Re: Suspicious fetch-pack behaviour

From: Guilhem Bonnefille <guilhem.bonnefille@gmail.com>
Date: Jan 8, 2019, 07:26 UTC
Message-ID: <CA+BUw6h5YdimR7cBV_=Mp4KqUMvJr6-njFPEpp-pjPBCcOKx6A@mail.gmail.com>
In-Reply-To: <20190108063456.GA17588@sigill.intra.peff.net>

Le mar. 8 janv. 2019 à 07:34, Jeff King <peff@peff.net> a écrit :

Show 26 quoted lines

>
> On Thu, Jan 03, 2019 at 10:52:48AM +0100, Guilhem Bonnefille wrote:
>
> > One of my users reported a strange problem: a simple HTTPS clone did
> > not work with Git 1.8.3.1 on RedHat 7.
> > I did many tests and I was not able to understand why his clone don't
> > work while I'm able to do it on other similar host.
> >
> > Nevertheless, we did more investigations. One of them: a raw strace.
> > I discovered two strange behaviours:
> > - fetch-pack closes its standard input and standard output and then
> > tries to print the references on standard input and finaly dies.
> > - git-remote-https does not react to fetch-pack death and continue
> > polling an empty set of FD.
> >
> > [...]
> >
> > 2769  poll(NULL, 0, 1000)               = 0 (Timeout)
>
> We actually don't use poll() very much in Git. And poking around the
> v1.8.3.1 source, I do not see any places where remote-https would call
> poll(), and none outside of "git help" and "git credential-cache-daemon"
> that would ever provide a timeout like "1000".
>
> I wonder if this poll is actually being run by libcurl.  Is it possible
> to get a backtrace of the looping process with gdb?

Quite hard to debug as it occured on a computer provided by a customer, far from me...

> I'd also point out that v1.8.3.1 is over 5 years old, and there have
> been quite a few http-related fixes over the years.

Yes, it is an old version, but it is the version provided with RedHat 7.

> There is a good
> chance that if this is a Git bug, it has long since been fixed. Is it
> possible to reproduce with a more modern version of Git?
>

What is surprisingly is that I was unable to reproduce with the same version on an other computer.

During this time, my user discovered the IT team of the customer prvide a much more recent version of Git (2.X). With this new version, the problem was not reproduced.

Thanks for all your investigations.

-- 
Guilhem BONNEFILLE
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