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

[Mark Wielaard <mjw at redhat dot com>]

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.
- src/elfcmp.c seems fine, just checks both files have the same stripped
  out sections.
- src/strip.c ebl_section_strip_p usage looks fine since it doesn't
  interpret the section data, but a testcase would be nice. But
  ebl_debugscn_p is used to see if --reloc-debug-sections makes
  sense, and it won't be able to handle zdebug sections.
- libelf/elf32_checksum.c: Seems fine since it just uses the raw
  data to calculate the checksum. O, and it seems SECTION_STRIP_P
  doesn't actually depend on ebl_debugscn_p anymore, despite the
  /* The SECTION_STRIP_P macro wants to call into libebl which we cannot
   do and do not have to do here.  Provide a dummy replacement.  */
  #define ebl_debugscn_p(ebl, name) true
  We should probably remove that then while we are at it.
- src/ldgeneric.c and src/ldscript.y might be fine, but I don't
  really know this code.
- src/readelf.c doesn't use it yet, but this patch will introduce it.
  Should be fine since all section data is accessed through libdw which
  would have uncompressed it.

Cheers,

Mark