Fix quoting shell args on Windows

pylib/gyp/msvs_emulation.py

+# Copyright (c) 2012 Google Inc. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""
+This module helps emulate Visual Studio 2008 behavior on top of other
+build systems, primarily ninja.
+"""
+
+import re
+
+windows_quoter_regex = re.compile(r'(\\*)"')
+
+def QuoteCmdExeArgument(arg):
+  """Quote a command line argument so that it appears as one argument when
+  processed via cmd.exe and parsed by CommandLineToArgvW (as is typical for
+  Windows programs)."""
+  # See http://goo.gl/cuFbX and http://goo.gl/dhPnp including the comment
+  # threads. This is actually the quoting rules for CommandLineToArgvW, not
+  # for the shell, because the shell doesn't do anything in Windows. This
+  # works more or less because most programs (including the compiler, etc.)
+  # use that function to handle command line arguments.
+  #
+  # For a literal quote, CommandLineToArgvW requires 2n+1 backslashes
+  # preceding it, and results in n backslashes + the quote. So we substitute
+  # in 2* what we match, +1 more, plus the quote.
+  tmp = windows_quoter_regex.sub(lambda mo: 2 * mo.group(1) + '\\"', arg)
+
+  # Now, we need to escape some things that are actually for the shell.
+  # ^-escape various characters that are otherwise interpreted by the shell.
+  tmp = re.sub(r'([&|^])', r'^\1', tmp)
+
+  # %'s also need to be doubled otherwise they're interpreted as batch
+  # positional arguments. Also make sure to escape the % so that they're
+  # passed literally through escaping so they can be singled to just the
+  # original %. Otherwise, trying to pass the literal representation that
+  # looks like an environment variable to the shell (e.g. %PATH%) would fail.
+  tmp = tmp.replace('%', '^%^%')
+
+  # Finally, wrap the whole thing in quotes so that the above quote rule
+  # applies and whitespace isn't a word break.
+  return '"' + tmp + '"'