Wrappers for custom allocators

[fcoiffie]

Is it possible to catch and to track calls to custom allocators (malloc()/free() like functions) (for detecting memory leaks) ?

In my specific case, I'm using DPDK which provides its own memory management functions (https://doc.dpdk.org/api/rte__malloc_8h.html). For this kind of heavy load application, Valgrind is unusable. MALT seems to work with my application for usual malloc()/free() but I would like to extend its use to the custom allocator.

[svalat]

Hi, yes we can make it without too much work, this is a really interesting use case.

I had the question at FOSDEM in the audience (maybe that's you ;)).

Will do somthing.

So I would think you have somehting like my_malloc()/my_free() inside your projet and I can find a way to intercept and redirect onto my malloc tracking.

I just need a clean way to pass as parameter to build a libray in flight or give hints to do your own by hand. That would match your expectation ?

Also, your internal alloc is inside a .so file ? Or built-in directly your executable ? For second case you will need to at least link a dedicated .so file pointing malt or just providing override capability on your funcitons.

[fcoiffie]

Hi,

I didn't attend FOSDEM but glad to know that someone else has the same needs.

As we link the allocation library statically with our executable, I think will have to modify the implementation itself (or use a little wrapper) but it's not a real problem.

[svalat]

Ok, thanks for details. So I will first provide functions you can call by linking a fake lib to your code or something similar. That might be fine for a first try then I will look on more automatic interception of allocators in .so files.

[svalat]

This is now done by providing some options on the malt command :

malt --wrap malloc:je_malloc,free:je_free ./prgm

Or more generic to wrap all the memoy managment function under a given prefix:

malt --wrap-prefix je_ ./prgm

You can wrap several prefix or set of function.

The only limitation is that you will not distinguish them from standard malloc in the final profile.