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> #include <sys/types.h>
> #include <sys/stat.h>
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> char *pty(int *ptyv);
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> char *pty();
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< 	signal(SIGPIPE, CatchPipeSignal);
< 	pipe(to_prog);
< 	pipe(from_prog);
---
>  	char *ttyname;
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>  	if ((ttyname = pty(&to_prog[1])) == (char *) NULL) {
>  		perror(program_name);
>  		exit(1);
>  	}
> 
>  	from_prog[0] = to_prog[1];
>  	to_prog[0] = from_prog[1] = open(ttyname, O_RDWR, 0);
> 
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> }
> 
> #define FIRST_PTY_LETTER 'p'
> #define SYSV_PTYS
> 
> /* Open an available pty, putting descriptor in *ptyv,
>   and return the file name of the pty.  Return 0 if none available.  */
> 
> char ptyname[24];
> 
> char *
> pty (ptyv)
>      int *ptyv;
> {
>   struct stat stb;
>   register c, i;
> 
> #ifdef PTY_ITERATION
>   PTY_ITERATION
> #else
>   for (c = FIRST_PTY_LETTER; c <= 'z'; c++)
>     for (i = 0; i < 16; i++)
> #endif
>       {
> #ifdef PTY_NAME_SPRINTF
> 	PTY_NAME_SPRINTF
> #else
> #ifdef HPUX
> 	sprintf (ptyname, "/dev/ptym/pty%c%x", c, i);
> #else
> #ifdef RTU
> 	sprintf (ptyname, "/dev/pty%x", i);
> #else
> 	sprintf (ptyname, "/dev/pty%c%x", c, i);
> #endif /* not RTU */
> #endif /* not HPUX */
> #endif /* no PTY_NAME_SPRINTF */
> 
> #ifndef IRIS
> 	if (stat (ptyname, &stb) < 0)
> 	  return 0;
> 	*ptyv = open (ptyname, O_RDWR | O_NDELAY, 0);
> #else /* Unusual IRIS code */
>  	*ptyv = open ("/dev/ptc", O_RDWR | O_NDELAY, 0);
>  	if (*ptyv < 0)
>  	  return 0;
> 	if (fstat (*ptyv, &stb) < 0)
> 	  return 0;
> #endif /* IRIS */
> 
> 	if (*ptyv >= 0)
> 	  {
> 	    /* check to make certain that both sides are available
> 	       this avoids a nasty yet stupid bug in rlogins */
> #ifdef PTY_TTY_NAME_SPRINTF
> 	    PTY_TTY_NAME_SPRINTF
> #else
> 	    /* In version 19, make these special cases use the macro above.  */
> #ifdef HPUX
>             sprintf (ptyname, "/dev/pty/tty%c%x", c, i);
> #else
> #ifdef RTU
>             sprintf (ptyname, "/dev/ttyp%x", i);
> #else
> #ifdef IRIS
>  	    sprintf (ptyname, "/dev/ttyq%d", minor (stb.st_rdev));
> #else
>             sprintf (ptyname, "/dev/tty%c%x", c, i);
> #endif /* not IRIS */
> #endif /* not RTU */
> #endif /* not HPUX */
> #endif /* no PTY_TTY_NAME_SPRINTF */
> #ifndef UNIPLUS
> 	    if (access (ptyname, 6) != 0)
> 	      {
> 		close (*ptyv);
> #ifndef IRIS
> 		continue;
> #else
> 		return (0);
> #endif /* IRIS */
> 	      }
> #endif /* not UNIPLUS */
> 	    /*
> 		* If the following statement is included,
> 		* then a 0 length record is EOT, but no other
> 		* control characters can be sent down the pty
> 		* (e.g., ^S/^Q, ^O, etc.).  If it is not
> 		* included, then sending ^D down the pty-pipe
> 		* makes a pretty good EOF.
> 		*/
> 	    /* I'm told that TOICREMOTE does not mean control chars
> 	       "can't be sent" but rather that they don't have
> 	       input-editing or signaling effects.
> 	       That should be good, because we have other ways
> 	       to do those things in Emacs.
> 	       However, telnet mode seems not to work on 4.2.
> 	       So TIOCREMOTE is turned off now. */
> 
> 	    /* Under hp-ux, if TIOCREMOTE is turned on, some calls
> 	       will hang.  In particular, the "timeout" feature (which
> 	       causes a read to return if there is no data available)
> 	       does this.  Also it is known that telnet mode will hang
> 	       in such a way that Emacs must be stopped (perhaps this
> 	       is the same problem).
> 
> 	       If TIOCREMOTE is turned off, then there is a bug in
> 	       hp-ux which sometimes loses data.  Apparently the
> 	       code which blocks the master process when the internal
> 	       buffer fills up does not work.  Other than this,
> 	       though, everything else seems to work fine.
> 
> 	       Since the latter lossage is more benign, we may as well
> 	       lose that way.  -- cph */
> #ifdef HPUX
> #if 0
> #define DID_REMOTE
> 	    ioctl (*ptyv, TIOCREMOTE, 1);
> /* Yes, HPUX has an incompatible interface for this.
>    Also, using it makes telnet.el fail (Emacs hangs sending text to
>    it).  */
> #endif
> #else /* not HPUX */
> #if 0
> #ifdef TIOCREMOTE
> 	    {
> 	      int on = 1;
> 	      ioctl (*ptyv, TIOCREMOTE, &on);
> 	    }
> #endif
> #endif
> #endif /* not HPUX */
> /* this is said to be unecessary, and to be harmful in 4.3.  */
> /*	    ioctl (*ptyv, FIONBIO, &on);  */
> #ifdef FIONBIO
> #ifdef SYSV_PTYS
> 	    {
> 	      int on = 1;
> 	      ioctl (*ptyv, FIONBIO, &on);
> 	    }
> #endif
> #endif
> #ifdef IBMRTAIX
>    /* On AIX, the parent gets SIGHUP when a pty attached child dies.  So, we */
>    /* ignore SIGHUP once we've started a child on a pty.  Note that this may */
>    /* cause EMACS not to die when it should, i.e., when its own controlling  */
>    /* tty goes away.  I've complained to the AIX developers, and they may    */
>    /* change this behavior, but I'm not going to hold my breath.             */
> 	    signal (SIGHUP, SIG_IGN);
> #endif
> 	    return ptyname;
> 	  }
>       }
>   return 0;