usr/src/lib/libc/port/gen/getlogin.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 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 }