ground_button.c

#include <stdio.h> //puts
#include <signal.h> //signal, kill
#include <unistd.h> //read,
#include <sys/types.h> //kill, getppid

pid_t cabin;
static int status = 0; //0 means that button is inactive, 1 - it is activated (or pressed)

void
react(int sig);

void
press(int sig)
{
	signal(SIGUSR1, SIG_IGN);
	if (status != 1) {
	    status = 1;
	    puts("You've called an elevator from street");
	    printf("%d\n",cabin);
	    sleep(4);
	    kill(cabin, SIGUSR1);
	}
	signal(SIGUSR1, press);
	return;
}

void
react(int sig)
{
	puts("Ground button is set inactive");
	status = 0;
	return;
}

void
sig_int_handl(int sig)
{
	//signal(SIGINT, sig_int_handl);
	if (status == 0) {
		puts("Button on ground - not pressed");
	}
	if (status == 1) {
		puts("Button on ground is pressed");
	}
	return;
}

int
main(void)
{
	//signal(SIGFPE, SIG_IGN);
	signal(SIGTERM, SIG_DFL);
	pid_t t;
	read(0, &t, sizeof(pid_t));
	printf("%d BLYA\n", t);
	//pid_t ppid = getppid();
	//kill(ppid, SIGUSR1);                //our process indicates that it is ready to work
	signal(SIGUSR1, press);            //вызвали лифт с поверхности
	signal(SIGTRAP, react);            //ответ от двери
	signal(SIGINT, sig_int_handl);
	while(1){
		pause();
	}
	return 0;
}