I'm writing a DLL in D which will be loaded (not automatically, but by LoadLibrary) by a C application (the Lua interpreter). I'm having problems with globals and static data. Everything is fine if I only access stuff on the stack, but as soon as I access a global or a static class variable, either the program crashes or if I am still in DllMain, the LoadLibrary function will fail and GetLastError will indicate an error with the message "Invalid access to memory location.".

I'll work on reproducing it in a smaller scale, but does anyone know how to fix it?

In case it is helpful info, in DllMain under the DLL_PROCESS_ATTACH case, I am just calling Runtime.initialize; even though the sample calls gc_init, _minit, _moduleCtor, and runModuleUnitTests.

Sounds like you might be running into this: http://d.puremagic.com/issues/show_bug.cgi?id=3342

On Thu, 24 Dec 2009 12:49:42 -0500, Richard Webb <webby@beardmouse.org.uk> wrote:

> Sounds like you might be running into this:
> http://d.puremagic.com/issues/show_bug.cgi?id=3342

Thanks for the link. That is probably my problem since I'm running Windows XP.

Phil

On Thu, 24 Dec 2009 10:49:01 -0500, Phil Deets <pjdeets2@gmail.com> wrote:

> I'll work on reproducing it in a smaller scale

Reduced test case:

test.c (compiled with Visual C++ 2008 Express Edition)

// Adapted from sample code at http://msdn.microsoft.com/en-us/library/ms680582(VS.85).aspx
#include <windows.h>
#include <strsafe.h>

void main()
{
	if(!LoadLibraryA("d.dll"))
	{
		LPVOID lpMsgBuf;
		DWORD dw = GetLastError();
		FormatMessageA(
			FORMAT_MESSAGE_ALLOCATE_BUFFER |
			FORMAT_MESSAGE_FROM_SYSTEM |
			FORMAT_MESSAGE_IGNORE_INSERTS,
			NULL,
			dw,
			MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
			(LPSTR) &lpMsgBuf,
			0, NULL );
		printf("LoadLibrary failed with error %d: %s\n", dw, lpMsgBuf);
		LocalFree(lpMsgBuf);
	}
}

dll.d:

import std.c.windows.windows;
int x;
extern (Windows) BOOL DllMain(HINSTANCE, ULONG, LPVOID) {
	x=0;
	return true;
}

dll.def:

LIBRARY         "d.dll"
EXETYPE         NT
SUBSYSTEM       WINDOWS
CODE            SHARED EXECUTE
DATA            WRITE

Compiled with:

dmd dll.d dll.def -ofd.dll

When I run the C app, I get the output "LoadLibrary failed with error 998: Invalid access to memory location."

On Thu, 24 Dec 2009 13:10:14 -0500, Phil Deets <pjdeets2@gmail.com> wrote:

> On Thu, 24 Dec 2009 12:49:42 -0500, Richard Webb <webby@beardmouse.org.uk> wrote:
>
>> Sounds like you might be running into this:
>> http://d.puremagic.com/issues/show_bug.cgi?id=3342
>
> Thanks for the link. That is probably my problem since I'm running Windows XP.
>
> Phil

I'm quite confident now that this is the issue. I added my vote to the bug. Does anybody know how much the runtime uses TLS? I'm thinking about the possibility of adding __gshared to all its static data.

An alternative workaround would be to install Vista or 7, but although I do have a legal Vista install disk, I would prefer an upgrade since I don't want to reinstall all my programs. Also, my computer barely meets Vista's minimum requirements.

I also might be able to rewrite lua.exe in D and preload my code in the executable. Most of Lua's functionality is in a library which would not need to be rewritten so this might be feasible.

Phil Deets wrote:
> On Thu, 24 Dec 2009 13:10:14 -0500, Phil Deets <pjdeets2@gmail.com> wrote:
> 
>> On Thu, 24 Dec 2009 12:49:42 -0500, Richard Webb <webby@beardmouse.org.uk> wrote:
>>
>>> Sounds like you might be running into this:
>>> http://d.puremagic.com/issues/show_bug.cgi?id=3342
>>
>> Thanks for the link. That is probably my problem since I'm running Windows XP.
>>
>> Phil
> 
> I'm quite confident now that this is the issue. I added my vote to the bug.

Yes, it's the most serious bug in Bugzilla. (It's quite appalling that such a terrible bug has existed in Windows for so long). I wish we had a solution to this. I guess we could replace all uses of implicit TLS with a Windows function call -- it'd be slow, but it ought to work.


 Does anybody know how much the runtime uses TLS? I'm thinking about
> the possibility of adding __gshared to all its static data.
> 
> An alternative workaround would be to install Vista or 7, but although I do have a legal Vista install disk, I would prefer an upgrade since I don't want to reinstall all my programs. Also, my computer barely meets Vista's minimum requirements.


> 
> I also might be able to rewrite lua.exe in D and preload my code in the executable. Most of Lua's functionality is in a library which would not need to be rewritten so this might be feasible.