通过一个C数组防锈功能 [英] Pass a C array to a Rust function

问题描述

我试图使防锈dylib和其他语言，如C，Python和其他人使用它。我已经成功地称为防锈功能了结和I32的说法从蟒蛇。现在，我想做一个功能，即带有一个数组（指针指向它，或任何必要通过一个数据集锈病LIB）。

I'm trying to make a Rust dylib and use it from other languages, like C, Python and others. I've successfully called a Rust function taking and i32 argument from python. Now I'm trying to make a function, that takes an array (pointer to it, or whatever necessary to pass a dataset to Rust lib).

#![crate_type = "dylib"]
#[no_mangle]
pub extern fn rust_multiply(size: i32, arrayPointer: &i32) -> i32
{
    *(arrayPointer)
}

这正常工作。但

#![crate_type = "dylib"]
#[no_mangle]
pub extern fn rust_multiply(size: i32, arrayPointer: &i32) -> i32
{
    *(arrayPointer + 1) // trying to get next element
}

失败

src/lib.rs:5:2: 6:2 error: type `i32` cannot be dereferenced
src/lib.rs:5    *(arrayPointer + 1)
src/lib.rs:6 }

另外这款：

pub extern fn rust_multiply(size: i32, array: &[i32]) -> i32

和做一些像数组[0] 失败，长度= 0的错误。

and doing something like array[0] fails with "length = 0" error.

推荐答案

您必须作出一些努力为客户提供纯 C API和使用不安全$ C $执行一些转换C。幸运的是，它不是那么难：

You have to make some efforts to provide pure C api and implement some conversions using unsafe code. Fortunately, it is not so difficult:

extern crate libc;

#[no_mangle]
pub extern fn rust_multiply(size: libc::size_t, array_pointer: *const libc::uint32_t) -> libc::uint32_t {
    internal_rust_multiply(unsafe { std::slice::from_raw_parts(array_pointer as *const i32, size as usize) }) as libc::uint32_t
}

fn internal_rust_multiply(array: &[i32]) -> i32
{
    assert!(!array.is_empty());
    array[0]
}

有是铁锈FFI 一个很好的介绍在官方网站。

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