usr/src/lib/libbc/libc/gen/common/ttyslot.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*
  28  * Copyright (c) 1984 Regents of the University of California.
  29  * All rights reserved.  The Berkeley software License Agreement
  30  * specifies the terms and conditions for redistribution.
  31  */
  32
  33 /*
  34  * Return the number of the slot in the utmp file
  35  * corresponding to the current user: try for file 0, 1, 2.
  36  * To mimic the behavior of getttyent, we loop through utmp
  37  * and try to find an entry with a matching line number.
  38  * If we don't find one we return the index of the end of
  39  * the file, so that the record can be added to the end of
  40  * the file.
  41  */
  42 #include "../../sys/common/compat.h"
  43 #include <sys/syscall.h>
  44 #include <sys/fcntl.h>
  45 #include <stdio.h>
  46 #include <unistd.h>
  47 #include <strings.h>
  48
  49 int
  50 ttyslot(void)
  51 {
  52         char *tp, *p;
  53         int s;
  54         int fd;
  55         struct utmpx utx;
  56
  57
  58         if ((tp = ttyname(0)) == NULL &&
  59             (tp = ttyname(1)) == NULL &&
  60             (tp = ttyname(2)) == NULL)
  61                 return (0);
  62         if ((p = rindex(tp, '/')) == NULL)
  63                 p = tp;
  64         else
  65                 p++;
  66
  67         if ((fd = _syscall(SYS_openat,
  68             AT_FDCWD, "/etc/utmpx", O_RDONLY)) == -1) {
  69                 perror("ttyslot: open of /etc/utmpx failed:");
  70                 return (0);
  71         }
  72
  73         s = 0;
  74         while (_read(fd, &utx, sizeof (struct utmpx)) > 0) {
  75                 s++;
  76                 if (strncmp(utx.ut_line, p, sizeof (utx.ut_line)) == 0) {
  77                         _syscall(SYS_close, fd);
  78                         return (s);
  79                 }
  80         }
  81         _syscall(SYS_close, fd);
  82         return (s);
  83 }