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