Hi Anatol, I don't see any problem adding ZEND_LONG_INT_OVF and similar macros into 7.0.
Thanks. Dmitry. On Mon, Aug 24, 2015 at 5:15 PM, Anatol Belski <anatol....@belski.net> wrote: > Hi Rowan, > > > -----Original Message----- > > From: Rowan Collins [mailto:rowan.coll...@gmail.com] > > Sent: Monday, August 24, 2015 12:29 AM > > To: internals@lists.php.net > > Subject: Re: [PHP-DEV] 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. > > > Yep, that's the exact point. Not touching arithmetic operations as it is a > complex thing. Even on 64-bit fe there are intrinsics for doing 128-bit > math which could be used. ASM could be helpful ofc, however it needs much > care, fe even within GCC versions. So it is big and should be another story > :) > > Overflows in the cast can happen when passing args, comparing variables of > different type or signess, or even with the numeric constants. Hence that > cast (zend_long)INT_MAX for example. At the end - it's still an > overflow/underflow issue. I'm going for an RFC with this to target 7.1. > > Thanks. > > anatol > > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: http://www.php.net/unsub.php > >
