More explanation on the writing to files with inheritance part

Hans Reiser (reiser@ceic.com)
Wed, 30 Jun 1999 23:51:46 +0000 (/etc/localtime)


The problem is that when you write to a file that inherits other files,
you have to decide what bytes go into what inherited files. Easy if the
length of the file has not changed. Hard if it has changed. Hard that
is until rms walked with me to dinner, and he suggested using
delimiters. Doesn't matter what syntax, and actually he said the syntax
should be configurable. Notice how this means that emacs needs no
changes at all to effectively edit these anti-streams. Then
loic@ceic.com said that rdf (http://www.w3.org/RDF/) was a good syntax.
I trust that loic@ceic.com is right, he's pretty sharp, I haven't
reviewed rdf. If not, then we can invent a syntax....

So, basically, a filter that reads and writes to directories on one
side, answers reads and writes to a delimitered flat file at the other
end should implement it fairly well for us. I expect that the first
filter will be rdf syntax, and who knows after that.

No, I don't care whether the filter is in user space or the kernel, user
space or kernel, it's all part of the file system.

Hans

Wesley Terpstra writes:
> > > Why do we need the glob ability? If there is an efficient FS for the
> > > overhead problem, why not just use the FS as is and have the user use tar?
> >
> > If /etc/passwd is a directory of one line files, it could be useful to
> > edit the /etc/passwd directory in one emacs buffer.
>
> Ok, but I think my magic number suggestion would be able to handle that.
> The file you edit would just have the # at the top of the file and when
> you wrote it back it would again be a dir/file thing.
>
> > > Have some semi-portable flag on the tarballish file that identifies it as
> > > a dir/file thing. Then whenever a tarballish thing this is copied to an fs
> > > that supports your extension, untar it to a file/dir thing transparently.
> > > When you open the file/dir thing as a file, return a tarballish thing with
> > > the semi-portable flag. The flag could be anything - perhaps a magic
> > > number as the first few bytes.
> > >
> > I think it needs to be the reverse, it is a file/dir in my filesystem,
> > and a tarballish thing elsewhere.
> That's what I meant.
>
> ---
> E-mail: terpstra@interchange.ubc.ca Host: iota.dhs.org
> Phone #: 1-604-221-8018, voice-mail: 1-604-221-8087

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