________________________________________ From: openssl-dev <openssl-dev-boun...@openssl.org> on behalf of Richard Levitte <levi...@openssl.org> Sent: Friday, January 22, 2016 2:20 AM To: openssl-dev@openssl.org Subject: Re: [openssl-dev] [eng_rdrand] alloc and free
In message <db5pr04mb1302bb3b91a8955dc8bb1dcfee...@db5pr04mb1302.eurprd04.prod.outlook.com> on Thu, 21 Jan 2016 10:57:19 +0000, Catalin Vasile <cata.vas...@nxp.com> said: cata.vasile> ENGINE_load_rdrand() creates a new engine, it adds cata.vasile> it/registers it and then frees it. Looking further into cata.vasile> these functions, the registration does NOT create a new cata.vasile> object and then copy the data into it, so the cata.vasile> registration is based on an object that it's later cata.vasile> released. Welllll.... not quite! Pointers to engines aren't merely pointers, they are more like handles and have reference counters. So, the called `ENGINE *toad = ENGINE_rdrand()' will create the reference to a new ENGINE object, that is correct. Three lines later, the call `ENGINE_add(toadd)' will create a new reference to the same object, by incrementing the reference counter, and will store the pointer to the object in OpenSSL's internal list. The following call `ENGINE_free(toadd)' simply decrements the reference counter (from 2 to 1) but does not actually free the object (that would require another ENGINE_free). Does that make it clearer? Absolutely clear For further info, may I suggest you do `perldoc doc/crypto/engine.pod', and most specifically read the section titled "Reference counting and handles"? Thanks for the reference. Cheers, Richard -- Richard Levitte levi...@openssl.org OpenSSL Project http://www.openssl.org/~levitte/ _______________________________________________ openssl-dev mailing list To unsubscribe: https://mta.openssl.org/mailman/listinfo/openssl-dev _______________________________________________ openssl-dev mailing list To unsubscribe: https://mta.openssl.org/mailman/listinfo/openssl-dev
