Re: Overflow checks and integral vars comparison

On 22/08/2015 02:38, Sherif Ramadan wrote:

I see. So you're not actually doing overflow checks then? Because at the point you'd be checking this zend_long or size_t it could have already overflowed or wrapped. The subject may have misled me to understand differently.

I think I understand the confusion: you are thinking of overflow as something which happens *within* a type based on some operation (addition, multiplication, etc). Anatol is talking about overflows which occur when casting *between* types: a value of 2^33 can safely be passed around as a 64-bit integer, no overflow has occurred; but attempting to cast it to a 32-bit integer will immediately overflow the 32-bit integer. Since many PHP extensions are wrappers around libraries which may only deal in 32-bit types, this cast is common, necessitating range checks like the ones proposed. Regards, -- Rowan Collins [IMSoP]