[openssl-users] Changing malloc/debug stuff

[Jakob Bohm]

On 17/12/2015 19:03, Salz, Rich wrote:
>> I don't need it so I don't object.  But if anyone objects, you could write a ...
> Good point!
>
>> I guess this is because that interface is not a part of a commercial grade full
>> featured SSL/TLS and general purpose crypto library, it is just a means to do
>> quality assurance on said library.
> That seems to be the main usage, yes.  I think it had more uses in the early days such as on old windows/msdos?
Old Windows/msdos was the most widespread platform where
the compiler provided malloc/free tended to be crap and
had to be overridden in a compiler specific way to make
it work reasonably.  Note that this was a *compiler*
specific issue and tended to depend on both the brand,
version and sometimes even command line options of the
compiler.

However even for Win16, MS-DOS and OS/2 16-bit, the
ability to redirect all memory calls through a user
provided set of malloc/free/realloc/msize functions
would do the job.  The hard part was writing those
override functions, even with a your copies of TAOCP
and K&R (2nd ed) handy.

A completely different use for special memory
allocation work would be to take advantage of
algorithm specific knowledge to optimize allocation
and system call patterns, such as keeping all the
small allocations for a decoded X.509 certificate or
all the intermediaries for an RSA calculation
together.


Enjoy and Merry Christmas

Jakob
-- 
Jakob Bohm, CIO, Partner, WiseMo A/S.  https://www.wisemo.com
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