MIT 6.S081 lab1

sleep

#include "kernel/types.h"
#include "user/user.h"

int main (int n, char *argv[]) {
    if(n == 1 || n >= 3) {
        printf("Error\n");
        exit(1);
    }
    int num = atoi(argv[1]);
    //printf("%d\n",num);
    sleep(num);
    
    exit(0);
}

pingpong

#include "kernel/types.h"
#include "user/user.h"


int main () {
    int p1[2]; // fa -> son  (0 read) (1 write)
    int p2[2]; // fa <- son
    pipe(p1);
    pipe(p2);
    int pid = fork();
    if(pid == 0) {
        write(p2[1], "k", 1);
        close(p2[0]);
        close(p1[1]);
        char ch_son[30];
        read(p1[0], ch_son, 1);
        int son = getpid();
        printf("%d: received ping\n", son);
        close(p2[1]);
        close(p1[0]);
        //printf("%c\n", ch_son[0]);
    } else {
        write(p1[1], "F", 1);
        wait(0);
        close(p1[0]);
        close(p2[1]);
        char ch_fa[30];
        read(p2[0], ch_fa, 1);
        int fa = getpid();
        printf("%d: received pong\n", fa);
        //printf("%c\n",  ch_fa[0]);
        close(p1[1]);
        close(p2[0]);
    }

    exit(0);
}

primes

#include "kernel/types.h"
#include "user/user.h"

#define N 35
#define READEND 0
#define WRITEEND 1

void child(int *p1);

int main(int argc, char *argv[]) {
    int p[2];
    pipe(p);
    if(fork() == 0) {
        child(p);
    } else {
        close(p[READEND]);
        for (int i = 2; i <= N; i++) {
            write(p[WRITEEND], &i, sizeof(int));
        }
        close(p[WRITEEND]);
        wait((int*)0);
    }

    exit(0);
}

void child(int *p1) {
    int pr[2];
    int n;
    close(p1[WRITEEND]);
    int read_result = read(p1[READEND], &n, sizeof(int));
    if(read_result == 0) {
        exit(0);
    }
    pipe(pr);
    if (fork() == 0) {
        child(pr);
    } else {
        close(pr[READEND]);
        printf("prime %d\n", n);
        int prime = n;
        while(read(p1[READEND], &n, sizeof(int)) != 0) {
            if(n % prime != 0) {
                write(pr[WRITEEND], &n, sizeof(int));
            }
        }
        close(pr[WRITEEND]);
        wait((int*)0);
        exit(0);
    }
}