1 | /* Copyright (C) 1991-2018 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | |
4 | The GNU C Library is free software; you can redistribute it and/or |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either |
7 | version 2.1 of the License, or (at your option) any later version. |
8 | |
9 | The GNU C Library is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
12 | Lesser General Public License for more details. |
13 | |
14 | You should have received a copy of the GNU Lesser General Public |
15 | License along with the GNU C Library; if not, see |
16 | <http://www.gnu.org/licenses/>. */ |
17 | |
18 | #include <errno.h> |
19 | #include <unistd.h> |
20 | #include <string.h> |
21 | #include <stdio.h> |
22 | #include <limits.h> |
23 | #include <fcntl.h> |
24 | |
25 | #include <utmp.h> |
26 | |
27 | static char name[UT_NAMESIZE + 1]; |
28 | |
29 | /* Return the login name of the user, or NULL if it can't be determined. |
30 | The returned pointer, if not NULL, is good only until the next call. */ |
31 | |
32 | #ifdef STATIC |
33 | STATIC |
34 | #endif |
35 | char * |
36 | getlogin (void) |
37 | { |
38 | char tty_pathname[2 + 2 * NAME_MAX]; |
39 | char *real_tty_path = tty_pathname; |
40 | int err; |
41 | char *result = NULL; |
42 | struct utmp *ut, line, buffer; |
43 | |
44 | /* Get name of tty connected to fd 0. Return NULL if not a tty or |
45 | if fd 0 isn't open. Note that a lot of documentation says that |
46 | getlogin() is based on the controlling terminal---what they |
47 | really mean is "the terminal connected to standard input". The |
48 | getlogin() implementation of DEC Unix, SunOS, Solaris, HP-UX all |
49 | return NULL if fd 0 has been closed, so this is the compatible |
50 | thing to do. Note that ttyname(open("/dev/tty")) on those |
51 | systems returns /dev/tty, so that is not a possible solution for |
52 | getlogin(). */ |
53 | err = __ttyname_r (0, real_tty_path, sizeof (tty_pathname)); |
54 | if (err != 0) |
55 | { |
56 | __set_errno (err); |
57 | return NULL; |
58 | } |
59 | |
60 | real_tty_path += 5; /* Remove "/dev/". */ |
61 | |
62 | __setutent (); |
63 | strncpy (line.ut_line, real_tty_path, sizeof line.ut_line); |
64 | if (__getutline_r (&line, &buffer, &ut) < 0) |
65 | { |
66 | if (errno == ESRCH) |
67 | /* The caller expects ENOENT if nothing is found. */ |
68 | __set_errno (ENOENT); |
69 | result = NULL; |
70 | } |
71 | else |
72 | { |
73 | strncpy (name, ut->ut_user, UT_NAMESIZE); |
74 | name[UT_NAMESIZE] = '\0'; |
75 | result = name; |
76 | } |
77 | |
78 | __endutent (); |
79 | |
80 | return result; |
81 | } |
82 | |