Subject: Re: Segfault under cygwin 1.7.62
From: Corinna Vinschen <[email-masked]>
To: [email-masked]
Cc: XEmacs developers <[email-masked]>
Date: Fri, 9 Oct 2009 15:44:23 +0200
List-Id: <cygwin.cygwin.com>

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On Oct  9 07:05, Andy Koppe wrote:
> \001's and the tab at the end.
>
> $ touch $'\001' $'\t'
> touch: cannot touch `\001': No such file or directory
> touch: cannot touch `\t': No such file or directory
> 
> In fact it appears that no control chars are allowed in filenames.

Indeed, and it's even documented.

http://msdn.microsoft.com/en-us/library/aa365247%28VS.85%29.aspx#basic_naming_conventions

  Use any character in the current code page for a name, including Unicode
  characters and characters in the extended character set (128–255),
  except for the following:

    * The following reserved characters:
          < > : " / \ | ? *
    * Integer value zero, sometimes referred to as the ASCII NUL character.
    * Characters whose integer representations are in the range from
      1 through 31, except for streams. For more information about file
      streams, see File Streams.
    * Any other character that the target file system does not allow.

If there's actually a demand to allow filenames with control chars,
we can do this by using the same technique described here:

http://cygwin.com/1.7/cygwin-ug-net/using-specialnames.html#pathnames-specialchars

So we create control chars as special Unicode characters in the private
use area U+f0XX.  It's a very easy change in Cygwin since the
translation back from the U+f0XX range to the original value already
works transparently for any character in the byte range.  We just have
to convert the chars <= 31 to the U+f0XX range just like the other
disallowed chars.

Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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