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Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends |
Date: |
Tue, 08 Dec 2009 09:30:16 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) |
Anthony Liguori <address@hidden> writes:
> Markus Armbruster wrote:
>> Commit a7d27b53 made zero-sized allocations a fatal error, deviating
>> from ISO C's malloc() & friends. Revert that, but take care never to
>> return a null pointer, like malloc() & friends may do (it's
>> implementation defined), because that's another source of bugs.
>>
>
> While it's always fun to argue about standards interpretation, I
> wanted to capture some action items from the discussion that I think
> there is agreement about. Since I want to make changes for 0.12, I
> think it would be best to try and settle these now so we can do this
> before -rc2.
>
> For 0.12.0-rc2:
>
> I will send out a patch tonight or tomorrow changing qemu_malloc() to
> return malloc(1) when size=0 only for production builds (via
> --enable-zero-mallocs). Development trees will maintain their current
> behavior.
I don't think 0.12 needs the compile-time option, it's a production
release after all. But since I won't actually hurt 0.12, I don't mind.
> For 0.13:
>
> Someone (Marcus?) will introduce four new allocation functions.
>
> type *qemu_new(type, n_types);
> type *qemu_new0(type, n_types);
>
> type *qemu_renew(type, mem, n_types);
> type *qemu_renew0(type, mem, n_types);
>
> NB: The names are borrowed from glib. I'm not tied to them.
I'll see what I can do post release.
> Will do our best to convert old code to use these functions where ever
> possible. New code will be required to use these functions unless not
> possible. n_types==0 is valid. sizeof(type)==0 is valid. Both
> circumstances return a unique non-NULL pointer. If memory allocation
> fails, execution will abort.
>
> The existing qemu_malloc() will maintain it's current behavior (with
> the exception of the relaxed size==0 assertion for production
> releases).
>
> Does anyone object to this moving forward?
Thanks, works for me.
- Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, (continued)
Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, Paul Brook, 2009/12/07
Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, malc, 2009/12/07
Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, Blue Swirl, 2009/12/07
Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends,
Markus Armbruster <=