vfs_stat()调用有什么问题? [英] What's wrong with vfs_stat() call?

问题描述

我正在尝试对文件进行统计，

I'm trying to do a stat on files,

    struct kstat stat;
    int error = vfs_stat ("/bin/ls", &stat); // /bin/ls exists

    if (error)
    {
            printk (KERN_INFO "error code %d\n", error);
    }
    else
    {
            printk (KERN_INFO "mode of ls: %o\n", stat.mode);
            printk (KERN_INFO "owner of ls: %o\n", stat.uid);
    }

    return error;

但是错误总是设置为14(错误地址)，代码出了什么问题?

But error was always set to 14 (Bad Address), what's wrong with the code?

我正在运行3.9内核.

I'm running 3.9 kernel.

推荐答案

vfs_stat()是和__user被定义为 :

# define __user __attribute__((noderef, address_space(1)))

换句话说，vfs_stat()仅支持使用指向用户空间的指针的文件名，并且不应在内核空间内取消引用.请注意，"/bin/ls"并不指向用户空间，而是指向内核空间，因此不能在此处使用.

In other words, vfs_stat() only supports using filename that is pointer into user space, and should not be dereferenced inside kernel space. Note that "/bin/ls" does NOT point into user space, but into kernel space, and thus cannot be used here.

实际上，错误消息14(错误的地址)告诉您这个问题:)

Actually, error message 14 (bad address) tells this issue right into your face :)

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