Title: Custom Error Handler (asm approach)
Question: Fast Error Handler
Answer:
//PUT Button1 on Form
procedure TForm1.Button1Click(Sender: TObject);
label cHandler,cResume;
var
ErrAddress:pointer;
ErrCode:cardinal;
begin
//HANDLER PROLOGUE
asm
and dword ptr [ErrAddress],0
and dword ptr [ErrCode],0
push offset cHandler
push dword ptr fs:[0]
mov dword ptr fs:[0],esp
end;
asm
cli //EXECUTE PRIVILEGED INSTRUCTION
end;
cResume: //RESUME HERE
if ErrCode0 then begin
messagebox(0,pansichar('Error Code:' + inttohex(ErrCode,1) +'h' + #13 + #10 +'At Address:' + inttohex(Cardinal(ErrAddress),1) + 'h'), pansichar('Error'),0);
end;
//HANDLER EPILOGUE
asm
pop dword ptr fs:[0]
lea esp,[esp+4]
end;
exit;
cHandler:
asm
mov eax,dword ptr [esp+12]
mov edx,ebp
mov ebp,dword ptr [eax+$b4]
mov ecx,CONTEXT[eax].eip
mov dword ptr [ErrAddress],ecx
mov ecx,dword ptr [esp+4]
push EXCEPTION_RECORD[ecx].ExceptionCode
pop dword ptr [ErrCode]
mov ebp,edx
mov CONTEXT[eax].eip,offset cResume
xor eax,eax
ret 16
end;
end;