DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:mime-version:content-type
	:content-transfer-encoding:date:from:to:subject:in-reply-to
	:references:message-id; q=dns; s=default; b=qpjLEFkzClPtQrV9whmY
	sHoe3vWUpeL80M2tNNxnXkILDhaM9FN5ezg+VzcEbsWCwhtLK8Ro6xVoJGt2afwo
	3rKhsW5nLm4uzr57GahBrQSdun38Wnfff54focFGfju9LyyjIIjCW8nGvjUABirF
	1Y9YepxLMOuq+wwtWpGAzkQ=
Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm
Sender: cygwin-owner@cygwin.com
Mail-Followup-To: cygwin@cygwin.com
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII; format=flowed
Content-Transfer-Encoding: 7bit
Date: Mon, 17 Dec 2018 05:30:26 +0100
From: Houder <houder@xs4all.nl>
To: cygwin@cygwin.com
Subject: Re: /dev/fd/N not synonymous with file descriptor N; it is on Linux
In-Reply-To: <20181216215549.GO28727@calimero.vinschen.de>
References: <0f030e809f063f5a5e64ff7a7a0c3227@xs4all.nl> <20181216202847.GK28727@calimero.vinschen.de> <CAHSx_SvqFgi5stKvYSNCPwyyu98miPHyYcDKJL1-=KP8NE9+JQ@mail.gmail.com> <20181216215549.GO28727@calimero.vinschen.de>
Message-ID: <12270f528754c1ce974e6ad8d22c4249@xs4all.nl>
User-Agent: XS4ALL Webmail

On 2018-12-16 22:55, Corinna Vinschen wrote:
[snip]

> I'm mulling over adding some hack to open().  It could try to recognize
> the special case of opening a processes' own descriptor symlink within
> /proc and then warp the open() call into dup().  No idea how tricky
> or even feasible that is, though...

That is why I wrote the following in my STC:

         // Q: does Cygwin attempt to read the /tmp directory? (an 
attempt that
         //    will fail, because the file has been unlinked)
         // it appears that reading a symlnk in /dev/fd can best be 
diverted to
         // the open file descriptor of the process ...

What I meant was, that I see no reason to modify the symlink in this
special case, but in stead of that to access the file using fd N, where
N is equal to the one in /dev/fd/N.

File descriptor N has been left open by bash and should not have been
closed as result of the exec ...

And indeed, I have _no_ clue if the above is feasible (and tricky?) in
Cygwin; otherwise I would have posted a solution.

Regards,
Henri

--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple