如何在没有Box::from_raw的情况下将*mut *mut c_void转换为&str？

use std::slice;
use std::str;

fn main() {
    let mut ptr: *mut *mut c_void = ...; // 获取*mut *mut c_void指针

    // 将*mut *mut c_void转换为*mut *mut u8
    let ptr_u8: *mut *mut u8 = ptr as *mut *mut u8;

    // 获取内存块的长度
    let len = unsafe { std::mem::size_of_val(&*ptr_u8) };

    // 将*mut *mut u8转换为&[u8]
    let slice_u8: &[u8] = unsafe { slice::from_raw_parts(*ptr_u8, len) };

    // 将&[u8]转换为&str
    let str_ref: &str = str::from_utf8(slice_u8).expect("Invalid UTF-8");

    println!("Converted string: {}", str_ref);
}