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Date: Fri, 11 Aug 2017 15:53:09 +0300
References: <C8CF5498-7451-4BDC-935F-17D010DBA6B6@bk.ru>
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Subject: Re: [Request][Discussion] Double value as array key improvement
From: newaltgroup@bk.ru (Andrew Nester)

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> On Aug 11, 2017, at 2:10 PM, Andrew Nester <newaltgroup@bk.ru> wrote:
>=20
> Hello everyone!
>=20
> I was working on following request =
https://bugs.php.net/bug.php?id=3D75053 =
<https://bugs.php.net/bug.php?id=3D75053> which resulted in following =
pull request https://github.com/php/php-src/pull/2676 =
<https://github.com/php/php-src/pull/2676>
>=20
> The problem here is following: when we=E2=80=99re 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.
>=20
> 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#L1=
648 =
<https://github.com/php/php-src/blob/master/Zend/zend_language_scanner.l#L=
1648>)
> 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=E2=80=99ve got index equal to =
5076964154930102272 and as a result - we=E2=80=99re overwriting =
previously set value.
>=20
> My suggestion is following:
> 1) when double key is less than maximum possible long integer - =
convert it to integer
> 2) if it=E2=80=99s larger - convert it to string.
>=20
> That=E2=80=99s what implemented in proposed PR.
>=20
> Another possible option is just to throw warning in this case =
(proposed by Nikita Popov)
>=20
> 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=

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