X-Recipient:	archive-cygwin AT delorie DOT com
DKIM-Filter:	OpenDKIM Filter v2.11.0 sourceware.org ACFCF3858C62
DKIM-Signature:	v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
	s=default; t=1706294178;
	bh=In4vPBkWp78wlzcS37E4tR57kjCy58RmAIYFud21Cq0=;
	h=To:Subject:Date:References:In-Reply-To:List-Id:List-Unsubscribe:
	List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:
	From;
	b=QJSUA3jSERH2SXEvhg8UAXNI8hsLfuC4Syq4VCjrl75Az+crn/Q+63tLV/hQ7cw7N
	L+PGVucFq3MXZIR8YvTZR0Y+9nnXPNj5S+WmNGdU+lSgXIR097xAGNJ5SDdwzI/seZ
	aXLq8U1loBHt4XU8zPq0iza9QJiREz8sIJ6dVI9g=
X-Original-To:	cygwin AT cygwin DOT com
Delivered-To:	cygwin AT cygwin DOT com
DMARC-Filter:	OpenDMARC Filter v1.4.2 sourceware.org 077BF3858D33
ARC-Filter:	OpenARC Filter v1.0.0 sourceware.org 077BF3858D33
ARC-Seal:	i=2; a=rsa-sha256; d=sourceware.org; s=key; t=1706294156; cv=pass;
	b=UC4AIdQLKNLERyM1tkk7vTpnUApA3gyKlumMyJytMHP2oqNZAlo2zt5V7l0XfXVmo6rrgBK8vPbB6Ux6vLhD/P9566VX15ToAdhpu7ZF+7a5i9I9kTArrPSb8ApNQr/q/n3FTscmyPuustU43N9sEJh21/yKOMPW8KBNxQ1B2gI=
ARC-Message-Signature:	i=2; a=rsa-sha256; d=sourceware.org; s=key;
	t=1706294156; c=relaxed/simple;
	bh=iy8Bd9njvPgS2CFi1I2TWKc9SQ5bg3m42nzzT9gV3xY=;
	h=DKIM-Signature:From:To:Subject:Date:Message-ID:MIME-Version;
	b=PqYzcIQJ3ivMEVUmrO1oq7tSeXt3EdVMNtBQcdUdY1iZ7kqkjRhHow5ysgUFntCcaOuT1Sy7eawPim78ZhW1isdAr8tGM8uZOdy2KmAFj7ntXWJZEBU1mvNjVBaREGVH20zI5Wwwjw9FFhY7zrLEQ3nxucbyNZcn1te/6D/CjJ4=
ARC-Authentication-Results:	i=2; server2.sourceware.org
ARC-Seal:	i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none;
	b=ANP1X6B6hlZjlgQjqejXP5zWv0EGhtGkI1b3z9bZnd7uFGR/WpeHjzVro4+xKxXO9V+G9ozHrhEsnp0kG9wqUVo4hPwKU6p8DRm4HH6qRGdh4HRnihBdAdymKzUcDylet3+Y/KDVppRpZsU7keesYcBLyM3TRKfVr1wtl3m2botujDSK9gi65CITtwuUs3zeV1YtEfcpFaAf2huLG0Q+uoNvXtfmjCef1EZ74pPn1XS2b3nxBuzpLOJpMsz/CLggPdhuuDd1+nHtF5HxFmbzttIzQLp3ApmPjcijEC36hbunhxIh7qBpJlEs1oHzGh6mAIrjjcb3p6/PNNdq1oPmeA==
ARC-Message-Signature:	i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com;
	s=arcselector9901;
	h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1;
	bh=7yIH+rrPkZxehZblJ2eAbGEhBP4XheHZDTm0cwiRa3M=;
	b=IjxwUmIzvQwuK4kO9vogjpf/AADjRPg3oxzioSmQtgt1QEupQV5+c90uC8t50FL6gv8CAHVXU0FnINbHp/Rf0R0+2bNIEvE791eD6ZaotLbeNjmI+2V+tQWLbfMMMelz1tfzMT3HLMmP7M68OegnnMQ4EyTi3sykMetI+xDUIct6/uT9EHDYc1+QUleUBO7+bnWf6VKUDbr3mIWAtehusGNLoGo/g5gAgI7ePX9W8OtCkq3ukADdV1nK4N5yQ3+j8RZwB/5g5J4dwGqAxTjzxSGjPQHSGoc64RNtMRsBGWw2JyCLQVXQ6XSV0xfHYUGtZG/mSM5JS8SlhFWPAwU3GA==
