tests/test-fseek.c

   1 /* Test of fseek() 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 /* Written by Bruno Haible <bruno@clisp.org>, 2007.  */
  18
  19 #include <config.h>
  20
  21 /* None of the files accessed by this test are large, so disable the
  22    fseek link warning if the user requested GNULIB_POSIXCHECK.  */
  23 #define _GL_NO_LARGE_FILES
  24 #include <stdio.h>
  25
  26 #include "signature.h"
  27 SIGNATURE_CHECK (fseek, int, (FILE *, long, int));
  28
  29 #include "macros.h"
  30
  31 #ifndef FUNC_UNGETC_BROKEN
  32 # define FUNC_UNGETC_BROKEN 0
  33 #endif
  34
  35 int
  36 main (int argc, char **argv)
  37 {
  38   /* Assume stdin is non-empty, seekable, and starts with '#!/bin/sh'
  39      iff argc > 1.  */
  40   int expected = argc > 1 ? 0 : -1;
  41   ASSERT (fseek (stdin, 0, SEEK_CUR) == expected);
  42   if (argc > 1)
  43     {
  44       /* Test that fseek discards previously read ungetc data.  */
  45       int ch = fgetc (stdin);
  46       ASSERT (ch == '#');
  47       ASSERT (ungetc (ch, stdin) == ch);
  48       ASSERT (fseek (stdin, 2, SEEK_SET) == 0);
  49       ch = fgetc (stdin);
  50       ASSERT (ch == '/');
  51       if (2 < argc)
  52         {
  53           if (FUNC_UNGETC_BROKEN)
  54             {
  55               if (test_exit_status != EXIT_SUCCESS)
  56                 return test_exit_status;
  57               fputs ("Skipping test: ungetc cannot handle arbitrary bytes\n",
  58                      stderr);
  59               return 77;
  60             }
  61           /* Test that fseek discards random ungetc data.  */
  62           ASSERT (ungetc (ch ^ 0xff, stdin) == (ch ^ 0xff));
  63         }
  64       ASSERT (fseek (stdin, 0, SEEK_END) == 0);
  65       ASSERT (fgetc (stdin) == EOF);
  66       /* Test that fseek resets end-of-file marker.  */
  67       ASSERT (feof (stdin));
  68       ASSERT (fseek (stdin, 0, SEEK_END) == 0);
  69       ASSERT (!feof (stdin));
  70     }
  71   return test_exit_status;
  72 }