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 utmpx 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 != 32) || (__UT_HOSTSIZE != 256))
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38 | /* __UT_NAMESIZE was checked with 64 above, but glibc-2.11 definitely uses 32! */
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39 | #error struct utmpx member char[] size(s) have changed!
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40 | #endif
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41 |
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42 | #if EMPTY != 0 || RUN_LVL != 1 || BOOT_TIME != 2 || NEW_TIME != 3 || \
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43 | OLD_TIME != 4
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44 | #error Values for the ut_type field of struct utmpx changed
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45 | #endif
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46 |
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47 | int last_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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48 | int last_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
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49 | {
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50 | struct utmpx ut;
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51 | int n, file = STDIN_FILENO;
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52 | time_t t_tmp;
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53 | off_t pos;
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54 | static const char _ut_usr[] ALIGN1 =
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55 | "runlevel\0" "reboot\0" "shutdown\0";
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56 | static const char _ut_lin[] ALIGN1 =
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57 | "~\0" "{\0" "|\0" /* "LOGIN\0" "date\0" */;
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58 | enum {
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59 | TYPE_RUN_LVL = RUN_LVL, /* 1 */
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60 | TYPE_BOOT_TIME = BOOT_TIME, /* 2 */
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61 | TYPE_SHUTDOWN_TIME = SHUTDOWN_TIME
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62 | };
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63 | enum {
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64 | _TILDE = EMPTY, /* 0 */
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65 | TYPE_NEW_TIME, /* NEW_TIME, 3 */
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66 | TYPE_OLD_TIME /* OLD_TIME, 4 */
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67 | };
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68 |
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69 | if (argv[1]) {
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70 | bb_show_usage();
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71 | }
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72 | file = xopen(bb_path_wtmp_file, O_RDONLY);
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73 |
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74 | printf("%-10s %-14s %-18s %-12.12s %s\n",
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75 | "USER", "TTY", "HOST", "LOGIN", "TIME");
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76 | /* yikes. We reverse over the file and that is a not too elegant way */
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77 | pos = xlseek(file, 0, SEEK_END);
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78 | pos = lseek(file, pos - sizeof(ut), SEEK_SET);
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79 | while ((n = full_read(file, &ut, sizeof(ut))) > 0) {
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80 | if (n != sizeof(ut)) {
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81 | bb_perror_msg_and_die("short read");
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82 | }
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83 | n = index_in_strings(_ut_lin, ut.ut_line);
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84 | if (n == _TILDE) { /* '~' */
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85 | #if 1
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86 | /* do we really need to be cautious here? */
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87 | n = index_in_strings(_ut_usr, ut.ut_user);
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88 | if (++n > 0)
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89 | ut.ut_type = n != 3 ? n : SHUTDOWN_TIME;
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90 | #else
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91 | if (is_prefixed_with(ut.ut_user, "shutdown"))
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92 | ut.ut_type = SHUTDOWN_TIME;
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93 | else if (is_prefixed_with(ut.ut_user, "reboot"))
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94 | ut.ut_type = BOOT_TIME;
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95 | else if (is_prefixed_with(ut.ut_user, "runlevel"))
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96 | ut.ut_type = RUN_LVL;
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97 | #endif
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98 | } else {
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99 | if (ut.ut_user[0] == '\0' || strcmp(ut.ut_user, "LOGIN") == 0) {
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100 | /* Don't bother. This means we can't find how long
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101 | * someone was logged in for. Oh well. */
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102 | goto next;
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103 | }
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104 | if (ut.ut_type != DEAD_PROCESS
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105 | && ut.ut_user[0]
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106 | && ut.ut_line[0]
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107 | ) {
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108 | ut.ut_type = USER_PROCESS;
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109 | }
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110 | if (strcmp(ut.ut_user, "date") == 0) {
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111 | if (n == TYPE_OLD_TIME) { /* '|' */
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112 | ut.ut_type = OLD_TIME;
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113 | }
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114 | if (n == TYPE_NEW_TIME) { /* '{' */
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115 | ut.ut_type = NEW_TIME;
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116 | }
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117 | }
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118 | }
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119 |
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120 | if (ut.ut_type != USER_PROCESS) {
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121 | switch (ut.ut_type) {
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122 | case OLD_TIME:
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123 | case NEW_TIME:
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124 | case RUN_LVL:
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125 | case SHUTDOWN_TIME:
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126 | goto next;
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127 | case BOOT_TIME:
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128 | strcpy(ut.ut_line, "system boot");
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129 | }
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130 | }
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131 | /* manpages say ut_tv.tv_sec *is* time_t,
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132 | * but some systems have it wrong */
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133 | t_tmp = (time_t)ut.ut_tv.tv_sec;
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134 | printf("%-10s %-14s %-18s %-12.12s\n",
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135 | ut.ut_user, ut.ut_line, ut.ut_host, ctime(&t_tmp) + 4);
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136 | next:
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137 | pos -= sizeof(ut);
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138 | if (pos <= 0)
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139 | break; /* done. */
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140 | xlseek(file, pos, SEEK_SET);
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141 | }
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142 |
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143 | fflush_stdout_and_exit(EXIT_SUCCESS);
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144 | }
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