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

//子进程个数
#define SUB_PRO_COUNT 10

//处理子进程的退出信号
void sub_quit_signal_handle(int sig);

//父进程的事件循环
void ParentCycle();

//子进程的事件循环
void ChildCycle();

int main(void)
{
    pid_t  pid;
    int i;

    //创建SUB_PRO_COUNT个子进程
    for(i=0; i<SUB_PRO_COUNT; i++)
    {
        pid = fork();
        if( 0 == pid || -1 == pid )
            break;
    }

    //创建子进程失败
    if( -1 == pid )
    {
        printf("No. %d: fork error\n", i);
    }
    //子进程的事件循环
    else if( 0 == pid )
    {
        ChildCycle();
    }
    //父进程的事件循环
    else
    {
        ParentCycle();
    }

    return 0;
}

void sub_quit_signal_handle(int sig)
{
    int status;
    //获取退出的那个子进程的状态
    int quit_pid = wait(&status);
    printf("sub process %d quit, exit status %d\n", quit_pid, status);

    //新创建一个子进程
    pid_t pid = fork();
    if( 0 == pid )
         ChildCycle();
}

void ParentCycle()
{
    printf("Parent process %d\n", getpid());
    signal(SIGCHLD, sub_quit_signal_handle);
    while(1)
        pause();
}

void ChildCycle()
{
    printf("create sub process id: %d, parent id: %d\n", getpid(), getppid());
    while(1)
        pause();
}