[PATCH v2] Guard against 'current_directory == NULL' on gdb_abspath (PR gdb/23613)

[Tom Tromey]

>>>>> "Sergio" == Sergio Durigan Junior <sergiodj@redhat.com> writes:

Sergio> gdb/ChangeLog:
Sergio> 2019-11-21  Sergio Durigan Junior  <sergiodj@redhat.com>

Sergio> 	https://bugzilla.redhat.com/show_bug.cgi?id=1728147
Sergio> 	PR gdb/23613
Sergio> 	* bsd-kvm.c (bsd_kvm_target_open): Use 'gdb_abspath'.
Sergio> 	* corelow.c: Include 'gdbsupport/pathstuff.h'.
Sergio> 	(core_target_open): Use 'gdb_abspath'.
Sergio> 	* gdbsupport/pathstuff.c (gdb_abspath): Guard against
Sergio> 	'current_directory == NULL' case.
Sergio> 	* gdbsupport/pathstuff.h (gdb_abspath): Expand comment and
Sergio> 	explain what happens when 'current_directory' is NULL.
Sergio> 	* go32-nat.c (go32_nat_target::wait): Check if
Sergio> 	'current_directory' is NULL before call to 'chdir'.
Sergio> 	* source.c (add_path): Use 'gdb_abspath'.
Sergio> 	* top.c: Include 'gdbsupport/pathstuff.h'.
Sergio> 	(init_history): Use 'gdb_abspath'.
Sergio> 	(set_history_filename): Likewise.
Sergio> 	* tracefile-tfile.c: Include 'gdbsupport/pathstuff.h'.
Sergio> 	(tfile_target_open): Use 'gdb_abspath'.

Thanks.  This is ok.

Tom