1  /* Test of freadahead() function.
       2     Copyright (C) 2007-2022 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  #include "freadahead.h"
      22  
      23  #include <stdlib.h>
      24  #include <unistd.h>
      25  
      26  #include "macros.h"
      27  
      28  int
      29  main (int argc, char **argv)
      30  {
      31    int nbytes = atoi (argv[1]);
      32    if (nbytes > 0)
      33      {
      34        void *buf = malloc (nbytes);
      35        ASSERT (fread (buf, 1, nbytes, stdin) == nbytes);
      36        free (buf);
      37      }
      38  
      39    if (nbytes == 0)
      40      ASSERT (freadahead (stdin) == 0);
      41    else
      42      {
      43        if (lseek (0, 0, SEEK_CUR) == nbytes)
      44          /* An unbuffered stdio, such as BeOS or on uClibc compiled without
      45             __STDIO_BUFFERS.  */
      46          ASSERT (freadahead (stdin) == 0);
      47        else
      48          {
      49            /* Normal buffered stdio.  */
      50            size_t buffered;
      51            int c, c2;
      52  
      53            ASSERT (freadahead (stdin) != 0);
      54            buffered = freadahead (stdin);
      55  
      56            c = fgetc (stdin);
      57            ASSERT (freadahead (stdin) == buffered - 1);
      58            ungetc (c, stdin);
      59            ASSERT (freadahead (stdin) == buffered);
      60            c2 = fgetc (stdin);
      61            ASSERT (c2 == c);
      62            ASSERT (freadahead (stdin) == buffered - 1);
      63  
      64            c = '@';
      65            ungetc (c, stdin);
      66            ASSERT (freadahead (stdin) == buffered);
      67            c2 = fgetc (stdin);
      68            ASSERT (c2 == c);
      69            ASSERT (freadahead (stdin) == buffered - 1);
      70          }
      71      }
      72  
      73    /* Free memory allocated during ungetc().  */
      74    fclose (stdin);
      75  
      76    return 0;
      77  }