Auto-updating script for Windows toolchain

tools/win/toolchain/get_toolchain_if_necessary.py

+# 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.
+
+import hashlib
+import os
+import subprocess
+import sys
+
+
+BASEDIR = os.path.dirname(os.path.abspath(__file__))
+
+
+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."""

[M-A Ruel, 2013/11/26 18:03:40]

you may want to:
assert not os.path.isabs(root)
assert os.path.normpath(root) == root

[scottmg, 2013/11/26 18:17:14]

Done.

+  digest = hashlib.sha1()
+  count = 0
+  for root, dirs, files in os.walk(root):
+    dirs.sort()
+    for name in sorted(f.lower() for f in files):
+      path = os.path.normpath(os.path.join(root, name))

[M-A Ruel, 2013/11/26 18:03:40]

technically, the normpath() call here will always be a no-op as long as root is
well formed.

[scottmg, 2013/11/26 18:17:14]

Yes, I guess with the assert it's ok to remove.

+      digest.update(path.lower())
+      with open(path, 'rb') as f:
+        digest.update(f.read())
+  return digest.hexdigest()
+
+
+def main():
+  if sys.platform not in ('win32', 'cygwin'):
+    return 0
+
+  if len(sys.argv) != 1:
+    print >> sys.stderr, 'Unexpected arguments.'
+    return 1
+
+  # Move to same location as .gclient. This is a no-op when run via gclient.
+  os.chdir(os.path.normpath(os.path.join(BASEDIR, '../../../..')))
+  toolchain_dir = 'src/third_party/win_toolchain'
+  target_dir = os.path.join(toolchain_dir, 'files')

[M-A Ruel, 2013/11/26 18:03:40]

Note that target_dir will be
'src/third_party/win_toolchain\\files'

I'm not super happy about that.

[scottmg, 2013/11/26 18:17:14]

Normalized all paths to Windows style.

+
+  sha1path = os.path.join(toolchain_dir, 'toolchain.sha1')
+  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.
+  # Note that this script is only run when a .sha1 file is updated (per DEPS)
+  # so this relatively expensive step of hashing everything only happens when
+  # the toolchain is updated.
+  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+    print 'Windows toolchain out of date or doesn\'t exist, updating...'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,
+        'src/tools/win/toolchain/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
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main())