This can be used to tell if a talloc stackframe is currently
available. Callers can use this to decide if they will use
talloc_tos() or instead use an alternative strategy. This gives us a
way to safely have calls to talloc_tos() in common code that may end
up in external libraries, as long as all talloc_tos() calls in these
pieces of common code check first that a stackframe is available.

This makes it easier to debug the code in future.

metze

In smbd there's a small gab between TALLOC_FREE(frame); before
be call smbd_parent_loop() where we don't have a valid talloc stackframe.

smbd_parent_loop() calls talloc_stackframe() only within the while(1) loop.
As DEBUG(2,("waiting for connections")) uses talloc_tos() to construct
the time header for the debug message we crash on some systems.

metze

- Now that we initialize for the non-thread-safe case in the macro, there's no
  need to do it here too.

Derrell

- This should make life easier for ourselves. We're no longer constrained to
  the semantics of pthread_once, so let's allow passing a parameter to the
  initialization function. Some of Samba's init functions return a
  value. Although I haven't searched, I suspect that some of the init
  functions require in input parameters. The parameter added here can be used
  for input, output, or both, as necessary... or ignored, as is now done in
  talloc_stackframe_init().

Derrell

Jeremy.

this.
Jeremy.