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[unix-history] / usr / src / usr.bin / window / wwpty.c

#ifndef lint
static char sccsid[] = "@(#)wwpty.c     3.11 %G%";
#endif

/*
* Copyright (c) 1983 Regents of the University of California,
* All rights reserved.  Redistribution permitted subject to
* the terms of the Berkeley Software License Agreement.
*/

#include "ww.h"

/*
* To satisfy Chris, we allocate pty's backwards, and if
* there are more than the ptyp's (i.e. the ptyq's)
* on the machine, we don't use the p's.
*/
wwgetpty(w)
register struct ww *w;
{
       register char c;
       register int i;
       int tty;
       int on = 1;
       char hasq = 0;
#define PTY "/dev/XtyXX"
#define _PT     5
#define _PQRS   8
#define _0_9    9

       (void) strcpy(w->ww_ttyname, PTY);
       for (c = 's'; c >= 'p'; c--) {
               w->ww_ttyname[_PT] = 'p';
               w->ww_ttyname[_PQRS] = c;
               w->ww_ttyname[_0_9] = '0';
               if (access(w->ww_ttyname, 0) < 0)
                       continue;
               if (c != 'p')
                       hasq = 1;
               else if (hasq)
                       break;
               for (i = 15; i >= 0; i--) {
                       w->ww_ttyname[_PT] = 'p';
                       w->ww_ttyname[_0_9] = "0123456789abcdef"[i];
                       if ((w->ww_pty = open(w->ww_ttyname, 2)) < 0)
                               continue;
                       w->ww_ttyname[_PT] = 't';
                       if ((tty = open(w->ww_ttyname, 2)) < 0) {
                               (void) close(w->ww_pty);
                               continue;
                       }
                       (void) close(tty);
                       if (ioctl(w->ww_pty, (int)TIOCPKT, (char *)&on) < 0) {
                               (void) close(w->ww_pty);
                               continue;
                       }
                       return 0;
               }
       }
       w->ww_pty = -1;
       wwerrno = WWE_NOPTY;
       return -1;
}