#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <setjmp.h>
#include <math.h>

struct trycatch
{
  jmp_buf * buf;
  struct trycatch * prev;
  void * exception;
} __thread * current_trycatch = NULL;

#define THROW_WITH_DATA(e,d) do { \
    current_trycatch->exception = d; \
    longjmp (*(current_trycatch->buf), e); \
  } while (0)

#define THROW(e) do { \
    longjmp (*(current_trycatch->buf), e); \
  } while (0)

#define TRY \
  do { \
    jmp_buf __bUf; \
    struct trycatch __tRy; \
    int __eRr; \
    __tRy.buf = &__bUf; \
    __tRy.prev = current_trycatch; \
    current_trycatch = &__tRy; \
    __eRr = setjmp (__bUf); \
    switch (__eRr) \
      { \
        case 0: \
          do {

#define CATCH_WITH_DATA(e,d) \
          } while (0); \
          break; \
        case e: \
          do { \
            void * (d) = current_trycatch->exception;

#define CATCH(e) \
          } while (0); \
          break; \
        case e: \
          do { \

#define ENDTRY \
          } while (0); \
          break; \
        default: \
          if (current_trycatch->prev) \
            { \
              current_trycatch = current_trycatch->prev; \
              THROW_WITH_DATA(__eRr, __tRy.exception); \
            } \
          else \
            { \
              fprintf (stderr, "Unhandled exception %i!\n", __eRr); \
            } \
      } \
      current_trycatch = current_trycatch->prev; \
  } while (0);

long int
isqrt (long int par)
{
  if (par < 0)
    THROW(EDOM);

  return (long int) sqrt((double) par);
}

void
nested (char * arg)
{
  long int res;

  TRY {
    char * end;
    long int number = strtol (arg, &end, 10);

    if (*end != '\0')
      THROW_WITH_DATA(EINVAL, (void *) "argument contains nondecadic characters!");

    res = isqrt (number);
    if (res > 1000)
      THROW(E2BIG);
  } CATCH (E2BIG) {
    printf ("number too big\n");
  } ENDTRY;

  printf("result = %li\n\n", res);
}

int
main (int argc, char ** argv)
{
  TRY {
    if (argc != 2)
      THROW_WITH_DATA(EINVAL, (void *) "bad argc!");

    nested (argv[1]);

  } CATCH_WITH_DATA (EINVAL, errstr) {
    printf("usage: trycatch arg   - (%s)\n\n", (char *) errstr);
  } ENDTRY;

  exit (EXIT_SUCCESS);
}