DMARC-Filter:	OpenDMARC Filter v1.4.2 delorie.com 561HIK433411561
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 561HIK433411561
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=jBDfQYxD
X-Recipient:	archive-cygwin AT delorie DOT com
DKIM-Filter:	OpenDKIM Filter v2.11.0 sourceware.org 0D1E63854816
DKIM-Signature:	v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
	s=default; t=1751390300;
	bh=X1ntpgqzpKQkZp0S8d/knXpJYN90yRw5NNBhPCXx6gA=;
	h=Date:Subject:To:References:In-Reply-To:List-Id:List-Unsubscribe:
	List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc:
	From;
	b=jBDfQYxDbYYP32JbH7yit5NKMSWUkjgWyIl5nzkzUsVqv1zhe5491nglEQYIvo0R4
	UHvtQQqLA8AHFhHG1BltzSXSAfHIPz7xNsNUF8Wtx5irR01w1m35exuH10LTcgh0B8
	mDStkbDcxZ0B6gqdCBrrTuFa6gZqBaDX18Lej5XM=
X-Original-To:	cygwin AT cygwin DOT com
Delivered-To:	cygwin AT cygwin DOT com
DMARC-Filter:	OpenDMARC Filter v1.4.2 sourceware.org B2EDE385C6FE
ARC-Filter:	OpenARC Filter v1.0.0 sourceware.org B2EDE385C6FE
ARC-Seal:	i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1751390231; cv=none;
	b=mbWs3cLKDP7TAgiw5JHcd8H9SDRR1IXOcz+AuSKSSm1DkDna8Qnr5WZ4dHDXn6GOJ91916PBtYiqrpoC9DSL/+MAJZcFWZTOwARmQmbV1R0bzsHxuDF7iuEerG53WM78zPuud265lGUgdSM2vbrr7UgZdLvB7mfKaSdqQ5KFjGs=
ARC-Message-Signature:	i=1; a=rsa-sha256; d=sourceware.org; s=key;
	t=1751390231; c=relaxed/simple;
	bh=O68fT/K+GVZ154AI/AqDl6RyxE1JTrPcFQZyWd7o/TE=;
	h=Message-ID:Date:MIME-Version:From:Subject:To:DKIM-Signature;
	b=MI9WC0kCjlQsDlGBWiLUpHhiPNfq2Asgt5CF6e40ucdHQ0jtgdZKFkVV8zm1XVuVME2n56k6ErGaXXX78vERYiBkMY1UB7JKCFsgb6pS78GCY7TQD2EVKDRp8JDrEMAGudkQ5fxtknwPlmWhpaLY8CenjSCdnOkPkz/Gbh3F8Rk=
ARC-Authentication-Results:	i=1; server2.sourceware.org
DKIM-Filter:	OpenDKIM Filter v2.11.0 sourceware.org B2EDE385C6FE
Message-ID:	<3b667ff0-7778-4b48-866f-1dd112317c84@SystematicSW.ab.ca>
Date:	Tue, 1 Jul 2025 11:17:08 -0600
MIME-Version:	1.0
User-Agent:	Mozilla Thunderbird
Subject:	Re: setpgid non-compliance with POSIX?
To:	cygwin AT cygwin DOT com
References:	<3391453b-7914-a319-fad8-4729610558ea AT jdrake DOT com>
	<aGJc0nVQ-1v1DqCO AT calimero DOT vinschen DOT de>
	<f5748be6-5730-ae25-20af-3ed60be5c100 AT jdrake DOT com>
Organization:	Systematic Software
In-Reply-To:	<f5748be6-5730-ae25-20af-3ed60be5c100@jdrake.com>
X-Rspamd-Queue-Id:	CEC802000E
X-Stat-Signature:	6h88dop5rd5rgzu4xewxkdwr598oers8
X-Rspamd-Server:	rspamout06
X-Session-Marker:	427269616E2E496E676C69734053797374656D6174696353572E61622E6361
X-Session-ID:	U2FsdGVkX1+/zJEiAuVaPsMY1rDk4qINghp2m37beSE=
X-HE-Tag:	1751390229-536855
X-HE-Meta:	U2FsdGVkX1/uQZl2Z1+zXMHE4ASkBsj3zyYsnKjmRAKE2Ne8DZSi28DZnpOndZTzxVomoVgb86sx+BPr0oe7znB5QjvULl+890z/XmVoOD0F0XFTnhUBrBVb2wLyNAOACIYFW6XoluQNrIVe+yHXy+Iw8URDtxaO31ATvSBiSGYVGmvEeU2+iBlC0HqdL9EFr4LMaC8qum6pXm+YP7LjBVKh/FBT1mQJhU4cWqiXUUiRjcIJLpGo3wjzESy2r6E4718/zWHtLdTQUbndBFC2zXZGlaiaG1nUx0tq0Iw1I0njLbVaFOS9xf7uLD8z0tOueTnzV2OodBD+LA263ZFiBwZi/9FS6WrD7Gd3t1d6ZtDP0Vrbncw2V0xHB7PreexhVz/cBnQAIyBtjovsJEIvbXgDZNqge0Dhv2QtFhL6sXppBrUT5/rxjg==
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:	Brian Inglis via Cygwin <cygwin AT cygwin DOT com>
Reply-To:	cygwin AT cygwin DOT com
Cc:	Brian Inglis <Brian DOT Inglis AT SystematicSW DOT ab DOT ca>
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>
X-MIME-Autoconverted:	from base64 to 8bit by delorie.com id 561HIK433411561

On 2025-06-30 13:07, Jeremy Drake via Cygwin wrote:
> On Mon, 30 Jun 2025, Corinna Vinschen via Cygwin wrote:
> 
>> On Jun 28 12:32, Jeremy Drake via Cygwin wrote:
>>> I was looking at setpgid yesterday, and it seems deficient with respect to
>>> the errors required to be returned by the POSIX docs in
>>> https://pubs.opengroup.org/onlinepubs/9799919799/functions/setpgid.html
>>>
>>> Basically, it seems that setpgid allows any arbitrary positive integer to
>>> be set as pgid, rather than restricting to setting it to either the
>>> process's pid or to an existing pgid in the same session (sid).
>>
>> Yeah, error checking in setpgid is a bit on the lacking side.  With only
>> minor changes, the function is basically 25 years old :}
> 
> The POSIX docs metioned that an old BSD allowed setting arbitrary pgid
> 
>> Off the top of my head I don't know how to check the pgid already exists.
>> Do you?
> 
> I think it'd have to iterate all processes and check pgid and sid members
> of pinfo until it found a match.

Shouldn't need to - pgid is the pid of a process spawned by init, or pid of a 
login shell, and sid is that pgid or that of the parent process, or pgid is that 
of a job shell or of the parent process.

So each process sid also pgid is either its pid or that of its parent process: 
they are only set either to the process pid or inherited.

Try head /proc/self/*id & and head /proc/$$/*id as demos.

Does any of that help? ;^>

-- 
Take care. Thanks, Brian Inglis              Calgary, Alberta, Canada

La perfection est atteinte                   Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter  not when there is no more to add
mais lorsqu'il n'y a plus rien à retrancher  but when there is no more to cut
                                 -- Antoine de Saint-Exupéry

-- 
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 -