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.