Re: ":" in filename

[Christian Franke <Christian dot Franke at t-online dot de>]

Igor Peshansky wrote:
> On Sat, 25 Mar 2006, Larry Hall (Cygwin) wrote:
>   
> > Eric Blake wrote:
> >
> > <snip>
> >     
> > > It would be nice if cygwin could be more proactive in recognizing : as
> > > invalid in non-managed mounts, rather than passing the : on to the
> > > Windows filename functions, in order to avoid the creation of
> > > undeletable filenames such as ".new." via the help of a colon, but I
> > > can live with the current behavior if adding such a check would slow
> > > down the common case.
> > >       
> > The latter affect is certainly the case here though, as usual, I'm sure
> > it's a PTC if someone has a great brainstorm for a way to do this
> > without the overhead.
> >     
>
> Well, normalize_posix_path() (in path.cc) already scans the whole path
> string looking for '\\' -- I can't imagine that adding a check for ':'
> would introduce all that much overhead.  But, of course, empirical
> evidence is always best, and I don't have any at the moment.
>   

Two month ago, I tested an experimental enhancement to 1.5.19-4 which 
includes such a check.

It adds a new setting to the CYGWIN environment variable:
"ads:deny" - Return EINVAL on path names with ":" (as suggested)
"ads:allow" - Allow path names with ":" (the current behavior)
"ads:list" - Expose ADS is directory listings

Example:
$ touch test:one test:two

$ ls
test

$ CYGWIN=ads:list ls
test test:one test:two

I didn't realize any overhead for the first two settings.
The third setting of course slows down directory listings (~x4), but it 
allows things like cp/tar'ing files including ADS.

The (very preliminary) patch is here:
http://franke.dvrdns.org/cygwin/cygwin-1.5.19-4-ads.patch
Due to the substantial changes to fhandler_disk_file.cc, the patch is 
not compatible with current CVS.
But the small test for ":" in path.cc:normalize_posix_path() may still 
work ;-)

Christian


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