[PATCH] Improve check against integer wraparound in hcreate_r [BZ #18240]

[Paul Eggert]

On 01/25/2016 12:09 PM, Florian Weimer wrote:
> -  while (div * div < number && number % div != 0)
> +  while (div * (unsigned long long) div < number && number % div != 0)

Good catch. But better yet, get rid of the '*' so that we needn't worry 
about whether the multiplication overflows. On typical platforms the 
divide instruction that the '%' is already doing will give us the 
information we need, so this is faster anyway. Something like the 
attached (untested) patch.
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