Re: [Request][Discussion] Double value as array key improvement

> On Aug 11, 2017, at 2:10 PM, Andrew Nester <newaltgroup@bk.ru> wrote: > > Hello everyone! > > I was working on following request > https://bugs.php.net/bug.php?id=75053 > <https://bugs.php.net/bug.php?id=75053> which resulted in > following pull request https://github.com/php/php-src/pull/2676 > <https://github.com/php/php-src/pull/2676> > > The problem here is following: when we’re using large numbers as array index when adding new > elements it could overwrite already existing value. > Assume we have 2 indexes 5076964154930102272 and 999999999999999999999999999999 with different > value set for them. > > Because 999999999999999999999999999999 is larger than maximum long int number for 64-bit > systems, it will be converted to double. (corresponding code here > https://github.com/php/php-src/blob/master/Zend/zend_language_scanner.l#L1648 > <https://github.com/php/php-src/blob/master/Zend/zend_language_scanner.l#L1648>) > But when double value is used as array indexes, it is converted to long integer. (f.e., code is > here > https://github.com/php/php-src/blob/master/Zend/zend_execute.c#L1573 > <https://github.com/php/php-src/blob/master/Zend/zend_execute.c#L1573>) > At this case it causes overflow and we’ve got index equal to 5076964154930102272 and as a > result - we’re overwriting previously set value. > > My suggestion is following: > 1) when double key is less than maximum possible long integer - convert it to integer > 2) if it’s larger - convert it to string. > > That’s what implemented in proposed PR. > > Another possible option is just to throw warning in this case (proposed by Nikita Popov) > > I would happy to hear any feedback and suggestions about this solution. > Thanks! Here is the alternative solution which emits E_WARNING in case of integer array index overflow. https://github.com/php/php-src/pull/2677