login/programs/utmpdump.c

   1 /* utmpdump - dump utmp-like files.
   2    Copyright (C) 1997-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <time.h>
  22 #include <unistd.h>
  23 #include <utmp.h>
  24
  25 static void
  26 print_entry (struct utmp *up)
  27 {
  28   /* Mixed 32-/64-bit systems may have timeval structs of different sixe
  29      but need struct utmp to be the same size.  So in 64-bit up->ut_tv may
  30      not be a timeval but a struct of __int32_t's.  This would cause a compile
  31      time warning and a formatting error when 32-bit int is passed where
  32      a 64-bit long is expected. So copy up->up_tv to a temporary timeval.
  33      This is 32-/64-bit agnostic and expands the timeval fields to the
  34      expected size as needed. */
  35   struct timeval temp_tv;
  36   temp_tv.tv_sec = up->ut_tv.tv_sec;
  37   temp_tv.tv_usec = up->ut_tv.tv_usec;
  38
  39   printf ("[%d] [%05d] [%-4.4s] [%-8.8s] [%-12.12s] [%-16.16s] [%-15.15s]"
  40           " [%ld]\n",
  41           up->ut_type, up->ut_pid, up->ut_id, up->ut_user, up->ut_line,
  42           up->ut_host, 4 + ctime (&temp_tv.tv_sec),
  43           (long int) temp_tv.tv_usec);
  44 }
  45
  46 int
  47 main (int argc, char *argv[])
  48 {
  49   struct utmp *up;
  50
  51   if (argc > 1)
  52     utmpname (argv[1]);
  53
  54   setutent ();
  55
  56   while ((up = getutent ()))
  57     print_entry (up);
  58
  59   endutent ();
  60
  61   return EXIT_SUCCESS;
  62 }