tests/test-fseeko-largefile.c

   1 /* Test of fseeko() function on large files.
   2    Copyright (C) 2024 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Bruno Haible <bruno@clisp.org>, 2024.  */
  18
  19 #include <config.h>
  20
  21 /* Specification.  */
  22 #include <stdio.h>
  23
  24 #include <fcntl.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27
  28 #include "macros.h"
  29
  30 #define TESTFILE "test-fseeko.data"
  31 #define TESTFILE_ZEROES 3000000000LL
  32 #define TESTFILE_DATA "GNU"
  33 #define TESTFILE_DATA_LEN 3
  34
  35 int
  36 main (void)
  37 {
  38   remove (TESTFILE);
  39
  40   if (sizeof (off_t) <= 4)
  41     {
  42       fprintf (stderr, "off_t is only 32 bits.\n");
  43       return 77;
  44     }
  45   /* off_t is larger than 32-bit.  */
  46
  47   /* Create a file that is larger than 2 GiB.
  48      On file systems such as ext2, the file will have "holes" and thus
  49      not consume much disk space.  */
  50   {
  51     int fd = open (TESTFILE, O_CREAT | O_TRUNC | O_RDWR, 0600);
  52     ASSERT (fd >= 0);
  53     if (ftruncate (fd, TESTFILE_ZEROES) < 0
  54         || lseek (fd, TESTFILE_ZEROES, SEEK_SET) < 0
  55         || write (fd, TESTFILE_DATA, TESTFILE_DATA_LEN) < 0
  56         || fsync (fd) < 0)
  57       {
  58         close (fd);
  59         remove (TESTFILE);
  60         fprintf (stderr, "Could not create 3 GB large file.\n");
  61         return 77;
  62       }
  63     close (fd);
  64   }
  65
  66   /* Check that fseeko() works.  */
  67   {
  68     FILE *fp = fopen (TESTFILE, "r");
  69     ASSERT (fp != NULL);
  70
  71     int ret;
  72     ret = fseeko (fp, TESTFILE_ZEROES, SEEK_SET);
  73     ASSERT (ret == 0);
  74
  75     char buf[TESTFILE_DATA_LEN];
  76     ASSERT (fread (buf, 1, TESTFILE_DATA_LEN, fp) == TESTFILE_DATA_LEN);
  77     ASSERT (memcmp (buf, TESTFILE_DATA, TESTFILE_DATA_LEN) == 0);
  78
  79     ret = fclose (fp);
  80     ASSERT (ret == 0);
  81   }
  82
  83   remove (TESTFILE);
  84
  85   return test_exit_status;
  86 }