Re: [Libguestfs] [PATCH 1/2] lib: Allow db_dump package to be a weak dependency (RHBZ#1409024).
On Fri, Oct 06, 2017 at 03:11:40PM +0200, Pino Toscano wrote:
On Friday, 6 October 2017 12:23:00 CEST Richard W.M. Jones wrote:
> I mostly agree with all of what you say, EXCEPT that in the past we've
> had cases where people have installed broken binaries on
> /usr/local/bin and then reported bugs against libguestfs.
I would consider this situation broken anyway, and as mentioned above
it will be spotted by looking at the verbose logs (which show the
executable run, and with my changes they are passed as absolute).
Certainly agreed the situation is broken when someone puts a broken
binary in /usr/local.
> Therefore at configure time we need to store the actual path of
the
> binaries we want to use (and the binaries that the packager tested
> against) and we shouldn't search $PATH at runtime.
The current system though will not prevent any of those mistakes if
the user builds libguestfs after installing the binaries in /usr/local
(or anywhere else in $PATH): the configure of libguestfs will pick
them, and thus back at the issue.
In that situation, the tests will run against those binaries from
/usr/local, and libguestfs will run against those same binaries.
That's fine - we have proved those binaries aren't broken!
But really I'm talking about the majority of consumers who get
libguestfs from their distro.
Instead, looking them only at
runtime means the user can just cleanup the broken binaries, with no
need to rebuild libguestfs later.
> So some generic mechanism is fine, and looking for binaries at runtime
> is also fine, but not one which is searching $PATH.
If $PATH has broken stuff, then it is a bigger problem than just
libguestfs. Do not get me wrong: I understand the concern here, but
IMHO it should be better to just rely on the good status of the system
(as it is supposed to be), rather than "hacking around it".
I really don't think this is hacking around anything.
It's addressing a problem which has come up in reality.
It's not hacking because the distro packager has built (and one hopes
checked) that libguestfs works against a certain mix of binaries,
namely those provided under /usr/bin by the distro. The distro is
responsible for those binaries, but not the ones under /usr/local/bin.
I think this is about the integrity of what we ship to the majority of
users.
FWIW I posted a v2 of this patch series (actually, before I saw this
email, because the mailing list is incredibly slow this week for some
reason). It attempts to address the problem in a way which is simple
yet allows weak dependencies.
Also I posted another patch to address the qemu-img situation which
you mentioned back in your posting in February.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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