有大佬熟悉 ffi 么,如何从 ffi 获取 array 返回值 - V2EX
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freehere
V2EX    Rust

有大佬熟悉 ffi 么,如何从 ffi 获取 array 返回值

  •  
  •   freehere 2022-08-07 21:52:43 +08:00 2291 次点击
    这是一个创建于 1160 天前的主题,其中的信息可能已经有所发展或是发生改变。
    #[no_mangle] pub extern "C" fn decode(raw: *const libc::c_char) -> *mut u32 { let str_raw = unsafe { CStr::from_ptr(raw) }.to_str().unwrap().to_string(); let bytes_raw = hex::decode(str_raw).unwrap(); let mut u8_fixed: [u32; 6] = Decode::decode(&mut &bytes_raw[..]).unwrap(); let ptr = u8_fixed.as_mut_ptr(); std::mem::forget(u8_fixed); ptr } 

    nodejs code

     let libm = ffi.Library(rootPath, { 'decode': [ref.refType("uint"), ['string']], } let value = libm.decode("010000000200000003000000040000000500000006000000") 

    decode 的 value 返回值应该是 []uint{1,2,3,4,5,6} ,现在打印出 value 看起来像是个 buffer, 不知道怎么解析这个 buffer

    8 条回复    2024-01-07 17:58:39 +08:00
    nomagick
        1
    nomagick  
       2022-08-07 22:01:01 +08:00
    freehere
        2
    freehere  
    OP
       2022-08-08 08:24:00 +08:00
    @nomagick 看过了 example 和 test ,测试了一下,还是没有搞出来
    nomagick
        3
    nomagick  
       2022-08-08 11:33:00 +08:00   1
    @freehere 你这个函数返回的是 ref(array(uint)), 第一层是个指针,你拿到的 buffer 是指针的值,把它 deref(), 才是 array(uint)
    freehere
        4
    freehere  
    OP
       2022-08-08 15:55:37 +08:00
    k1263
        5
    k1263  
       2022-08-26 16:59:26 +08:00
    Decode::decode 哪里来的?自己定义的吗?
    k1263
        7
    k1263  
       2022-09-07 14:01:41 +08:00
    @freehere
    我的这一步会出错,CStr::from_ptr(raw).to_str(), 你的出错吗?

    #[no_mangle]
    pub extern "C" fn decode(raw: *const libc::c_char) -> *mut u32 {
    if raw.is_null() {
    return ptr::null_mut();
    }
    if let Ok(str_raw) = unsafe { CStr::from_ptr(raw).to_str() } {
    println!("str_raw: {:?}", str_raw);
    let bytes_raw = hex::decode(str_raw).unwrap();
    let mut u8_fixed: [u32; 6] = Decode::decode(&mut &bytes_raw[..]).unwrap();
    let ptr = u8_fixed.as_mut_ptr();
    std::mem::forget(u8_fixed);
    ptr
    } else {
    println!("str_raw fail");
    return ptr::null_mut();
    }

    }

    pub fn main() {
    let raw = "010000000200000003000000040000000500000006000000";
    let aa = decode(raw.as_ptr() as *const i8);
    println!("{:?}", aa);
    }
    zhangyuang
        8
    zhangyuang  
       2024-01-07 17:58:39 +08:00
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