gistfile1.go

// .net-sysversion project main.go
package main

// // importing C will increase the stack size. this is useful
// // if loading a .NET COM object, beacuse the CLR requires a larger stack
// #cgo LDFLAGS: -loleaut32
// #include "windows.h"
// #include "OleAuto.h"
import "C"

import (
	"fmt"
	"github.com/mattn/go-ole"
	"github.com/mattn/go-ole/oleutil"
	"log"
	"runtime"
	"unsafe"
)

func leakyFunc() {
	errr := ole.CoInitializeEx(0, ole.COINIT_MULTITHREADED) // can interact in a bad way with go threads
	if errr != nil {
		log.Fatal(errr)
	}
	defer ole.CoUninitialize()

	unknown, errr := oleutil.CreateObject("System.Version")
	if errr != nil {
		log.Fatal(errr)
	}
	defer unknown.Release()

	sysver, errr := unknown.QueryInterface(ole.IID_IDispatch)
	if errr != nil {
		log.Fatal(errr)
	}
	defer sysver.Release()

	res, errr := oleutil.CallMethod(sysver, "ToString")
	fmt.Println(res.ToString())

	for {
		oleutil.CallMethod(sysver, "ToString")
	}
}

func nonleakyFunc() {
	errr := ole.CoInitializeEx(0, ole.COINIT_MULTITHREADED) // can interact in a bad way with go threads
	if errr != nil {
		log.Fatal(errr)
	}
	defer ole.CoUninitialize()

	unknown, errr := oleutil.CreateObject("System.Version")
	if errr != nil {
		log.Fatal(errr)
	}
	defer unknown.Release()

	sysver, errr := unknown.QueryInterface(ole.IID_IDispatch)
	if errr != nil {
		log.Fatal(errr)
	}
	defer sysver.Release()

	res, errr := oleutil.CallMethod(sysver, "ToString")
	fmt.Println(res.ToString())

	for {
		res, err := oleutil.CallMethod(sysver, "ToString")
		if err == nil {

			runtime.SetFinalizer(res, func(f *ole.VARIANT) {
				C.VariantClear((*C.struct_tagVARIANT)(unsafe.Pointer(f)))
			})
		}
	}
}

func main() {
	//leakyFunc()
	nonleakyFunc()
}