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 (6.1 kb)"
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 "Output 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;
last_main(int argc UNUSED_PARAM,char ** argv UNUSED_PARAM)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_simple_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