path: root/miscutils/last.c (plain)
blob: 67c1343f10c421dad7f16da94a2fb964698718ba

1	/* vi: set sw=4 ts=4: */
2	/*
3	* last implementation for busybox
4	*
5	* Copyright (C) 2003-2004 by Erik Andersen <andersen@codepoet.org>
6	*
7	* Licensed under GPLv2, see file LICENSE in this source tree.
8	*/
9	//config:config LAST
10	//config: bool "last"
11	//config: default y
12	//config: depends on FEATURE_WTMP
13	//config: help
14	//config: 'last' displays a list of the last users that logged into the system.
15	//config:
16	//config:config FEATURE_LAST_FANCY
17	//config: bool "Turn on output of extra information"
18	//config: default y
19	//config: depends on LAST
20	//config: help
21	//config: 'last' displays detailed information about the last users that
22	//config: logged into the system (mimics sysvinit last). +900 bytes.
23
24	//applet:IF_LAST(APPLET(last, BB_DIR_USR_BIN, BB_SUID_DROP))
25
26	//kbuild:ifeq ($(CONFIG_FEATURE_LAST_FANCY),y)
27	//kbuild:lib-$(CONFIG_FEATURE_LAST_FANCY) += last_fancy.o
28	//kbuild:else
29	//kbuild:lib-$(CONFIG_LAST) += last.o
30	//kbuild:endif
31
32	//usage:#define last_trivial_usage
33	//usage: ""IF_FEATURE_LAST_FANCY("[-HW] [-f FILE]")
34	//usage:#define last_full_usage "\n\n"
35	//usage: "Show listing of the last users that logged into the system"
36	//usage: IF_FEATURE_LAST_FANCY( "\n"
37	/* //usage: "\n -H Show header line" */
38	//usage: "\n -W Display with no host column truncation"
39	//usage: "\n -f FILE Read from FILE instead of /var/log/wtmp"
40	//usage: )
41
42	#include "libbb.h"
43
44	/* NB: ut_name and ut_user are the same field, use only one name (ut_user)
45	* to reduce confusion */
46
47	#ifndef SHUTDOWN_TIME
48	# define SHUTDOWN_TIME 254
49	#endif
50
51	/* Grr... utmp char[] members do not have to be nul-terminated.
52	* Do what we can while still keeping this reasonably small.
53	* Note: We are assuming the ut_id[] size is fixed at 4. */
54
55	#if defined UT_LINESIZE \
56	&& ((UT_LINESIZE != 32) || (UT_NAMESIZE != 32) || (UT_HOSTSIZE != 256))
57	#error struct utmpx member char[] size(s) have changed!
58	#elif defined __UT_LINESIZE \
59	&& ((__UT_LINESIZE != 32) || (__UT_NAMESIZE != 32) || (__UT_HOSTSIZE != 256))
60	/* __UT_NAMESIZE was checked with 64 above, but glibc-2.11 definitely uses 32! */
61	#error struct utmpx member char[] size(s) have changed!
62	#endif
63
64	#if EMPTY != 0 || RUN_LVL != 1 || BOOT_TIME != 2 || NEW_TIME != 3 || \
65	OLD_TIME != 4
66	#error Values for the ut_type field of struct utmpx changed
67	#endif
68
69	int last_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
70	int last_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
71	{
72	struct utmpx ut;
73	int n, file = STDIN_FILENO;
74	time_t t_tmp;
75	off_t pos;
76	static const char _ut_usr[] ALIGN1 =
77	"runlevel\0" "reboot\0" "shutdown\0";
78	static const char _ut_lin[] ALIGN1 =
79	"~\0" "{\0" "|\0" /* "LOGIN\0" "date\0" */;
80	enum {
81	TYPE_RUN_LVL = RUN_LVL, /* 1 */
82	TYPE_BOOT_TIME = BOOT_TIME, /* 2 */
83	TYPE_SHUTDOWN_TIME = SHUTDOWN_TIME
84	};
85	enum {
86	_TILDE = EMPTY, /* 0 */
87	TYPE_NEW_TIME, /* NEW_TIME, 3 */
88	TYPE_OLD_TIME /* OLD_TIME, 4 */
89	};
90
91	if (argv[1]) {
92	bb_show_usage();
93	}
94	file = xopen(bb_path_wtmp_file, O_RDONLY);
95
96	printf("%-10s %-14s %-18s %-12.12s %s\n",
97	"USER", "TTY", "HOST", "LOGIN", "TIME");
98	/* yikes. We reverse over the file and that is a not too elegant way */
99	pos = xlseek(file, 0, SEEK_END);
100	pos = lseek(file, pos - sizeof(ut), SEEK_SET);
101	while ((n = full_read(file, &ut, sizeof(ut))) > 0) {
102	if (n != sizeof(ut)) {
103	bb_perror_msg_and_die("short read");
104	}
105	n = index_in_strings(_ut_lin, ut.ut_line);
106	if (n == _TILDE) { /* '~' */
107	#if 1
108	/* do we really need to be cautious here? */
109	n = index_in_strings(_ut_usr, ut.ut_user);
110	if (++n > 0)
111	ut.ut_type = n != 3 ? n : SHUTDOWN_TIME;
112	#else
113	if (is_prefixed_with(ut.ut_user, "shutdown"))
114	ut.ut_type = SHUTDOWN_TIME;
115	else if (is_prefixed_with(ut.ut_user, "reboot"))
116	ut.ut_type = BOOT_TIME;
117	else if (is_prefixed_with(ut.ut_user, "runlevel"))
118	ut.ut_type = RUN_LVL;
119	#endif
120	} else {
121	if (ut.ut_user[0] == '\0' || strcmp(ut.ut_user, "LOGIN") == 0) {
122	/* Don't bother. This means we can't find how long
123	* someone was logged in for. Oh well. */
124	goto next;
125	}
126	if (ut.ut_type != DEAD_PROCESS
127	&& ut.ut_user[0]
128	&& ut.ut_line[0]
129	) {
130	ut.ut_type = USER_PROCESS;
131	}
132	if (strcmp(ut.ut_user, "date") == 0) {
133	if (n == TYPE_OLD_TIME) { /* '|' */
134	ut.ut_type = OLD_TIME;
135	}
136	if (n == TYPE_NEW_TIME) { /* '{' */
137	ut.ut_type = NEW_TIME;
138	}
139	}
140	}
141
142	if (ut.ut_type != USER_PROCESS) {
143	switch (ut.ut_type) {
144	case OLD_TIME:
145	case NEW_TIME:
146	case RUN_LVL:
147	case SHUTDOWN_TIME:
148	goto next;
149	case BOOT_TIME:
150	strcpy(ut.ut_line, "system boot");
151	}
152	}
153	/* manpages say ut_tv.tv_sec *is* time_t,
154	* but some systems have it wrong */
155	t_tmp = (time_t)ut.ut_tv.tv_sec;
156	printf("%-10s %-14s %-18s %-12.12s\n",
157	ut.ut_user, ut.ut_line, ut.ut_host, ctime(&t_tmp) + 4);
158	next:
159	pos -= sizeof(ut);
160	if (pos <= 0)
161	break; /* done. */
162	xlseek(file, pos, SEEK_SET);
163	}
164
165	fflush_stdout_and_exit(EXIT_SUCCESS);
166	}
167