[patch] init_array/fini_array support

[Joakim Tjernlund]

> libpthreads.so:
> 
> int *__strong_errno_location() {
>    /* the correct libpthreads implementation */ }
> 
> /* no definition of __errno_location */
> 
> libc.so:
> 
> extern int * (weak __strong_errno_location) ();
>   /* i.e. a weak reference to a strong symbol */
> 
> int *__errno_location() {
>    if (__strong_errno_location != 0)
>       return __strong_errno_location();
>    /* do the old implementation */
> }

You can do this a little better:
extern int * (weak __strong_errno_location) ();
int * (*my_errno_location) () = __strong_errno_location;

at init do:
if (!my_errno_location)
  my_errno_location = my_old_errno_location;

then use in your code:
    my_errno_location();

 Jocke
> 
> I.e. in libc check to see if there is an alternate implementation.
> 
> This code is effectively implementing 'strong' definitions in 
> C - that seems a waste of time to me since they can be 
> implemented in ld.so!
> 
> The code also has a significan overhead - the extra test on 
> each reference to (errno), it's doing run-time-weak rather 
> than dynamic-link-time-weak!
> 
> John Bowler <jbowler at acm.org>
> 
> 
>