Re: Stuff dragged in by crt1 (was Re: Announce: initrd-tftp 0.1)

[Zack Weinberg]

On Mon, Jan 10, 2000 at 03:41:31PM -0800, Ulrich Drepper wrote:
> Zack Weinberg <[e-mail]> writes:
> 
> > I created an internal entry point that doesn't use malloc, which is safe
> > because we're executing before any user code does so we know we have room
> > in the static atexit table.
> 
> That's not true.  Global constructors unfortunately exist and it is
> allowed (and through C++ code will happen very frequently) to call
> atexit etc.
> 
> There is a problem with all these constructors and until we have
> priorities in constructors (or at least the preinit support) there
> will always be problems popping up.

I know about global constructors, but if you look closely at libc-start.c
you will see that what I said is still true.

  /* Register the destructor of the dynamic linker if there is any.  */
  if (rtld_fini != NULL)
    __internal_atexit (rtld_fini);

  /* Call the initializer of the libc.  */
  __libc_init_first (argc, argv, __environ);

  /* Register the destructor of the program, if any.  */
  if (fini)
    __internal_atexit (fini);

  /* Call the initializer of the program, if any.  */
  if (init)
    (*init) ();

The constructors you are worried about are all executed by (*init)().
We control the code executed by __libc_init_first, and in the current source
base none of it calls atexit.  Therefore, we can be absolutely certain that
the above __internal_atexit calls are safe.

zw