Shell Shell Handling

shell.c

#include<stdio.h>
#include<stdlib.h>
#include<pthread.h>
#include<string.h>
#include<unistd.h>
#include<sys/types.h>
#include<signal.h>

static void shellHandler(int signo, siginfo_t* info, void* context)
{
	// Passes it into the child first
	if (signo == SIGINT || signo == SIGKILL || signo == SIGQUIT)
	{
        printf("Ahoy\n");
		kill(childPID, signo);
		kill(parentPID, SIGCHLD);
	}

    else if (signo == SIGTSTP)
    {
        // Suspend Signal
        printf("Suspend Signal\n");
        int fg_pid = findFG_STATUS(jobSet);
        if (fg_pid != -1)
        {
            jobSet = changeStatus(jobSet, fg_pid, STATUS_SUSPENDED);
            kill(fg_pid, SIGSTOP);
        }
    }

    else if (signo == SIGCHLD)
    {
        printf("Child Handler\n");
        if (!isSuspended)
        {
            pid_t child = info->si_pid; 
            jobSet = removeJob(jobSet, child);
            signal(signo, SIG_DFL);
        }
        else{
            printf("Case 2\n");
            isSuspended = false;
            kill(info->si_pid, SIGTSTP);
        }
    }

	else
	{
		signal(signo, SIG_IGN);
		printf("\n");
		printPrompt();
	}
}

int main(int argc, char* argv[])
{
    int signalArray[] = {SIGINT, SIGKILL, SIGTSTP, -1};
	sigset_t set = createSignalSet(signalArray);
	struct sigaction sa;
	sa.sa_handler = shellHandler;
	sa.sa_flags = SA_SIGINFO;

	// Parent must be blocked from these signals
	sigprocmask(SIG_BLOCK, &set, NULL);


    int pid = fork();
    if (pid == 0)
    {
        // Child
        if (isBackground == true)

        {
            printf("[bg]\t%d\n",getpid());
            setpgid(0, 0);
        }


        else
        {
            // Add to foreground process group
            pid_t cgrp = getpgrp();
            tcsetpgrp(STDIN_FILENO, cgrp);
            setpgid(getpid(), getppid());

        }

        //The child must receive the previously blocked signals
        sigprocmask(SIG\_UNBLOCK, &set, NULL);
        sigaction(SIGINT, &sa, NULL);
        sigaction(SIGTSTP, &sa, NULL);
        sigaction(SIGSTOP, &sa, NULL);
        childPID = getpid();
        }

        else

        {
			// Parent
            parentPID = getpid();
            setpgid(0, 0);
            if (isBackground)

            {
                Node node;
                [node.pid](https://node.pid) = pid;
                node.status = STATUS\_BACKGROUND;
                char* name = (char*) malloc (sizeof(char));
                strcpy(name, argVector[0]);
                jobSet = insert(jobSet, node);
                setpgrp();
            }

            else

            {
                int status;
                if((waitpid(pid, &status, WUNTRACED | WNOHANG) >= 0)){
                    printf("PID = %d\\t", pid);
                    if (WIFEXITED(status)){
                    printf("Normal Exit\\n");
                }

                else if (WIFSIGNALED(status)){
                printf("Job terminated by signal %d\\n", WTERMSIG(status));
                }

                else if (WIFSTOPPED(status)){
                    printf("Job stopped by signal %d\\n", WTERMSIG(status));
                    isSuspended = true;
                }

                sigaction(SIGCHLD, &sa, NULL);
            }

            waitpid(pid, NULL, 0);
        }
}