Re: [patch] lib/login_tty.c: Controlling terminal in OpenBSD.

[Eric Blake]

On 09/16/2010 04:01 PM, Mats Erik Andersson wrote:
> Hello again,
>
> a new observation from my bug chasing.
>
> The assumptions made in "lib/login_tty.c", which are set
> on display as inherited from Solaris, these prerequisites
> are __NOT__ sufficient for OpenBSD. The reason is clearly
> displayed in tty(4) of OpenBSD origin. Only after an ioctl
> call with TIOCSCTTY is the controlling terminal established.

Thanks for chasing this.

> +#if __OpenBSD__
> +# include<sys/ioctl.h>
> +#endif
> +
>   int
>   login_tty (int slave_fd)
>   {
> @@ -53,6 +57,11 @@ login_tty (int slave_fd)
>       close (dummy_fd);
>     }
>
> +#if __OpenBSD__
> +  /* Needed to activate the controlling terminal, see tty(4).  */
> +  ioctl (slave_fd, TIOCSCTTY, NULL);
> +#endif

Rather than hard-coding this for just __OpenBSD__, wouldn't it be better 
to have a configure-time check for ioctl, and:

#if HAVE_SYS_IOCTL_H
# include <sys/ioctl.h>
#endif
#if !HAVE_FUNC_IOCTL || !defined TIOCSCTTY
# define ioctl(a, b, c) /* ignored */
#endif


so that in the function body, we can just blindly call this without #ifdefs:

  ioctl (slave_fd, TIOCSCTTY, NULL);

--
Eric Blake   address@hidden    +1-801-349-2682
Libvirt virtualization library http://libvirt.org