1 | /* Reentrant function to return the current login name. Unix version. |
2 | Copyright (C) 1991-2017 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
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 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <errno.h> |
20 | #include <unistd.h> |
21 | #include <string.h> |
22 | #include <stdio.h> |
23 | #include <limits.h> |
24 | #include <fcntl.h> |
25 | |
26 | #include <utmp.h> |
27 | #include "../login/utmp-private.h" |
28 | |
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. */ |
32 | |
33 | #ifdef STATIC |
34 | STATIC |
35 | #endif |
36 | int |
37 | __getlogin_r (char *name, size_t name_len) |
38 | { |
39 | char tty_pathname[2 + 2 * NAME_MAX]; |
40 | char *real_tty_path = tty_pathname; |
41 | int result; |
42 | struct utmp *ut, line, buffer; |
43 | |
44 | /* Get name of tty connected to fd 0. Return 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 | |
54 | result = __ttyname_r (0, real_tty_path, sizeof (tty_pathname)); |
55 | |
56 | if (result != 0) |
57 | return result; |
58 | |
59 | real_tty_path += 5; /* Remove "/dev/". */ |
60 | strncpy (line.ut_line, real_tty_path, sizeof line.ut_line); |
61 | |
62 | /* We don't use the normal entry points __setutent et al, because we |
63 | want setutent + getutline_r + endutent all to happen with the lock |
64 | held so that our search is thread-safe. */ |
65 | |
66 | __libc_lock_lock (__libc_utmp_lock); |
67 | (*__libc_utmp_jump_table->setutent) (); |
68 | result = (*__libc_utmp_jump_table->getutline_r) (&line, &buffer, &ut); |
69 | if (result < 0) |
70 | { |
71 | if (errno == ESRCH) |
72 | /* The caller expects ENOENT if nothing is found. */ |
73 | result = ENOENT; |
74 | else |
75 | result = errno; |
76 | } |
77 | (*__libc_utmp_jump_table->endutent) (); |
78 | __libc_utmp_jump_table = &__libc_utmp_unknown_functions; |
79 | __libc_lock_unlock (__libc_utmp_lock); |
80 | |
81 | if (result == 0) |
82 | { |
83 | size_t needed = __strnlen (ut->ut_user, UT_NAMESIZE) + 1; |
84 | |
85 | if (needed > name_len) |
86 | { |
87 | __set_errno (ERANGE); |
88 | result = ERANGE; |
89 | } |
90 | else |
91 | { |
92 | memcpy (name, ut->ut_user, needed - 1); |
93 | name[needed - 1] = 0; |
94 | result = 0; |
95 | } |
96 | } |
97 | |
98 | return result; |
99 | } |
100 | #ifndef STATIC |
101 | libc_hidden_def (__getlogin_r) |
102 | weak_alias (__getlogin_r, getlogin_r) |
103 | libc_hidden_weak (getlogin_r) |
104 | #endif |
105 | |