How to open file with exclusive lock?

[Charles Hixson via Digitalmars-d-learn]

I want to open a file with an exclusive lock.  It would be important 
that no other thread be able to access the file in write mode, and 
desirable that no other thread be able to access the file in read mode.  
(Ditto for other processes.)

stdio.file.lock (or is it stdio.file.File.lock?) seems to demand a range 
of chunks to lock, but the file is not fixed in length. Is it 
appropriate to just specify the maximum possible number of bytes (i.e. 
ulong.max)?