/* -*- Mode: C; -*-
 * ----------------------------------------------------------------------------
 *     Title: unwind_protect macro
 *   Created: 2020-05-24
 *    Author: Gilbert Baumann <gilbert@bauhh.de>
 * ----------------------------------------------------------------------------
 *  (c) copyright 2020 by Gilbert Baumann
 */

#include <stdio.h>
#include <string.h>

static void uwp_invoke (void (**fun)(void))
{
  (*fun) ();
}

#define unwind_protect(body, cleanup)                   \
do{                                                     \
  void (*uwp_dummy) (void)                              \
    __attribute__ ((__cleanup__ (uwp_invoke)))          \
    = ({                                                \
        void uwp_aux (void)                             \
        {                                               \
          for (int uwp_run = 1; uwp_run; uwp_run = 0)   \
            cleanup                                     \
        }                                               \
        uwp_aux;                                        \
      });                                               \
                                                        \
  for (int uwp_run = 1; uwp_run; uwp_run = 0)           \
    body                                                \
}while(0)

void foo (void)
{
  unwind_protect
    ({
      printf ("hi, there\n");
      return;
    },
    {
      printf ("cleanup\n");
    });
}

int main (int argc, char **argv)
{
  (void)argc;
  (void)argv;
  foo ();
  return 0;
}