Automatic Windows toolchain

win_toolchain/get_toolchain_if_necessary.py

Index: win_toolchain/get_toolchain_if_necessary.py
diff --git a/win_toolchain/get_toolchain_if_necessary.py b/win_toolchain/get_toolchain_if_necessary.py
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+#!/usr/bin/env python
+# Copyright 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.
+
+"""Downloads and unpacks a toolchain for building on Windows. The contents are
+matched by sha1 which will be updated when the toolchain is updated.
+
+Having a toolchain script in depot_tools means that it's not versioned
+directly with the source code. That is, if the toolchain is upgraded, but
+you're trying to build an historical version of Chromium from before the
+toolchain upgrade, this will cause you to build with a newer toolchain than
+was available when that code was committed. This is done for a two main
+reasons: 1) it would likely be annoying to have the up-to-date toolchain
+removed and replaced by one without a service pack applied); 2) it would
+require maintaining scripts that can build older not-up-to-date revisions of
+the toolchain. This is likely to be a poorly tested code path that probably
+won't be properly maintained. See http://crbug.com/323300.
+
+This does not extend to major versions of the toolchain however, on the
+assumption that there are more likely to be source incompatibilities between
+major revisions. This script calls a subscript (currently, toolchain2013.py)
+to do the main work. It is expected that toolchain2013.py will always be able
+to acquire/build the most current revision of a VS2013-based toolchain. In the
+future when a hypothetical VS2015 is released, the 2013 script will be
+maintained, and a new 2015 script would be added.
+"""
+
+import ctypes.wintypes
+import hashlib
+import json
+import os
+import subprocess
+import sys
+
+
+BASEDIR = os.path.dirname(os.path.abspath(__file__))
+
+
+GetFileAttributes = ctypes.windll.kernel32.GetFileAttributesW
+GetFileAttributes.argtypes = (ctypes.wintypes.LPWSTR,)
+GetFileAttributes.restype = ctypes.wintypes.DWORD
+FILE_ATTRIBUTE_HIDDEN = 0x2
+FILE_ATTRIBUTE_SYSTEM = 0x4
+
+
+def IsHidden(file_path):
+  """Returns whether the given |file_path| has the 'system' or 'hidden'
+  attribute set."""
+  p = GetFileAttributes(file_path)
+  assert p != 0xffffffff
+  return bool(p & (FILE_ATTRIBUTE_HIDDEN | FILE_ATTRIBUTE_SYSTEM))
+
+
+def GetFileList(root):
+  """Gets a normalized list of files under |root|."""
+  assert not os.path.isabs(root)
+  assert os.path.normpath(root) == root
+  file_list = []
+  for base, _, files in os.walk(root):
+    paths = [os.path.join(base, f) for f in files]
+    file_list.extend(x.lower() for x in paths if not IsHidden(x))
+  return sorted(file_list)
+
+
+def MakeTimestampsFileName(root):
+  return os.path.join(root, '..', '.timestamps')
+
+
+def CalculateHash(root):
+  """Calculates the sha1 of the paths to all files in the given |root| and the
+  contents of those files, and returns as a hex string."""
+  file_list = GetFileList(root)
+
+  # Check whether we previously saved timestamps in $root/../.timestamps. If
+  # we didn't, or they don't match, then do the full calculation, otherwise
+  # return the saved value.
+  timestamps_file = MakeTimestampsFileName(root)
+  timestamps_data = {'files': [], 'sha1': ''}
+  if os.path.exists(timestamps_file):
+    with open(timestamps_file, 'rb') as f:
+      try:
+        timestamps_data = json.load(f)
+      except ValueError:
+        # json couldn't be loaded, empty data will force a re-hash.
+        pass
+
+  matches = len(file_list) == len(timestamps_data['files'])
+  if matches:
+    for disk, cached in zip(file_list, timestamps_data['files']):
+      if disk != cached[0] or os.stat(disk).st_mtime != cached[1]:
+        matches = False
+        break
+  if matches:
+    return timestamps_data['sha1']
+
+  digest = hashlib.sha1()
+  for path in file_list:
+    digest.update(path)
+    with open(path, 'rb') as f:
+      digest.update(f.read())
+  return digest.hexdigest()
+
+
+def SaveTimestampsAndHash(root, sha1):
+  """Save timestamps and the final hash to be able to early-out more quickly
+  next time."""
+  file_list = GetFileList(root)
+  timestamps_data = {
+    'files': [[f, os.stat(f).st_mtime] for f in file_list],
+    'sha1': sha1,
+  }
+  with open(MakeTimestampsFileName(root), 'wb') as f:
+    json.dump(timestamps_data, f)
+
+
+def main():
+  if not sys.platform.startswith(('cygwin', 'win32')):
+    return 0
+
+  if len(sys.argv) != 1:
+    print >> sys.stderr, 'Unexpected arguments.'
+    return 1
+
+  # Move to depot_tools\win_toolchain where we'll store our files, and where
+  # the downloader script is.
+  os.chdir(os.path.normpath(os.path.join(BASEDIR)))
+  toolchain_dir = '.'
+  target_dir = os.path.normpath(os.path.join(toolchain_dir, 'vs2013_files'))
+
+  sha1path = os.path.join(toolchain_dir, 'toolchain_vs2013.hash')
+  desired_hash = ''
+  if os.path.isfile(sha1path):
+    with open(sha1path, 'rb') as f:
+      desired_hash = f.read().strip()
+
+  # If the current hash doesn't match what we want in the file, nuke and pave.
+  # Typically this script is only run when the .sha1 one file is updated, but
+  # directly calling "gclient runhooks" will also run it, so we cache
+  # based on timestamps to make that case fast.
+  current_hash = CalculateHash(target_dir)
+  if current_hash != desired_hash:
+    print 'Windows toolchain out of date or doesn\'t exist, updating...'
+    if os.path.isdir(target_dir):
+      subprocess.check_call('rmdir /s/q "%s"' % target_dir, shell=True)
+    subprocess.check_call([
+        sys.executable,
+        'toolchain2013.py',
+        '--targetdir', target_dir])
+    current_hash = CalculateHash(target_dir)
+    if current_hash != desired_hash:
+      print >> sys.stderr, (
+          'Got wrong hash after pulling a new toolchain. '
+          'Wanted \'%s\', got \'%s\'.' % (
+              desired_hash, current_hash))
+      return 1
+    SaveTimestampsAndHash(target_dir, current_hash)
+
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main())