DMARC-Filter:	OpenDMARC Filter v1.4.2 delorie.com 68EJkjxc1192877
Authentication-Results:	delorie.com; dmarc=pass (p=none dis=none) header.from=cygwin.com
Authentication-Results:	delorie.com; spf=pass smtp.mailfrom=cygwin.com
DKIM-Filter:	OpenDKIM Filter v2.11.0 delorie.com 68EJkjxc1192877
Authentication-Results:	delorie.com;
	dkim=pass (1024-bit key, unprotected) header.d=cygwin.com header.i=@cygwin.com header.a=rsa-sha256 header.s=default header.b=aQRmDpuO
X-Recipient:	archive-cygwin AT delorie DOT com
DKIM-Filter:	OpenDKIM Filter v2.11.0 sourceware.org A1C744BB592E
DKIM-Signature:	v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
	s=default; t=1789206676;
	bh=wtx2KqlPCiDF841VAHu9ZTRQ4fZQs8zvUghXUCdWWM4=;
	h=Date:Subject:To:References:In-Reply-To:List-Id:List-Unsubscribe:
	List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:
	From;
	b=aQRmDpuOC9ykTTaY4VIcinsF3M1xCGYcPyKZ7K3jqaTu0SMOE6J0Dl9sjw4ZDXA2q
	crz03zBz13A3DP4k6I1Q4XoEtoYAtZusXHq+TYIiuhRx9DjOOol6qeKnK+ZdGEhzMI
	NBUvIeVcXRTjnmHEvLaqfU/uQLg8gPByxoZPhPcA=
X-Original-To:	cygwin AT cygwin DOT com
Delivered-To:	cygwin AT cygwin DOT com
DMARC-Filter:	OpenDMARC Filter v1.4.2 sourceware.org C1FCB4BB592E
ARC-Filter:	OpenARC Filter v1.0.0 sourceware.org C1FCB4BB592E
ARC-Seal:	i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1789206655; cv=none;
	b=a71bl0VvzlLplrjkUI+So3pniuGALyfEj/FX3X1WtU1VU6lmxuG+lKaakNNW0Wtev8loKZAaRAsWY0oaiX71PNsISFjvgD53bDFSLF6DMlF3bFt4yyw1cJ2naCuo2saELZssIxJHYfNH/h5Iopw4OU46rqrjC7mch5PN8OJguNI=
ARC-Message-Signature:	i=1; a=rsa-sha256; d=sourceware.org; s=key;
	t=1789206655; c=relaxed/simple;
	bh=0DznTZinkaBnTMZWIfhMHHGxLHnySMX0Ts3ws+XfgrM=;
	h=Message-ID:Date:MIME-Version:Subject:To:From;
	b=j7q2HNyIrDI/qtVoT6g9e89vavxZqAxXUHERVlswZsumBMafIlXO8EENow5iYVPRsbX8x2ghcokZz16ndKDdeux2x1w5dTc04tQbHiDXkDMLhVBgNF+alLHiwVuCrDwchx+JGkPUPHlijBURzgm6zKr1MPVGPZ1RC2c36nzxweE=
ARC-Authentication-Results:	i=1; sourceware.org
DKIM-Filter:	OpenDKIM Filter v2.11.0 sourceware.org C1FCB4BB592E
Message-ID:	<224c2a02-7ab6-48a7-b84f-bf5236799883@maxrnd.com>
Date:	Sat, 12 Sep 2026 02:50:56 -0700
MIME-Version:	1.0
User-Agent:	Mozilla Thunderbird
Subject:	Re: fstatat of symlink to fifo gets st_mode from symlink, not from
	fifo
To:	cygwin AT cygwin DOT com
References:	<ap5MnTuoylBGxwBm AT raf DOT org>
In-Reply-To:	<ap5MnTuoylBGxwBm@raf.org>
X-BeenThere:	cygwin AT cygwin DOT com
X-Mailman-Version:	2.1.30
List-Id:	General Cygwin discussions and problem reports <cygwin.cygwin.com>
List-Unsubscribe:	<https://cygwin.com/mailman/options/cygwin>,
	<mailto:cygwin-request AT cygwin DOT com?subject=unsubscribe>
List-Archive:	<https://cygwin.com/pipermail/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-request AT cygwin DOT com?subject=help>
List-Subscribe:	<https://cygwin.com/mailman/listinfo/cygwin>,
	<mailto:cygwin-request AT cygwin DOT com?subject=subscribe>
From:	Mark Geisert via Cygwin <cygwin AT cygwin DOT com>
Reply-To:	Mark Geisert <mark AT maxrnd DOT com>
Errors-To:	cygwin-bounces~archive-cygwin=delorie DOT com AT cygwin DOT com
Sender:	"Cygwin" <cygwin-bounces~archive-cygwin=delorie DOT com AT cygwin DOT com>

