Re: [PATCH v3 3/6] libdwelf: Add dwelf_dwarf_gnu_debugaltlink

[Mark Wielaard <mjw at redhat dot com>]

> On Thu, 2014-04-24 at 14:23 +0200, Florian Weimer wrote:
> > Do you want me to resubmit the final part concerning libdwfl?
>
> No, thanks. I am experimenting with that patch and changed it to use the
> Dwfl find_debuginfo callback to locate the altlink file so that the user
> can override the search strategy (and put all resources in the Dwfl so
> the free_alt flag in libdw is unnecessary).
> 
> I'll post the modified patch when I get it working properly and have it
> rebased against your work again.

Sorry, that took longer than anticipated. What I ended up with is your
original patch to Move .gnu_debugaltlink handling from libdw to libdwfl.
And then I added 3 additional patches on top of it:
- libdwelf: Add dwelf_elf_gnu_build_id.
- libdwfl: Move dwz alt multi file searching to find_debuginfo.
- Remove --enable-dwz. dwz alt debug is no longer experimental.

That should make it easier to see what changes were really made.
The real change is the "libdwfl: Move dwz alt multi file searching to
find_debuginfo." one. That makes it so that the standard callbacks
dwfl_build_id_find_debuginfo and dwfl_standard_find_debuginfo will
now try to resolve and set the alternative debug file depending on
the given debuginfo_path. When using the build-id it works exactly as
finding the separate debug file since an alt file is exactly like that.
When using a path based lookup with the default path it will look in the
directory of the main or debug file and under /usr/lib/debug/.dwz. But
the user can of course adjust the debuginfo_path or provide its own
find_debuginfo callback. It was tested against systemtap which has a
non-trivial find_debuginfo callback and it works completely unchanged.

Finally I made --enable-dwz the default and removed the EXPERIMENTAL
marker.

All patches are on the mjw/dwelf branch and I'll post them as follow-ups
to this message. The first 6 have already been discussed a couple of
times on the list. Let me know if there are any concerns with the last
3 or with pushing the whole branch to master.

Thanks,

Mark