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Date: Thu, 11 May 2006 10:14:40 -0400 (EDT)
From: Igor Peshansky <pechtcha AT cs DOT nyu DOT edu>
Reply-To: cygwin AT cygwin DOT com
To: Charles Wilson <cygwin AT cwilson DOT fastmail DOT fm>
cc: cygwin AT cygwin DOT com
Subject: Re: cvs pserver issue with new cygwin packages
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On Thu, 11 May 2006, Charles Wilson wrote:

> Eric Blake wrote:
> > > > $ cvs co test
> > > > cannot mkdir /tmp/cvs-serv3172/.
> > > > No such file or directory
> > > This was a bug in Cygwin 1.5.19, which returned the wrong error code for
> > > creating this directory, and CVS didn't know to ignore it.  Try a
> > > snapshot.
> >
> > It wasn't the 'wrong' errno, so much as a different errno than Linux
> > used in the same situation, and a bug that still exists in CVS for
> > blindly assuming that only the Linux errno will be used even on
> > non-Linux platforms.  POSIX allows any number of errno
> > returns when more than one simultaneous error condition exists.
>
> Well now.  That's news to me.  I thought it WAS a pure cygwin bug, not a
> misinterpretation of POSIX by the cvs guys.  After folks discovered the
> errno issue and it was "fixed" in the cygwin snapshots, I said "I don't
> want to clutter up the cvs sourcecode with a workaround for a bug that's
> already fixed.  We'll just wait for cygwin-1.5.20"

There was some analysis of this back in February.  The problem was that
Cygwin's behavior was contrary to POSIX.  POSIX states:

The mkdir() function shall fail if:

[ENOENT]
    A component of the path prefix specified by path does not name an
    existing directory or path is an empty string.
[EEXIST]
    The named file exists.

Cygwin set errno to ENOENT for somedir/., even if somedir existed.  This
was just plain wrong (i.e., nothing in the above allows such behavior).

> Given Eric's explanation, that was the wrong decision.  Given the
> controversy over cvs-1.11.21, I'll release an update of cvs-1.11.17 with
> a workaround for this...difference of opinion? as soon as I can.  Which
> would be sooner if someone sent me a P to TC.

Chuck, the problem with adding a workaround is that there may be a
legitimate ENOENT (e.g., you call mkdir("/path/to/somedir/."), and "/path"
doesn't exist).  So, even the hack you proposed in
<http://cygwin.com/ml/cygwin/2006-02/msg00175.html> will not work...  The
only safe (but very inefficient) fix is to test every path component, and
ignore ENOENT only if all of them exist.
	Igor
-- 
				http://cs.nyu.edu/~pechtcha/
      |\      _,,,---,,_	    pechtcha AT cs DOT nyu DOT edu | igor AT watson DOT ibm DOT com
ZZZzz /,`.-'`'    -.  ;-;;,_		Igor Peshansky, Ph.D. (name changed!)
     |,4-  ) )-,_. ,\ (  `'-'		old name: Igor Pechtchanski
    '---''(_/--'  `-'\_) fL	a.k.a JaguaR-R-R-r-r-r-.-.-.  Meow!

"Las! je suis sot... -Mais non, tu ne l'es pas, puisque tu t'en rends compte."
"But no -- you are no fool; you call yourself a fool, there's proof enough in
that!" -- Rostand, "Cyrano de Bergerac"

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