Hello raf,

On 9/6/2026 10:33 PM, raf via Cygwin wrote:
> Hi,
> 
> This is on Win10.
> 
> I have a seemingly impossible problem with fstatat following a symlink to
> a fifo. Most of the resulting struct stat correctly contains details of the
> fifo except for the st_mode field. It contains the type and permissions
> of the symlink itself.
> 
> I assume I must be doing something wrong but the same code works on
> six other operating systems.
> 
> Any idea what the cause might be? My tests relating to this have been
> failing for ages, and I just accepted that this wierd little case just
> might not work on Cygwin, but looking into it closely shows that it
> almost does work, just not quite.
> 
> Actually, the same problem happens with stat(1), not just my program.
> Here's a demonstration:
> 
>    mkdir t
>    cd t
>    mkfifo fifo
>    sleep 5
>    ln -s fifo symfifo
>    stat symfifo fifo
>    stat -L symfifo
>    cd ..
>    rm -r t
> 
> The above commands show this ouptut:
> 
>    $ stat symfifo fifo
>      File: symfifo -> fifo
>      Size: 4               Blocks: 0          IO Block: 65536  symbolic link
>    Device: 15518,20572     Inode: 7599824372130494  Links: 1
>    Access: (0777/lrwxrwxrwx)  Uid: (197609/    john)   Gid: (197121/    None)
>    Access: 2026-09-07 15:25:50.209111800 +1000
>    Modify: 2026-09-07 15:25:50.209111800 +1000
>    Change: 2026-09-07 15:25:50.209111800 +1000
>     Birth: 2026-09-07 15:25:50.209111800 +1000
>      File: fifo
>      Size: 0               Blocks: 1          IO Block: 65536  fifo
>    Device: 0,196   Inode: 8162774325551800  Links: 1
>    Access: (0666/prw-rw-rw-)  Uid: (197609/    john)   Gid: (197121/    None)
>    Access: 2026-09-07 15:25:49.754243600 +1000
>    Modify: 2026-09-07 15:25:43.732451800 +1000
>    Change: 2026-09-07 15:25:43.732451800 +1000
>     Birth: 2026-09-07 15:25:43.732451800 +1000
>    
>    $ stat -L symfifo
>      File: symfifo -> fifo
>      Size: 4294953488      Blocks: 1          IO Block: 65536  symbolic link
>    Device: 0,196   Inode: 8162774325551800  Links: 1
>    Access: (0777/lrwxrwxrwx)  Uid: (197609/    john)   Gid: (197121/    None)
>    Access: 2026-09-07 15:25:53.970058800 +1000
>    Modify: 2026-09-07 15:25:43.732451800 +1000
>    Change: 2026-09-07 15:25:43.732451800 +1000
>     Birth: 2026-09-07 15:25:43.732451800 +1000
> 
> Note that the last command that follows the symlink
> states that the fifo is a "symbolic link" rather than "fifo"
> and permissions "0777/lrwxrwxrwx" rather than "0666/prw-rw-rw-".
> 
> Is this fixable? Or is it just this pc?

I've reproduced this locally, so it's not your pc ;-).  What version of 
Cygwin are you running on your Windows 10 machine?

I've also reproduced this on Cygwin 3.3.6, which is pretty old.  You may 
have just run into a bug that has gone undiscovered for a long time. 
I'll look into investigating and patching this issue.
Thanks for the report,

..mark


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

- Raw text -