从 Rust 到 Go 的回调函数

我正在尝试创建从 go 调用 rust 函数的可能性，然后所述 rust 函数将函数回调到 go。我使用 cgo 作为 go 和 rust 之间的 ffi 接口。 以下是我的 go 代码（class="lazy" data-src/main.go）：

package main

import (
    "c"
    "fmt"
    "unsafe"
)



//export cosmoscallbackwrapper
func cosmoscallbackwrapper(data *c.uchar, datalen c.int) {
    // convert data to go slice
    godata := c.gobytes(unsafe.pointer(data), datalen)

    // call the actual callback function
    cosmoscallback(godata)
}

// setcosmoscallback sets the callback function to be called by the move vm.
func setcosmoscallback(callback func([]byte)) {
    cosmoscallback = callback
    c.set_cosmos_callback((c.cosmos_callback)(unsafe.pointer(c.cosmoscallbackwrapper)))
}

var cosmoscallback func([]byte)

func main() {
    // create a new move interpreter

    // set the callback function
    setcosmoscallback(func(data []byte) {
        fmt.println("received data from move vm:", data)
        // handle data and call cosmos sdk functions as needed
    })
}

这是我的 rust 代码 (class="lazy" data-src/lib.rs)

use std::os::raw::{c_char, c_int};
use std::ffi::cstring;
use std::sync::mutex;
#[macro_use] extern crate lazy_static;
pub fn main() {
}
pub type cosmoscallback = extern "c" fn(*const c_char, c_int);

lazy_static! {
        static ref callback: mutex> = mutex::new(none);
}

#[no_mangle]
pub extern "c" fn set_cosmos_callback(callback: cosmoscallback) {
        let mut cb = callback.lock().unwrap();
        *cb = some(callback);
}
#[no_mangle]
pub extern "c" fn cosmoscallbackwrapper(data: *const c_char, data_len: c_int) {
    let cb = callback.lock().unwrap();
    if let some(callback) = &*cb {
        callback(data, data_len);
    }
}

这是我的 cargo.toml 文件：

[package]
name = "go-move"
version = "0.1.0"
edition = "2021"

[lib]
crate-type = ["cdylib"]

[dependencies]
libc = "0.2"
lazy_static = "1.4.0"


[workspace]
members = [    ".",]

这是 lib/move.h（共享库的头文件）：

#ifndef move_vm_lib_h
#define move_vm_lib_h

#include 
//typedef void (*cosmos_callback)(const unsigned char *data, int data_len);
//void set_cosmos_callback(cosmos_callback callback);

typedef void (*cosmos_callback)(const uint8_t* data, int32_t data_len);

void set_cosmos_callback(cosmos_callback callback);
#endif

这是我的 makefile：

shell := /bin/bash
.phony: build
os = $(shell uname)
clean:
        rm -rf bin
        rm -rf target
build:
        @echo the os is $(os)
        mkdir bin
        cargo build --release
ifeq ($(os),linux)
        cp target/release/libgo_move.so bin/
else
        cp target/release/libgo_move.dylib bin/
endif
        cp -a lib/. bin/
        go build --ldflags="-l./bin -lgo_move" -o bin/main class="lazy" data-src/main.go
run:
        export ld_library_path=./bin && ./main

文件结构如下：

class="lazy" data-src
    main.go
    main.rs
bin
    libgo_move.so (after cargo build)
lib
    move.h
cargo.toml
makefile

运行 make clean build 后，我得到以下输出：

cp target/release/libgo_move.so bin/
cp -a lib/. bin/
go build -o bin/main  class="lazy" data-src/main.go
# command-line-arguments
class="lazy" data-src/main.go:27:59: could not determine kind of name for C.cosmosCallbackWrapper
class="lazy" data-src/main.go:27:25: could not determine kind of name for C.cosmos_callback
class="lazy" data-src/main.go:27:2: could not determine kind of name for C.set_cosmos_callback

由于某种原因，它找不到 ffi 函数。

正确答案

这是一个愚蠢的错误：

必须在导入之前进行。仅此而已。

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