Re: [PATCH 0/10] towards clean leak-checker output

From: Jeff King <peff@peff.net>
Date: Sep 6, 2017, 12:39 UTC
Message-ID: <20170906123943.335degmzmokqrd7p@sigill.intra.peff.net>
In-Reply-To: <CAN0heSrz=tVHj13X+yHJpAR=5o7j8EqbBdw8hvrhcnhbA04QAA@mail.gmail.com>

On Tue, Sep 05, 2017 at 10:41:51PM +0200, Martin Ågren wrote:

Show 7 quoted lines

> FWIW, this series (combined with the other series you mentioned) makes
> t0000 and t0001 pass for me with gcc/clang. There are actually some
> leaks in t0000, they're just silently being reported to stderr, since
> the exit statuses from git are hidden by pipes. Maybe you're already
> aware of it. Depending on your definition of "running clean" it might be
> out of scope for this series, which is of course still very interesting
> and enlightening as it stands.

Yeah, I saw those. I don't think they're worth hunting down at this point. It's quite probable that the same leaks are exercised elsewhere, and we'll catch them later.

Once the whole test suite runs without reporting any leaks via abort(), I'll feel more compelled to start grepping stderr for other cases. :)

> One is in cmd_show (you did mention git show) where we leak data in rev.
> The other is some use of strdup. I can't immediately figure out how to
> get a useful stacktrace (you mentioned this as well) and it's past
> bed-time here. I'll try to play more with this tomorrow.

I think I got funny truncated stack traces with just LSAN that went away with ASAN, but I didn't dig. If you try that, remember that:

  - Technically just SANITIZE=address turns on the leak detector, but
    you need "leak" in the string to turn on the UNLEAK() magic. So use
    "SANITIZE=address,leak".

  - You'll have to set ASAN_OPTIONS=abort_on_error=1 in the environment
    manually to enable leak detection.

Once the test suite passes with leak detection on, I think we'd probably do both of those automatically (but until then they make ASAN by itself unusable).

> Note for self: getting rid of all pipes would probably also help flush
> out a few leaks (or "introduce" them, depending on your viewpoint).

Agreed. These leaks are really just a special form of bug. Those pipes could be hiding other bugs, too. But again, I'm not too concerned. The places that pipe git are doing so because they are not meant to be testing that particular command (and it should generally be covered elsewhere).

-Peff