Re: Forcing BIND_NOW for a symbol

[Florian Weimer <fweimer at redhat dot com>]

On 04/26/2016 04:13 PM, Adhemerval Zanella wrote:
> On 25/04/2016 18:45, Florian Weimer wrote:
> > On 04/25/2016 10:45 PM, Carlos O'Donell wrote:
> > > On Mon, Apr 25, 2016 at 5:32 AM, Florian Weimer <fweimer@redhat.com> wrote:
> > > > Could we look at the âVersion needsâ section (.gnu.version_r) and perhaps
> > > > use a special symbol version for getrandom?
> > >
> > > Such a special symbol would mark getrandom as needing early resolution?
> >
> > We already scan .gnu.version_r, so we can quickly detect special cases at very little extra cost.  It's somewhat ugly because it's not a generic mechanism like IFUNC (but then, the IFUNC experience suggests it's better to gather internal users first before providing a generic interface).
> >
> > Florian
>
> If I understood your problem correctly, why instead of using IFUNC+BIND_NOW
> you provide the getrandom to check by itself if ENOSYS is returned and
> then call either the alternative the getrandom or return the error to the
> user?

The problem I'm trying to solve is to support emulation even in chrooted 
processes.  If the process calls chroot and chroot does not contain a 
suitable /dev/urandom and /dev/random, emulation fails.

I do not want to open these files just in case the process may need them 
later.

Florian