To attach controlling terminal (CT) to a process:
I have following code similar in OpenSSH

1. disconnect from old CT
2. become a session leader setsid()
3. attach psuedo tty to process calling ioctl(fd, TIOCSCTTY, NULL)

I dont want my process being a session leader to avoid SIGHUP for child
process.

But if I comment out setsid, I get error in ioctl and subsequent open
calls for terminals-
ioctl - (Input/output error)
/dev/pts/4: No such file or directory
open /dev/tty failed

(fd is associated with /dev/pts/4)

Is there any mechanism to attach psuedo terminal to process as its
Controlling Terminal without being a session leader?

OR can a process give up session leadership after attaching CT ?

ioctl(fd, TIOCSCTTY, NULL) gives following error
ioctl(TIOCSCTTY):  Operation not permitted


pankajtakawale wrote:

> To attach controlling terminal (CT) to a process:
> I have following code similar in OpenSSH
>
> 1. disconnect from old CT
> 2. become a session leader setsid()
> 3. attach psuedo tty to process calling ioctl(fd, TIOCSCTTY, NULL)
>
> I dont want my process being a session leader to avoid SIGHUP for child
> process.
>
> But if I comment out setsid, I get error in ioctl and subsequent open
> calls for terminals-
> ioctl - (Input/output error)
> /dev/pts/4: No such file or directory
> open /dev/tty failed
>
> (fd is associated with /dev/pts/4)
>
> Is there any mechanism to attach psuedo terminal to process as its
> Controlling Terminal without being a session leader?
> 
> OR can a process give up session leadership after attaching CT ?

pankajtakawale wrote:
> To attach controlling terminal (CT) to a process:
> I have following code similar in OpenSSH
>
> 1. disconnect from old CT
> 2. become a session leader setsid()
> 3. attach psuedo tty to process calling ioctl(fd, TIOCSCTTY, NULL)
>
> I dont want my process being a session leader to avoid SIGHUP for child
> process.

Is there a reason why you can't block SIGHUP before spawning a child?
This way children would not receive SIGHUP since the signal mask is
inherited by child processed.

http://www.opengroup.org/onlinepubs/009695399/functions/sigprocmask.html

P.S. If you are using Solaris 8, it's broken in this regard. The signal
mask on this operating system is only inherited by threads, not child
processes.

Maxim Yegorushkin wrote:

> pankajtakawale wrote:
> > To attach controlling terminal (CT) to a process:
> > I have following code similar in OpenSSH
> >
> > 1. disconnect from old CT
> > 2. become a session leader setsid()
> > 3. attach psuedo tty to process calling ioctl(fd, TIOCSCTTY, NULL)
> >
> > I dont want my process being a session leader to avoid SIGHUP for child
> > process.
>
> Is there a reason why you can't block SIGHUP before spawning a child?
> This way children would not receive SIGHUP since the signal mask is
> inherited by child processed.
>
Yes blocking SIGHUP is one way. I dont want block SIGHUP in all cases.
foreground process wouldnt receive SIGHUP if I close the session. I
think I have to cpmpromise somewhere.

> http://www.opengroup.org/onlinepubs/009695399/functions/sigprocmask.html
>
> P.S. If you are using Solaris 8, it's broken in this regard. The signal
> mask on this operating system is only inherited by threads, not child
> processes.

Thanks