On 5/28/22 12:15 PM, Dallin Dahl wrote:
> It turns out I had the same issue as Rio, since my login shell was still
> controlling my terminal. If I run:
>
> exec s6-setsid X :3 vt3
>
> while logged into tty3, I get an X display. However, I still can't
> seem to get it to work with s6-svscan. If I exec into s6-svscan from
> my login shell, svscan then controls the tty. If I exec into s6-setsid
> s6-svscan, it still seems attached to the tty. I thought that maybe
> using the tiocnotty ioctl call would free the tty for X to pick up,
> so I wrote the following wrapper program:
>
> #include <fcntl.h>
> #include <sys/ioctl.h>
> #include <stdio.h>
> #include <unistd.h>
>
> int main(int argc, char **argv) {
> int tty = open("/dev/tty", O_RDONLY);
This doesn't close the TTY. I don't know if that makes a difference.
> int res = ioctl(tty, TIOCNOTTY);
> if(!~res) perror("tiocnotty");
> argv++;
> execvp(*argv, argv);
> return 0;
> }
>
> and tried to exec into that before s6-svscan, both with and without
> s6-setsid. Unfortunately, the process immediately exits. I don't think
> it's my wrapper program, since I can run other programs with it without
> problems, and they do indeed show up in the output of ps aux without a
> controlling terminal.
>
> So I guess the new question is how can I free the tty after login,
> allowing X to open it and control it?
Have you tried redirecting all three standard fds elsewhere (/dev/null or a
file) when running s6-svscan? Possibly either s6-svscan or s6-supervise is doing
some fd manipulation that steals control of the TTY before X can get it. You
could also try running s6-supervise directly to narrow this down.
Regards,
Samuel
