Re: DIE chains not ending with null entry

[Roland McGrath <roland at redhat dot com>]

> The thing is, many real-world DWARF files have this problem, so the

Really?  Do you have examples?  Are they generated by current compilers?

> message is now only a warning in --strict mode, and such files have
> always been deemed safe for consumption by <dwarf>.  Alas, the case that
> we see here is special:
> 
>   Dwarf_Die die_mem, *die = dwarf_offdie (dw, 0xab, &die_mem);
>   Dwarf_Die child;
>   dwarf_child (die, &child); // this actually passes
> 
> So libdw happily gives us a DIE that supposedly lies at 0xb1,
> interpreting the first bytes of .debug_abbrev as DIE.

I agree that this is a libdw bug.

> I might turn that combination (empty chain + no null entry) into a hard
> error in dwarflint, but that seems rather convoluted.  I think this is
> something that should be fixed in libdw.  I've done that, the result is
> on the branch pmachata/dwarf_child_overrun.

I committed it with some cosmetic cleanup.


Thanks,
Roland