I have a DLL which exports a function GetFunction. GetFunction returns a pointer to RealFunction. Now I want to run RealFunction from my D program, but for some reason I get the wrong address. Here is the code.

---- dll64.c -----
#define WIN32_LEAN_AND_MEAN
#include <windows.h>

int __stdcall RealFunction(int a)
{
    return a + 1;
}

typedef int (__stdcall *FuncPtr)(int);

FuncPtr __stdcall GetFunction()
{
    return &RealFunction;
}

---- mydll64.def ----
LIBRARY mydll64.dll
EXPORTS
GetFunction
---------------------

build with MSVC64:
cl -c dll64.c -Fomydll64.obj
link /DLL /OUT:mydll64.dll mydll64.obj /DEF:mydll64.def

And this is the D program.

---- testdll64d.d ----
// dmd -m64 -c testdll64d.d -oftestdll64d.obj
// link /OUT:testdll64d.exe testdll64d.obj

import core.runtime;
import std.c.windows.windows;
import std.stdio;

alias extern(Windows) int function(int) FuncPtr;

int main(string[] args)
{
    HMODULE dll          = LoadLibraryA("mydll64.DLL");
    FARPROC getFunction  = GetProcAddress(dll, "GetFunction");
    FuncPtr realFunction = cast(FuncPtr) getFunction();

    writefln("dll address:          %08x", dll);
    writefln("GetFunction address:  %08x", getFunction);
    writefln("RealFunction address: %08x", realFunction);
    writefln("RealFunction result:  %d",   realFunction(7));//<-- CRASH

    return 0;
}
----------------------

Output:
dll address:          180000000
GetFunction address:  180001020
RealFunction address: ffffffff80001000
<CRASH>

BTW, this works:
FuncPtr realFunction = cast(FuncPtr) (getFunction() & 0x00000000ffffffff | cast(size_t) dll);

http://dlang.org/type.html

int => signed 32 bits

but don't you need long in D

Am 14.01.2013 10:13, schrieb dnewbie:
> I have a DLL which exports a function GetFunction. GetFunction
> returns a pointer to RealFunction. Now I want to run RealFunction
> from my D program, but for some reason I get the wrong address.
> Here is the code.
>
> ---- dll64.c -----
> #define WIN32_LEAN_AND_MEAN
> #include <windows.h>
>
> int __stdcall RealFunction(int a)
> {
>       return a + 1;
> }
>
> typedef int (__stdcall *FuncPtr)(int);
>
> FuncPtr __stdcall GetFunction()
> {
>       return &RealFunction;
> }
>
> ---- mydll64.def ----
> LIBRARY mydll64.dll
> EXPORTS
> GetFunction
> ---------------------
>
> build with MSVC64:
> cl -c dll64.c -Fomydll64.obj
> link /DLL /OUT:mydll64.dll mydll64.obj /DEF:mydll64.def
>
> And this is the D program.
>
> ---- testdll64d.d ----
> // dmd -m64 -c testdll64d.d -oftestdll64d.obj
> // link /OUT:testdll64d.exe testdll64d.obj
>
> import core.runtime;
> import std.c.windows.windows;
> import std.stdio;
>
> alias extern(Windows) int function(int) FuncPtr;
>
> int main(string[] args)
> {
>       HMODULE dll          = LoadLibraryA("mydll64.DLL");
>       FARPROC getFunction  = GetProcAddress(dll, "GetFunction");
>       FuncPtr realFunction = cast(FuncPtr) getFunction();
>
>       writefln("dll address:          %08x", dll);
>       writefln("GetFunction address:  %08x", getFunction);
>       writefln("RealFunction address: %08x", realFunction);
>       writefln("RealFunction result:  %d",   realFunction(7));//<--
> CRASH
>
>       return 0;
> }
> ----------------------
>
> Output:
> dll address:          180000000
> GetFunction address:  180001020
> RealFunction address: ffffffff80001000
> <CRASH>
>
> BTW, this works:
> FuncPtr realFunction = cast(FuncPtr) (getFunction() &
> 0x00000000ffffffff | cast(size_t) dll);
>

Just ignore my post - too early in the morning :(

Am 14.01.2013 10:19, schrieb dennis luehring:
> http://dlang.org/type.html
>
> int => signed 32 bits
>
> but don't you need long in D
>
> Am 14.01.2013 10:13, schrieb dnewbie:
>> I have a DLL which exports a function GetFunction. GetFunction
>> returns a pointer to RealFunction. Now I want to run RealFunction
>> from my D program, but for some reason I get the wrong address.
>> Here is the code.
>>
>> ---- dll64.c -----
>> #define WIN32_LEAN_AND_MEAN
>> #include <windows.h>
>>
>> int __stdcall RealFunction(int a)
>> {
>>       return a + 1;
>> }
>>
>> typedef int (__stdcall *FuncPtr)(int);
>>
>> FuncPtr __stdcall GetFunction()
>> {
>>       return &RealFunction;
>> }
>>
>> ---- mydll64.def ----
>> LIBRARY mydll64.dll
>> EXPORTS
>> GetFunction
>> ---------------------
>>
>> build with MSVC64:
>> cl -c dll64.c -Fomydll64.obj
>> link /DLL /OUT:mydll64.dll mydll64.obj /DEF:mydll64.def
>>
>> And this is the D program.
>>
>> ---- testdll64d.d ----
>> // dmd -m64 -c testdll64d.d -oftestdll64d.obj
>> // link /OUT:testdll64d.exe testdll64d.obj
>>
>> import core.runtime;
>> import std.c.windows.windows;
>> import std.stdio;
>>
>> alias extern(Windows) int function(int) FuncPtr;
>>
>> int main(string[] args)
>> {
>>       HMODULE dll          = LoadLibraryA("mydll64.DLL");
>>       FARPROC getFunction  = GetProcAddress(dll, "GetFunction");
>>       FuncPtr realFunction = cast(FuncPtr) getFunction();
>>
>>       writefln("dll address:          %08x", dll);
>>       writefln("GetFunction address:  %08x", getFunction);
>>       writefln("RealFunction address: %08x", realFunction);
>>       writefln("RealFunction result:  %d",   realFunction(7));//<--
>> CRASH
>>
>>       return 0;
>> }
>> ----------------------
>>
>> Output:
>> dll address:          180000000
>> GetFunction address:  180001020
>> RealFunction address: ffffffff80001000
>> <CRASH>
>>
>> BTW, this works:
>> FuncPtr realFunction = cast(FuncPtr) (getFunction() &
>> 0x00000000ffffffff | cast(size_t) dll);
>>
>

On 1/14/13, dnewbie <run3@myopera.com> wrote:
>      FuncPtr realFunction = cast(FuncPtr) getFunction();

Make that:

FuncPtr realFunction = cast(FuncPtr) getFunction;

Don't call the FARPROC, just cast it.

The problem is FARPROC. Thank you everybody.

Solution:
import core.runtime;
import std.c.windows.windows;
import std.stdio;

alias extern(Windows) int function(int) FuncPtr;
alias extern(Windows) FuncPtr function() GetFuncPtr;

int main(string[] args)
{
	HMODULE dll            = LoadLibraryA("mydll64.DLL");
	GetFuncPtr getFunction = cast(GetFuncPtr) GetProcAddress(dll, "GetFunction");	
	FuncPtr realFunction   = cast(FuncPtr) getFunction();
	
	writefln("dll address:          %08x", dll);
	writefln("GetFunction address:  %08x", getFunction);
	writefln("RealFunction address: %08x", realFunction);
	writefln("RealFunction result:  %d",   realFunction(7));

    return 0;	
}