LXR busybox/miscutils/last.c

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