Thanks, now I understood. :) anyway I see a problem. For example on x86_64 double is not always able to keep a long number without precision lost. May be you should receive arguments as zvals and use old or new code depending on input types.
BTW: I'm not sure if rand() should be fixed at all. According to http://php.net/manual/en/function.rand.php it should accept integers and return integer. Thanks. Dmitry. On Fri, Mar 22, 2013 at 12:08 PM, Anatol Belski <a...@php.net> wrote: > Dmitry, > > first of all thanks for taking a look :) > > The issue in a few words > - mt_rand reads arguments as long > - user pass a float from the userspace > - zend_parse_parameters with 'l' casts to long > > Here's the essential snippet > echo mt_rand(0,pow(10,12)); > PHP Warning: mt_rand(): max(-727379968) is smaller than min(0) > > So reading as long would probably not work, in the first place because the > input data exceeding LONG_MAX will be corrupted by the conversion. So what > I did > - read input as max precision possible, no corruption > - calculate as well with double > - return the old way int if it's in LONG_MAX range, otherwise return float > > Is there a solution I don't see (or do I get your suggestion wrong)? It's > just essential to get the input as precise as it can be across PHP. > > Besides that what could be impacts changing input arg types in this > concrete case? User probably wouldn't realize that at all. > > Thanks > > Anatol > > On Fri, March 22, 2013 07:40, Dmitry Stogov wrote: > > Hi Anatol, > > > > > > To be honest, I didn't understand all the details of the patch :) > > > > > > However, I see a problem: > > You changed the prototype of user level rand() function to receive double > > arguments instead of long. I think it's disallowed, but you may get > > arguments as longs and then convert them to double. Will it work? > > > > > > Thanks. Dmitry. > > > > > > On Thu, Mar 21, 2013 at 9:26 PM, Dmitry Stogov <dmi...@zend.com> wrote: > > > > > >> I'll able to look only tomorrow morning. > >> > >> > >> Thanks. Dmitry. > >> > >> > >> > >> On Thu, Mar 21, 2013 at 8:46 PM, Anatol Belski <a...@php.net> wrote: > >> > >> > >>> Hi Dmitry, > >>> > >>> > >>> I developed a patch for this one > >>> https://bugs.php.net/bug.php?id=64450 . > >>> It's regarding to the long overflow in mt_rand(). The main idea is to > >>> work with the args as double internally and then return php float if > >>> it exceeds the LONG_MAX. I strived to let the old behavior to be > >>> unchanged, all the older tests pass. Please take a look. > >>> > >>> Regards > >>> > >>> > >>> Anatol > >>> > >>> > >> > >> > > > >
