Re: [patch] Fix uninitialized section index internal error

[Joel Brobecker <brobecker at act-europe dot fr>]

Hi Elena,

  thank you very much for reviewing this patch.

> I see what's happening, your symbol is in section scSBss and not in scBss.
> This macro in mdebugread.c:
> SC_IS_BSS(sc) ((sc) == scBss || (sc) == scSBss)
> 
> evaluates to true, so you get to execute:
> 
> 	  else if (SC_IS_BSS (ext_in->asym.sc))
> 	    {
> 	      ms_type = mst_bss;
> 	      svalue += ANOFFSET (objfile->section_offsets, SECT_OFF_BSS (objfile));
> 
> or (a few lines below):
> 
> 	  else if (SC_IS_BSS (ext_in->asym.sc))
> 	    {
> 	      ms_type = mst_file_bss;
> 	      svalue += ANOFFSET (objfile->section_offsets, SECT_OFF_BSS (objfile));
> 	    }
> 
> 
> The SECT_OFF_BSS then is -1. It shouldn't be used in this case,
> because the symbol may not be in the bss section.
> 
> That said, may I suggest a different approach?  I think the bug is
> really in mdebugread.c, not symfile.c.  I think the SC_IS_BSS macro
> should be split in 2 separate ones: a proper SC_IS_BSS and another
> SC_IS_SBSS for your case.  Then the above code would work ok, if you
> don't have the .bss section, because it wouldn't trigger.  As for the
> SC_IS_SBSS case, you would have to figure out what the correct value
> to be added to svalue needs to be, and for this you need to find the
> index of the .sbss section.

  Ok, our patch was based on the assumption that the .bss and .sbss
sections were mutually exclusive. Your approach is more solid. 

May I suggest then to go a little further with your approach, which
cries out for the addition of a new sect_index_sbss in the objfile
structure:
  - in struct objfile (objfiles.h), add a new section index called
    sect_index_sbss
  - still in objfiles.h, add a new SECT_OFF_SBSS macro
  - initialize the sbss section index in default_symfile_offset
    (symfile.c) at the same time we're initializing the indexes of
    the other common sections
  - in mdebugread.c, fix the SC_IS_BSS macro, add a new SC_IS_SBSS
    macro, and then update the parse_partial_symbols () procedure
    to use the .sbss section if the symbol is there

If you agree with this approach, I'll then submit the new patch.

Thanks,
-- 
Joel