Following a slight error in hitting the return key instead of the delete
key, I accidently tried to save a file over it self by using UnixFS. I
was meaning to transfer the file from my RiscBSD partition to RISC OS
but ended up truncating the file on the RiscBSD partition to zero
length.

The directory was rwxrwxrwx and the file was r--r--r--, so when UnixFS
tried to write the file, the directory permission test allowed writing
by UnixFS, but the file permission test didn't. UnixFS popped up an
error box, but in the mean-time had truncated the file to zero bytes :-(

I would claim that this is a bug in UnixFS.

regards,
Pete