X-Recipient: archive-cygwin AT delorie DOT com
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 4FA62383F42D
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
	s=default; t=1626021259;
	bh=NM5IrxtU1P3rPsn022y7XtytEAcBHpyjhA4JUikd6dk=;
	h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post:
	 List-Help:List-Subscribe:From:Reply-To:From;
	b=NSj6uxc4mr3BoC3Wj2+fEj1JU1D+YZ9Y5nvM7bYhSYWy3aL/KIPVuAJc8MwSNMPjo
	 OPdmriHHbOfS79qLtLdWlQscdUI9QBug4z2b+rlkkrDWxQgioqDz0T6wDM+0zM5KqX
	 dQP2Cs0EolFT4wNmsPYD29hFOFLWdflp/gvNP19c=
X-Original-To: cygwin AT cygwin DOT com
Delivered-To: cygwin AT cygwin DOT com
DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 3080A385E007
ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none;
 b=DpRcVvFCvKEH0zi/NjbgdaMCpx/U6SqNUtaYMQes4uCPhD6EdG/hsmtN9OKs0SszRykw0GM+NIRus7ILlNEg8fa5PO7rEqlmIbhSqcmqb1JqdD7j3b5EqhoLQkDSYz5AUUPy1hR7k5W9tw/8T9dvkJDmdl5WN8VT6ffsQylT1BjNp2OtCsChoZ/7XRF4KBcrh+hnfLaGVb/JQ1mUSAKftBF9LDCzL3IM4cAXZq6Vto9t8cl0lIRsdf73PzWHfx+Jy8IEN0icT/uGr1NUHhUhwbPZ+sQFpJ5MlfmM3ifSbdOIy0GFHAICJJUO+DmmITnnz1eQXRKXiO47Vwh5iBJ9nw==
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-SenderADCheck;
 bh=S3tXKo3UFyahs3FEYzZtSerrgMNsajaCCHbfn/5xCSo=;
 b=HW4Br3toGwpe9XKwEs0mSsi3EiF4x0G9PjJ1VYtCa0qZ/FS6gxAmg73V2aE0+FiHhAwKyn9id1FfrlikNp8r6bGO7Zc2um4akTcxAz/Bdds5KacVURv0oh4Mgw9wPmVQcKddGDHppL87bj7WFblqwxVYG1UBLP2YFErNnwF1JLAGVgf5RB9yUf8ZuSCP40MLAYnFMgkNbMvhYyPJvy0TZf0nX3rwfm0is2hr6sFkcPMGwuIqBfIyW4hnSyLXVlCzGNsJ9vNC3asl/lSR1uutRpBXdjvNbSoKC4a2c9738GiKMi0Ef4s7c0Eet63y+MA78ZUV91QfCgfzJAZYOQBkUA==
ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass
 smtp.mailfrom=cornell.edu; dmarc=pass action=none header.from=cornell.edu;
 dkim=pass header.d=cornell.edu; arc=none
To: cygwin <cygwin AT cygwin DOT com>
Subject: cfsetspeed is not consistent with Linux
Message-ID: <466e52fb-bda0-b5c0-f201-033a85e8de29@cornell.edu>
Date: Sun, 11 Jul 2021 12:33:42 -0400
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101
 Thunderbird/78.11.0
Content-Language: en-US
X-ClientProxiedBy: MN2PR10CA0017.namprd10.prod.outlook.com
 (2603:10b6:208:120::30) To BN7PR04MB4388.namprd04.prod.outlook.com
 (2603:10b6:406:f8::19)
MIME-Version: 1.0
X-MS-Exchange-MessageSentRepresentingType: 1
X-MS-PublicTrafficType: Email
X-MS-Office365-Filtering-Correlation-Id: 66a8e102-ebd1-4a10-f3a8-08d94489a683
X-MS-TrafficTypeDiagnostic: BN6PR04MB0898:
X-Microsoft-Antispam-PRVS: <BN6PR04MB08989CC9A3CDDD04F32C0338D8169 AT BN6PR04MB0898 DOT namprd04 DOT prod DOT outlook DOT com>
X-MS-Oob-TLC-OOBClassifiers: OLM:8273;
X-MS-Exchange-SenderADCheck: 1
X-Microsoft-Antispam: BCL:0;
X-Microsoft-Antispam-Message-Info: 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
X-Forefront-Antispam-Report: CIP:255.255.255.255; CTRY:; LANG:en; SCL:1; SRV:;
 IPV:NLI; SFV:NSPM; H:BN7PR04MB4388.namprd04.prod.outlook.com; PTR:; CAT:NONE;
 SFS:(4636009)(366004)(39860400002)(346002)(376002)(396003)(136003)(186003)(478600001)(8676002)(6486002)(26005)(66556008)(66476007)(66946007)(75432002)(38100700002)(31686004)(8936002)(5660300002)(83380400001)(6916009)(2616005)(956004)(36756003)(86362001)(31696002)(16576012)(786003)(2906002)(316002)(43740500002)(45980500001);
 DIR:OUT; SFP:1102; 
