TComboBox patch for Delphi 7

unit D7ComboBoxStringsGetPatch;



 



// The patch fixes TCustomComboBoxStrings.Get method for empty string item in Delphi 7.



 



interface



 



{$IF RTLVersion <> 15.0}



'This patch is intended for Delphi 7 only';



{$IFEND}



 



implementation



 



uses



  Windows, SysUtils, StdCtrls;



 



resourcestring



  RsPatchingFailed = 'TCustomComboBoxStrings.Get patching failed.';



 



type



  TPatchResult = (prNotNeeded, prOk, prError);



 



function PatchCode(RoutineStartAddr: Pointer; PatchOffset: Cardinal; OriginalCode: Pointer;



  OriginalCodeLen: Cardinal; PatchedCode: Pointer; PatchedCodeLen: Cardinal): TPatchResult;



const



  JmpOpCode = $25FF;



type



  PPackageThunk = ^TPackageThunk;



  TPackageThunk = packed record



    JmpInstruction: Word;



    JmpAddress: PPointer;



  end;



var



  CodeStart: Pointer;



  BytesWritten: DWORD;



begin



  if FindClassHInstance(System.TObject) <> HInstance then



    with PPackageThunk(RoutineStartAddr)^ do



      if JmpInstruction = JmpOpCode then



        RoutineStartAddr := JmpAddress^



      else



      begin



        Result := prError;



        Exit;



      end;



  CodeStart := Pointer(LongWord(RoutineStartAddr) + PatchOffset);



  if CompareMem(CodeStart, OriginalCode, OriginalCodeLen) then



  begin



    if WriteProcessMemory(GetCurrentProcess, CodeStart, PatchedCode, PatchedCodeLen, BytesWritten) and



      (BytesWritten = PatchedCodeLen) then



    begin



      FlushInstructionCache(GetCurrentProcess, CodeStart, PatchedCodeLen);



      Result := prOk;



    end



    else



      Result := prError;



  end



  else



    Result := prNotNeeded;



end;



 



type



  TCustomComboBoxStringsHack = class(TCustomComboBoxStrings);



 



function AddrOfTCustomComboBoxStringsGet: Pointer;



begin



  Result := @TCustomComboBoxStringsHack.Get;



end;



 



procedure PatchTCustomComboBoxStringsGet;



const



  OriginalCode: Cardinal  = $74FFF883; // CMP EAX, -1 | JZ  +$26



  PatchedCode: Cardinal   = $7E00F883; // CMP EAX,  0 | JLE +$26



  PatchOffset             = $1F;



  // for DEBUG DCU by Pavel Rogulin



  OriginalCodeD: Cardinal = $FFF07D83;



  PatchedCodeD: Cardinal  = $00F07D83;



  PatchOffsetD            = $2E;



var



  PatchResult: TPatchResult;



begin



  PatchResult := PatchCode(AddrOfTCustomComboBoxStringsGet, PatchOffset, @OriginalCode, SizeOf(OriginalCode),



    @PatchedCode, SizeOf(PatchedCode));



  if PatchResult = prNotNeeded then



    PatchResult := PatchCode(AddrOfTCustomComboBoxStringsGet, PatchOffsetD, @OriginalCodeD, SizeOf(OriginalCodeD),



      @PatchedCodeD, SizeOf(PatchedCodeD));



  case PatchResult of



    prError:



      begin



        if IsConsole then



          WriteLn(ErrOutput, RsPatchingFailed)



        else



          MessageBox(0, PChar(RsPatchingFailed), nil, MB_OK or MB_ICONSTOP or MB_TASKMODAL);



        RunError(1);



      end;



  end;



end;



 



initialization



  PatchTCustomComboBoxStringsGet;



 



end.

 

官方BUG解决地址:

http://cc.embarcadero.com/item/18872