RFC: Illegal Characters in File Names

[Joseph Wagner <theman@josephdwagner.info>]

IMHO, e2fsck is not sufficiently aggressive in examining a file name for 
illegal characters. While it is possible to place non-printing control 
characters in a file name, few (if any) programs support opening a file 
with control characters in the file name.  In fact, 'rm' doesn't even 
support control characters.  To remove such a file, one must substitute a
wildcard character and run rm interactively (i.e. 'rm -i').

Some of us in the e2fsprogs project are considering a change which would 
mark all non-printing control characters (i.e. ASCII <=31 and ASCII == 127) 
as illegal.

I decided not to flag characters > ASCII 127 as illegal in case some day in 
the future the encoding changes to UTF-8, in which case valid printing 
non-control characters exist > 127.  On the flip side, ASCII and UTF-8 are 
100% compatible when <= 127, so the changes I did make will be fine with 
both.

Can anyone suggest a good reason not to good forward with this?

If it is OK to go forward, should the kernel be changed to disallow a file 
name from having these same non-printing control characters?

Joseph D. Wagner