[e-lang] Design issue: Virtualized filesystem

[Ben Laurie]

On 8 February 2011 18:02, Kevin Reid <kpreid at switchb.org> wrote:
> I've just written up a couple of design issues on the wiki:
> http://wiki.erights.org/wiki/Virtualized_privileged_environment
> http://wiki.erights.org/wiki/Opaque_file_objects
>
> I would particularly like comment on the latter, because it is a
> specific major change to the file object protocols. The text follows.
>
> -----------------------------------------------------------------------
> Problem
> -------
>
>     1.  See Virtualized privileged environment.
>
>     2.  In general, a program should not be unnecessarily aware of the
>         non-capability environment around it, in particular absolute
>         paths in the filesystem.
>
>     3.  We would like E to be compatible with actually interacting with
>          a capability filesystem.
>
> Furthermore, we want to accomplish this while still using java.io.File
> objects in E-on-Java.
>
> Proposal
> --------
>
> Currently,
>     * the file__uriGetter is uniquely the root of the filesystem and
> has
>       a distinct interface.
>
>     * every File object reveals its absolute pathname.
>
> Instead,
>     * Every directory is equally usable as a root;
>       file__uriGetter == <file:///>
>
>     * File objects cannot be asked for their pathnames; instead,
>       <file:///a>.optUnget(<file:///a/b/c>) returns "/b/c"
>       (or possibly "b/c"), much as a SturdyRef can only be converted to
>       a cap-URL using <captp>.
>
> XXX Write up exactly what the File interface would become.
>
> XXX Write up and crosslink the "file: should use true URI syntax
> including %xx" issue.

This sounds like a FIle object doesn't map onto a UNIX file descriptor
(which can't be asked for its filename and may not even have one).

>
> ------------------------------------------------------------------------
>
> --
> Kevin Reid                                  <http://switchb.org/kpreid/>
>
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