Add treehash tool for win_toolchain

win_toolchain/treehash/treehash.py

Index: win_toolchain/treehash/treehash.py
diff --git a/win_toolchain/treehash/treehash.py b/win_toolchain/treehash/treehash.py
new file mode 100644
index 0000000000000000000000000000000000000000..ac821146114ca8123d607ac49592fac161cee953
--- /dev/null
+++ b/win_toolchain/treehash/treehash.py
@@ -0,0 +1,55 @@
+# Copyright 2014 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.
+
+# Python implementation for verification. Doesn't do timestamping, just the
+# tree hash.
+
+import ctypes.wintypes
+import hashlib
+import os
+import sys
+
+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 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)
+  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 main():
+  print CalculateHash(sys.argv[1])
+
+if __name__ == '__main__':
+  sys.exit(main())