如何通过单个fork()调用使子进程保持活动状态?

我有一个从fork()调用创建子进程的程序。子系统将连续接收来自用户的1字节整数输入。将整数发送给子级后,子级将使用管道将值发送给父级。当父级收到该值时,它会将其添加到数组中-发送1以结束程序。一旦子级发送父级-1,父级将对数组中以前的值求和,并使用另一个管道将此求和值发送给子级,子级将在其中打印并终止程序。

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

//Gets input from the user
int getInput() {
    int val; char temp;
    scanf("%hhd", &temp);
    val = temp;
    return val;
}

//Sums the values of the entered numbers and returns it
int finish(int arr[], int i) {
    int sum = 0;
    for (int j = 0; j < i; j++) {sum+= arr[j];}
    return(sum);
}

int main() {

    int fd[2], fd2[2], val = 0, i = 0, sum, final = -9999999;
    int arr[1000];
    pid_t pidVal;

    //Pipe for sending numbers from child to parent
    pipe(fd);

    //Pipe for sending the final sum from parent to child
    pipe(fd2);

    //Create parent and child processes
    pidVal = fork();

    //Used to make it run continously until -1 is pressed
    while(1) {

        //Child Process
        if (pidVal == 0) {
            printf("Child Process (should be 0): %d\n", pidVal);
            val = getInput();
            printf("You typed: %d\n", val);
            //Write to parent
            close(fd[0]);
            write(fd[1], &val, sizeof(val));
            //Read if parent sends sum yet
            close(fd2[1]);
            read(fd2[0], &final, sizeof(final));
            //If sum sent from parent, print and terminate
            if (final != -9999999) {
                printf("%d\n", final);
                exit(0);
            }           
        }

        //Parent Process
        if (pidVal > 0) {
            printf("I'm the parent (should be > 0): %d\n", pidVal);
            //Read what child sent to the pipe
            close(fd[1]);
            read(fd[0], &val, sizeof(val));
            //If exit value recieved
            if (val == -1) {
                //Sum the numbers sent
                sum = finish(arr, i);
                //Close read directory
                close(fd2[0]);
                //Write the sum to the pipe
                write(fd2[1], &sum, sizeof(sum));
            } 

            //Not -1 as input
            else {
                //Collect input
                arr[i] = val;
                i++;
            }
        }
    }
}

但是,问题是,当我尝试发送多个号码时,程序被卡住了,正如您从该示例输出中看到的:

I'm the parent (should be > 0): 5673
Child Process (should be 0): 0
3 //My Input
You typed: 3
I'm the parent (should be > 0): 5673
1 //My Input
2 //My Input

一 父母和 一 仅从整个程序的单个fork调用派生的子进程。这可能吗?