1  /* Test of fseek() function.
       2     Copyright (C) 2007-2023 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                fputs ("Skipping test: ungetc cannot handle arbitrary bytes\n",
      56                       stderr);
      57                return 77;
      58              }
      59            /* Test that fseek discards random ungetc data.  */
      60            ASSERT (ungetc (ch ^ 0xff, stdin) == (ch ^ 0xff));
      61          }
      62        ASSERT (fseek (stdin, 0, SEEK_END) == 0);
      63        ASSERT (fgetc (stdin) == EOF);
      64        /* Test that fseek resets end-of-file marker.  */
      65        ASSERT (feof (stdin));
      66        ASSERT (fseek (stdin, 0, SEEK_END) == 0);
      67        ASSERT (!feof (stdin));
      68      }
      69    return 0;
      70  }