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Date: Sun, 06 Dec 2009 14:07:06 +0200
From: Avi Kivity <avi@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends
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To: malc <av1474@comtv.ru>
Cc: Paul Brook <paul@codesourcery.com>, Markus Armbruster <armbru@redhat.com>, qemu-devel@nongnu.org

On 12/06/2009 01:53 PM, malc wrote:
> On Sun, 6 Dec 2009, Avi Kivity wrote:
>
>    
>> On 12/06/2009 12:22 PM, malc wrote:
>>      
>>> Here, i believe, you are inventing artificial restrictions on how
>>> malloc behaves, i don't see anything that prevents the implementor
>>> from setting aside a range of addresses with 31st bit set as an
>>> indicator of "zero" allocations, and then happily giving it to the
>>> user of malloc and consumming it in free.
>>>
>>>        
>> The implementation needs to track which addresses it handed out, since it is
>> required that malloc(0) != malloc(0) (unless both are NULL).
>>      
> You haven't read carefully, i said range.
>    

I did in fact.  Consider a loop

   malloc(0);
   p = malloc(0);
   while (1) {
       n = malloc(0);
       free(p);
       p = n;
   }

without some form of tracking, you won't be able to return unique 
addresses eventually.

-- 
error compiling committee.c: too many arguments to function