LXR busybox/util-linux/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//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
  69int last_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  70int 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