From: Corinna Vinschen <corinna-cygwin@cygwin.com>
To: cygwin@cygwin.com
Subject: Re: cfsetspeed is not consistent with Linux
Date: Mon, 12 Jul 2021 10:16:42 +0200 [thread overview]
Message-ID: <YOv6an75uho0rRW7@calimero.vinschen.de> (raw)
In-Reply-To: <466e52fb-bda0-b5c0-f201-033a85e8de29@cornell.edu>
On Jul 11 12:33, Ken Brown via Cygwin wrote:
> 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:
> [...]
> $ ./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.
We can do this too. For historical reasons we should stay careful
taking over other GPLed code into the Cygwin DLL itself, but just
copying the speed_struct struct should be fine.
Corinna
prev parent reply other threads:[~2021-07-12 8:16 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-11 16:33 Ken Brown
2021-07-12 8:16 ` Corinna Vinschen [this message]
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