#include <iostream>
#include <unistd.h>
#include <sys/wait.h>

using namespace std;

void sig_handler( int signo ); //signal handler
int spawnProcess(char *name); //spawns a particular process by name, returns PID
void syserr(const char *msg); //ignore this

int main(int argc, char * argv[]) {
	if(argc != 4){
		cerr << "Lab5: Program takes 3 processes as arguments" << endl;
		//syserr("Program takes 3 arguments");
		return 1;
	}

	//Initial spawn of our processes
	int pids[3];
	for(int i = 1; i < 4; i++){
		pids[i-1] = spawnProcess(argv[i]);
	}

	//Keep track of how many times each process has been restarted
	int p1Res=1, p2Res=1, p3Res=1;

   struct sigaction act;

	act.sa_handler = sig_handler;
	sigemptyset( &act.sa_mask );
	act.sa_flags = SA_NOCLDWAIT;

	if( sigaction( SIGCHLD , &act, NULL ) == -1 ) {

    	perror( "sigaction" );
    	exit( 1 );
	}

	cout << "Parent has exited" << endl;
return 0;
}

void sig_handler( int signo ) {
	}

//Spawn the process "name" and return its PID
int spawnProcess(char *name) {
	int pid;
	switch( (pid = vfork()) ){
		case -1:
			//syserr("vfork");
			cerr << "Error calling vfork()" << endl;
			return 1;
		case 0:
			if(execl(name, NULL) == -1){
			//syserr("execl");
			cerr << "Error calling execl" << endl;
			return 1;
			}
	};
return pid;
}

#include <iostream>
#include <string>
#include <unistd.h>
#include <sys/wait.h>

using namespace std;

// These need to be global so the signal handler can access them as well
int run_count[3] = {0, 0, 0};
int child_pids[3];
string processes[3];


void sig_handler( int signo ); //signal handler
int spawnProcess(const char *name); //spawns a particular process by name, returns PID

int main(int argc, char * argv[]) {
	if(argc != 4){
		cerr << "Lab5: Program takes 3 processes as arguments" << endl;
		return 1;
	}

    // Setup the signal handler
    struct sigaction act;
    act.sa_handler = sig_handler;
	sigemptyset( &act.sa_mask );
	act.sa_flags = SA_NOCLDWAIT;

    if( sigaction( SIGCHLD , &act, NULL ) == -1 ) {
    	perror( "sigaction" );
    	exit( 1 );
	}

	// Initial spawn of our processes
	for(int i = 1; i < 4; i++){
	    processes[i-1] = string(argv[i]);
		child_pids[i-1] = spawnProcess(argv[i]);
	}


    // Sleep for 20 seconds even if the timer is interupted by a signal
	int sleep_time = 20;
	while (0 != (sleep_time = sleep(sleep_time)))
	{}

	cout << "Parent has exited" << endl;

    return 0;
}

void sig_handler( int signo ) {
    int status;
    for (int i = 0; i < 4; ++i)
    {
        // If we get negative one the child is dead
        if ((-1 == waitpid(child_pids[i], &status, WNOHANG)) &&
            (run_count[i] < 4))
        {
            // Increment the run count
            run_count[i]++;

            cout << "Restarting child '" << processes[i] << "' for the "
                <<  run_count[i] << " time" << endl;
            // Run the process again and record its new pid, then
            child_pids[i] = spawnProcess(processes[i].c_str());
        }
    }
}

//Spawn the process "name" and return its PID
int spawnProcess(const char *name) {
	int pid;
	switch( (pid = vfork()) ){
		case -1:
			cerr << "Error calling vfork()" << endl;
			return 1;
		case 0:
			if(execl(name, NULL) == -1){
			cerr << "Error calling execl" << endl;
			return 1;
			}
	};
return pid;
}