fix third_party_headers to work properly on Windows w/ ninja.

webkit/support/setup_third_party.py

 #!/usr/bin/env python
 # 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.
 
 """A helper script for setting up forwarding headers."""
 
 import errno
 import os
 import sys
 
 
 def GetHeaderFilesInDir(dir_path):
-  """Return a list of all header files in dir_path."""
+  """Return a list of all header files under dir_path
+  (as absolute native paths)."""
   all_files = []
   for root, dirs, files in os.walk(dir_path):
-    # Backslashes get shell escaped by gyp, so force forward slash for
-    # path separators.
-    all_files.extend([os.path.join(root, f).replace(os.sep, '/')
-                      for f in files if f.endswith('.h')])
+    all_files.extend([os.path.join(root, f) for f in files if f.endswith('.h')])
   return all_files
 
 
+def PathForInclude(path):
+    # We should always use unix-style forward slashes in #includes.
+    return path.replace(os.sep, '/')
+
+
+def NativePath(path):
+    return path.replace('/', os.sep)
+
+
+def PathForGyp(path):
+    # GYP will try to shell-escape backslashes, so we should always
+    # return unix-style paths with forward slashes as the directory separators.
+    return path.replace(os.sep, '/')
+
+
 def Inputs(args):
   """List the files in the provided input dir.
 
   args: A list with 1 value, the input dir.
   Returns: 0 on success, other value on error."""
   if len(args) != 1:
     print "'inputs' expects only one input directory."
     return -1
 
   for filename in GetHeaderFilesInDir(args[0]):
-    print filename
+    print PathForGyp(filename)
   return 0
 
 
 def Outputs(args):
   """Takes an input dir and an output dir and figures out new output files
   based on copying from the input dir to the output dir.
 
   args: A list with 2 values, the input dir and the output dir.
   Returns: 0 on success, other value on error."""
   if len(args) != 2:
     print "'outputs' expects an input directory and an output directory."
     return -1
 
-  base_input_dir = args[0]
-  output_dir = args[1]
+  base_input_dir = NativePath(args[0])
+  output_dir = NativePath(args[1])
   input_files = GetHeaderFilesInDir(base_input_dir)
   for filename in input_files:
-    rel_path = filename[len(base_input_dir) + 1:]
-    # Backslashes get shell escaped by gyp, so force forward slash for
-    # path separators.
-    print os.path.join(output_dir, rel_path).replace(os.sep, '/')
+    rel_path = os.path.relpath(filename, base_input_dir)
+    print PathForGyp(os.path.join(output_dir, rel_path))
 
 
 def SetupHeaders(args):
   """Takes an input dir and an output dir and sets up forwarding headers
   from output dir to files in input dir.
   args: A list with 2 values, the input dir and the output dir.

[tony, 2013/02/11 18:16:50]

Nit: Can you update this docstring?

[Dirk Pranke, 2013/02/11 23:42:30]

good catch. done.

   Returns: 0 on success, other value on error."""
-  if len(args) != 2 and len(args) != 3:
+  if len(args) != 3:
     print ("'setup_headers' expects an input directory, an output directory, ."
-        "and an optional directory to make includes relative to.")
+        "and a directory to make includes relative to.")
     return -1
 
-  base_input_dir = args[0]
-  output_dir = args[1]
-  relative_to_dir = None
-  if len(args) == 3:
-    relative_to_dir = args[2]
+  base_input_dir = NativePath(args[0])
+  output_dir = NativePath(args[1])
+  relative_to_dir = NativePath(args[2])
   input_files = GetHeaderFilesInDir(base_input_dir)
   for input_filename in input_files:
-    rel_path = input_filename[len(base_input_dir) + 1:]
+    rel_path = os.path.relpath(input_filename, base_input_dir)
     out_filename = os.path.join(output_dir, rel_path)
     TryToMakeDir(os.path.split(out_filename)[0])
-    WriteSetupFilename(input_filename, out_filename, relative_to_dir)
+    WriteForwardingHeader(input_filename, out_filename, relative_to_dir)
 
 
 def TryToMakeDir(dir_name):
   """Create the directory dir_name if it doesn't exist."""
   try:
     os.makedirs(dir_name)
   except OSError, e:
     if e.errno != errno.EEXIST:
       raise e
 
 
-def NormalizePath(path):
-  """Normalize path for use with os.path.commonprefix.
-  On windows, this makes sure that the drive letters are always in the
-  same case."""
-  abs_path = os.path.abspath(path)
-  drive, rest = os.path.splitdrive(abs_path)
-  return os.path.join(drive.lower(), rest)
-
-
-def WriteSetupFilename(input_filename, out_filename, relative_to_dir):
+def WriteForwardingHeader(input_filename, out_filename, relative_to_dir):
   """Create a forwarding header from out_filename to input_filename."""
-  # Figure out the relative path from out_filename to input_filename.
-  # We can't use os.path.relpath since that's a python2.6 feature and we
-  # support python 2.5.
-  input_filename = NormalizePath(input_filename)
-  out_filename = NormalizePath(out_filename)
-  ancestor = os.path.commonprefix([input_filename, out_filename])
-
-  assert os.path.isdir(ancestor)
-  num_parent_dirs = 0
-  out_dir = os.path.split(out_filename)[0]
-  while os.path.normpath(ancestor) != os.path.normpath(out_dir):
-    num_parent_dirs += 1
-    out_dir = os.path.split(out_dir)[0]
-
-  if sys.platform == 'win32':
-    # Windows has a file path limit of 260 characters that we can hit when
-    # generating these forwarding headers.  Instead of writing the full
-    # relative path, just write the path relative to the WebKit/chromium dir,
-    # which is in the include path.
-    rel_path = input_filename[len(ancestor):]
-    if relative_to_dir:
-      rel_path = os.path.join(relative_to_dir, rel_path)
-  else:
-    rel_path = os.path.join('/'.join(['..'] * num_parent_dirs),
-                            input_filename[len(ancestor):])
-
+  # Windows has a file path limit of 260 characters, which can be hit when
+  # generating these forwarding headers.  Instead of using an include
+  # that specifies the path relative to out_filename's dir, we compute a path
+  # relative to relative_to_dir, which must be included in gyp's include_dirs
+  # settings for this to work. Even those this is really only needed on
+  # Windows, we do this on all platforms to be consistent.
+  rel_path = os.path.relpath(input_filename, relative_to_dir)
   out_file = open(out_filename, 'w')
   out_file.write("""// This file is generated.  Do not edit.
+// The include is relative to "%s".
 #include "%s"
-""" % rel_path)
+""" % (os.path.abspath(relative_to_dir), PathForInclude(rel_path)))
   out_file.close()
 
 
 def Main(argv):
   commands = {
     'inputs': Inputs,
     'outputs': Outputs,
     'setup_headers': SetupHeaders,
   }
   command = argv[1]
   args = argv[2:]
   return commands[command](args)
 
 
 if __name__ == '__main__':
   sys.exit(Main(sys.argv))