z505 / godll Goto Github PK

Been trying to return a string, not printing it to console, but there seem not to be a way.

I did try 2 different approaches

//export PrintHello2
func PrintHello2(Input *C.char, Output **C.char) int32 {
	*Output = C.CString(fmt.Sprintf("From DLL: Hello, %s!\n", C.GoString(Input)))
	return 1
}

and

//export PrintHello4
func PrintHello4(Input *C.char) *C.char{
	return C.CString(fmt.Sprintf("From DLL: Hello, %s!\n", C.GoString(Input)))
}

I'm calling this code from .net using the following test code

class Program
{
	[DllImport("goDLL.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)]
	public static extern int PrintHello2([In] byte[] data, [MarshalAs(UnmanagedType.I1)] ref SByte[] output);

	[DllImport("goDLL.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.StdCall)]
	public static extern SByte[] PrintHello4(byte[] data);

	static void Main(string[] args)
	{
		string res = "demo";
		SByte[] output= { };

		Console.WriteLine("PrintHello4 Returns: " + PrintHello4(Encoding.UTF8.GetBytes(res)).Length);

		Console.WriteLine("PrintHello2 Returns: " + PrintHello2(Encoding.UTF8.GetBytes(res), ref output));
		Console.WriteLine("Ref Val changed to: " + output.Length + "\n");
	}
}

None of the Go function works as expected and program chashes with System.Runtime.InteropServices.MarshalDirectiveException for any of the 2 functions

Can you show example of import PrintHello function?

When try to export as in godll.c
PrintHello(GoString p1);
goDLL.c: In function 'dummy':
goDLL.c:6:13: error: expected expression before 'GoString'
6 | PrintHello(GoString p1);
| ^~~~~~~~

Problem Description : There is dll( A1.dll- compiled in C++) in which a function is defined as
EXPORT void S3(HWND hwnd, HINSTANCE hinst, LPSTR lpszCmdLine, int nCmdShow){}

A1.dll
`// dllmain.cpp : Defines the entry point for the DLL application.
#include "pch.h"
#include
//#include

#define EXPORT extern "C" __declspec(dllexport)

EXPORT void S3(HWND hwnd, HINSTANCE hinst, LPSTR lpszCmdLine, int nCmdShow)
{
MessageBox(NULL, TEXT("Hello World"),
TEXT("In a DLL"), MB_OK);
}
**I want to load this DLL using GO lang. For this I am writing below program:**package main

import (
"fmt"
"syscall"
"golang.org/x/sys/windows"
)

func main() {
dll, err := syscall.LoadDLL("A1.dll")
proc, err := dll.FindProc("S3")
_, _, dllError := proc.Call()
fmt.Println("calling S3")
fmt.Printf("Error, err: %s\n", dllError)
fmt.Printf("Error, err: %s\n", err)
}`

This is not working. Also I am not able to understand that here how to pass the parameter in call function according to function S3 definition. Could anybody help me in understanding this issue?