Re: [patch] Set bfd field in target_section

Pedro Alves
2009-07-28T15:06:14Z

On Tuesday 28 July 2009 15:45:25, Aleksandar Ristovski wrote:
> Pedro Alves wrote:
> > On Tuesday 28 July 2009 15:28:33, Aleksandar Ristovski wrote:
> >> Hello,
> >>
> >> I believe this is related to Pedro's patch from 03-Jun-09. I
> >> didn't see where we set target_section.bfd field - maybe I
> >> am overlooking something, but in bfd-target, in function
> >> target_bfd_xclose we will call bfd_close
> >> (table->sections->bfd); bfd_close doesn't like NULL argument.
> >>
> >> Am I missing something, or is this (the patch) missing?
> >
> > Doesn't add_to_section_table set the bfd in each new
> > target section?
>
> Indeed it does. However, the problem is if we don't find any
> sections in a bfd, it will exit and will leave bfd field 0.

Right, but table->sections will be equal to table->sections_end,
meaning the table is empty. Your fix isn't correct, since you
should never write to *sections_end, which is one-past-the-end
of the sections in the table. In the degenerate case of
bfd_count_sections == 0 (not 0 ALLOC sections), xmalloc will
still return something non-NULL, but, writing to this pointer
invokes undefined behaviour.

> I get this situation at the moment because I broke my
> xfer_partial, but I think it could happen in general?

Testing finished succesfully, so I've applied the patch
with this ChangeLog entry. Let me know if something is still wrong.

2009-07-28 Pedro Alves <pedro@codesourcery.com>

* bfd-target.c (target_bfd_xclose): Only close the bfd if the
section table is not empty.
(target_bfd_reopen): If the section table ends up empty, close the
bfd here.

--
Pedro Alves