xref: /illumos-gate/usr/src/lib/libc/port/gen/getlogin.c (revision fd7c59804fad02c3863ef57c544fa7af0fd35068)
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 (c) 2013 Gary Mills
24  *
25  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
26  * Use is subject to license terms.
27  */
28 
29 /*	Copyright (c) 1988 AT&T	*/
30 /*	  All Rights Reserved  	*/
31 
32 #pragma weak _getlogin = getloginx
33 #pragma weak _getlogin_r = getloginx_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 /* Revert the renames done in unistd.h */
51 #ifdef	__PRAGMA_REDEFINE_EXTNAME
52 #pragma	redefine_extname	getlogint	getlogin
53 #pragma	redefine_extname	getlogint_r	getlogin_r
54 #pragma	redefine_extname	__posix_getlogint_r	__posix_getlogin_r
55 #else	/* __PRAGMA_REDEFINE_EXTNAME */
56 #ifdef	getlogin
57 #undef	getlogin
58 #endif	/* getlogin */
59 #ifdef	getlogin_r
60 #undef	getlogin_r
61 #endif	/* getlogin_r */
62 #ifdef	__posix_getlogin_r
63 #undef	__posix_getlogin_r
64 #endif	/* __posix_getlogin_r */
65 #define	getlogint	getlogin
66 #define	getlogint_r	getlogin_r
67 #define	__posix_getlogint_r	__posix_getlogin_r
68 #endif	/* __PRAGMA_REDEFINE_EXTNAME */
69 extern char *getlogint(void);
70 extern char *getlogint_r(char *, int);
71 extern int __posix_getlogint_r(char *, int);
72 
73 /*
74  * Use the full length of a login name.
75  * The utmpx interface provides for a 32 character login name.
76  */
77 #define	NMAX	(sizeof (((struct utmpx *)0)->ut_user))
78 
79 /*
80  * Common function
81  */
82 static char *
83 getl_r_common(char *answer, size_t namelen, size_t maxlen)
84 {
85 	int		uf;
86 	off64_t		me;
87 	struct futmpx	ubuf;
88 	size_t		ulen;
89 
90 	if ((me = (off64_t)ttyslot()) < 0)
91 		return (NULL);
92 	if ((uf = open64(UTMPX_FILE, 0)) < 0)
93 		return (NULL);
94 	(void) lseek64(uf, me * sizeof (ubuf), SEEK_SET);
95 	if (read(uf, &ubuf, sizeof (ubuf)) != sizeof (ubuf)) {
96 		(void) close(uf);
97 		return (NULL);
98 	}
99 	(void) close(uf);
100 	if (ubuf.ut_user[0] == '\0')
101 		return (NULL);
102 
103 	/* Insufficient buffer size */
104 	ulen = strnlen(ubuf.ut_user, maxlen);
105 	if (namelen <= ulen) {
106 		errno = ERANGE;
107 		return (NULL);
108 	}
109 
110 	/*
111 	 * While the interface to getlogin_r says that a user should supply a
112 	 * buffer with at least LOGIN_NAME_MAX bytes, we shouldn't assume they
113 	 * have, especially since we've been supplied with its actual size.
114 	 * Doing otherwise is just asking us to corrupt memory (and has in the
115 	 * past).
116 	 */
117 	(void) strncpy(answer, ubuf.ut_user, ulen);
118 	answer[ulen] = '\0';
119 	return (answer);
120 }
121 
122 /*
123  * POSIX.1c Draft-6 version of the function getlogin_r.
124  * It was implemented by Solaris 2.3.
125  */
126 char *
127 getlogint_r(char *answer, int namelen)
128 {
129 	return (getl_r_common(answer, (size_t)namelen, LOGNAME_MAX_TRAD));
130 }
131 
132 /*
133  * POSIX.1c standard version of the function getlogin_r.
134  * User gets it via static getlogin_r from the header file.
135  */
136 int
137 __posix_getlogint_r(char *name, int namelen)
138 {
139 	int nerrno = 0;
140 	int oerrno = errno;
141 
142 	errno = 0;
143 	if (getl_r_common(name, (size_t)namelen, LOGNAME_MAX_TRAD) == NULL) {
144 		if (errno == 0)
145 			nerrno = EINVAL;
146 		else
147 			nerrno = errno;
148 	}
149 	errno = oerrno;
150 	return (nerrno);
151 }
152 
153 char *
154 getlogint(void)
155 {
156 	char *answer = tsdalloc(_T_LOGIN, LOGIN_NAME_MAX_TRAD, NULL);
157 
158 	if (answer == NULL)
159 		return (NULL);
160 	return (getl_r_common(answer, LOGIN_NAME_MAX_TRAD, LOGNAME_MAX_TRAD));
161 }
162 
163 /*
164  * POSIX.1c Draft-6 version of the function getlogin_r.
165  * It was implemented by Solaris 2.3.
166  * For extended login names, selected by redefine_extname in unistd.h.
167  */
168 char *
169 getloginx_r(char *answer, int namelen)
170 {
171 	return (getl_r_common(answer, (size_t)namelen, NMAX));
172 }
173 
174 /*
175  * POSIX.1c standard version of the function getlogin_r.
176  * User gets it via static getlogin_r from the header file.
177  * For extended login names, selected by redefine_extname in unistd.h.
178  */
179 int
180 __posix_getloginx_r(char *name, int namelen)
181 {
182 	int nerrno = 0;
183 	int oerrno = errno;
184 
185 	errno = 0;
186 	if (getl_r_common(name, (size_t)namelen, NMAX) == NULL) {
187 		if (errno == 0)
188 			nerrno = EINVAL;
189 		else
190 			nerrno = errno;
191 	}
192 	errno = oerrno;
193 	return (nerrno);
194 }
195 
196 /*
197  * For extended login names, selected by redefine_extname in unistd.h.
198  */
199 char *
200 getloginx(void)
201 {
202 	char *answer = tsdalloc(_T_LOGIN, LOGIN_NAME_MAX, NULL);
203 
204 	if (answer == NULL)
205 		return (NULL);
206 	return (getl_r_common(answer, LOGIN_NAME_MAX, NMAX));
207 }
208