
   return url_opener.open(request)
 
 
-def MakeProgressFunction(file_size=0):
+def MakeProgressFunction(file_size):
   # An inner function can only read nonlocal variables, not assign them. We can
   # work around this by using a list of one element.
   dots = [0]
   def ShowKnownProgress(progress):
     '''Returns a progress function based on a known file size'''
     if progress == 0:
       sys.stdout.write('|%s|\n' % ('=' * 48))
+    elif progress == -1:
+      sys.stdout.write('\n')
     else:
       new_dots = progress * 50 / file_size - dots[0]
       sys.stdout.write('.' * new_dots)
       dots[0] += new_dots
-      if progress == file_size:
-        sys.stdout.write('\n')
     sys.stdout.flush()
 
   return ShowKnownProgress
 
 
 def DownloadAndComputeHash(from_stream, to_stream=None, progress_func=None):
   '''Read from from-stream and generate sha1 and size info.
 
   Args:
     from_stream:   An input stream that supports read.
     to_stream:     [optional] the data is written to to_stream if it is
                    provided.
     progress_func: [optional] A function used to report download progress. If
                    provided, progress_func is called with progress=0 at the
-                   beginning of the download, periodically with progress=1
-                   during the download, and progress=100 at the end.
+                   beginning of the download, periodically with progress>0
+                   (== number of bytes read do far) during the download, and
+                   progress=-1 at the end or if the download was aborted.
 
   Return
     A tuple (sha1, size) where sha1 is a sha1-hash for the archive data and
     size is the size of the archive data in bytes.'''
   # Use a no-op progress function if none is specified.
   def progress_no_op(progress):
     pass
   if not progress_func:
     progress_func = progress_no_op
 
   sha1_hash = hashlib.sha1()
   size = 0
-  progress_func(progress=0)
-  while(1):
-    data = from_stream.read(32768)
-    if not data:
-      break
-    sha1_hash.update(data)
-    size += len(data)
-    if to_stream:
-      to_stream.write(data)
-    progress_func(size)
-
-  progress_func(progress=100)
+  try:
+    progress_func(progress=0)
+    while True:
+      data = from_stream.read(32768)
+      if not data:
+        break
+      sha1_hash.update(data)
+      size += len(data)
+      if to_stream:
+        to_stream.write(data)
+      progress_func(size)
+  finally:
+    progress_func(progress=-1)
   return sha1_hash.hexdigest(), size