Btukfyl

I have the following 32bit Delphi project source:

program TestApp;



uses

  SysUtils, Dialogs, Windows;



var

  filename: String = 'C:Program Files (x86)Some Applicationfoo.txt';

  fd: TWIN32FindData;

  h: THandle;



begin

  FillChar(fd, SizeOf(fd), 0);

  h := FindFirstFile(PChar(filename), fd);

  if h = INVALID_HANDLE_VALUE then

    ShowMessage('FindFirstFile=false')

  else

  begin

    ShowMessage('FindFirstFile=true');

    FindClose(h);

  end;



  if FileExists(filename) then

    ShowMessage('FileExists=true')

  else

    ShowMessage('FileExists=false');

end.

When I run it, both the Windows API FindFirst call and the FileExists call return True, even though the file does not exist in that directory.

Why is it claiming a file is there when it is not?

The file exists in the VirtualStore directory located in

C:Users{username}AppDataLocalVirtualStoreProgram Files (x86)

This is a feature called UAC Virtualization first introduced in Windows Vista. It allows applications to write to restricted directories that they otherwise have no permissions to. When a 32 bit application with UAC Virtualization enabled writes to the real directory and would receive an access denied result, Windows instead creates a copy of the file in the VirtualStore .

When this application or another 32 bit application with UAC Virtualization enabled tries to read from the file, it will first check the VirtualStore for the file. You can see that UAC Virtualization is Enabled by adding this column in Task Manager.

This happens in a Delphi program when you remove the {$R *.res} directive. If you change the project source to add the {$R *.res} directive back in

program TestApp;



uses

  SysUtils, Dialogs, Windows;



{$R *.res}



var

  filename: String = 'C:Program Files (x86)Some Applicationfoo.txt';

  fd: TWIN32FindData;

  h: THandle;



begin

  FillChar(fd, SizeOf(fd), 0);

  h := FindFirstFile(PChar(filename), fd);

  if h = INVALID_HANDLE_VALUE then

    ShowMessage('FindFirstFile=false')

  else

  begin

    ShowMessage('FindFirstFile=true');

    FindClose(h);

  end;



  if FileExists(filename) then

    ShowMessage('FileExists=true')

  else

    ShowMessage('FileExists=false');

end.

it will recognize your app as having UAC Virtualization disabled (as is the norm for most applications). You can see that in Task Manager, and the results of the file finding operations will be what you expect.

The reason why leaving out the .RES file causes this is that it includes a manifest. The following line in this manifest disables UAC Virtualization:

<requestedExecutionLevel level="asInvoker" uiAccess="false"/>

When level is omitted, UAC Virtualization is enabled.