tests/test-ftell3.c

   1 /* Test of ftell() function.
   2    Copyright (C) 2007-2024 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 #include <config.h>
  18
  19 /* None of the files accessed by this test are large, so disable the
  20    fseek link warning if we are not using the gnulib fseek module.  */
  21 #define _GL_NO_LARGE_FILES
  22 #include <stdio.h>
  23
  24 #include <string.h>
  25
  26 #include "macros.h"
  27
  28 #define TESTFILE "t-ftell3.tmp"
  29
  30 int
  31 main (void)
  32 {
  33   FILE *fp;
  34
  35   /* Create a file with some contents.  */
  36   fp = fopen (TESTFILE, "w");
  37   if (fp == NULL)
  38     goto skip;
  39   if (fwrite ("foogarsh", 1, 8, fp) < 8)
  40     goto skip;
  41   if (fclose (fp))
  42     goto skip;
  43
  44   /* The file's contents is now "foogarsh".  */
  45
  46   /* Try writing after reading to EOF.  */
  47   fp = fopen (TESTFILE, "r+");
  48   if (fp == NULL)
  49     goto skip;
  50   if (fseek (fp, -1, SEEK_END))
  51     goto skip;
  52   ASSERT (getc (fp) == 'h');
  53   ASSERT (getc (fp) == EOF);
  54   ASSERT (ftell (fp) == 8);
  55   ASSERT (ftell (fp) == 8);
  56   ASSERT (putc ('!', fp) == '!');
  57   ASSERT (ftell (fp) == 9);
  58   ASSERT (fclose (fp) == 0);
  59   fp = fopen (TESTFILE, "r");
  60   if (fp == NULL)
  61     goto skip;
  62   {
  63     char buf[10];
  64     ASSERT (fread (buf, 1, 10, fp) == 9);
  65     ASSERT (memcmp (buf, "foogarsh!", 9) == 0);
  66   }
  67   ASSERT (fclose (fp) == 0);
  68
  69   /* The file's contents is now "foogarsh!".  */
  70
  71   remove (TESTFILE);
  72   return test_exit_status;
  73
  74  skip:
  75   remove (TESTFILE);
  76   if (test_exit_status != EXIT_SUCCESS)
  77     return test_exit_status;
  78   fprintf (stderr, "Skipping test: prerequisite file operations failed.\n");
  79   return 77;
  80 }