/* This file is part of the sample code and exercises
 * used by the class "Advanced Programming in the UNIX
 * Environment" taught by Jan Schaumann
 * <jschauma@netmeister.org> at Stevens Institute of
 * Technology.
 *
 * This file is in the public domain.
 *
 * You don't have to, but if you feel like
 * acknowledging where you got this code, you may
 * reference me by name, email address, or point
 * people to the course website:
 * https://stevens.netmeister.org/631/
 */

/* A simple illustration of exit handlers.  Note that exit handlers are
 * pushed onto a stack and thus execute in reverse order.
 *
 * Illustrate exiting at different times by invoking
 * this program as
 * ./a.out            exit handlers invoked after return from main
 * ./a.out 1          exit handlers invoked from within func
 * ./a.out 1 2        no exit handlers invoked
 * ./a.out 1 2 3      we call abort(3), no exit handlers invoked
 *
 *
 * */

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

void
my_exit1(void) {
	(void)printf("first exit handler\n");
}

void
my_exit2(void) {
	(void)printf("second exit handler\n");
}

void
func(int argc) {
	(void)printf("In func.\n");
	if (argc == 2) {
		exit(EXIT_SUCCESS);
	} else if (argc == 3) {
		_exit(EXIT_SUCCESS);
	} else if (argc == 4) {
		abort();
	}
}


int
main(int argc, char **argv) {
	(void)argv;
	if (atexit(my_exit2) != 0) {
		perror("can't register my_exit2\n");
		exit(EXIT_FAILURE);
	}

	if (atexit(my_exit1) != 0) {
		perror("can't register my_exit1");
		exit(EXIT_FAILURE);
	}

	if (atexit(my_exit1) != 0) {
		perror("can't register my_exit1");
		exit(EXIT_FAILURE);
	}

	func(argc);

	(void)printf("main is done\n");

	return EXIT_SUCCESS;
}