Launch Windows Optimize application (Windows 10) from Delphi

Question

We have a legacy Delphi 7 application that launches the Windows Defrag and On-screen Keyboard applications as follows:

// Defragmentation application
ShellExecute(0, 'open', PChar('C:\Windows\System32\dfrg.msc'), nil, nil, SW_SHOWNORMAL);

// On-screen keyboard
ShellExecute(0, 'open', PChar('C:\Windows\System32\osk.exe'), nil, nil, SW_SHOWNORMAL);

Both work on Windows XP but fail on Windows 10. I spotted that the defragmentation application has had a name change to dfrgui.exe, but updating the code does not help. The On-screen Keyboard is still called osk.exe on Windows 10.

Both applications can be launched manually / directly from the command line or by double-clicking them in Windows Explorer.

My suspicion is that Windows security is preventing my application from launching anything from C:\Windows\System32, because I can launch several other applications from Program Files and from C:\Windows.

Can anyone help?

Answer 1

Delphi 7 produces only 32-bit apps, there is no option to produce 64-bit apps (that was added in XE2).

Accessing a path under %WINDIR%\System32 from a 32-bit app running on a 64-bit system is subject to WOW64's File System Redirector, which will silently redirect requests for the 64-bit System32 folder to the 32-bit SysWOW64 folder instead.

Chances are, the apps you are trying to run only exist in the 64-bit System32 folder and not in the 32-bit SysWOW64 folder.

To avoid redirection, you need to either:

• replace System32 with the special Sysnative alias in your paths (ie 'C:\Windows\Sysnative\osk.exe'), which only works when running under WOW64, so you have to detect that dynamically at runtime via IsWow64Process():

  function GetSystem32Folder: string;
  var
    Folder: array[0..MAX_PATH] of Char;
    IsWow64: BOOL;
  begin
    Result := '';
    if IsWow64Process(GetCurrentProcess(), @IsWow64) and IsWow64 then
    begin
      SetString(Result, Folder, GetWindowsDirectory(Folder, Length(Folder)));
      if Result <> '' then
        Result := IncludeTrailingPathDelimiter(Result) + 'Sysnative' + PathDelim;
    end else
    begin
      SetString(Result, Folder, GetSystemDirectory(Folder, Length(Folder)));
      if Result <> '' then
        Result := IncludeTrailingPathDelimiter(Result);
    end;
  end;
  
  function RunDefrag: Boolean;
  var
    SysFolder: string;
    Res: Integer;
  begin
    SysFolder := GetSystem32Folder;
    Res := Integer(ShellExecute(0, nil, PChar(SysFolder + 'dfrgui.exe'), nil, nil, SW_SHOWNORMAL));
    if Res = ERROR_FILE_NOT_FOUND then
      Res := Integer(ShellExecute(0, nil, PChar(SysFolder + 'dfrg.msc'), nil, nil, SW_SHOWNORMAL));
    Result := (Res = 0);
  end;
  
  function RunOnScreenKeyboard: Boolean;
  begin
    Result := (ShellExecute(0, nil, PChar(GetSystem32Folder + 'osk.exe'), nil, nil, SW_SHOWNORMAL) = 0);
  end;
  

• temporarily disable the Redirector via Wow64DisableWow64FsRedirection(), and then re-enable it via Wow64RevertWow64FsRedirection() when done:

  function GetSystem32Folder: string
  var
    Folder: array[0..MAX_PATH] of Char;
  begin
    SetString(Result, Folder, GetSystemDirectory(Folder, Length(Folder)));
    if Result <> '' then
      Result := IncludeTrailingPathDelimiter(Result);
  end;
  
  function RunDefrag: Boolean;
  var
    SysFolder: string;
    OldState: Pointer;
    Res: Integer;
  begin    
    Wow64DisableWow64FsRedirection(@OldState);
    try
      SysFolder := GetSystem32Folder;
      Res := Integer(ShellExecute(0, nil, PChar(SysFolder + 'dfrgui.exe'), nil, nil, SW_SHOWNORMAL));
      if Res = ERROR_FILE_NOT_FOUND then
        Res := Integer(ShellExecute(0, nil, PChar(SysFolder + 'dfrg.msc'), nil, nil, SW_SHOWNORMAL));
      Result := Res = 0;
    finally
      Wow64RevertWow64FsRedirection(OldState);
    end;
  end;
  
  function RunOnScreenKeyboard: Boolean;
  var
    OldState: Pointer;
  begin
    Wow64DisableWow64FsRedirection(@OldState);
    try
      Result := (ShellExecute(0, nil, PChar(GetSystem32Folder + 'osk.exe'), nil, nil, SW_SHOWNORMAL) = 0);
    finally
      Wow64RevertWow64FsRedirection(OldState);
    end;
  end;
  

Update: that being said, it turns out that a 32-bit process running under WOW64 is not allowed to run osk.exe when UAC is enabled:

Delphi - On Screen Keyboard (osk.exe) works on Win32 but fails on Win64

So, you will have to create a helper 64-bit process to launch osk.exe on your app's behalf when it is running under WOW64.