xref: /illumos-gate/usr/src/lib/libc/port/gen/getlogin.c (revision 8b80e8cb6855118d46f605e91b5ed4ce83417395)
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 2008 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /*	Copyright (c) 1988 AT&T	*/
28 /*	  All Rights Reserved  	*/
29 
30 #pragma ident	"%Z%%M%	%I%	%E% SMI"
31 
32 #pragma weak _getlogin = getlogin
33 #pragma weak _getlogin_r = getlogin_r
34 
35 #include "lint.h"
36 #include <sys/types.h>
37 #include <sys/stat.h>
38 #include <fcntl.h>
39 #include <string.h>
40 #include <stdlib.h>
41 #include <limits.h>
42 #include "utmpx.h"
43 #include <unistd.h>
44 #include <errno.h>
45 #include <thread.h>
46 #include <synch.h>
47 #include <mtlib.h>
48 #include "tsd.h"
49 
50 /*
51  * XXX - _POSIX_LOGIN_NAME_MAX limits the length of a login name.  The utmpx
52  * interface provides for a 32 character login name, but for the sake of
53  * compatibility, we are still using the old utmp-imposed limit.
54  */
55 
56 /*
57  * POSIX.1c Draft-6 version of the function getlogin_r.
58  * It was implemented by Solaris 2.3.
59  */
60 char *
61 getlogin_r(char *answer, int namelen)
62 {
63 	int		uf;
64 	off64_t		me;
65 	struct futmpx	ubuf;
66 
67 	if (namelen < _POSIX_LOGIN_NAME_MAX) {
68 		errno = ERANGE;
69 		return (NULL);
70 	}
71 
72 	if ((me = (off64_t)ttyslot()) < 0)
73 		return (NULL);
74 	if ((uf = open64(UTMPX_FILE, 0)) < 0)
75 		return (NULL);
76 	(void) lseek64(uf, me * sizeof (ubuf), SEEK_SET);
77 	if (read(uf, &ubuf, sizeof (ubuf)) != sizeof (ubuf)) {
78 		(void) close(uf);
79 		return (NULL);
80 	}
81 	(void) close(uf);
82 	if (ubuf.ut_user[0] == '\0')
83 		return (NULL);
84 	(void) strncpy(&answer[0], &ubuf.ut_user[0],
85 	    _POSIX_LOGIN_NAME_MAX - 1);
86 	answer[_POSIX_LOGIN_NAME_MAX - 1] = '\0';
87 	return (&answer[0]);
88 }
89 
90 /*
91  * POSIX.1c standard version of the function getlogin_r.
92  * User gets it via static getlogin_r from the header file.
93  */
94 int
95 __posix_getlogin_r(char *name, int namelen)
96 {
97 	int nerrno = 0;
98 	int oerrno = errno;
99 
100 	errno = 0;
101 	if (getlogin_r(name, namelen) == NULL) {
102 		if (errno == 0)
103 			nerrno = EINVAL;
104 		else
105 			nerrno = errno;
106 	}
107 	errno = oerrno;
108 	return (nerrno);
109 }
110 
111 char *
112 getlogin(void)
113 {
114 	char *answer = tsdalloc(_T_LOGIN, _POSIX_LOGIN_NAME_MAX, NULL);
115 
116 	if (answer == NULL)
117 		return (NULL);
118 	return (getlogin_r(answer, _POSIX_LOGIN_NAME_MAX));
119 }
120