Re: [Xen-devel] [PATCH 1/5] xen: add ssize_t

[Jean Guyader <jean.guyader@xxxxxxxxx>]

On 9 August 2012 10:51, Tim Deegan <tim@xxxxxxx> wrote:
> At 15:47 +0100 on 06 Aug (1344268059), Jean Guyader wrote:
>> On 6 August 2012 09:08, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>> >>>> On 03.08.12 at 21:50, Jean Guyader <jean.guyader@xxxxxxxxxx> wrote:
>> >
>> > Without finally explaining why you need this type in the first place,
>> > I'll continue to NAK this patch. (This is made even worse by the fact
>> > taht the two inline functions in patch 5 that make use of the type
>> > appear to be unused.)
>> >
>>
>> Understood. I'll switch to use long instead of ssize_t in my
>> forthcoming patch serie.
>
> Please use an explicitly 64-bit type - AFAICS you're holding the sum of
> some 64-bit length fields.
>

Ok but ssize_t is kind of a funny one. It should accept everything
that size_t can accept + negative values.

The linux kernel is defining ssize_t as int for 32b and long for 64b.
I could do the same then check for the
size of the copy and if it's bigger than MAX_INT|MAX_LONG return -EMSGSIZE.

http://lxr.free-electrons.com/source/include/asm-generic/posix_types.h#L68
(look for __kernel_ssize_t)

Jean

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