Holy cow, I wrote a book!
Earlier, I discussed the interactions of the various FILE_SHARE_* flags,
then Larry Osterman took this as
inspiration to give
history of the file sharing flags.
If a file is opened with delete-sharing enabled and you delete the file,
the file doesn't actually go away until the open handles are closed.
In the meantime, the file hangs around as a zombie.
(Under Unix, a deleted file with open handles is removed from the
directory and merely floats around in the happy sea of inodes
with no name.)
Why doesn't the file go away?
Well, one reason is that
device drivers can ask for the name of the file that corresponds
to an open handle.
If the directory entry were removed, then there would be no name
(What would you expect to be returned from GetModuleFileName if
the module no longer exists? Should it be possible for
GetModuleFileName to return ERROR_FILE_NOT_FOUND?)
Another reason is that if power were to be lost while a
"forgotten but not lost" handle was still open,
you would now have
lost clusters on the disk.
And a final reason is that a "pending delete" file isn't
actually gone for good. A driver can
"undelete" the file by clearing the delete-on-close flag!