[Qemu-devel] Re: [PATCH] Make strtosz() return int64_t instead of ssize_t

[Anthony Liguori <anthony@codemonkey.ws>]

On 01/05/2011 08:40 AM, Jes Sorensen wrote:
> On 01/05/11 14:46, Anthony Liguori wrote:
>    
>> On 01/05/2011 04:41 AM, Jes.Sorensen@redhat.com wrote:
>>      
>>> From: Jes Sorensen<Jes.Sorensen@redhat.com>
>>>
>>> strtosz() needs to return a 64 bit type even on 32 bit
>>> architectures. Otherwise qemu-img will fail to create disk
>>> images>= 2GB
>>>
>>> Signed-off-by: Jes Sorensen<Jes.Sorensen@redhat.com>
>>>
>>>        
>> off_t would be the proper type to use.
>>      
> I discussed this with Markus, and we both agree that it isn't.
>
> Two reasons, off_t is for filesystem offsets, not random sizes. Second,
> off_t doesn't have an unsigned type or a max to compare against.
>    

That's because the size of off_t depends on whether it's a 32 or 64-bit 
platform and what FILESIZEBITS is defined to be.

Basically, if you're looking for the type to represent offsets in a 
file, it's off_t.  That's why it exists.

That said, using this to represent memory too, I can buy that as a 
justification to use int64_t.

> Using int64_t is cleaner and safer.
>    

I wouldn't make such bold claims but I'll concede that one is not 
significantly better than the other and won't object to int64_t if you 
feel strongly.

Regards,

Anthony Liguori

> Cheers,
> Jes
>