gists/c-programming/jokes/extol.c

/*
 * extol.c [joke!]
 *
 * Author: Intel A80486DX2-66
 * License: Creative Commons Zero 1.0 Universal
 */

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

enum
{
  EXTOL_NORMAL,
  EXTOL_QUIET
} EXTOL_MODE;

#define EXTOL_PROTOTYPE "int extol(FILE* f)"
#define EXTOL_FILE_NAME "extol.txt"
#define EXTOL_FILE_LIMIT 128

int
extol (FILE *f)
{
  static bool spec_run = true;
  int result;
  off_t size;

  if (spec_run == false)
    {
      printf ("\n");
      return !(spec_run = true) - spec_run;
    }

  if (f == NULL)
    {
      FILE *fs = fopen (EXTOL_FILE_NAME, "a+");
      if (fs == NULL)
        {
          perror ("fopen");
          exit (EXIT_FAILURE);
        }
      fseek (fs, 0L, SEEK_END);
      size = ftello (fs);
      if (size == -1)
        {
          perror ("ftello");
          exit (EXIT_FAILURE);
        }
      else if (size > EXTOL_FILE_LIMIT)
        {
          FILE *new_fs = freopen (EXTOL_FILE_NAME, "w", fs);
          if (new_fs == NULL)
            {
              perror ("freopen");
              exit (EXIT_FAILURE);
            }
          fs = new_fs;
        }
      result = extol (fs);
      for (result <<= 4, result &= ~15;
           (result & 15) != 15 || (result >>= 4, 0); result++)
        fputc ('=', fs);
      fprintf (fs, "\n");
      fclose (fs);
    }
  else
    {
      result = fprintf (f, "PRAISE THE USER!\n");
    }
  spec_run = false;
  return result;
}

int
extol_interface (signed char type)
{
  FILE *f;

  f = type == EXTOL_NORMAL ? stdout : NULL;
  return printf (EXTOL_PROTOTYPE " returns %d\n", extol (f));
}

void
extol_quiet (void)
{
  extol_interface (EXTOL_QUIET);
}

int
main (void)
{
  int i;

  for (i = 0; i < 2; i++)
    printf (EXTOL_PROTOTYPE ": %d\n", extol_interface (EXTOL_NORMAL));
  atexit (&extol_quiet);
  return 0;
}