win32mbcs: allow win32mbcs extension to be enabled on cygwin platform

this patch allows win32mbcs extension to be enabled on cygwin platform
for problematic character encodings.

on recent cygwin platform, even though
"os.path.supports_unicode_filenames" is False, "os.listdir()" and
other path manipulation functions can return the result correctly
decoded in unicode for invocations with unicode arguments, if locale
is configured properly.

existing code to check "os.path.supports_unicode_filenames" is kept to
prevent win32mbcs from being enabled on unexpected platform.

hgext/win32mbcs.py

@@ -1,160 +1,167 b''
 # win32mbcs.py -- MBCS filename support for Mercurial
 #
 # Copyright (c) 2008 Shun-ichi Goto <[e-mail]>
 #
 # Version: 0.3
 # Author:  Shun-ichi Goto <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 #
 
 '''allow the use of MBCS paths with problematic encodings
 
 Some MBCS encodings are not good for some path operations (i.e.
 splitting path, case conversion, etc.) with its encoded bytes. We call
 such a encoding (i.e. shift_jis and big5) as "problematic encoding".
 This extension can be used to fix the issue with those encodings by
 wrapping some functions to convert to Unicode string before path
 operation.
 
 This extension is useful for:
 
 - Japanese Windows users using shift_jis encoding.
 - Chinese Windows users using big5 encoding.
 - All users who use a repository with one of problematic encodings on
   case-insensitive file system.
 
 This extension is not needed for:
 
 - Any user who use only ASCII chars in path.
 - Any user who do not use any of problematic encodings.
 
 Note that there are some limitations on using this extension:
 
 - You should use single encoding in one repository.
 - If the repository path ends with 0x5c, .hg/hgrc cannot be read.
 - win32mbcs is not compatible with fixutf8 extension.
 
 By default, win32mbcs uses encoding.encoding decided by Mercurial.
 You can specify the encoding by config option::
 
  [win32mbcs]
  encoding = sjis
 
 It is useful for the users who want to commit with UTF-8 log message.
 '''
 
 import os, sys
 from mercurial.i18n import _
 from mercurial import util, encoding
 
 _encoding = None                                # see extsetup
 
 def decode(arg):
     if isinstance(arg, str):
         uarg = arg.decode(_encoding)
         if arg == uarg.encode(_encoding):
             return uarg
         raise UnicodeError("Not local encoding")
     elif isinstance(arg, tuple):
         return tuple(map(decode, arg))
     elif isinstance(arg, list):
         return map(decode, arg)
     elif isinstance(arg, dict):
         for k, v in arg.items():
             arg[k] = decode(v)
     return arg
 
 def encode(arg):
     if isinstance(arg, unicode):
         return arg.encode(_encoding)
     elif isinstance(arg, tuple):
         return tuple(map(encode, arg))
     elif isinstance(arg, list):
         return map(encode, arg)
     elif isinstance(arg, dict):
         for k, v in arg.items():
             arg[k] = encode(v)
     return arg
 
 def appendsep(s):
     # ensure the path ends with os.sep, appending it if necessary.
     try:
         us = decode(s)
     except UnicodeError:
         us = s
     if us and us[-1] not in ':/\\':
         s += os.sep
     return s
 
 def wrapper(func, args, kwds):
     # check argument is unicode, then call original
     for arg in args:
         if isinstance(arg, unicode):
             return func(*args, **kwds)
 
     try:
         # convert arguments to unicode, call func, then convert back
         return encode(func(*decode(args), **decode(kwds)))
     except UnicodeError:
         raise util.Abort(_("[win32mbcs] filename conversion failed with"
                          " %s encoding\n") % (_encoding))
 
 def wrapperforlistdir(func, args, kwds):
     # Ensure 'path' argument ends with os.sep to avoids
     # misinterpreting last 0x5c of MBCS 2nd byte as path separator.
     if args:
         args = list(args)
         args[0] = appendsep(args[0])
     if 'path' in kwds:
         kwds['path'] = appendsep(kwds['path'])
     return func(*args, **kwds)
 
 def wrapname(name, wrapper):
     module, name = name.rsplit('.', 1)
     module = sys.modules[module]
     func = getattr(module, name)
     def f(*args, **kwds):
         return wrapper(func, args, kwds)
     try:
         f.__name__ = func.__name__                # fail with python23
     except Exception:
         pass
     setattr(module, name, f)
 
 # List of functions to be wrapped.
 # NOTE: os.path.dirname() and os.path.basename() are safe because
 #       they use result of os.path.split()
 funcs = '''os.path.join os.path.split os.path.splitext
- os.path.splitunc os.path.normpath os.makedirs
+ os.path.normpath os.makedirs
  mercurial.util.endswithsep mercurial.util.splitpath mercurial.util.checkcase
  mercurial.util.fspath mercurial.util.pconvert mercurial.util.normpath
  mercurial.util.checkwinfilename mercurial.util.checkosfilename'''
 
+# List of Windows specific functions to be wrapped.
+winfuncs = '''os.path.splitunc'''
+
 # codec and alias names of sjis and big5 to be faked.
 problematic_encodings = '''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 950 cp950 ms950 '''
 
 def extsetup(ui):
     # TODO: decide use of config section for this extension
-    if not os.path.supports_unicode_filenames:
+    if ((not os.path.supports_unicode_filenames) and
+        (sys.platform != 'cygwin')):
         ui.warn(_("[win32mbcs] cannot activate on this platform.\n"))
         return
     # determine encoding for filename
     global _encoding
     _encoding = ui.config('win32mbcs', 'encoding', encoding.encoding)
     # fake is only for relevant environment.
     if _encoding.lower() in problematic_encodings.split():
         for f in funcs.split():
             wrapname(f, wrapper)
+        if os.name == 'nt':
+            for f in winfuncs.split():
+                wrapname(f, wrapper)
         wrapname("mercurial.osutil.listdir", wrapperforlistdir)
         # Check sys.args manually instead of using ui.debug() because
         # command line options is not yet applied when
         # extensions.loadall() is called.
         if '--debug' in sys.argv:
             ui.write("[win32mbcs] activated with encoding: %s\n"
                      % _encoding)