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/*
 * This is a simple program that calls BC and terminates it if it takes longer
 * than five seconds to complete. There is no real reason for this to be done
 * in C instead of Python, however there are some key advantages:
 *
 *  - Mango gets to play with C making him happy
 *  - C is compiled instead of interpreted so this is technically more efficient
 *    - Ok mayyyybe is slower because it uses a seperate process?
 *  - It makes us look smarter?
 */
#define _POSIX_SOURCE
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>

#include "math.h"

bool timeout = false, child_done = false;

void timeout_hander(int UNUSED(sig))
{
	timeout = true;
}

void child_handler(int UNUSED(sig))
{
	child_done = true;
}

int main(void)
{
	pid_t pid = fork();
	switch (pid) {
	case 0:
		execlp("bc", "bc", "-q", "bc_funcs/lib.bc", "bc_funcs/init.bc",
			   FILE_NAME, "bc_funcs/exit.bc", NULL);
		fallthrough;
	case -1:
		perror("calc");
		return EXIT_FAILURE;
	default:
		/* Setup signal handlers after fork so the child doesnt inherit them */
		signal(SIGALRM, timeout_hander);
		signal(SIGCHLD, child_handler);
		alarm(TIMEOUT);
		pause();

		/*
		 * Wait for either the child process to terminate, or for 5 seconds to
		 * have passed
		 */
		if (timeout) {
			puts("Error: 5 second timeout reached");
			kill(pid, 9);
		}

		break;
	}

	return EXIT_SUCCESS;
}