tests/ckmtime.c

   1 /* Check if filesystem timestamps are consistent with the system time.
   2    Copyright (C) 2016-2021 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify it
   5    under the terms of the GNU General Public License as published by the
   6    Free Software Foundation; either version 3, or (at your option) any later
   7    version.
   8
   9    This program is distributed in the hope that it will be useful, but
  10    WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
  12    Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License along
  15    with this program.  If not, see <http://www.gnu.org/licenses/>.
  16 */
  17 #include <config.h>
  18 #include <sys/stat.h>
  19 #include <sys/time.h>
  20 #include <unistd.h>
  21 #include <string.h>
  22 #include <assert.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <stat-time.h>
  26 #include <timespec.h>
  27
  28 #define TEMPLATE "ckmtime.XXXXXX"
  29 #define BILLION 1000000000
  30
  31 /* Some filesystems can slightly offset the timestamps of newly created files.
  32    To compensate for it, tar testsuite waits at least 1 second before creating
  33    next level of incremental backups.
  34
  35    However, NFS mounts can offset the timestamps by bigger amounts.
  36
  37    This program returns with success (0) if a newly created file is assigned
  38    mtime matching the system time to the nearest second.
  39 */
  40 int
  41 main (int argc, char **argv)
  42 {
  43   int fd;
  44   char name[sizeof(TEMPLATE)];
  45   struct stat st;
  46   struct timespec ts, td;
  47   double diff;
  48
  49   gettime (&ts);
  50
  51   strcpy (name, TEMPLATE);
  52   umask (077);
  53   fd = mkstemp (name);
  54   assert (fd != -1);
  55   unlink (name);
  56   assert (fstat (fd, &st) == 0);
  57   close (fd);
  58
  59   td = timespec_sub (get_stat_mtime (&st), ts);
  60   diff = td.tv_sec * BILLION + td.tv_nsec;
  61   if (diff < 0)
  62     diff = - diff;
  63   if (diff / BILLION >= 1)
  64     {
  65       fprintf (stderr, "file timestamp unreliable\n");
  66       return 1;
  67     }
  68   return 0;
  69 }