[WIN11 - Java 21] GetProcAddress by name issue

[Ocean Breath]

Hi to all,

I experience an unexpected behavior if I call the GetProcAddress function, passing it the name of a function exported from a DLL. The DLL itself is very simple:

#include "windows.h"
#include <iostream>
#include <mutex>

static std::mutex load_mutex;
extern "C" __declspec(dllexport)
BOOL __cdecl test()
{
    std::cerr << "[TEST MUTEX] start" << std::endl;
    std::lock_guard<std::mutex> lock(load_mutex); //crash here
    std::cerr << "[TEST MUTEX] passed" << std::endl;
    return TRUE;
}

and I use it from Java with this code:

import com.sun.jna.Function;
import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.Pointer;
import com.sun.jna.WString;
import com.sun.jna.win32.W32APIOptions;

public class Probe {
    public interface Kernel32Ext extends Library {

        Kernel32Ext INSTANCE = Native.load("kernel32", Kernel32Ext.class, W32APIOptions.DEFAULT_OPTIONS);

        Pointer LoadLibraryW(WString lpFileName);
        Pointer GetProcAddress(Pointer hModule, String lpProcName);
        Pointer GetProcAddress(Pointer hModule, Pointer ordinal);
    }
    public static void main(String[] args) {
        Pointer hDll = Kernel32Ext.INSTANCE.LoadLibraryW(new WString("test-mutex.dll"));

        if (hDll == null) {
            int err = Native.getLastError();
            throw new IllegalStateException("LoadLibraryExW failed: " + err);
        }

        System.out.println("DLL loaded with handle: " + hDll);

        Pointer ordinalPtr = Pointer.createConstant(1);
        //Pointer fnPtr = Kernel32Ext.INSTANCE.GetProcAddress(hDll, ordinalPtr);
        Pointer fnPtr = Kernel32Ext.INSTANCE.GetProcAddress(hDll, "test");
        if (fnPtr == null) {
            throw new IllegalStateException("GetProcAddress failed, error: " + Native.getLastError());
        } else {
            Function f = Function.getFunction(fnPtr, Function.C_CONVENTION);
            f.invoke(null);
        }

    }
}

If I use the version of GetProcAddress that passes the function name, I get an error 127 (ERROR_PROC_NOT_FOUND), but if I use the ordinal instead, I can retrieve the function address and execute it.

I've checked several trivial error sources using tools like the Dependencies program, dumpbin, and PE-bear, without finding any problems with the DLL. I've written a small C++ program that uses the same instructions as the Java program:

#include <windows.h>
#include <iostream>
#include <string>

int main(int argc, char* argv[]) {
    std::cout << "[TEST] Loading DLL..." << std::endl;

    HMODULE hDll = LoadLibraryExW(L"test-mutex.dll", NULL, 0);
    if (!hDll) {
        std::cerr << "[TEST] LoadLibrary failed" << std::endl;
        return -1;
    }

    typedef BOOL(__cdecl* TestFunc)();
    TestFunc test = (TestFunc)GetProcAddress(hDll, "test");

    if (!test) {
        std::cerr << "[TEST] GetProcAddress failed: "  << GetLastError() << std::endl;
        return -2;
    }

    else {

        std::cout << "[TEST] Calling test()..." << std::endl;
        BOOL result = test();
        std::cout << "[TEST] Result: " << result << std::endl;

    }

    return 0;
}

and I haven't encountered any problems with the same DLL. Incidentally, the mutex instruction crashes in Java, but not in C++, but that's another topic. But, if anyone has an explanation for this, it would be welcome. 

Does anyone know why the name resolution problem occurs? I also tried declaring GetProcAddress as:

Pointer GetProcAddress(Pointer hModule, byte[] lpProcName)

and calling it with 

fnPtr = Kernel32Ext.INSTANCE.GetProcAddress(hDll, "test".getBytes(StandardCharsets.ISO_8859_1))

but sometimes it works for the first function, but if I have other functions, it no longer works.

Thanks for any helpful hints.

Ocean

[L Will Ahonen]

My crystal ball says your mutex crash is this mutex issue

You can solve it with a simple preprocessor define.

Did you try null-terminating your function name, so ”hello\0”.getbytes(ascii)

[Matthias Bläsing]

Hi,

If this is not just "I want to learn" code, this is awfully hard and can be simplified to:

import com.sun.jna.Function;

import com.sun.jna.NativeLibrary;

public class Probe {

    public static void main(String[] args) {

        NativeLibrary hDll = NativeLibrary.getInstance("test-mutex.dll");

        Function f = hDll.getFunction("test", Function.C_CONVENTION);

        f.invoke(null);

    }

}

and I haven't encountered any problems with the same DLL. Incidentally, the mutex instruction crashes in Java, but not in C++, but that's another topic. But, if anyone has an explanation for this, it would be welcome. 

Will hinted the problem solution, try to run with the Microsoft JDK. @work we saw crashes in the ONNXRuntime, which occured on Amazon Corretto, but was fixed on the MS JDK. I suspect that MS bundles a newer C++ runtime.

Does anyone know why the name resolution problem occurs? I also tried declaring GetProcAddress as:

Pointer GetProcAddress(Pointer hModule, byte[] lpProcName)

and calling it with 

fnPtr = Kernel32Ext.INSTANCE.GetProcAddress(hDll, "test".getBytes(StandardCharsets.ISO_8859_1))

but sometimes it works for the first function, but if I have other functions, it no longer works.

This is the correct binding. W32APIOptions implies a mapping of java string to native wchar[]. That is right for most of the windows api, but not here.

As Will also already pointed out, you are missing the NULL terminator for the string. Have a look at Native#toByteArray.

Greetings

Matthias

[Ocean Breath]

Thanks for the helpful tips. Yes, I tried using the directive you mentioned, and it does indeed solve this specific problem. Adding the termination, however, solves the problem of functions not being found.