Re: patch to make init_array work (3nd version)

["H. J. Lu" <hjl at lucon dot org>]

On Wed, Nov 27, 2002 at 02:35:33PM -0800, David Mosberger wrote:
> Below is a revised patch to get init_array working.  This is basically
> what Richard suggested.  Roland, you suggested that the new routines
> in csu/init.c could be "static", but I don't see how this would work
> given that the routines need to be accessed from start.S.
> 
> A problem with this new approach is that the preinit_array functions
> need to be executed by csu/init.c only for statically linked programs.
> I don't know of a good way to detect this inside init.c, so I changed
> the init callback to take an extra argument (which will be ignored on
> platforms that don't support init_array).
> 
> To be honest, HJ's original solution seems nicer to me (e.g., doesn't
> require changes to platform-specific code), though I see the point
> about additional relocs.

I am not sure how this approach will work. If I get it right,
__libc_do_init_calls and __libc_do_fini_calls are defined in
executables. But they are only available when executables are
linked against with the new glibc. For the existing executables,
there are no __libc_do_init_calls nor __libc_do_fini_calls. That
is why my original solution has

#ifdef HAVE_INITFINI_ARRAY
# ifdef SHARED
extern void __libc_init_array (void) __attribute__ ((weak));
extern void __libc_fini_array (void) __attribute__ ((weak));
# else
extern void __libc_preinit_array (void); 
extern void __libc_init_array (void); 
extern void __libc_fini_array (void); 
# endif
#endif

...

#ifdef HAVE_INITFINI_ARRAY
# ifdef SHARED
  if (__libc_fini_array)
# endif
    __cxa_atexit ((void (*) (void *)) __libc_fini_array, NULL, NULL);

# ifndef SHARED
  __libc_preinit_array ();
# endif
#endif

which will work with all exutables.

> 
> Note: the patch below makes init_array working on ia64 only.  Other
> platforms would have to make the analogous (trivial) change to
> start.S.
> 
> In terms of testing, "make check" passed, so the basics seem to be
> right.
> 
> 	--david
> 
> ChangeLog
> 
> 2002-11-27  David Mosberger  <davidm@hpl.hp.com>
> 
> 	* sysdeps/generic/libc-start.c (__libc_start_main): Declare
> 	INIT callback as taking an integer argument indicating whether
> 	program is a statically-linked executable.  Update call-site
> 	accordingly.
> 
> 	* elf/Makefile (tests): Re-enable init_array tests.
> 
> 	* csu/init.c (__preinit_array_start): Declare.
> 	(__preinit_array_end): Ditto.
> 	(__init_array_start): Ditto.
> 	(__init_array_end): Ditto.
> 	(__fini_array_start): Ditto.
> 	(__fini_array_end): Ditto.
> 	(_init): Declare as an external function.
> 	(_fini): Ditto.
> 	(__libc_do_init_calls): New function.
> 	(__libc_do_fini_calls): Ditto.
> 

You missed the ChangeLog entry for sysdeps/ia64/elf/start.S.


H.J.