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From: Jeff King <>
To: "René Scharfe" <>
Cc: Git Mailing List <>,
	Junio C Hamano <>
Subject: Re: [PATCH] diff-lib: plug minor memory leaks in do_diff_cache()
Date: Mon, 16 Nov 2020 19:35:11 -0500	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Sat, Nov 14, 2020 at 07:37:03PM +0100, René Scharfe wrote:

> do_diff_cache() builds a struct rev_info to hand to diff_cache() from
> scratch by initializing it using repo_init_revisions() and then
> replacing its diffopt and prune_data members.
> The diffopt member is initialized to a heap-allocated list of options,
> though.  Release it using diff_setup_done() before overwriting it.

Makes sense. This whole "rewrite the options as a heap-allocated list"
thing is pretty gross, but is probably the least-bad solution to the
problem. I wondered if there might be other unpaired diff_setup() /
diff_setup_done() calls. Curiously, there are more of the latter:

  $ git grep 'diff_setup(' | wc -l

  $ git grep 'diff_setup_done(' | wc -l

I think because repo_init_revisions() makes an implicit call to

> The initial value of the prune_data member doesn't need to be released,
> but the copy created using copy_pathspec() does.  Clear it after use.

I suspect there are more elements of rev_info that could be allocated
(e.g., in a traversal without "--objects", I think trees and blobs are
left sitting in the pending array). It's a prime candidate for UNLEAK()
in most cases where we do a single traversal and then exit the program.
But for sub-functions like this, we perhaps should bite the bullet and
just make a rev_info_clear() function that can be used everywhere.

(I'm not opposed to your patch here in the meantime, though).


      reply	other threads:[~2020-11-17  0:36 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-14 18:37 René Scharfe
2020-11-17  0:35 ` Jeff King [this message]

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