native_client_sdk/src/build_tools/sdk_tools/download.py

   1 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 import hashlib
   6 import os
   7 import sys
   8 # when pylint runs the third_party module is the one from depot_tools
   9 # pylint: disable=E0611
  10 from third_party import fancy_urllib
  11 import urllib2
  12
  13
  14 SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
  15
  16
  17 def UrlOpen(url):
  18   request = fancy_urllib.FancyRequest(url)
  19   ca_certs = os.path.join(SCRIPT_DIR, 'cacerts.txt')
  20   request.set_ssl_info(ca_certs=ca_certs)
  21   url_opener = urllib2.build_opener(
  22       fancy_urllib.FancyProxyHandler(),
  23       fancy_urllib.FancyRedirectHandler(),
  24       fancy_urllib.FancyHTTPSHandler())
  25   return url_opener.open(request)
  26
  27
  28 def MakeProgressFunction(file_size):
  29   # An inner function can only read nonlocal variables, not assign them. We can
  30   # work around this by using a list of one element.
  31   dots = [0]
  32   def ShowKnownProgress(progress):
  33     '''Returns a progress function based on a known file size'''
  34     if progress == 0:
  35       sys.stdout.write('|%s|\n' % ('=' * 48))
  36     elif progress == -1:
  37       sys.stdout.write('\n')
  38     else:
  39       new_dots = progress * 50 / file_size - dots[0]
  40       sys.stdout.write('.' * new_dots)
  41       dots[0] += new_dots
  42     sys.stdout.flush()
  43
  44   return ShowKnownProgress
  45
  46
  47 def DownloadAndComputeHash(from_stream, to_stream=None, progress_func=None):
  48   '''Read from from-stream and generate sha1 and size info.
  49
  50   Args:
  51     from_stream:   An input stream that supports read.
  52     to_stream:     [optional] the data is written to to_stream if it is
  53                    provided.
  54     progress_func: [optional] A function used to report download progress. If
  55                    provided, progress_func is called with progress=0 at the
  56                    beginning of the download, periodically with progress>0
  57                    (== number of bytes read do far) during the download, and
  58                    progress=-1 at the end or if the download was aborted.
  59
  60   Return
  61     A tuple (sha1, size) where sha1 is a sha1-hash for the archive data and
  62     size is the size of the archive data in bytes.'''
  63   # Use a no-op progress function if none is specified.
  64   def progress_no_op(progress):
  65     pass
  66   if not progress_func:
  67     progress_func = progress_no_op
  68
  69   sha1_hash = hashlib.sha1()
  70   size = 0
  71   try:
  72     progress_func(progress=0)
  73     while True:
  74       data = from_stream.read(32768)
  75       if not data:
  76         break
  77       sha1_hash.update(data)
  78       size += len(data)
  79       if to_stream:
  80         to_stream.write(data)
  81       progress_func(size)
  82   finally:
  83     progress_func(progress=-1)
  84   return sha1_hash.hexdigest(), size