misc/ttyslot.c

   1 /*
   2  * Copyright (c) 1988, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #if defined(LIBC_SCCS) && !defined(lint)
  31 static char sccsid[] = "@(#)ttyslot.c   8.1 (Berkeley) 6/4/93";
  32 #endif /* LIBC_SCCS and not lint */
  33
  34 #include <ttyent.h>
  35 #include <alloca.h>
  36 #include <stdio.h>
  37 #include <string.h>
  38 #include <unistd.h>
  39
  40 int
  41 ttyslot (void)
  42 {
  43         struct ttyent *ttyp;
  44         int slot;
  45         char *p;
  46         int cnt;
  47         size_t buflen = __sysconf (_SC_TTY_NAME_MAX) + 1;
  48         char *name;
  49
  50         if (buflen == 0)
  51           /* This should be enough if no fixed value is given.  */
  52           buflen = 32;
  53
  54         name = __alloca (buflen);
  55
  56         setttyent();
  57         for (cnt = 0; cnt < 3; ++cnt)
  58                 if (__ttyname_r (cnt, name, buflen) == 0) {
  59                         if ((p = rindex(name, '/')))
  60                                 ++p;
  61                         else
  62                                 p = name;
  63                         for (slot = 1; (ttyp = getttyent()); ++slot)
  64                                 if (!strcmp(ttyp->ty_name, p)) {
  65                                         endttyent();
  66                                         return(slot);
  67                                 }
  68                         break;
  69                 }
  70         endttyent();
  71         return(0);
  72 }