tests/checkseekhole.c

   1 /* Test suite for GNU tar - SEEK_HOLE detector.
   2
   3    Copyright 2015-2017 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify it
   6    under the terms of the GNU General Public License as published by the
   7    Free Software Foundation; either version 3, or (at your option) any later
   8    version.
   9
  10    This program is distributed in the hope that it will be useful, but
  11    WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
  13    Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License along
  16    with this program.  If not, see <http://www.gnu.org/licenses/>.
  17
  18    Description:  detect whether it is possible to work with SEEK_HOLE on
  19    particular operating system and file system. */
  20
  21 #include "config.h"
  22
  23 #include <sys/stat.h>
  24 #include <sys/types.h>
  25 #include <unistd.h>
  26 #include <stdlib.h>
  27 #include <fcntl.h>
  28
  29 enum {
  30     EX_OK = 0,    /* SEEK_HOLE support */
  31     EX_FAIL,      /* test failed - no SEEK_HOLE support */
  32     EX_BAD,       /* test is not relevant */
  33 };
  34
  35 int
  36 check_seek_hole (int fd)
  37 {
  38 #ifdef SEEK_HOLE
  39   struct stat stat;
  40   off_t offset;
  41
  42   /* hole of 100MB */
  43   if (lseek (fd, 100*1024*1024, SEEK_END) < 0)
  44     return EX_BAD;
  45
  46   /* piece of data */
  47   if (write (fd, "data\n", 5) != 5)
  48     return EX_BAD;
  49
  50   /* another hole */
  51   if (lseek (fd, 100*1024*1024, SEEK_END) < 0)
  52     return EX_BAD;
  53
  54   /* piece of data */
  55   if (write (fd, "data\n", 5) != 5)
  56     return EX_BAD;
  57
  58   if (fstat (fd, &stat))
  59     return EX_BAD;
  60
  61   offset = lseek (fd, 0, SEEK_DATA);
  62   if (offset == (off_t)-1)
  63     return EX_FAIL;
  64
  65   offset = lseek (fd, offset, SEEK_HOLE);
  66   if (offset == (off_t)-1 || offset == stat.st_size)
  67     return EX_FAIL;
  68
  69   return EX_OK;
  70 #else
  71   return EX_BAD;
  72 #endif
  73 }
  74
  75 int
  76 main ()
  77 {
  78 #ifdef SEEK_HOLE
  79   int rc;
  80   char template[] = "testseekhole-XXXXXX";
  81   int fd = mkstemp (template);
  82   if (fd == -1)
  83     return EX_BAD;
  84   rc = check_seek_hole (fd);
  85   close (fd);
  86   unlink (template);
  87
  88   return rc;
  89 #else
  90   return EX_FAIL;
  91 #endif
  92 }