Re: So Delphi can't do this ...

From: Brian Cook (bcook_at_rowdydogsoftware[REMOVE)
Date: 10/12/03 

Date: Sun, 12 Oct 2003 12:31:36 -0500

> The only thing that I can't figure out is that the structure is actually a
> container to accept values from the calling app.
> It's an import structure that receives a function ID and pointer.
> Your example is setting the values not receiving the values.
> How do I go about receiving values?

The page where ImpStruct is located needs to be change to allow writing.
The new example is below my signature.

> > It does assuming the record alignment is correct; which is VERY likely.
> All the data is double word aligned - the code has a #pragma pack(4) before
> all the declarations.

Then you're good-to-go.

- Brian

library Project1;

uses
  Windows, SysUtils;

{$R *.res}

function SomeFunction: Integer;
begin
  Result := 1313;
end;

{
type
  TImpStruct = record
    fnID: Integer;
    fnPtr: Pointer;
  end;
}
procedure ImpStructPre;
asm
end;

procedure ImpStruct;
asm
  dd 13 // This is fnID
  dd SomeFunction // This is fnPtr
end;

procedure ImpStructPost;
asm
end;

exports
  ImpStruct;

procedure MakeImpStructReadWrite;
var
  Junk: DWORD;
begin
  VirtualProtect(
      @ImpStructPre,
      Cardinal(@ImpStructPost) - Cardinal(@ImpStructPre),
      PAGE_EXECUTE_WRITECOPY, Junk );
end;

begin
  MakeImpStructReadWrite;
end.