When opening a BFD for update, as gdb --write does, modifications to
anything but the contents of sections is restricted.
Do not try to write back any ELF headers in this case.
bfd/ChangeLog
2018-09-24 Jozef Lawrynowicz <jozef.l@mittosystems.com>
PR gdb/20948
* elf.c (_bfd_elf_write_object_contents): Return from function
early if abfd->direction == both_direction.
gdb/testsuite/ChangeLog
2018-09-24 Jozef Lawrynowicz <jozef.l@mittosystems.com>
PR gdb/20948
* gdb.base/write_mem.exp: New test.
* gdb.base/write_mem.c: Likewise.
Jozef Lawrynowicz