打印给定pid的子进程(MINIX) [英] Printing child processes given a pid (MINIX)

问题描述

我目前正在研究一个项目，作为项目的一部分，我需要在MINIX中实现系统调用/库函数.

I'm working on a project at the moment and as part of it I need to implement system calls/library functions in MINIX.

为此，我需要能够使用其pid打印给定进程的子进程列表.我想我已经找到了我需要的一部分，但我坚持使其与给定的pid一起使用.

As part of this I need to be able to print a list of child processes of a given process, using its pid. I think I've found part of what I need, but I'm stuck with making it work with a given pid.

struct task_struct *task; 
struct list_head *list;

list_for_each(list, &current->children) { 
    task = list_entry(list, struct task_struct, children); 
}

这看起来像我需要的东西吗?我知道要传递pid供我使用，我需要使用:

Does this seem like something close to what I'd need? I know that for passing a pid for me to use I'd need to use:

struct task_struct find_task_by_pid(pid_t pid);

但是，将其与以上内容结合起来并不是我以前做过的事情.

But combining this with the above isn't something I've done before.

推荐答案

我发现了这一点，对我来说似乎不太有效，但它可行.

I figured it out, doesn't seem too efficient to me but it works.

#include <stdio.h>
#include "pm.h"
#include "mproc.h"

int do_printchildpids(){
int i = m_in.m1_i1; //pid received 
int c = 0; //Counter


printf("Searching for children of process: %d \n", i);

while (c < NR_PROCS)
  {
    int n = mproc[c].mp_pid; //First process in the list of availableprocess
    int pinx = mproc[c].mp_parent; //Index of parent of the current process
    int ppid = mproc[pinx].mp_pid; //pid of parent process


    if(i == ppid) //If parents pid matches the given value
    {
    printf("%d \n", n); //Print the childs id
    c++;
    }
    else
    {
    c++;
    }
  }
return -1;
}

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