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Date: Tue, 11 Jul 2006 21:22:18 +0200
From: Christian Franke <Christian DOT Franke AT t-online DOT de>
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Subject: Re: ":" in filename
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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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