Hi,


this patch introduces a framework for looking up multiply defined global symbols 
from shared libraries. Solib handler like for example solib-svr4.c can now install a callback 
to implement a library-specific routine for looking up global symbols.


As an example I implemented a special lookup routine for ELF shared libraries
linked with -Bsymbolic. While the focus is within such a library, the global 
symbol lookup shall first search for the symbol within this library and then
go through the main executable if not found.

The patch also includes a testcase for this new feature. The testsuite
showed no regressions.

I would appreciate your comment on this patch. Would this be ok for mainline?
Thanks in advance.

ChangeLog:
	* cp-namespace.c (lookup_symbol_file): Add block
	to call for lookup_symbol_global.
	* Makefile.in (solist_h): Update dependencies.
	(solib.o): Likewise.
	(symtab.o): Likewise.
	* solib.c: New include "symtab.h".
	(solib_global_lookup): New function.
	* solib-svr4.c (has_SYMBOLIC): New function.
	(elf_lookup_lib_symbol): New function.
	(_initialize_svr4_solib): Add elf_lookup_lib_symbol
	to svr4_so_ops.
	* solist.h: New include "symtab.h".
	(target_so_ops): New member lookup_lib_global_symbol.
	(solib_global_lookup): Declare.
	* symtab.c: New include "solist.h".
	(lookup_objfile_from_block): New function.
	(lookup_global_symbol_from_objfile): New function.
	(basic_lookup_symbol_nonlocal): Add block to call
	for lookup_symbol_global.
	(lookup_symbol_global): Change lookup order. First
	call solib_global_lookup then lookup global symbol
	in both symtab and psymtab.
	* symtab.h (lookup_symbol_global): Add block to
	declaration.
	(lookup_objfile_from_block): Declare.
	(lookup_global_symbol_from_objfile): Declare.
	* gdb.base/libmd.c: New file for testcase.
	* gdb.base/libmd.h: Likewise.
	* gdb.base/solib_symbol.c: Likewise.
	* gdb.base/solib_symbol.exp: New testcase for
	multiply defined global symbol lookup.


-- 
Markus Deuling
GNU Toolchain for Linux on Cell BE
deuling@de.ibm.com