[NaCl SDK] Refactor sdk_update*.

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):
+  # 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))
+    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.
+
+  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)
+  return sha1_hash.hexdigest(), size