I've run into a problem with controlling tty semantics. I've got
a native init, getty, login, and  tcsh running on NetBSD.

I often try and start an xterm on the NetBSD machine, to get an X
window on a machine with a window system. This worked fine when I did
it from a session on the NetBSD box running from an Ultrix shell.  But
when I try it now, with the native binaries, the (Ultrix) xterm fails;
and prints a message indicating it's failed to open /dev/tty ,
incurring an EPERM error.

Xterm currently exits when it sees such an error. The following
patch fixes it; but it's rather ugly.

I wonder if the right thing to do is to "fix" binary emulation to support
something closer to old Berkeley semantics of opening dev/tty; or
to hack on Xterm?

------
*** /tmp/RCSAa01793	Fri Sep  2 12:18:31 1994
--- X11/R6/xc/programs/xterm/main.c	Fri Sep  2 12:07:09 1994
***************
*** 1660,1703 ****
   		 * that has gone away).  Simply make up some reasonable
   		 * defaults.
   		 */
   		signal(SIGALRM, hungtty);
   		alarm(2);		/* alarm(1) might return too soon */
   		if (! setjmp(env)) {
   			tty = open ("/dev/tty", O_RDWR, 0);
   			alarm(0);
   		} else {
  			tty_got_hung = True;
   			tty = -1;
   			errno = ENXIO;
   		}
   		signal(SIGALRM, SIG_DFL);
   
  		/*
  		 * Check results and ignore current control terminal if
  		 * necessary.  ENXIO is what is normally returned if there is
  		 * no controlling terminal, but some systems (e.g. SunOS 4.0)
  		 * seem to return EIO.
  		 */
   		if (tty < 0) {
  			if (tty_got_hung || errno == ENXIO || errno == EIO ||
! 			    errno == ENOTTY) {
  				no_dev_tty = TRUE;
  #ifdef TIOCSLTC
  				ltc = d_ltc;
  #endif	/* TIOCSLTC */
  #ifdef TIOCLSET
  				lmode = d_lmode;
  #endif	/* TIOCLSET */
  #ifdef USE_SYSV_TERMIO
  				tio = d_tio;
  #else	/* not USE_SYSV_TERMIO */
  				sg = d_sg;
  				tc = d_tc;
  				discipline = d_disipline;
  #ifdef sony
  				jmode = d_jmode;
  				jtc = d_jtc;
  #endif /* sony */
  #endif	/* USE_SYSV_TERMIO */
  			} else {
  			    SysError(ERROR_OPDEVTTY);
--- 1660,1705 ----
   		 * that has gone away).  Simply make up some reasonable
   		 * defaults.
   		 */
   		signal(SIGALRM, hungtty);
   		alarm(2);		/* alarm(1) might return too soon */
   		if (! setjmp(env)) {
   			tty = open ("/dev/tty", O_RDWR, 0);
   			alarm(0);
   		} else {
  			tty_got_hung = True;
   			tty = -1;
   			errno = ENXIO;
   		}
   		signal(SIGALRM, SIG_DFL);
   
  		/*
  		 * Check results and ignore current control terminal if
  		 * necessary.  ENXIO is what is normally returned if there is
  		 * no controlling terminal, but some systems (e.g. SunOS 4.0)
  		 * seem to return EIO.
+ 		 * (XXX) NetBSD emulation returns EPERM, because on 4.4BSD
+ 		 * opening a tty doesn't make it a a controlling  tty.
  		 */
   		if (tty < 0) {
  			if (tty_got_hung || errno == ENXIO || errno == EIO ||
! 			    errno == ENOTTY || errno == EPERM) {
  				no_dev_tty = TRUE;
  #ifdef TIOCSLTC
  				ltc = d_ltc;
  #endif	/* TIOCSLTC */
  #ifdef TIOCLSET
  				lmode = d_lmode;
  #endif	/* TIOCLSET */
  #ifdef USE_SYSV_TERMIO
  				tio = d_tio;
  #else	/* not USE_SYSV_TERMIO */
  				sg = d_sg;
  				tc = d_tc;
  				discipline = d_disipline;
  #ifdef sony
  				jmode = d_jmode;
  				jtc = d_jtc;
  #endif /* sony */
  #endif	/* USE_SYSV_TERMIO */
  			} else {
  			    SysError(ERROR_OPDEVTTY);

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