如何在Rust for C中表示指向数组的指针 [英] How to represent a pointer to an array in Rust for C

问题描述

我在Rust中需要一个extern "C" FFI函数，并且想要接受一个固定大小的数组. C代码传递如下内容:

I need an extern "C" FFI function in Rust and want to accept an array of fixed size. The C code passes something like:

// C code
extern int(*)[4] call_rust_funct(unsigned char (*)[3]);
....
unsigned char a[] = { 11, 255, 212 };
int(*p)[4] = call_rust_funct(&a);

如何为其编写Rust函数?

How do I write my Rust function for it ?

// Pseudo code - DOESN'T COMPILE
pub unsafe extern "C" fn call_rust_funct(_p: *mut u8[3]) -> *mut i32[4] {
    Box::into_raw(Box::new([99i32; 4]))
}

推荐答案

您只需要对固定大小的数组使用Rust的语法:

You just need to use Rust's syntax for fixed size arrays:

pub unsafe extern "C" fn call_rust_funct(_p: *mut [u8; 3]) -> *mut [i32; 4] {
   Box::into_raw(Box::new([99i32; 4]))
}

或者您始终可以使用*mut std::os::raw::c_void并将其转换为正确的类型.

Or you can always use *mut std::os::raw::c_void and transmute it to the correct type.

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