Partition full BUG?

[Bob]

Hi.  I have looked for an answer to a question all over the net and
haven't found an answer.  Hopefully someone here can answer it.  When
modifying a file on a nearly full disk partition, if the opened file
can't contain all of the data appended to it, the whole file is
truncated to zero bytes (only the filename remains).  Is that supposed
to happen?  (The partition is /boot, the filesystem ext3, the file is
grub.conf).  It just seems like it would be better if it reported an
error like '/dev/hda1 full' and left the file intact.
   
Thanks in advance,

Bob.