From: Pierre Habouzit <madcoder@debian.org>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org
Subject: Re: Use of strbuf.buf when strbuf.len == 0
Date: Thu, 27 Sep 2007 12:13:00 +0200 [thread overview]
Message-ID: <20070927101300.GD10289@artemis.corp> (raw)
In-Reply-To: <7vir5wy6fv.fsf@gitster.siamese.dyndns.org>
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On Thu, Sep 27, 2007 at 06:21:24AM +0000, Junio C Hamano wrote:
> It might be an easier and safer fix to define that strbuf_init()
> to always have allocation. Use of a strbuf in the code _and_
> not adding any contents to the buffer should be an exception and
> avoiding malloc()/free() for that special case feels optimizing
> for the wrong case.
>
> However, there are strbuf instances that are not initialized
> (i.e. in BSS or initialized by declaring with STRBUF_INIT), so
> we still need to handle (.len == 0 && .alloc == 0) case
> specially anyway.
I can see a way, that would need special proof-reading of the strbuf
module, but should not harm its users, that would be to change
STRBUF_INIT to work this way:
{ .buf = "", .len = 0, .alloc = 0 }
It needs to make strbuf_grow and strbuf_release check for ->alloc
before doing anything stupid.
Though we may have some bits of code that rely on .buf being NULL if
nothing happened. I tried to track them down, but some may remain.
If you agree with this change, that would solve most of the issues
with almost no cost, then I'll propose a new patch with this change.
--
·O· Pierre Habouzit
··O madcoder@debian.org
OOO http://www.madism.org
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next prev parent reply other threads:[~2007-09-27 10:13 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-27 6:21 Use of strbuf.buf when strbuf.len == 0 Junio C Hamano
2007-09-27 10:13 ` Pierre Habouzit [this message]
2007-09-27 10:51 ` [PATCH 1/2] double free in builtin-update-index.c Pierre Habouzit
2007-09-27 10:58 ` [PATCH 2/2] strbuf change: be sure ->buf is never ever NULL Pierre Habouzit
2007-09-29 0:51 ` Use of strbuf.buf when strbuf.len == 0 Linus Torvalds
2007-09-29 7:48 ` Pierre Habouzit
2007-09-27 11:22 ` Pierre Habouzit
2007-09-27 11:33 ` [PROPER PATCH 1/1] Make read_patch_file work on a strbuf Pierre Habouzit
2007-09-27 11:33 ` [PATCH " Pierre Habouzit
2007-09-27 11:37 ` Use of strbuf.buf when strbuf.len == 0 Pierre Habouzit
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