New extension to support problematic MBCS on Windows.

The aim of this extension is to clear the problem related to having
0x5c in 2nd byte of encoded bytes.  So this extension is usefull for:
 * Japanese Windows user shift_jis encoding.
 * Chinese Windows user using big5 encoding.

To use this extension, simply enable it without any customization.

Note that some important python built-in functions and mercurial
functions are altered for this extension to convert argument if need
to handle MBCS.

hgext/win32mbcs.py

@@ -0,0 +1,158 b''
+# win32mbcs.py -- MBCS filename support for Mercurial on Windows
+#
+# Copyright (c) 2008 Shun-ichi Goto <[e-mail]>
+#
+# Version: 0.1
+# Author:  Shun-ichi Goto <[e-mail]>
+#
+# This software may be used and distributed according to the terms
+# of the GNU General Public License, incorporated herein by reference.
+#
+"""Allow to use shift_jis/big5 filenames on Windows.
+
+There is a well known issue "0x5c problem" on Windows.  It is a
+trouble on handling path name as raw encoded byte sequence of
+problematic encodings like shift_jis or big5.  The primary intent
+of this extension is to allow using such a encoding on Mercurial
+without strange file operation error.
+
+By enabling this extension, hook mechanism is activated and some
+functions are altered.  Usually, this encoding is your local encoding
+on your system by default. So you can get benefit simply by enabling
+this extension.
+
+The encoding for filename is same one for terminal by default.  You
+can change the encoding by setting HGENCODING environment variable.
+
+This extension is usefull for:
+ * Japanese Windows user using shift_jis encoding.
+ * Chinese Windows user using big5 encoding.
+ * Users who want to use a repository created with such a encoding.
+
+Note: Unix people does not need to use this extension.
+
+"""
+
+import os
+from mercurial.i18n import _
+from mercurial import util
+
+__all__ = ['install', 'uninstall', 'reposetup']
+
+
+# codec and alias names of sjis and big5 to be faked.
+_problematic_encodings = util.frozenset([
+        'big5', 'big5-tw', 'csbig5',
+        'big5hkscs', 'big5-hkscs', 'hkscs',
+        'cp932', '932', 'ms932', 'mskanji', 'ms-kanji',
+        'shift_jis', 'csshiftjis', 'shiftjis', 'sjis', 's_jis',
+        'shift_jis_2004', 'shiftjis2004', 'sjis_2004', 'sjis2004',
+        'shift_jisx0213', 'shiftjisx0213', 'sjisx0213', 's_jisx0213',
+        ])
+
+# attribute name to store original function
+_ORIGINAL = '_original'
+
+_ui = None
+
+def decode_with_check(arg):
+    if isinstance(arg, tuple):
+        return tuple(map(decode_with_check, arg))
+    elif isinstance(arg, list):
+        return map(decode_with_check, arg)
+    elif isinstance(arg, str):
+        uarg = arg.decode(util._encoding)
+        if arg == uarg.encode(util._encoding):
+            return uarg
+        else:
+            raise UnicodeError("Not local encoding")
+    else:
+        return arg
+
+def encode_with_check(arg):
+    if isinstance(arg, tuple):
+        return tuple(map(encode_with_check, arg))
+    elif isinstance(arg, list):
+        return map(encode_with_check, arg)
+    elif isinstance(arg, unicode):
+        ret = arg.encode(util._encoding)
+        return ret
+    else:
+        return arg
+
+def wrap(func):
+    
+    def wrapped(*args):
+        # check argument is unicode, then call original
+        for arg in args:
+            if isinstance(arg, unicode):
+                return func(*args)
+        # make decoded argument list into uargs
+        try:
+            args = decode_with_check(args)
+        except UnicodeError, exc:
+            # If not encoded with _local_fs_encoding, report it then
+            # continue with calling original function.
+            _ui.warn(_("WARNING: [win32mbcs] filename conversion fail for" +
+                     " %s: '%s'\n") % (util._encoding, args))
+            return func(*args)
+        # call as unicode operation, then return with encoding
+        return encode_with_check(func(*args))
+
+    # fake is only for relevant environment.
+    if hasattr(func, _ORIGINAL) or \
+            util._encoding.lower() not in _problematic_encodings:
+        return func
+    else:
+        f = wrapped
+        f.__name__ = func.__name__
+        setattr(f, _ORIGINAL, func)   # hold original to restore
+        return f
+
+def unwrap(func):
+    return getattr(func, _ORIGINAL, func)
+
+def install():
+    # wrap some python functions and mercurial functions
+    # to handle raw bytes on Windows.
+    # NOTE: dirname and basename is safe because they use result
+    # of os.path.split()
+    global _ui
+    if not _ui:
+        from mercurial import ui
+        _ui = ui.ui()
+    os.path.join = wrap(os.path.join)
+    os.path.split = wrap(os.path.split) 
+    os.path.splitext = wrap(os.path.splitext)
+    os.path.splitunc = wrap(os.path.splitunc)
+    os.path.normpath = wrap(os.path.normpath)
+    os.path.normcase = wrap(os.path.normcase)
+    os.makedirs = wrap(os.makedirs)
+    util.endswithsep = wrap(util.endswithsep)
+    util.splitpath = wrap(util.splitpath)
+
+def uninstall():
+    # restore original functions.
+    os.path.join = unwrap(os.path.join)
+    os.path.split = unwrap(os.path.split) 
+    os.path.splitext = unwrap(os.path.splitext)
+    os.path.splitunc = unwrap(os.path.splitunc)
+    os.path.normpath = unwrap(os.path.normpath)
+    os.path.normcase = unwrap(os.path.normcase)
+    os.makedirs = unwrap(os.makedirs)
+    util.endswithsep = unwrap(util.endswithsep)
+    util.splitpath = unwrap(util.splitpath)
+
+
+def reposetup(ui, repo):
+    # TODO: decide use of config section for this extension
+    global _ui
+    _ui = ui
+    if not os.path.supports_unicode_filenames:
+        ui.warn(_("[win32mbcs] cannot activate on this platform.\n"))
+        return
+    # install features of this extension
+    install()
+    ui.debug(_("[win32mbcs] activeted with encoding: %s\n") % util._encoding)
+
+# win32mbcs.py ends here