tests/test-freadahead.c

   1 /* Test of freadahead() function.
   2    Copyright (C) 2007-2025 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 test_exit_status;
  77 }