[Python-Dev] casefolding in pathlib (PEP 428)

Ralf Schmitt ralf at systemexit.de
Fri Apr 12 19:42:25 CEST 2013

Guido van Rossum <guido at python.org> writes:

> Actually, I've heard of code that dynamically falls back on short
> names when paths using long names exceed the system limit for path
> length (either 256 or 1024 IIRC). But short names pretty much require
> consulting the filesystem, so we can probably ignore them.

The limit is 260 characters. But longer paths can be handled by
prepending \\?\ and using the unicode APIs.

see http://msdn.microsoft.com/en-us/library/aa365247.aspx#maxpath

we have the following code to handle the above insanity:
| def prepend_magic_win32(path):
|     assert isinstance(path, unicode), "path must be of type unicode"
|     if path.startswith(u"\\\\"):
|         if path.startswith(u"\\\\?\\"):
|             return path
|         else:
|             return u"\\\\?\\UNC\\" + path[2:]
|     else:
|         return u"\\\\?\\" + path


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