Can't detect network drive under Debugger with Delphi 2007 on Windows 10

Question

It is probably me being stupid, but I am having problems detecting if a network drive is up, but only when running the program in the IDE – when running the program outside of the IDE, the network drive is correctly detected. The IDE works fine on Windows 7.

While the program in question is different, I can reproduce the issue by creating a new project and adding the following into the Forms OnActivate event:

var
  bRet: Boolean;
  LTemp2: string;
  LFreeSpace: Int64;
  LTotalSpace: Int64;
begin
  LTemp2 := 'T:\';
  bRet := GetDiskFreeSpaceEx(PAnsiChar(LTemp2), @LFreeSpace, @LTotalSpace, nil);
  ShowMessage('GetDiskFreeSpaceEx: Drive T: is up? '+BoolToStr(bRet, True));
end;

Assuming I have a networked drive T:, if I run the program in the IDE then the above always returns False, but if I run the built program from a desktop shortcut then it returns True. I get the same behaviour if I run it via a button click after the program starts. Doing DiskSize() and FindFirst() on the root directory give the same results.

It is a clean Windows 10 install, not an upgrade, with a clean install of CodeGear 2007 with all the patches applied. I have tried “Run as administrator” and all the Compatibility Modes back to Windows 7.

Am I doing something stupid?

Answer 1

After R. Hoek's great insight, and while it does not fully sort out the issue, it is at least enough for a workaround. By the way, at least in my case, it does not matter if I launch Delphi 2007 with "Run as administrator" or not.

I added a TOpenDialog hooked up to a button: once I run this and select a file on T: then GetLogicalDrives() works fine.

So what I now suspect is that I installed Delphi 2007 as an administrator - not sure how, but I think I will re-install everything.

Even if that does not resolve it, and since it only occurs in the IDE and not in production usage, I can add code to pop up a TOpenDialog if GetLogicalDrives() returns 4.

Weird. Thank you all very much.

By the way, one aspect of this discussion may not have been clear: Delphi 2007 was running under the user account (and it could see the network drive without problems) - it is only the program which is being debugged that cannot see the networked drive. That is why using the TOpenDialog resolved the issue (until Delphi or the computer was restarted).