[Python-Dev] Debug entry points for PyMalloc

[Tim Peters]

[Michael Hudson]
> ...
> Presuambly it would be possible to do this wrapped around malloc() &
> free() too?

Provided they were spelled PyMem_Malloc etc, sure.  The debug routines as
sketched don't make any secret assumptions about the underlying allocators
they call.

> No real point, I guess.

There may be an excellent point to it:  one of the pad bytes could be used
to record which "API family" a block of memory came from.  Then a
mismatching realloc/free could be caught directly at the time it happened.

>> + The Debug free first uses the address to find the number of bytes
>>   originally asked for, then checks the 8 bytes on each end for
>>   sanity (in particular, that the PYMALLOC_FORBIDDENBYTEs are still
>>   intact).
>>   XXX Make this checking a distinct entry point.

> Yes.  Particularly if you can call it from gdb.

Is something extraordinary required to make that possible?  I had in mind
nothing fancier than

extern void _PyMalloc_DebugCheckAddress(void* p);

> ...
> Is it worth having an option where you *don't* call _Free?

Not if I have to code it.

> ...
> What are you waiting for? <wink>

For endless silly objections to fade away <wink>.