Bluetooth address macros are broken

[zooey]

The bluetooth.h header defines these bdaddr_t macros:

#define BDADDR_NULL		(&(bdaddr_t) {{0, 0, 0, 0, 0, 0}})
#define BDADDR_LOCAL		(&(bdaddr_t) {{0, 0, 0, 0xff, 0xff, 0xff}})
#define BDADDR_BROADCAST	(&(bdaddr_t) {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff}})

However, the concept of getting an address of a compound literal is pretty much broken, as compound literals are neither part of the C++ standard (though gcc supports them) and their lifetime is not well-controlled inside of a macro.

As an example:

struct foo {
    bdaddr_t peer;
};

void bar()
{
    foo myfoo;
    if (...)
        myfoo.peer = BDADDR_LOCAL;
    else
        myfoo.peer = BDADDR_NULL;

    // try doing something with myfoo, but the actuall bdaddr_t object will
    // be dead here already, so the data at the address myfoo.peer may have
    // been overwritten
}

Instead, I suggest doing something along the lines of:

extern const bdaddr_t __BDADDR_NULL;
extern const bdaddr_t __BDADDR_LOCAL;
extern const bdaddr_t __BDADDR_BROADCAST;

#define BDADDR_NULL		(&__BDADDR_NULL)
#define BDADDR_LOCAL		(&__BDADDR_LOCAL)
#define BDADDR_BROADCAST	(&__BDADDR_BROADCAST)

and then define these constants somewhere in an implementation file that gets linked by all users of those macros.

[zooey]

Should be fixed in hrev38213.

[oruizdorantes]

Hi,

The problem of this solution is that these data needs to be explicitly instantiated in each module using it.

Have you tried declarig them inside the class(bdaddrUtils) as a static member? I wonder if this results in symbol duplication at linking.

Regards.

[zooey]

Right - thanks for the note.

Reverted hrev38213 and fixed differently in hrev38265.

[oruizdorantes]

Thank you for your time devoted in this, was in my TODO :)