Update.
[glibc.git] / sysdeps / unix / getlogin_r.c
blob8ec2fae754311f24da30d7612f7afe8b2502c357
1 /* Reentrant function to return the current login name. Unix version.
2 Copyright (C) 1991, 1992, 1996, 1997 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Library General Public License as
7 published by the Free Software Foundation; either version 2 of the
8 License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Library General Public License for more details.
15 You should have received a copy of the GNU Library General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If not,
17 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA. */
20 #include <errno.h>
21 #include <unistd.h>
22 #include <string.h>
23 #include <stdio.h>
24 #include <limits.h>
25 #include <fcntl.h>
27 #include <utmp.h>
29 /* Return at most NAME_LEN characters of the login name of the user in NAME.
30 If it cannot be determined or some other error occurred, return the error
31 code. Otherwise return 0. */
33 int
34 getlogin_r (name, name_len)
35 char *name;
36 size_t name_len;
38 char tty_pathname[2 + 2 * NAME_MAX];
39 char *real_tty_path = tty_pathname;
40 int result = 0;
41 struct utmp *ut, line, buffer;
44 int d = __open ("/dev/tty", 0);
45 if (d < 0)
46 return errno;
48 result = ttyname_r (d, real_tty_path, sizeof (tty_pathname));
49 (void) close (d);
51 if (result != 0)
53 __set_errno (result);
54 return result;
58 real_tty_path += 5; /* Remove "/dev/". */
60 __setutent ();
61 strncpy (line.ut_line, real_tty_path, sizeof line.ut_line);
62 if (__getutline_r (&line, &buffer, &ut) < 0)
64 if (errno == ESRCH)
65 /* The caller expects ENOENT if nothing is found. */
66 result = ENOENT;
67 else
68 result = errno;
70 else
72 size_t needed = strlen (ut->ut_line) + 1;
74 if (needed < name_len)
76 __set_errno (ERANGE);
77 result = ERANGE;
79 else
81 memcpy (name, ut->ut_line, needed);
82 result = 0;
85 __endutent ();
87 return result;