Re: Bug #72828

On 13.08.2016 at 15:08, Nikita Popov wrote: > On Sat, Aug 13, 2016 at 2:42 PM, Christoph M. Becker <cmbecker69@gmx.de> > wrote: > >> You have commented on >> <https://bugs.php.net/bug.php?id=72828>: >> >> | Unless the allocations explicitly use the system allocator (i.e. do >> | not use emalloc and variants), do NOT introduce NULL checks. >> >> Can you please elaborate, why that shouldn't be done. >> >> Actually, the allocations use safe_emalloc() and emalloc(), >> respectively[1]. However, the only client of the function does >> explicitly check for a NULL return[2], which can only happen, if >> safe_emalloc() fails. So if no NULL checks should be done, this one >> should be removed as well. >> >> [1] >> <https://github.com/php/php-src/blob/php-5.6.24/ext/ >> standard/string.c#L2926-L2927> >> [2] >> <https://github.com/php/php-src/blob/php-5.6.24/ext/ >> standard/string.c#L3133-L3134> > > If that's the only failure condition of the function, the check can indeed > be dropped. Fine; I'll do that. > ZMM is an infallible allocator, it will bail out (or abort) if the > allocation fails. The return value should never be checked -- if it is > checked, it's a mistake. Thanks for the explanation! > If you are concerned about USE_ZEND_ALLOC=0 using a fallible allocator, the > system allocator hooks in ZMM should be adjusted to check for NULL and > abort instead (use __zend_malloc instead of malloc, for example). I don't know whether USE_ZEND_ALLOC=0 is in use on any production systems, but if that is so, that should be catered to. And maybe also to zero size allocations, which have implemention defined behavior (either NULL or a valid pointer may be returned). -- Christoph M. Becker