From: Junio C Hamano <gitster@pobox.com>
To: "René Scharfe" <l.s.r@web.de>
Cc: Git List <git@vger.kernel.org>,
Johannes Schindelin <johannes.schindelin@gmx.de>
Subject: Re: [PATCH] fast-export: avoid NULL pointer arithmetic
Date: Fri, 11 May 2018 11:16:04 +0900 [thread overview]
Message-ID: <xmqqbmdnhr8b.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <654fac2a-8dca-7bee-2bab-a3986aa7e52d@web.de> ("René Scharfe"'s message of "Thu, 10 May 2018 21:47:56 +0200")
René Scharfe <l.s.r@web.de> writes:
>> But it somehow feels backwards in spirit to me, as the reason why we
>> use "void *" there in the decoration field is because we expect that
>> we'd have a pointer to some struture most of the time, and we have
>> to occasionally store a small integer there.
>
> Yes, fast-export seems to be the only place that stores an integer as
> a decoration.
With the decoration subsystem that might be the case, but I think
we have other codepaths where "void * .util" field in the structure
is used to store (void *)1, expecting that a normal allocation will
never yield a pointer that is indistinguishable from that value.
> Using struct decorate in fast-export has the benefit of not
> requiring separate allocations for individual entries. Switching to
> struct hashmap would require individual allocations. Adding a
> custom clone of decorate with a uint32_t payload would be an option.
As long as we know uint32_t is no wider than uintptr_t, your patch
should be safe, shouldn't it?
next prev parent reply other threads:[~2018-05-11 2:16 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-09 21:06 [PATCH] fast-export: avoid NULL pointer arithmetic René Scharfe
2018-05-09 21:43 ` Johannes Schindelin
2018-05-10 9:24 ` René Scharfe
2018-05-10 10:51 ` Junio C Hamano
2018-05-10 19:47 ` René Scharfe
2018-05-11 2:16 ` Junio C Hamano [this message]
2018-05-11 4:49 ` Junio C Hamano
2018-05-11 6:19 ` Duy Nguyen
2018-05-11 8:56 ` Jeff King
2018-05-11 13:11 ` Duy Nguyen
2018-05-11 13:34 ` Duy Nguyen
2018-05-11 17:42 ` Jeff King
2018-05-12 8:45 ` René Scharfe
2018-05-12 8:49 ` René Scharfe
2018-05-14 1:37 ` Junio C Hamano
2018-05-15 19:36 ` René Scharfe
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