Re: [libvirt] gnulib tests in libvirt broken by newer glibc 2.26

[Christian Ehrhardt]

On Thu, Sep 28, 2017 at 12:25 AM, Eric Blake <address@hidden> wrote:

[adding gnulib]

On 09/27/2017 04:36 PM, Christian Ehrhardt wrote:
> Hi,
> there seems to be an incompatibility to the last glibc due to [1].

Gnulib needs to be updated to track the glibc changes (it looks like
that is actually under way already),

Yeah that seems to be part of the effort I linked.

 

then libvirt needs to pick up the
updated gnulib.

I copied in current gnulib from git and it didn't resolve yet. But maybe it is just something that still is work in progress.

 

I'll leave the rest of your email intact in case it
helps gnulib readers, but I'll probably help resolve the issue when I
get a chance.

 

I'm assuming you hit this failure on rawhide, as that is the platform
most likely to be using bleeding-edge glibc with the getopt changes?

 

It was Ubuntu 17.10 (Artful) which is on 2.26

>
> Eventually this breaks gnulib unittests (and maybe more).
> Debugging went from an assert, to bidngin different symbols, to changed
> function names to different header resolution.
>
> Because it expects it to behave "posixly" but arguments are changed
> differently.
> FAIL: test-getopt-posix
> =======================
>
> ../../../../gnulib/tests/test-getopt.h:754: assertion 'strcmp (argv[1],
> "donald") == 0' failed
>
> # get and build latest libvirt to get the local gnulib
> $ wget http://libvirt.org/sources/libvirt-3.7.0.tar.xz
> $ tar xf libvirt-3.7.0.tar.xz
> $ cd libvirt
> $ apt build-dep libvirt
> $ ./autogen.sh
> $ make -j4
>
>
> You can run the following simplified test derived from the unit test (it is
> much shorter, so easier to debug e.g. in -E).
>
> $ cat << EOF >> test1.c
> #include <config.h>
> #include <unistd.h>
>
> #include <stdbool.h>
> #include <stdio.h>
> #include <stdlib.h>
>
> int main (void)
> {
>         return 0;
> }
> EOF
> $ gcc -I ./gnulib/lib -I . test1.c -H
>
> You can see in -H output already the difference in the paths of the headers
> that it uses:
>
> Glibc <2.26
> . ./config.h
> .. ./config-post.h
> . /usr/include/unistd.h
> [...]
> .. /usr/include/getopt.h
>
> Glibc >=2.26
> . ./config.h
> .. ./config-post.h
> . ./gnulib/lib/unistd.h
> [...]
>
> ... /usr/include/x86_64-linux-gnu/bits/getopt_posix.h
> .... /usr/include/x86_64-linux-gnu/bits/getopt_core.
>
>
> If you build with -E you'll also see that it now uses getopt from glibc
> instead of the prefixed rpl_getopt from gnulib.
>
> It behaves as if it would not find gnulib and instead fall back to glibc.
> But it finds gnulib, instead due to glibc's changes its implementation is
> fetched before and due to that pulling in glibc's behavior while the unit
> test is verifying against the one it expects from gnulib.
>
>
> Sorry, but I don't see the right fix here yet - I could easily silence the
> test but that is no fix. Especially if there might be implications due to
> handling the args (slightly) differently.
>
> I really wanted to come up with the same test against gnulib alone, but I
> was lost in the build system for too long and could not get the example to
> fail without libvirt (OTOH I'm sure it would).
>
> Therefore I'm reaching out to you for your help and experience on the build
> system what could be done.
>
> [1]: https://sourceware.org/ml/libc-alpha/2017-04/msg00115.html
>
>
>
> --

> libvir-list mailing list
> address@hidden
> https://www.redhat.com/mailman/listinfo/libvir-list
>

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

--

Christian Ehrhardt

Software Engineer, Ubuntu Server

Canonical Ltd