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From: Jeff King <peff@peff.net>
To: "Martin Ågren" <martin.agren@gmail.com>
Cc: Git Mailing List <git@vger.kernel.org>,
	"brian m . carlson" <sandals@crustytoothpaste.net>
Subject: Re: [PATCH v3 2/2] setup: fix memory leaks with `struct repository_format`
Date: Fri, 25 Jan 2019 14:51:07 -0500	[thread overview]
Message-ID: <20190125195107.GA6520@sigill.intra.peff.net> (raw)
In-Reply-To: <CAN0heSoNvTVfC6A8fFK83u4TBX3sLaTJ_NqKwkCZORiCKdVwcA@mail.gmail.com>

On Fri, Jan 25, 2019 at 08:24:35PM +0100, Martin Ågren wrote:

> On Wed, 23 Jan 2019 at 06:57, Jeff King <peff@peff.net> wrote:
> >
> > On Tue, Jan 22, 2019 at 10:45:48PM +0100, Martin Ågren wrote:
> >
> > > Call `clear_...()` at the start of `read_...()` instead of just zeroing
> > > the struct, since we sometimes enter the function multiple times. This
> > > means that it is important to initialize the struct before calling
> > > `read_...()`, so document that.
> >
> > This part is a little counter-intuitive to me. Is anybody ever going to
> > pass in anything except a struct initialized to REPOSITORY_FORMAT_INIT?
> 
> I do update all users in git.git, but yeah, out-of-tree users and
> in-flight topics would segfault.
> 
> > If so, might it be kinder for read_...() to not assume anything about
> > the incoming struct, and initialize it from scratch? I.e., not to use
> > clear() but just do the initialization step?
> 
> I have some vague memory from going down that route and giving up. Now
> that I'm looking at it again, I think we can at least try to do
> something. We can make sure that "external" users that call into setup.c
> are fine (they'll leak, but won't crash). Out-of-tree users inside
> setup.c will still be able to trip on this. I don't have much spare time
> over the next few days, but I'll get to this.
> 
> Or we could accept that we may leak when we end up calling `read()`
> multiple times (I could catch all leaks now, but new ones might sneak in
> after that) and come back to this after X months, when we can perhaps
> afford to be a bit more aggressive.
> 
> I guess we could just rename the struct to have the compiler catch
> out-of-tree users...

I'm less worried about out-of-tree users, and more concerned with just
having a calling convention that matches usual conventions (and is
harder to get wrong).

It's a pretty minor point, though, so I can live with it either way.

-Peff

  reply	other threads:[~2019-01-25 19:51 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-18  7:25 [PATCH 0/3] setup: add `clear_repository_format()` Martin Ågren
2018-12-18  7:25 ` [PATCH 1/3] setup: drop return value from `read_repository_format()` Martin Ågren
2018-12-19 15:27   ` Jeff King
2018-12-19 21:42     ` Martin Ågren
2018-12-20  0:17     ` brian m. carlson
2018-12-20  2:52       ` Jeff King
2018-12-20  3:45         ` brian m. carlson
2018-12-20 14:53           ` Jeff King
2018-12-18  7:25 ` [PATCH 2/3] setup: do not use invalid `repository_format` Martin Ågren
2018-12-19  0:18   ` brian m. carlson
2018-12-19 21:43     ` Martin Ågren
2018-12-19 15:38   ` Jeff King
2018-12-19 21:46     ` Martin Ågren
2018-12-19 23:17       ` Jeff King
2018-12-20  0:21     ` brian m. carlson
2018-12-18  7:25 ` [PATCH 3/3] setup: add `clear_repository_format()` Martin Ågren
2018-12-19 15:48   ` Jeff King
2018-12-19 21:49     ` Martin Ågren
2019-01-14 18:34 ` [PATCH v2 0/3] " Martin Ågren
2019-01-14 18:34   ` [PATCH v2 1/3] setup: free old value before setting `work_tree` Martin Ågren
2019-01-14 18:34   ` [PATCH v2 2/3] setup: do not use invalid `repository_format` Martin Ågren
2019-01-15 19:31     ` Jeff King
2019-01-17  6:31       ` Martin Ågren
2019-01-22  7:07         ` Jeff King
2019-01-22 13:34           ` Martin Ågren
2019-01-22 21:45             ` [PATCH v3 0/2] setup: fix memory leaks with `struct repository_format` Martin Ågren
2019-01-22 21:45               ` [PATCH v3 1/2] setup: free old value before setting `work_tree` Martin Ågren
2019-01-22 21:45               ` [PATCH v3 2/2] setup: fix memory leaks with `struct repository_format` Martin Ågren
2019-01-23  5:57                 ` Jeff King
2019-01-24  0:14                   ` brian m. carlson
2019-01-25 19:25                     ` Martin Ågren
2019-01-25 19:24                   ` Martin Ågren
2019-01-25 19:51                     ` Jeff King [this message]
2019-02-25 19:21                       ` Martin Ågren
2019-02-26 17:46                         ` Jeff King
2019-02-28 20:36                           ` [PATCH v4 0/2] " Martin Ågren
2019-02-28 20:36                             ` [PATCH v4 1/2] setup: free old value before setting `work_tree` Martin Ågren
2019-02-28 20:36                             ` [PATCH v4 2/2] setup: fix memory leaks with `struct repository_format` Martin Ågren
2019-03-06  4:56                             ` [PATCH v4 0/2] " Jeff King
2019-01-14 18:34   ` [PATCH v2 3/3] setup: add `clear_repository_format()` Martin Ågren

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