Kernel Hacks & Weird Filenames

[Naim Abdullah]

As the person who started this unprintable filenames discussion
by asking why BSD disallows certain file names, let me say
what my *fundamental* objection to this business of "protecting"
the user is.

I think the most wonderful thing about UNIX is it's generality
and elegance. Sadly, people who don't appreciate that, add
gratuitous options to cat(1) and ls(1), and now (horrors!)
make proposals that unprintable filenames be disallowed.

To understand the UNIX philosophy, we must go back to the original
source. The following is from the paper, "UNIX Implementation"
by Ken Thompson:

>The kernel is the only UNIX code that cannot be substituted
>by a user to his own liking. For this reason, the kernel
>should make as few real decisions as possible. This does not 
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Important point!
>mean to allow the user a million options to do the same thing.
>Rather, it means to allow only one way to do one thing, but have
>that way be the least-common divisor of all the options that
>might have been provided.
>
>What is or is not implemented in the kernel represents both
>a great responsibility and a great power. It is a soap-box
>platform on "the way things should be done." Even so, if
>"the way" is too radical, no one will follow it. Every
>important decision was weighed carefully. Throughout, simplicity
>has been substitued for efficiency. Complex algorithms are used
>only if their complexity can be localized.
>

I think the proposal that unprintable filenames be disallowed by the
kernel follows from a VMS/IBM mentality. Sorry to be so harsh, but
it totally goes against the whole spirit of UNIX.

If you want to protect naive users from unprintable filenames, then
by all means write a special shell or relink your utilities with
a special version of the C library, but don't put that decision
in the kernel.

The kernel should allow very general things. It is all the crap
above it, that should "protect" the user. This is because, you
and I differ whether this "protection" is needed or not. You
can have all the "protection" you want, but don't force it
on me!

This is why I am disappointed that 4.3BSD disallows filenames
with the high bit set. I am glad that SunOS 4.0 lifts this
restriction. Guy mentioned that the reason for this is to support
other languages. I think the reason should have been simply because
of generality/elegance or because it is The Right Thing.

Does anybody know whether V9 or 4.3-tahoe allow arbitrary bytes
in filename (excepting ofcourse, '\0' and '/') ?

		      Naim Abdullah
		      Dept. of EECS,
		      Northwestern University

		      Internet: naim at eecs.nwu.edu
		      Uucp: {ihnp4, chinet, gargoyle}!nucsrl!naim