SHGetFolderPath doesn't work for me - delphi

Question

I have this function:
function GetProfilePath: string;
const
SHGFP_TYPE_CURRENT = 0;
var
hToken: THandle;
ProfilePath: packed array[ 0..MAX_PATH ] of Char;
begin
ZeroMemory(#ProfilePath[0], SizeOf(ProfilePath));
OpenProcessToken( GetCurrentProcess, TOKEN_QUERY, hToken );
SHGetFolderPath( 0, CSIDL_APPDATA, hToken , SHGFP_TYPE_CURRENT, #ProfilePath[ 0 ] );
CloseHandle( hToken );
Result := ProfilePath;
end;
SHGetFolderPath returns E_FAIL (0x80004005) and an empty ProfilePath buffer. MSDN says that E_FAIL means "The CSIDL in nFolder is valid, but the folder does not exist". But the folder does exist, I'm pretty sure. When I'm creating a simple test application and running the same code, it works well.
What might be wrong with that?
update:
I found that my application doesn't work well when running under Delphi. When I run it separately, all is OK.
Thanks,
Roman

Answer 1

The use of a user token looks needlessly complex. But, having said that, when I ran your code on my machine it worked fine with no error. Perhaps the user token for your process doesn't have sufficient rights to that folder. Or perhaps the folder really does not exist!
For what it's worth I think you would be better off using the simpler off API SHGetSpecialFolderPath. My wrapper for that looks like this:
function GetSpecialFolderPath(const CSIDL: Integer): string;
var
Buffer: TWin32PathBuffer;
begin
if SHGetSpecialFolderPath(Application.Handle, #Buffer[0], CSIDL, False) then begin
Result := Buffer;
end else begin
RaiseLastOSError;
end;
end;
Of course, this may fail in just the same way as your version if the folder really does not exist.
OK, I've just re-read this comment in your question:
When I'm creating a simple test application and running the same code, it works well.
That sounds like you are running the real code in a different context. Perhaps in a service? Or with user impersonation. Maybe that's the clue to solving this. What are you not telling us about the environment/context/setting where the code fails?
And some very minor comments on your code. You've defined ProfilePath with one more element than needed, and packed is superfluous for an array:
ProfilePath: array[ 0..MAX_PATH-1 ] of Char;
Or, even better, re-use the type defined in the Delphi RTL, TWin32PathBuffer.