1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
|
/* readutmp - Basic test of existing utmp/utmpx access.
Copyright (C) 2010-2025 Free Software Foundation, Inc.
This file is part of GNU Inetutils.
GNU Inetutils is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
GNU Inetutils is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see `http://www.gnu.org/licenses/'. */
/* Written by Mats Erik Andersson. */
/* Readutmp reads the system's standard UTMP or UTMPX file
* and verifies that a specific user is logged in.
*
* Invocation:
*
* readutmp
* readutmp name
*
* The first mode investigates the present user.
*/
#include <config.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <pwd.h>
#include <progname.h>
#include <readutmp.h>
#include <xalloc.h>
int
main (int argc, char *argv[])
{
#ifndef HAVE_GETUTXUSER
STRUCT_UTMP *utmpp, *uptr;
size_t count;
#endif
struct passwd *pw;
char *name;
int found = 0;
set_program_name (argv[0]);
if (argc > 1)
pw = getpwnam (argv[1]);
else
pw = getpwuid (getuid ());
if (pw)
name = xstrdup (pw->pw_name);
else
{
fprintf (stderr, "Unknown user '%s'.\n",
(argc > 1) ? argv[1] : "my own UID");
return EXIT_FAILURE;
}
#ifdef HAVE_GETUTXUSER
setutxent ();
found = (getutxuser (name) != 0);
endutxent ();
#else /* !HAVE_GETUTXUSER */
if (read_utmp (UTMP_FILE, &count, &utmpp,
READ_UTMP_USER_PROCESS | READ_UTMP_CHECK_PIDS))
{
perror ("read_utmp");
return EXIT_FAILURE;
}
for (uptr = utmpp; uptr < utmpp + count; uptr++)
if (!strncmp (name, UT_USER (uptr), sizeof (UT_USER (uptr))))
{
found = 1;
break;
}
free (utmpp);
#endif /* HAVE_GETUTXUSER */
if (found)
return EXIT_SUCCESS;
fprintf (stderr, "User '%s' is not logged in.\n", name);
return EXIT_FAILURE;
}
|