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?Windows-1252?Q?yo3B+btdJyaaPDlsWJrEtPn377xpSfQrMi/nGwm1FlPoxy0Z+cowhbru?=
 =?Windows-1252?Q?46G7rCCyJbSkBTup+JhDknl6xV+1Gr/hRjWwy+Dov26XzGLh+TLZzslb?=
 =?Windows-1252?Q?Mhk5pBIr5CyC2BKSMyuHjT7nWk0+GPV0tO6fJk4Qembr2e9790NmG4/X?=
 =?Windows-1252?Q?ohPMyLPUHUNeAhbPapCviYV3UOcGFLaENcArO3AmZ/s+wAMBF/ypXFOw?=
 =?Windows-1252?Q?Bt13J5uv+hhwQYgfI/9q3MqZbquKgmdQv4coEcFGZvKLzviV+e049fxr?=
 =?Windows-1252?Q?VfCotkWYUFFYQuPKuTSFc0ZDQEnvlvfPeE7q+toCcEm2T+5usZMQBthJ?=
 =?Windows-1252?Q?lYyylGGv37PlyWpDGEEAvbLKnpsfokHQBkcPcqgMzLUVu8hccOAZ0Vly?=
 =?Windows-1252?Q?1lLiVmS5IFVHMh7dP5VJ7QoxdLq7avTMeVs9ac6xoJ+p1CS+sN7xeKby?=
 =?Windows-1252?Q?2PpQKG+VgVGNr6GfJ5Qi+KkCM5Dm2EV0raUePKYpbIoRSvSZPvObzFwA?=
 =?Windows-1252?Q?lq1Vms7sE/4LyuvF9HCqR5O1cUjk3Cv3jjkr97QUthrNwT7CuM74uIa2?=
 =?Windows-1252?Q?EfQEskBfJ6Ky+9K5Jnwt9o0HzwTnXynwry5h4EF9007CjYBKBhBJgDlU?=
 =?Windows-1252?Q?JpcjBYH/5nR+knX1o0kXc5dxaHOeLCMG5AaJfZQ1du1hRd2yP/dnS86k?=
 =?Windows-1252?Q?hbN9UXqQI3fVb5WRbIxzK8LwAOnuNZEb/Yt+WgOD8DT0Y/m8rbd9wNf9?=
 =?Windows-1252?Q?aAgr90gztyMREcEJ2CeNe+f2gvRk1jmaMaVP5lfBVQeLzMDCDEcUBTlo?=
 =?Windows-1252?Q?ex8UdwQXcm1544ms65OhXypKC8W3pgG5bi48h6WtiEB8GQU2BTI+ZNSb?=
 =?Windows-1252?Q?9GEIg6/bw32l84PKvnY3gvQkqxTC66g6dTgO0u9YC2bsdO5Ehi7l9kD1?=
 =?Windows-1252?Q?3RVGH16w7XK8JAnvr3/VvHGNrLYAadtLEGAU8fjfCAA1D1++JbNVdSYe?=
 =?Windows-1252?Q?odo56XoIyb6OeijUNDgAewPPezxZtBo2Q6rU/3sQsa0+sFeu8ZjqGxjM?=
 =?Windows-1252?Q?rGs+NkKoHfQ0yTv6u8LRaHQNvFVnvZxkkhlMwfFr7JhMqlKVW+UQtD69?=
 =?Windows-1252?Q?cYAdKfXC908cFi5pgZ0VJZr/ctZoQZ8F4UmknaPuFlPZXAquVRSRdrTu?=
 =?Windows-1252?Q?0eXuRiGp0hQEY1XTW64/2kQyx9gRZH/boTXSfhggHmLOc/umDm0q4/QI?=
 =?Windows-1252?Q?F+sdrweHFnebhwr1klFhYlqlGAsLuLCLkoVlwjTOV/s/y3dyX+IkJdV0?=
 =?Windows-1252?Q?gNCbjO55T6Q1M5k7nOY4HO18mNxLrMBcpBZvIEskktpMskruett1Mehf?=
 =?Windows-1252?Q?WPep7QeHA4a9b99eXUtChy2zCQDBTgXrZi5A7iH8mFQ18rL+hD0DqZ+E?=
X-OriginatorOrg: cornell.edu
X-MS-Exchange-CrossTenant-Network-Message-Id: 66a8e102-ebd1-4a10-f3a8-08d94489a683
X-MS-Exchange-CrossTenant-AuthSource: BN7PR04MB4388.namprd04.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Jul 2021 16:33:44.5588 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 5d7e4366-1b9b-45cf-8e79-b14b27df46e1
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: bJGKJT5kKh0HlsdzCRNHDGIDiD8kBDqc4qir6LvW5adPqLHICwslHYbX07iYftp24hInpTFk3m+yg20Yj/xx7w==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN6PR04MB0898
X-Spam-Status: No, score=-3.5 required=5.0 tests=BAYES_00, DKIM_SIGNED,
 DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, MSGID_FROM_MTA_HEADER,
 RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SPF_HELO_PASS, SPF_PASS,
 TXREP autolearn=ham autolearn_force=no version=3.4.4
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on
 server2.sourceware.org
X-BeenThere: cygwin AT cygwin DOT com
X-Mailman-Version: 2.1.29
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: Ken Brown via Cygwin <cygwin AT cygwin DOT com>
Reply-To: Ken Brown <kbrown AT cornell DOT edu>
Content-Transfer-Encoding: 7bit
Content-Type: text/plain; charset="us-ascii"; Format="flowed"
Sender: "Cygwin" <cygwin-bounces+archive-cygwin=delorie DOT com AT cygwin DOT com>

