[PATCH] ash: setsid and TIOCSCTTY when enabling job control.

[Michael Conrad]

Would this have an effect on scripts being used as init which did not 
previously have a controlling terminal?  There are quite a few commands 
which change behavior when run with/without a tty.

(the usual fix for enabling job control is to run agetty in your init 
script)

-Mike

On 3/12/2012 7:56 PM, Avery Pennarun wrote:
> Both calls will fail if we are already a process group leader, or the
> process group leader is not us, or we already have a controlling terminal.
> So basically these calls are harmless in the worst case, and get rid of the
> annoying "can't access tty; job control turned off" problem in the best
> case.  In other words, CTRL-C and CTRL-Z will work.
>
> This makes busybox sh job control usable with "init=/bin/sh" on the Linux
> kernel command line.
> ---
>   shell/ash.c |    2 ++
>   1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/shell/ash.c b/shell/ash.c
> index 5671a52..5259dd2 100644
> --- a/shell/ash.c
> +++ b/shell/ash.c
> @@ -3727,6 +3727,8 @@ setjobctl(int on)
>   		if (fd<  0)
>   			goto out;
>   		/* fd is a tty at this point */
> +		setsid();
> +		ioctl(fd, TIOCSCTTY, 0);
>   		close_on_exec_on(fd);
>   		do { /* while we are in the background */
>   			pgrp = tcgetpgrp(fd);