z505/godll

how to create windows golang DLL and load into C, or delphi, or freepascal

godll's Issues

Go functions with params

Can you show example of import PrintHello function?

DLL with parameters

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);
| ^~~~~~~~

Return **C.Char

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

Issue in calling a function from DLL in GO Lang

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?