Forcing BIND_NOW for a symbol

[Florian Weimer]

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 “Version needs” 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