Re: [PATCH] opcache bug #69090, prepend user identifier to keys

On Nov 15, 2016 18:50, Nikita Popov <nikita.ppv@gmail.com> wrote: > > On Tue, Nov 15, 2016 at 4:19 PM, Dmitry Stogov <dmitry@zend.com> wrote: >> >> New patch, attached to bug report, should fix both problems. >> >> I'm going to commit it tomorrow, if no objections. >> >> >> Thanks. Dmitry. > > For the new validate_root patch, wouldn't we still end up with inode collisions caused by > the hash function? It looks like for inodes > 2^16 collisions should be "common". > > Nikita It's not a problem to add inode check, but I think we don't need it. Let S1 and S2 strings, R1 and R2 root_hashes and F a hash function. You propose the following comparison for collision checks F(S1) ^ R1 == F(S2) ^ R2 && R1 == R2 && S1 == S2 R1 == R2 seems useless. The existing condition: F(S1) ^ R1 == F(S2) ^ R2 && S1 == S2 fails if S1 != S2 independently on R1 and R2. If S1 and S2 are the same, than F(S1) equal to F(S2) and consequently, to satisfy the whole condition, R1 should be equal to R2 Am I wrong? Thanks. Dmitry.