| Новости | Поиск | FAQ | Статьи | Книги | Новости VCL | | Форумы ЧАТ | Орешник | KOL и MCK |
Форумы -» Основная («Начинающим»)/ Базы / WinAPI / Компоненты / Сети / Media / Игры / Corba и COM / KOL / FreePascal / .Net / Прочее / RSDN.ORG

	« предыдущая ветвь | форум | следующая ветвь »

urgent: kol+freelibrary - access violation [Delphi]

Riton ©   (2005-09-07 19:06:00) 

Hello,

I used the Demo "DemoVCL2KOLDLL" (kol website : downloads > demos > ModalVCL2KOLDLL) and tried to modify it so that the dll becomes dynamic.

I encountered a problem by using Freelibrary !
When I quit the application "VCLProject1.exe", the error message which occurs is :
Access Violation at the address 00AF3DD8. Read of address 00AF3DD8.
What happens ?

Here is the code with the modifications in VCLUnit.pas :

unit VCLUnit1;

interface

uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls;

type
TForm1 = class(TForm)
  Button1: TButton;
  procedure Button1Click(Sender: TObject);
private
  { Private declarations }
public
  { Public declarations }
end;

var
Form1: TForm1;

implementation

//procedure CallKOLFormModal; external 'KOLDll.dll' name 'CallKOLFormModal';
var
CallKOLFormModal: procedure;
dll:thandle;

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
begin
//  CallKOLFormModal;
dll:=loadlibrary('KOLDLL.dll');
CallKOLFormModal:=GetProcAddress(dll,'CallKOLFormModal');
CallKOLFormModal;
Freelibrary(dll);//if I use freelibrary, problem is "Access Violation"!
end;

end.

Thank you very much for resolving this problem.
Riton.

---

Riton   (2005-09-09 18:34:00) [1]

Alas, it doesn't work.

- On the one hand there is a type compatibility problem with the following code :
if CallKOLFormModal <> 0 then CallKOLFormModal;

- On the other hand, if I suppress this code, I find again the access violation error :
Access Violation at the address 00AF3DD8. Read of address 00AF3DD8.

Sorry that your code doesn't work.

If you want or have time to, I can send a zip file to you where the modifications are brought by me.

Riton.

---

Thaddy   (2005-09-08 20:36:00) [2]

Yes. Or an example if you don't need it after it was modal and to save resources:

procedure TForm1.Button1Click(Sender: TObject);
var dll:THandle;
begin
//  CallKOLFormModal;

 dll:=loadlibrary('KOLDLL.dll');
 if dll <> 0 {or really >=32 i think, no win32.hlp on my GSM ;) } then
 begin
   CallKOLFormModal:=GetProcAddress(dll,'CallKOLFormModal');
   if CallKOLFormModal <> 0 then CallKOLFormModal;
   Freelibrary(dll);
 end;
end;



---

Riton   (2005-09-08 19:52:00) [3]

Thanks very much for your help Wiz@rd and Thaddy.

Maybe a solution ?
The dll is unloaded when application is destroying.

There is anyway no more error with this procedure. I hope that it is a good way to solve the problem with freelibrary.

procedure TForm1.Form1Destroy(Sender: TObject);
begin
Freelibrary(dll);
end;

---

Thaddy   (2005-09-08 16:07:00) [4]

If you have the error address, why do you not use the debugger?
The example as such does not contain erronious code.
Strategy one:
Check if the library is still loaded!
Check the call stack!

Strategy two:
Steps:
1. write down error address.
2. press F7 to start debugging session (step through mode)
3. press alt+G and enter address.

Look where it jumps to.

If this doesn't work, compile in full debug mode and repeat the above.

I am afraid you will not get any serious answer here before you properly debug your code yourself.

---

Wiz@rd   (2005-09-07 23:59:00) [5]

Try use Freelibrary on program terminating

---

Наверх