在golang中使用CString和cgo时如何正确释放内存？

Question

我试图了解在

cgo

 中使用 CString 和 

golang

时如何正确释放内存

这是我想要制作的工作代码“内存安全”：

basic.go

：

package main

// #include <stdlib.h>
import "C"

import (
        "github.com/pemistahl/lingua-go"
)

var lan lingua.Language


//export Langdetectfunct
func Langdetectfunct(text *C.char) int {


    textS := C.GoString(text);

    detector := lingua.NewLanguageDetectorBuilder().
        FromAllLanguages().
        Build()

    language, _ := detector.DetectLanguageOf(textS)

    return int(language)

}

func main() {}

basic1.cpp

：

#include "basic.h"

int main() {
    auto text = "It is a beautiful day, today";
    int res = Langdetectfunct(const_cast<char *>(text));
    std::cout << "res: " << res << std::endl;
}

使用

c-shared

buildmode 构建 basic.go 后：

raphy@raohy:~/go-lang-detect$ go build -o basic.so -buildmode=c-shared basic.go

并使用

basic.so

:

编译 basic1.cpp

raphy@raohy:~/go-lang-detect$ g++ -o basic basic1.cpp ./basic.so

我得到了正确的输出：

raphy@raohy:~/go-lang-detect$ ./basic 
res: 17

那很好...

但是：如何使代码“内存安全”？

我尝试过这样的方式：

basic.go

：

package main

// #include <stdlib.h>
import "C"
import "unsafe"

import (
        "github.com/pemistahl/lingua-go"
)

var lan lingua.Language

//export Langdetectfunct
func Langdetectfunct(text *C.char) int {

    textS := C.GoString(text);

    detector := lingua.NewLanguageDetectorBuilder().
        FromAllLanguages().
        Build()

    language, _ := detector.DetectLanguageOf(textS)

    return int(language)

    C.free(unsafe.Pointer(text))
}

func main() {}

但是，当构建时，我得到了，可以理解的是，这个错误：

raphy@raohy:~/go-lang-detect$ go build -o basic.so -buildmode=c-shared basic.go
./basic.go:39:1: missing return

如果我将

C.free(unsafe.Pointer(text))

放在 return 语句之前：

package main

// #include <stdlib.h>
import "C"
import "unsafe"

import (
        "github.com/pemistahl/lingua-go"
)

var lan lingua.Language

//export Langdetectfunct
func Langdetectfunct(text *C.char) int {

    textS := C.GoString(text);

    detector := lingua.NewLanguageDetectorBuilder().
        FromAllLanguages().
        Build()

    language, _ := detector.DetectLanguageOf(textS)

    C.free(unsafe.Pointer(text))

    return int(language)

}

func main() {}

运行可执行文件时，出现：

free(): invalid pointer

错误：

raphy@raohy:~/go-lang-detect$ go build -o basic.so -buildmode=c-shared basic.go
raphy@raohy:~/go-lang-detect$ g++ -o basic basic1.cpp ./basic.so
raphy@raohy:~/go-lang-detect$ ./basic 
free(): invalid pointer
Aborted (core dumped)

Answer 1

auto text =“今天是美好的一天”;

text

位于堆栈位置。你无法释放它。