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SubjectRe: Getting IOCTL's into VFS File System Drivers (H. Peter Anvin)  wrote on 14.11.99 in <80mucc$172$>:

> Followup to: <>
> By author: (Kai Henningsen)
> In newsgroup:
> >
> > > Obviously modeled after v7, but _what_ a mess had they slapped onto
> > > the upper half for CP/M emulation... Scary. It almost looked like a
> > > small subset of UNIX placed on a box with rather shitty IO and buried
> > > under the heaploads of CP/M compatibility crap. They might start with
> > > CP/M clone, but 3.x internals looked rather like a castrated and
> > > mutilated Xenix.
> >
> > That was true since 2.x, actually, and what they mutilated was Xenix. It
> > was officially called "Xenix compatibility".
> >
> > There is a persistent rumour that the "\" thing was because one of the
> > developers simply got things wrong by accident.
> >
> And it is also obviously bull.

I always suspected that, but it's hard to be sure - the guy was even
named, but I forget who it was.

>DOS 1.x (which was a pure CP/M clone)
> used / as the option character, so for compatibility they couldn't use
> it for paths... *especially* since DOS made it legal to type the
> option immediately adjacent to a pathname (COPY FOO BAR/V). DOS 2.x
> actually had an option to use - as the option character, which made it

Actually, any character you wanted. I think the syscall for this got
mangled into unusability around DOS 6, and COMMAND.COM stopped using it
after 3.x.

> possible to use / as a pathname separator.

... in COMMAND.COM. You could always use it in the syscalls.

>DOS 2.x also had a kernel
> option to only recognize devices if the path was prepended with \DEV\
> (or /DEV/), instead of polluting the namespace of every single
> directory. I believe OS/2 actually used this.

I saw the code for this in 3.x, but I think I couldn't figure out how to
activate it.

DOS contains a heap of dead code. From looking at the Caldera-M$ suit,
Windoze is even worse.

> To this day, every version of DOS 2.0 and later allows you to use / as
> the pathname separator in system calls -- but most utilities will see
> it as an option marker.)

It's legal in all versions of Windoze, too. Also was legal in OS/2, IIRC.

I remember when OS/2 2.0 came out, all people talking about those illegal
filenames "EA DATA.something" that CHKDSK wouldn't remove. Well, duh -
those were perfectly legal FAT filenames, and always had been. You just
couldn't access them with the COMMAND.COM command line parser. (And you
could remove them the same way the FAQs say about Unix filenames with
weird characters.)

MfG Kai

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