ARC-Authentication-Results:	i=1; mx.microsoft.com 1; spf=none; dmarc=none;
	dkim=none; arc=none
To:	"Lavrentiev, Anton (NIH/NLM/NCBI) [C]" <lavr AT ncbi DOT nlm DOT nih DOT gov>,
	"cygwin AT cygwin DOT com" <cygwin AT cygwin DOT com>
Subject:	Re: Setting process command name in forked process
Thread-Topic:	Setting process command name in forked process
Thread-Index:	AQHaTjFJbF93zhLsSUS7kXKt2AFVP7DsPw7ggAAu1lg=
Date:	Fri, 26 Jan 2024 18:35:51 +0000
Message-ID:	<DM6PR20MB347644CA2D99E18B0F468578B1792@DM6PR20MB3476.namprd20.prod.outlook.com>
References:	<DM6PR20MB34760DA0A9B07EDB6BC5C214B1742 AT DM6PR20MB3476 DOT namprd20 DOT prod DOT outlook DOT com>
	<DM8PR09MB7095E65F7C281621A1A7A63BA5792 AT DM8PR09MB7095 DOT namprd09 DOT prod DOT outlook DOT com>
In-Reply-To:	<DM8PR09MB7095E65F7C281621A1A7A63BA5792@DM8PR09MB7095.namprd09.prod.outlook.com>
Accept-Language:	en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
msip_labels:
x-ms-exchange-messagesentrepresentingtype:	1
x-tmn:	[uxLMCG0lV7oO1b9x7vgrwGpoUOc23ALk]
x-ms-publictraffictype:	Email
x-ms-traffictypediagnostic:	DM6PR20MB3476:EE_|MW3PR20MB3340:EE_
x-ms-office365-filtering-correlation-id:	1b47117a-b928-49a5-5e46-08dc1e9d9fd1
x-microsoft-antispam:	BCL:0;
x-microsoft-antispam-message-info:	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
x-ms-exchange-antispam-messagedata-chunkcount:	1
x-ms-exchange-antispam-messagedata-0:	=?iso-8859-1?Q?rNESvMQJ0xu2bsXWKUt319xwv8BVQnskLU4/Hy2IO+gViOFKfRFKl3XsU8?=
	=?iso-8859-1?Q?ea8m13jpdXDVJ75eHL0fCRhkR4B34eXuXWZJufLnU10Ed4hlob9q77vGB3?=
	=?iso-8859-1?Q?2TOIa/BbO4zCSaQUzA9dC/o+K+1ecH5vCgTC906luuOw5yKmtHqQe9NRLA?=
	=?iso-8859-1?Q?G07t8c3FXY44oUIxjoPZZisd1VnbVM6Ku9neIlYNjtKXgRkbiuFgY08Pmf?=
	=?iso-8859-1?Q?l/vTt1iSPnQT8VUm4qu/ATTRGo8xKFwbBwnjLCm+rbfH9GTAMMPJk47Emf?=
	=?iso-8859-1?Q?e3+da00YkwZToyYAykWR3yWWkfM379bHbmRrvyv+6m/YVCF5DvVaUau7sQ?=
	=?iso-8859-1?Q?DZ6ehOE46c+kahivGO0uQOUR7e2ZVnw2r5w3lrcCXnuJPvvC7In1UeFDGb?=
	=?iso-8859-1?Q?BD9Cg/UOBOJ8qE//JQcED9+hDZ+Cfvi+WRhdfcaNE9hT4Qlf//yI0b/zGh?=
	=?iso-8859-1?Q?ce8di2lFbSTEbu1uW3+DQDSh20gTZX+yTKL1U/itD5xpfBu5VWhFg2jDZz?=
	=?iso-8859-1?Q?t6FthjXbgIGnEBq0KBpD+PSqFvz5UVE8wYCdY8Ar/oi0xvoZEKs2297Ckz?=
