Re: [PATCH 1/4] default_debugscn_p: Add support for compressed debug section.

[Mark Wielaard <mjw at redhat dot com>]

On Wed, 2012-08-15 at 00:54 +0200, Kurt Roeckx wrote:
> On Tue, Aug 14, 2012 at 04:18:58PM +0200, Mark Wielaard wrote:
> > On Mon, 2012-08-13 at 21:01 +0200, Mark Wielaard wrote:
> > > But this comes back to my comment on the other patch.
> > > In the case of readelf.c this makes sense, since it uses libdwfl
> > > to access the elf data it can "transparently" read the compressed
> > > data. But other callers might not be able to process compressed
> > > sections. So I think we should carefully audit all callers to
> > > make sure that if debugscn_p () returns true for a compressed
> > > section then they are actually able to process the data.
> > 
> > So a quick scan of uses of ebl_debugscn_p, ebl_section_strip_p and
> > SECTION_STRIP_P:
> > 
> > - libdwfl/relocate.c (relocate_section)
> >   Uses elf_rawdata () so won't be able to handle the section.
> 
> I assume that this is not a new problem, just something it
> didn't handle before either?

Yes, but it wouldn't even try for compressed sections before, because
ebl_debugscn_p would not return true for them.

> What would need to happen in this case?

In this case I think the easiest would be to ignore these sections for
now like before. I made the list just to see where there are behavioral
changes that we need to look at if we change this test. Testcases that
trigger the change would be good so we can decide what to do (if
anything).

There is a bug open against handling compressed debug sections more
generically: https://bugzilla.redhat.com/show_bug.cgi?id=807053


Cheers,

Mark