`wait()` 和 `exit()` 这两种用法哪个更好？

Question

这是我从https://github.com/karelzak/util-linux/blob/200769b6c0dff6863089ea2a9ff4ea9ccbd15d0f/login-utils/login.c#L939

中了解到的wait()和exit()的一些用法

f(){
    child_pid = fork();

    if (child_pid) { 
        // parent part
        ...
        while (wait(NULL) == -1 && errno == EINTR) ;
        ...
        exit();
    }

    // common part, which is actually child part
    ...
}

f();

// common part 2, which is actually child part
...

和这个一样吗？

f(){
    child_pid = fork();

    if (child_pid) { 
        // parent part
        ...
        while (wait(NULL) == -1 && errno == EINTR) ;
        ...
        exit();
    }

    if (child_pid == 0) { 
        // common part, which is actually child part
        ...   

        // common part 2, which is actually child part
        ...         
    }
}

f();

第二个比第一个更容易理解吗？ That is what I feel (especially the above code is wrapped in a function, and a call to that function has other common code following it in main())，但我真的不是很了解

有没有第一个比第二个更好的原因或案例？特别是login（上面第一个link）的实现为什么选择第一种方式？

Answer 1

这实际上是一个函数内部属于什么的问题，有点模糊。但是，如果您的函数类似于 "put me into a new process that has its environment set up in some particular way"，那么该代码具有如下结构是有意义的：

void switch_to_child(){
    int pid = fork();
    if (pid < 0){
        exit_with_an_error();
    }
    if (pid > 0){
        wait_and_exit_in_parent();
    }
    set_up_child_environment();
}

initialize_stuff();
switch_to_child();
do_child_stuff();

另一方面，如果您的函数类似于 "spawn a new process to do something"，则代码具有如下结构更有意义：

void make_child(){
    int pid = fork();
    if (pid < 0){
        exit_with_an_error();
    }
    if (pid == 0){
        do_child_stuff();
        exit_in_child();
    }
}

initialize_stuff();
make_child();
wait_and_exit_in_parent();

`wait()` 和 `exit()` 这两种用法哪个更好？

Which of these two usages of `wait()` and `exit()` is better?

linux

wait