Re: [PATCH 3/3] pkt-line: support tracing verbatim pack contents

On Tue, Jun 16, 2015 at 1:10 PM, Jeff King [off-list ref] wrote:

On Tue, Jun 16, 2015 at 11:38:41AM -0400, Augie Fackler wrote:

quoted

quoted

We already have a GIT_TRACE_PACKET mechanism for tracing
packets. Let's extend it with GIT_TRACE_PACK to dump the
verbatim packfile.

FWIW, this also works for me - I have no preference between my patches
and Jeff's. I suspect yours are much better given that you have a clue
about git internals ;).

I like mine better than yours, if only because it hooks into the
existing tracing mechanism. But I am sad that neither of our proposals
works for tracing pushed packs (something that is useful for the
opposite situation: you have a sane git server, and some unknown
misbehaving _client_ is sending you bogus packs).

Yeah, not having it for the push side is a slight bummer, but in
general I haven't had problems debugging git clients pushing bogus
data in the same way that I've had problems with weirdness in new
server features.

Here's a rough cut at the "trace stdin" idea I mentioned earlier (which
is essentially an internal "tee"). You can collect the incoming pack
like:

Neat, but not sure I like the extra overhead of having to grab the
full trace and then reconstruct some arguments to be able to diagnose
the pack. Having the verbatim pack just land on disk is really handy,
because then any existing tools one has cooked up (my team has a few
weird one-off ones by now) just work without extra fussing or looking
up steps to reconstruct the whole file.