	=?iso-8859-1?Q?BSk5zUH41pDMSDa5Vw3EWqK7EHD6rqMLHZxUnz7k7x2oMyDIwkwECQyEQF?=
	=?iso-8859-1?Q?YwZSi4JiQiTJtDK7Z2lvARwKuml4uBcC+wa4Agl3XbGOfhZWp3jaBpLcW+?=
	=?iso-8859-1?Q?JUOYxlJYbh1V4SVzlG1gJjyKa9Xws/eJ8BNtqtLs0mjmS2todq5v3ndCO+?=
	=?iso-8859-1?Q?yfNIltPJUilcU6y8ZPrEft1M/gOGOAFvPBm/+lifEWWzlq9RcajMgNaseN?=
	=?iso-8859-1?Q?xhbz2RY9XrA2GfmWTAf67MsoUZYiSpTyFAmki91hcId7KJ3/eHUBw3itq6?=
	=?iso-8859-1?Q?aV/zFUwye0FdDC0OXjaksALroxfcchwfGiLrfJSYQUoP62+Trk8+PTR0PW?=
	=?iso-8859-1?Q?NUMzYLB0psl2p3lJoMA0m+xsaaEEAx5b5VaItAXz2Mz+ifuv2bktm3iCnE?=
	=?iso-8859-1?Q?fZHPN1WZctjY3tYKSlyE3BgPXByCMlMkzCmAd6tcvLumSrQeBBHUDiBtDQ?=
	=?iso-8859-1?Q?cNWYwAOikqz4HtK5dDYeYjFqAzSrP3hu+9nQKw/5H2UCYBT5msHf3LgZx1?=
	=?iso-8859-1?Q?4ELxls1sU4Hh5HizdbOFfIyTc0x/W2f59SohGKqhWRhfTyeiRHGx+VgiUF?=
	=?iso-8859-1?Q?isjkr/SwNIr4mhGQHKh6WUAySa+2nVoj8lLMcZAe8PJnR4Pc7o+o/xz0KW?=
	=?iso-8859-1?Q?CY/qRC6UZJX4ndcBhokA=3D=3D?=
MIME-Version:	1.0
X-OriginatorOrg:	sct-15-20-4755-11-msonline-outlook-9803a.templateTenant
X-MS-Exchange-CrossTenant-AuthAs:	Internal
X-MS-Exchange-CrossTenant-AuthSource:	DM6PR20MB3476.namprd20.prod.outlook.com
X-MS-Exchange-CrossTenant-RMS-PersistedConsumerOrg:	00000000-0000-0000-0000-000000000000
X-MS-Exchange-CrossTenant-Network-Message-Id:	1b47117a-b928-49a5-5e46-08dc1e9d9fd1
X-MS-Exchange-CrossTenant-originalarrivaltime:	26 Jan 2024 18:35:51.9264 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader:	Hosted
X-MS-Exchange-CrossTenant-id:	84df9e7f-e9f6-40af-b435-aaaaaaaaaaaa
X-MS-Exchange-CrossTenant-rms-persistedconsumerorg:	00000000-0000-0000-0000-000000000000
X-MS-Exchange-Transport-CrossTenantHeadersStamped:	MW3PR20MB3340
X-Spam-Status:	No, score=-1.4 required=5.0 tests=BAYES_00, DKIM_SIGNED,
	DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_ENVFROM_END_DIGIT,
	FREEMAIL_FROM, HTML_MESSAGE, SPF_HELO_PASS, SPF_PASS, TXREP,
	T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version:	SpamAssassin 3.4.6 (2021-04-09) on
	server2.sourceware.org
X-Content-Filtered-By:	Mailman/MimeDel 2.1.30
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-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:	Steve Beck via Cygwin <cygwin AT cygwin DOT com>
Reply-To:	Steve Beck <stevebeck99 AT hotmail DOT com>
Sender:	"Cygwin" <cygwin-bounces+archive-cygwin=delorie DOT com AT cygwin DOT com>

