Re: capabilities and POSIX ``emulation''

[Marcus Brinkmann]

At Tue, 14 Feb 2006 23:01:41 +0600,
Ivan Shmakov <address@hidden> wrote:
>       The third side of the problem is that there might be a need to
>       pass not only a specific interface, but the specific
>       implementation to the POSIX program.  I'm not sure in using the
>       term right, but it seems that the ``capability'' passed from one
>       HURD process to the other could be implemented to posses a
>       ``default view'', which the originating process could explicitly
>       set.  Thus, the problem is in allowing POSIX programs to use the
>       capabilities passed to them.

That's the poly class idea.

>       Similar problem exists in passing the file descriptor from the
>       parent process to the child.  That's no problem if it's a
>       standard descriptor -- 0, 1 or 2 (stdin, stdout, stderr), but
>       the programs commonly used aren't able to interpret any other
>       descriptor they get.  That's how it's solved by Bash on
>       GNU/Linux system:
> 
> $ cat <(echo hello,) <(echo world\!)
> hello,
> world!
> $ 

Nice.
 
>       Would the implemented ``capabilities namespace'' be global, the
>       following will also be possible, given the <(...) construct be
>       implemented using the capabilities as well:
> 
> $ emacsclient <(echo hello,\ world\!)

No, it wouldn't, as bash would still create a pipe for this, and emacs
can't edit a pipe, presumably because it needs random access to the
file.

Thanks,
Marcus