c - 为什么我在只读对象中收到错误消息 "assignment of member ‘readdir’”

Question

当我编译这个文件时，它抛出以下错误。

kit.c: In function ‘hide_pid’://rootkit.c:109:9: error: assignment of member ‘readdir’ in read-only kit.c:
In function ‘restore’ 127
error: assignment of member ‘readdir’ in read-only object

有人知道为什么吗？

int hide_pid(readdir_t *orig_readdir, readdir_t new_readdir)
{
        struct file *filep;

        /*open /proc */
        if((filep = filp_open("/proc",O_RDONLY,0))==NULL)
        {
                return -1;
        }
        /*store proc's readdir*/
        if(orig_readdir)
                *orig_readdir = filep->f_op->readdir;

        /*set proc's readdir to new_readdir*/ //ERROR IN THE LINE BELOW
        filep->f_op->readdir=new_readdir;

        filp_close(filep,0);

        return 0;
}


int restore (readdir_t orig_readdir)
{
        struct file *filep;

        /*open /proc */
if ((filep = filp_open("/proc", O_RDONLY, 0)) == NULL) {
                return -1;
        }

        /*restore /proc's readdir*/ //ERROR BELOW
        filep->f_op->readdir = orig_readdir;

        filp_close(filep, 0);

        return 0;
}

Answer 1

定义 ops vector (f_op) 的结构可能在其 readdir 字段的定义中使用了 const - 也可能是所有其他字段。设置自己的 ops vector 比替换现有 ops vector 中的一种或两种方法要正常得多。