From: Jeff King <peff@peff.net>
To: "René Scharfe" <l.s.r@web.de>
Cc: Git Mailing List <git@vger.kernel.org>,
Junio C Hamano <gitster@pobox.com>,
Derrick Stolee <stolee@gmail.com>,
Derrick Stolee <dstolee@microsoft.com>
Subject: Re: [PATCH] commit-reach: plug minor memory leak after using is_descendant_of()
Date: Fri, 19 Jun 2020 09:31:59 -0400 [thread overview]
Message-ID: <20200619133159.GB2540897@coredump.intra.peff.net> (raw)
In-Reply-To: <ada13c16-d964-c6ee-80ac-626edbc5f52d@web.de>
On Fri, Jun 19, 2020 at 03:13:46PM +0200, René Scharfe wrote:
> ref_newer() builds a commit_list to pass a single potential ancestor to
> is_descendant_of(). The latter leaves the list intact. Release the
> allocated memory after the call.
Looks obviously correct.
> ---
> We could allocate the commit_list on the stack, which would simplify such
> glue code quite a bit. That would be dangerous in case is_descendant_of()
> or some other function that is handed such a list tries to consume/free()
> it. How can we be tell a function is safe to be given a stack-allocated
> list? Perhaps by marking its argument as const. Or by converting all
> functions to arrays.
Yeah, if we're not worried about the performance implications of the
extra allocation, I think it's better to err on the side of safety.
I do agree that if we consistently passed an array (and length), some of
these functions would get less awkward. I tried a few years ago to
convert many of the commit_list uses to arrays, but it was a bit of a
yak shave, since often they get lists from callers, who get it from
rev_info, etc. And some of those callers _do_ like having lists, because
they want to do O(1) splicing, etc.
-Peff
next prev parent reply other threads:[~2020-06-19 13:32 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-19 13:13 [PATCH] commit-reach: plug minor memory leak after using is_descendant_of() René Scharfe
2020-06-19 13:31 ` Jeff King [this message]
2020-06-19 14:07 ` Derrick Stolee
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