Ticket #3145: fseek-bug.c

/* Test of fseek() function. */

#include <stdio.h>
#include <stdlib.h>

#define ASSERT(expr) \
  do                                         \
    {                                        \
      if (!(expr))                               \
        {                                    \
          fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__); \
          fflush (stderr);                           \
          abort ();                              \
        }                                    \
    }                                        \
  while (0)

int
main ()
{
  int ch;
  ASSERT (fseek (stdin, 0, SEEK_CUR) == 0);
  /* Test that fseek discards previously read ungetc data.  */
  ch = fgetc (stdin);
  ASSERT (ch == '/');
  ASSERT (ungetc (ch, stdin) == ch);
  ASSERT (fseek (stdin, 2, SEEK_SET) == 0);
  /* Test that fseek discards random ungetc data.  */
  ch = fgetc (stdin);
  ASSERT (ch == ' ');
  ASSERT (ungetc (ch ^ 0xff, stdin) == (ch ^ 0xff));
  ASSERT (fseek (stdin, 0, SEEK_END) == 0);
  ASSERT (fgetc (stdin) == EOF);
  return 0;
}