While investigating an emacs bug 
(https://debbugs.gnu.org/cgi/bugreport.cgi?bug=49524), I noticed a difference in 
the behavior of cfsetspeed(3) on Cygwin and Linux.  I'm not sure we should "fix" 
this, because Cygwin's behavior is consistent with the Linux man page, and 
Linux's behavior is not.  But I thought I should point it out for the sake of 
discussion, because Cygwin generally tries to emulate Linux.  Here are the details:

The Linux man page for cfsetspeed(3) specifies that the speed argument must be 
one of the constants Bnnn (e.g., B9600) defined in termios.h.  But Linux in fact 
allows the speed to be the numerical baud rate (e.g., 9600).  Test case:

$ cat cfsetspeed_test.c
#include <termios.h>
#include <stdio.h>

int
main ()
{
   struct termios tp;

   printf ("Calling cfsetspeed with speed B9600\n");
   if (cfsetspeed (&tp, B9600) < 0)
     perror ("cfsetspeed");
   else
     printf ("cfgetispeed reports speed %u\n", cfgetispeed (&tp));
   printf ("Calling cfsetspeed with speed 9600\n");
   if (cfsetspeed (&tp, 9600) < 0)
     perror ("cfsetspeed");
   else
     printf ("cfgetispeed reports speed %u\n", cfgetispeed (&tp));
}

$ gcc cfsetspeed_test.c

$ ./a.out
Calling cfsetspeed with speed B9600
cfgetispeed reports speed 13
Calling cfsetspeed with speed 9600
cfgetispeed reports speed 13

On Cygwin, however, the output of the same program is:

$ ./a
Calling cfsetspeed with speed B9600
cfgetispeed reports speed 13
Calling cfsetspeed with speed 9600
cfsetspeed: Invalid argument

If we decide that Cygwin should emulate Linux here, it would be a simple matter 
to copy the glibc code, which checks whether the speed is a numerical baud rate 
and, if so, converts it to a Bnnn constant.

Ken

-- 
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