The goal here is to make it so applications can take the rights one would
normally get by calling caph_limit_stream() on a descriptor and build on
them as needed.
The tentatively planned use-case is an application that takes a socket and
hooks it up to std{err,out,in} for a fork()d child. It may be feasible to
apply limitations to such descriptors as long as it's a superset of those
normally applied to stdio.
Reviewed by: markj, oshobo (prior version; sans manpage addition)
Differential Revision: https://reviews.freebsd.org/D22993
The idea behind those functions is not to force consumers to remember that there
is a need to check errno on failure. We already have a caph_enter(3) function
which does the same for cap_enter(2).
MFC after: 2 weeks
The caph_enter function should made it easier to sandbox application
and not force us to remember that we need to check errno on failure.
Another function is also checking if casper is present.
Reviewed by: emaste, cem (partially)
Differential Revision: https://reviews.freebsd.org/D14557
