Re: subtty field in process

["Jan D." <jan.h.d@swipnet.se>]

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>     > It looks like subtty is obsolete.  We could delete it,
>     > unless there is some system on which really using it would
>     > solve some problem today.
> 
>     I propose we delete it.  If it served some purpose it should have been
>     noticed over the last 8-9 years :-).
> 
> It MAY be the case that on some system it works better to do certain
> things to the subprocess (perhaps, send signals) using the tty desc
> rather than the pty desc.  I am not sure such a case ever exists, but
> there are some systems where sending signals to subprocesses doesn't
> work entirely right.

Indeed there are.

> I guess it is sufficient if I send this message to emacs-devel.  Then
> if we ever encounter a problem for which subtty would be a solution,
> with luck someone will remember that.

I can put in some comments about it.

> 
> So please do delete the code for subtty.

Will do.

>     Is this a change we want to put in RC as well?
> 
> We certainly don't want to delete the code for subtty in RC.
> We should make the minimum necessary changes there.
> 
> What change would you propose for RC?

I propose the attached patch.

	Jan D.


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Index: src/process.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/process.c,v
retrieving revision 1.341.4.3
diff -c -r1.341.4.3 process.c
*** src/process.c	23 Oct 2002 17:40:15 -0000	1.341.4.3
--- src/process.c	15 Feb 2003 16:56:35 -0000
***************
*** 3571,3576 ****
--- 3571,3603 ----
    return Qnil;
  }
  \f
+ /* Return the foreground process group for the tty/pty that
+    the process P uses.  */
+ static int
+ emacs_get_tty_pgrp (p)
+      struct Lisp_Process *p;
+ {
+   int gid = -1;
+ 
+ #ifdef TIOCGPGRP 
+   if (ioctl (XINT (p->infd), TIOCGPGRP, &gid) == -1 && ! NILP (p->tty_name))
+     {
+       int fd;
+       /* Some OS:es (Solaris 8/9) does not allow TIOCGPGRP from the
+ 	 master side.  Try the slave side.  */
+       fd = emacs_open (XSTRING (p->tty_name)->data, O_RDONLY, 0);
+ 
+       if (fd != -1)
+ 	{
+ 	  ioctl (fd, TIOCGPGRP, &gid);
+ 	  emacs_close (fd);
+ 	}
+     }
+ #endif /* defined (TIOCGPGRP ) */
+ 
+   return gid;
+ }
+ 
  DEFUN ("process-running-child-p", Fprocess_running_child_p,
         Sprocess_running_child_p, 0, 1, 0,
    "Return t if PROCESS has given the terminal to a child.\n\
***************
*** 3581,3587 ****
  {
    /* Initialize in case ioctl doesn't exist or gives an error,
       in a way that will cause returning t.  */
!   int gid = 0;
    Lisp_Object proc;
    struct Lisp_Process *p;
  
--- 3608,3614 ----
  {
    /* Initialize in case ioctl doesn't exist or gives an error,
       in a way that will cause returning t.  */
!   int gid;
    Lisp_Object proc;
    struct Lisp_Process *p;
  
***************
*** 3595,3606 ****
      error ("Process %s is not active",
  	   XSTRING (p->name)->data);
  
! #ifdef TIOCGPGRP 
!   if (!NILP (p->subtty))
!     ioctl (XFASTINT (p->subtty), TIOCGPGRP, &gid);
!   else
!     ioctl (XINT (p->infd), TIOCGPGRP, &gid);
! #endif /* defined (TIOCGPGRP ) */
  
    if (gid == XFASTINT (p->pid))
      return Qnil;
--- 3622,3628 ----
      error ("Process %s is not active",
  	   XSTRING (p->name)->data);
  
!   gid = emacs_get_tty_pgrp (p);
  
    if (gid == XFASTINT (p->pid))
      return Qnil;
***************
*** 3747,3765 ****
  	 But, TIOCGPGRP does not work on E50 ;-P works fine on E60"
  	 His patch indicates that if TIOCGPGRP returns an error, then
  	 we should just assume that p->pid is also the process group id.  */
-       {
- 	int err;
  
! 	if (!NILP (p->subtty))
! 	  err = ioctl (XFASTINT (p->subtty), TIOCGPGRP, &gid);
! 	else
! 	  err = ioctl (XINT (p->infd), TIOCGPGRP, &gid);
  
  #ifdef pfa
! 	if (err == -1)
! 	  gid = - XFASTINT (p->pid);
  #endif /* ! defined (pfa) */
!       }
        if (gid == -1)
  	no_pgrp = 1;
        else
--- 3769,3782 ----
  	 But, TIOCGPGRP does not work on E50 ;-P works fine on E60"
  	 His patch indicates that if TIOCGPGRP returns an error, then
  	 we should just assume that p->pid is also the process group id.  */
  
!       gid = emacs_get_tty_pgrp (p);
  
  #ifdef pfa
!       if (gid == -1)
!         gid = - XFASTINT (p->pid);
  #endif /* ! defined (pfa) */
! 
        if (gid == -1)
  	no_pgrp = 1;
        else
***************
*** 3821,3827 ****
    /* gid may be a pid, or minus a pgrp's number */
  #ifdef TIOCSIGSEND
    if (!NILP (current_group))
!     ioctl (XINT (p->infd), TIOCSIGSEND, signo);
    else
      {
        gid = - XFASTINT (p->pid);
--- 3838,3847 ----
    /* gid may be a pid, or minus a pgrp's number */
  #ifdef TIOCSIGSEND
    if (!NILP (current_group))
!     {
!       if (ioctl (XINT (p->infd), TIOCSIGSEND, signo) == -1)
! 	EMACS_KILLPG (-gid, signo);
!     }
    else
      {
        gid = - XFASTINT (p->pid);

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