Re: On time64 and Large File Support

[Eric Blake]

[replying to the original post, because I'm not sure where else in the
more recent activity on this thread would be more appropriate]

On Fri, Nov 11, 2022 at 08:38:18AM +0000, Sam James wrote:
> Hi all,
> 
> In Gentoo, we've been planning out what we should do for time64 on glibc [0]
> and concluded that we need some support in glibc for a newer option. I'll 
> outline
> why below.
>
...
> 
> Indeed, the gnulib version of change #2 is exactly how we ended up with
> wget/gnutls breaking [1]. I feel this shows that the only approach
> "supported" by glibc right now is untenable.

> [1] https://bugs.gentoo.org/828001

Now Fedora is also being hit by the gnutls ABI change due to time_t in
public interfaces being silently changed.  From an IRC conversation I
had with Dan Berrange and Rich Jones (I think Rich mean i686 below):

<danpb> rjones (IRC): oh wow, the certificates created on i696 are not quite 
right .....
<danpb>         Validity:
<danpb>                 Not Before: Sat Sep 05 00:23:57 UTC 2703
<danpb>                 Not After: Sun Sep 06 00:23:57 UTC 2703
<danpb> just a few years too early
<danpb> i think this is looking like a gnutls regression,   downgrading gnutls 
makes it work
...
<danpb> rjones (IRC): hmm, i'm beginning to think gnutls has been miscompiled 
by gcc
<danpb> gnutls_x509_crt_get_activation_time inside the gnutls verification api 
returns garbage
<danpb> but the very same call done from a demo program returns the right answer
...
<danpb> OMG, gnulib-- has silently changed gnutls to use 64-bit time_t
<danpb> ...which is an ABI incompatibility because gnutls has public APIs which 
have time_t parameters
<danpb> so apps talking to gnutls will expect 32-bit time_t, but gnutls is 
processing 64-bit time_t
<danpb> this is utterly insane

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org