Re: UTF-8 practically vs. theoretically in the VFS API

Linus Torvalds
2004-02-18T03:14:02Z

On Wed, 18 Feb 2004, H. Peter Anvin wrote:
>
> Those of us who have been involved with the issue have fought
> *extremely* hard against DWIM decoders which try to decode the latter
> sequences into ".." -- it's incorrect, and a security hazard. The
> only acceptable decodings is to throw an error, or use an out-of-band
> encoding mechanism to denote "bad bytecode."

Somebody correctly pointed out that you do not need any out-of-band
encoding mechanism - the very fact that it's an invalid sequence is in
itself a perfectly fine flag. No out-of-band signalling required.

The only thing you should make sure of is to not try to normalize it (that
would hide the error). Just keep carrying the bad sequence along, and
everybody is happy. Including the filesystem functions that get the "bad"
name and match it exactly to what it should be matched against.

Linus