Thanks so much for the reply, Anton!  Really appreciate it.

I tried what you proposed.  Here is the code trying both ways (overwriting what is referenced by __argv[0] and then reassigning the reference).  I compile this code (foo.c) simply as follows: gcc -o foo foo.c (with no errors or warnings):

#include        <stdio.h>
#include        <sys/types.h>
#include        <stdlib.h>
#include        <string.h>

extern  pid_t   getpid(void), fork(void);
extern  int     sleep(int);

int
main (int argc, char *argv[])
{
        printf("%s with pid %d: Entered.  About to fork child ...\n",
                argv[0], getpid());

        if (fork() == 0)
        {
                extern  char    **__argv;

                strcpy(__argv[0], "bar");

                printf("Child '%s' (argv[0]) with pid %d: ps ...\n",
                        argv[0], getpid());
                system("ps");

                __argv[0] = "bar";

                printf("Retry in Child '%s' (argv[0]) with pid %d setting __argv[0] = 'bar': ps ...\n", argv[0], getpid());
                system("ps");

                exit(0);
        }

        printf("%s parent with pid %d: sleep(5) ...\n", argv[0], getpid());
        sleep(5);

        exit(0);
}

Here is the output when running foo.exe:

foo with pid 497: Entered.  About to fork child ...
foo parent with pid 497: sleep(5) ...
Child 'bar' (argv[0]) with pid 498: ps ...
      PID    PPID    PGID     WINPID   TTY         UID    STIME COMMAND
      446     445     446     108276  pty0     1207519 10:19:37 /usr/bin/bash
      445       1     445     126652  ?        1207519 10:19:36 /usr/bin/mintty
      499     498     497     125904  pty0     1207519 10:26:41 /usr/bin/ps
      498     497     497     128424  pty0     1207519 10:26:41 /home/sbeck/foo
      497     446     497     123772  pty0     1207519 10:26:41 /home/sbeck/foo
Retry in Child 'bar' (argv[0]) with pid 498 setting __argv[0] = 'bar': ps ...
      PID    PPID    PGID     WINPID   TTY         UID    STIME COMMAND
      446     445     446     108276  pty0     1207519 10:19:37 /usr/bin/bash
      445       1     445     126652  ?        1207519 10:19:36 /usr/bin/mintty
      498     497     497     128424  pty0     1207519 10:26:41 /home/sbeck/foo
      497     446     497     123772  pty0     1207519 10:26:41 /home/sbeck/foo
      500     498     497     128948  pty0     1207519 10:26:41 /usr/bin/ps

As you can see, in neither case does the ps command seem to accurately reflect the change in __argv[0] (although within the program, the change occurs to argv[0]).

Can you see what I'm doing wrong?

Many thanks,
Steve

________________________________
From: Lavrentiev, Anton (NIH/NLM/NCBI) [C] <lavr AT ncbi DOT nlm DOT nih DOT gov>
Sent: Friday, January 26, 2024 7:47 AM
To: Steve Beck <stevebeck99 AT hotmail DOT com>; cygwin AT cygwin DOT com <cygwin AT cygwin DOT com>
Subject: RE: Setting process command name in forked process

> (I'm assuming it's too late by the time the /proc entry has been set up).

Actually, it's not.  But beware, the suggested solution is absolutely NOT portable:

These are the externals that /proc is referring to...  (Not argc, argv passed to main().)

    extern char** __argv;
    extern int    __argc;

So you can change everything that it shows by reassigning __argv(and/or __argc) with a totally
different set of arguments, or just modify __argv[0], provided that it fits into the space
occupied by the original argument [0].

HTH,

Anton Lavrentiev
Contractor NIH/NLM/NCBI


-- 
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 -