Re: [PATCH newlib] libc/include/malloc.h: Add prototype for GNU extension malloc_usable_size()

On Tue, Mar 15, 2022 at 4:04 PM Mike Frysinger <[email protected]> wrote:

> On 15 Mar 2022 19:42, Sebastian Huber wrote:
> > On 15/03/2022 16:47, Mike Frysinger wrote:
> > > On 15 Mar 2022 10:16, Joel Sherrill wrote:
> > >> This is not provided by the newlib malloc implementation but may
> > >> be available in external implementations.
> > >> ---
> > >>   newlib/libc/include/malloc.h | 4 ++++
> > >>   1 file changed, 4 insertions(+)
> > >>
> > >> diff --git a/newlib/libc/include/malloc.h
> b/newlib/libc/include/malloc.h
> > >> index a9dc5bca6..e73095e1e 100644
> > >> --- a/newlib/libc/include/malloc.h
> > >> +++ b/newlib/libc/include/malloc.h
> > >> @@ -137,6 +137,10 @@ extern void __malloc_lock(struct _reent *);
> > >>
> > >>   extern void __malloc_unlock(struct _reent *);
> > >>
> > >> +#if __GNU_VISIBLE
> > >> +extern size_t malloc_usable_size(void *);
> > >> +#endif
> > >> +
> > > i'm confused.  isn't this prototype already defined in this header file
> > > on line 101 above where you added this ?
> >
> > Yes, and it is implemented by the Newlib malloc.
>
> while true, we disable malloc in newlib for rtems:
>
> newlib/configure.host:
> # RTEMS supplies its own versions of some routines:
> #       malloc()            (reentrant version)
> #...
>   *-*-rtems*)
>     ...
>     newlib_cflags="${newlib_cflags} ... -DMALLOC_PROVIDED ...
>

We disable their implementation -- not the malloc.h header.

>
> so i'm not sure what trouble Joel is running into.  maybe rtems also
> provides
> its own malloc.h and that's what is missing this prototype.
>

I was reviewing the submitted code which added malloc_usable_size
to RTEMS. It also added the prototype to an RTEMS internal file. I took
it on faith that the prototype was missing and looked at the Linux man
page for where the prototype should be. Then I just stupidly missed it.

Their code should have include malloc.h and not an internal RTEMS file.

Sorry and thanks.

--joel

-mike
>