getlogin.c revision 1.13 
1/*	$OpenBSD: getlogin.c,v 1.13 2015/09/12 14:56:50 guenther Exp $ */
2/*
3 * Copyright (c) 1988, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 *    may be used to endorse or promote products derived from this software
16 *    without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#include <errno.h>
32#include <limits.h>
33#include <pwd.h>
34#include <stdio.h>
35#include <string.h>
36#include <unistd.h>
37#include <utmp.h>
38
39#include "thread_private.h"
40
41_THREAD_PRIVATE_MUTEX(logname);
42static int  logname_valid = 0;
43static char logname[LOGIN_NAME_MAX + 1];
44
45int	_getlogin(char *, size_t);
46int	_setlogin(const char *);
47
48char *
49getlogin(void)
50{
51	_THREAD_PRIVATE_KEY(getlogin);
52	char * name = (char *)_THREAD_PRIVATE(getlogin, logname, NULL);
53
54	if ((errno = getlogin_r(name, sizeof logname)) != 0)
55		return NULL;
56	if (*name == '\0') {
57		errno = ENOENT;  /* well? */
58		return NULL;
59	}
60	return name;
61}
62
63int
64getlogin_r(char *name, size_t namelen)
65{
66	int logname_size;
67
68	_THREAD_PRIVATE_MUTEX_LOCK(logname);
69	if (!logname_valid) {
70		if (_getlogin(logname, sizeof(logname) - 1) < 0) {
71			_THREAD_PRIVATE_MUTEX_UNLOCK(logname);
72			return errno;
73		}
74		logname_valid = 1;
75		logname[LOGIN_NAME_MAX] = '\0';	/* paranoia */
76	}
77	logname_size = strlen(logname) + 1;
78	if (namelen < logname_size) {
79		_THREAD_PRIVATE_MUTEX_UNLOCK(logname);
80		return ERANGE;
81	}
82	memcpy(name, logname, logname_size);
83	_THREAD_PRIVATE_MUTEX_UNLOCK(logname);
84	return 0;
85}
86DEF_WEAK(getlogin_r);
87
88int
89setlogin(const char *name)
90{
91	int ret;
92
93	_THREAD_PRIVATE_MUTEX_LOCK(logname);
94	ret = _setlogin(name);
95	if (ret == 0)
96		logname_valid = 0;
97	_THREAD_PRIVATE_MUTEX_UNLOCK(logname);
98	return ret;
99}
100