[cap-talk] Plash: the Principle of Least Authority Shell

[Jed at Webstart]

At 03:43 PM 12/16/2004, Mark Seaborn wrote:
>Jed at Webstart <donnelley1 at webstart.com> wrote:
>
> > At 09:13 AM 12/12/2004, Mark Seaborn wrote:
> > >Jed at Webstart <donnelley1 at webstart.com> wrote:
> > >...
> > > > I wonder if Oracle (or perhaps more relevantly commands like
> > > > sqlplus) would actually run under Plash?  Hmmm.
> > >
> > >You can find out what it dynamically links with by running
> > >"ldd <executable-pathname>".
> >
> > bash-2.05$ which oracle
> > /opt/app/oracle/product/9.2.0/bin/oracle
> > bash-2.05$ ldd /opt/app/oracle/product/9.2.0/bin/oracle
> >          libodm9.so => /opt/app/oracle/product/9.2.0/lib/libodm9.so
> >...
> >
> > Is there any way to tell from the above whether there is something missing
> > from the above that would cause a problem?
> >
> > It looks like it dynamically loads libc.so.6.  Does that suffice?
>
>There's nothing there that says it won't work.  The main thing is that
>it has to link with libc.so.6, the non-TLS version.  (The TLS version
>is /lib/tls/libc.so.6.  The New Posix Thread Library (NPTL) uses TLS
>(thread local storage), and I haven't tried compiling a version of
>libc with TLS or NPTL yet.)
>
>The next question is how the program behaves at runtime.  eg. Some
>system calls are not yet implemented in Plash.  If the program expects
>to be able to open directories using open(), that's not implemented
>either.  I also haven't made my additions to libc thread-safe yet.

Hmmm.  I would expect Oracle to be pretty heavy on system calls,
e.g. with things like raw I/O, etc.  Also now that I think of it
how is the performance of Plash for I/O bound programs?  Since
it does direct I/O to real files I guess it would only run into problems
with a program that was constantly opening and closing files -
right?

>There are a couple of bugs in the current version of Plash that mean
>it probably won't work.  I've fixed them in a newer version that I'll
>release in the next couple of days.

I see.  I guess I should just give it a try and get some experience
with it.  Both from the perspective of getting experience with the
user interface and from the perspective of seeing how it operates,
both in terms of functionality and performance.

I'll let you know about any experience I get with it.  Wow, an RPM.
That makes it easy.  I'll look for version 1.2 then (?).

--Jed http://www.webstart.com/jed/