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 the GPL version 2, see the file LICENSE in this tarball.
   8 */
   9
  10#include "libbb.h"
  11#include <utmp.h>
  12
  13/* NB: ut_name and ut_user are the same field, use only one name (ut_user)
  14 * to reduce confusion */
  15
  16#ifndef SHUTDOWN_TIME
  17#  define SHUTDOWN_TIME 254
  18#endif
  19
  20/* Grr... utmp char[] members do not have to be nul-terminated.
  21 * Do what we can while still keeping this reasonably small.
  22 * Note: We are assuming the ut_id[] size is fixed at 4. */
  23
  24#if defined UT_LINESIZE \
  25        && ((UT_LINESIZE != 32) || (UT_NAMESIZE != 32) || (UT_HOSTSIZE != 256))
  26#error struct utmp member char[] size(s) have changed!
  27#elif defined __UT_LINESIZE \
  28        && ((__UT_LINESIZE != 32) || (__UT_NAMESIZE != 64) || (__UT_HOSTSIZE != 256))
  29#error struct utmp member char[] size(s) have changed!
  30#endif
  31
  32#if EMPTY != 0 || RUN_LVL != 1 || BOOT_TIME != 2 || NEW_TIME != 3 || \
  33        OLD_TIME != 4
  34#error Values for the ut_type field of struct utmp changed
  35#endif
  36
  37int last_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  38int last_main(int argc, char **argv UNUSED_PARAM)
  39{
  40        struct utmp ut;
  41        int n, file = STDIN_FILENO;
  42        time_t t_tmp;
  43        off_t pos;
  44        static const char _ut_usr[] ALIGN1 =
  45                        "runlevel\0" "reboot\0" "shutdown\0";
  46        static const char _ut_lin[] ALIGN1 =
  47                        "~\0" "{\0" "|\0" /* "LOGIN\0" "date\0" */;
  48        enum {
  49                TYPE_RUN_LVL = RUN_LVL,         /* 1 */
  50                TYPE_BOOT_TIME = BOOT_TIME,     /* 2 */
  51                TYPE_SHUTDOWN_TIME = SHUTDOWN_TIME
  52        };
  53        enum {
  54                _TILDE = EMPTY,                         /* 0 */
  55                TYPE_NEW_TIME,  /* NEW_TIME, 3 */
  56                TYPE_OLD_TIME   /* OLD_TIME, 4 */
  57        };
  58
  59        if (argc > 1) {
  60                bb_show_usage();
  61        }
  62        file = xopen(bb_path_wtmp_file, O_RDONLY);
  63
  64        printf("%-10s %-14s %-18s %-12.12s %s\n",
  65               "USER", "TTY", "HOST", "LOGIN", "TIME");
  66        /* yikes. We reverse over the file and that is a not too elegant way */
  67        pos = xlseek(file, 0, SEEK_END);
  68        pos = lseek(file, pos - sizeof(ut), SEEK_SET);
  69        while ((n = full_read(file, &ut, sizeof(ut))) > 0) {
  70                if (n != sizeof(ut)) {
  71                        bb_perror_msg_and_die("short read");
  72                }
  73                n = index_in_strings(_ut_lin, ut.ut_line);
  74                if (n == _TILDE) { /* '~' */
  75#if 1
  76/* do we really need to be cautious here? */
  77                        n = index_in_strings(_ut_usr, ut.ut_user);
  78                        if (++n > 0)
  79                                ut.ut_type = n != 3 ? n : SHUTDOWN_TIME;
  80#else
  81                        if (strncmp(ut.ut_user, "shutdown", 8) == 0)
  82                                ut.ut_type = SHUTDOWN_TIME;
  83                        else if (strncmp(ut.ut_user, "reboot", 6) == 0)
  84                                ut.ut_type = BOOT_TIME;
  85                        else if (strncmp(ut.ut_user, "runlevel", 8) == 0)
  86                                ut.ut_type = RUN_LVL;
  87#endif
  88                } else {
  89                        if (ut.ut_user[0] == '\0' || strcmp(ut.ut_user, "LOGIN") == 0) {
  90                                /* Don't bother.  This means we can't find how long
  91                                 * someone was logged in for.  Oh well. */
  92                                goto next;
  93                        }
  94                        if (ut.ut_type != DEAD_PROCESS
  95                         && ut.ut_user[0] && ut.ut_line[0]
  96                        ) {
  97                                ut.ut_type = USER_PROCESS;
  98                        }
  99                        if (strcmp(ut.ut_user, "date") == 0) {
 100                                if (n == TYPE_OLD_TIME) { /* '|' */
 101                                        ut.ut_type = OLD_TIME;
 102                                }
 103                                if (n == TYPE_NEW_TIME) { /* '{' */
 104                                        ut.ut_type = NEW_TIME;
 105                                }
 106                        }
 107                }
 108
 109                if (ut.ut_type != USER_PROCESS) {
 110                        switch (ut.ut_type) {
 111                                case OLD_TIME:
 112                                case NEW_TIME:
 113                                case RUN_LVL:
 114                                case SHUTDOWN_TIME:
 115                                        goto next;
 116                                case BOOT_TIME:
 117                                        strcpy(ut.ut_line, "system boot");
 118                        }
 119                }
 120                /* manpages say ut_tv.tv_sec *is* time_t,
 121                 * but some systems have it wrong */
 122                t_tmp = (time_t)ut.ut_tv.tv_sec;
 123                printf("%-10s %-14s %-18s %-12.12s\n",
 124                       ut.ut_user, ut.ut_line, ut.ut_host, ctime(&t_tmp) + 4);
 125 next:
 126                pos -= sizeof(ut);
 127                if (pos <= 0)
 128                        break; /* done. */
 129                xlseek(file, pos, SEEK_SET);
 130        }
 131
 132        fflush_stdout_and_exit(EXIT_SUCCESS);
 133}
 134