ttyslot.c revision 722:636b850d4ee9 
1/*
2 * Copyright 1991 Sun Microsystems, Inc.  All rights reserved.
3 * Use is subject to license terms.
4 */
5
6/*
7 * Copyright (c) 1984 Regents of the University of California.
8 * All rights reserved.  The Berkeley software License Agreement
9 * specifies the terms and conditions for redistribution.
10 */
11
12#pragma ident	"%Z%%M%	%I%	%E% SMI"
13
14/*
15 * Return the number of the slot in the utmp file
16 * corresponding to the current user: try for file 0, 1, 2.
17 * To mimic the behavior of getttyent, we loop through utmp
18 * and try to find an entry with a matching line number.
19 * If we don't find one we return the index of the end of
20 * the file, so that the record can be added to the end of
21 * the file.
22 */
23#include "../../sys/common/compat.h"
24#include <sys/syscall.h>
25#include <sys/fcntl.h>
26#include <stdio.h>
27#include <unistd.h>
28#include <strings.h>
29
30int
31ttyslot(void)
32{
33	char *tp, *p;
34	int s;
35	int fd;
36	struct utmpx utx;
37
38
39	if ((tp = ttyname(0)) == NULL &&
40	    (tp = ttyname(1)) == NULL &&
41	    (tp = ttyname(2)) == NULL)
42		return(0);
43	if ((p = rindex(tp, '/')) == NULL)
44		p = tp;
45	else
46		p++;
47
48	if ((fd = _syscall(SYS_open, "/etc/utmpx", O_RDONLY)) == -1) {
49		perror("ttyslot: open of /etc/utmpx failed:");
50		return(0);
51	}
52
53	s = 0;
54	while (_read(fd, &utx, sizeof(struct utmpx)) > 0) {
55		s++;
56		if (strncmp(utx.ut_line, p, sizeof(utx.ut_line)) == 0) {
57			_syscall(SYS_close, fd);
58			return(s);
59		}
60	}
61	_syscall(SYS_close, fd);
62	return (s);
63}
64