[PATCH 2/3] [binutils/readelf] Add fixme in display_debug_str_offsets

[Alan Modra]

On Tue, May 14, 2024 at 12:55:21PM +0200, Tom de Vries wrote:
> While reading display_debug_str_offsets, I realized that the v4 split dwarf
> handling bit doesn't assign entry_length, so it can be either 4 (32-bit dwarf)
> or 8 (64-bit dwarf).  However, I think the cases for which it'll be 8 are
> rare and odd enough to conclude that in practise we default to 32-bit
> dwarf.
> 
> As mentioned in the fission documentation [1], whether a .debug_str_offsets
> section is 32-bit or 64-bit dwarf depends on the compilation unit header in
> the .debug_info.dwo section, which is currently not inspected.
> 
> For now:
> - make an explicit choice for 32-bit dwarf by assiging 4 to entry_length, and
> - add a fixme comment.
> 
> [1] https://gcc.gnu.org/wiki/DebugFission
> ---
>  binutils/dwarf.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/binutils/dwarf.c b/binutils/dwarf.c
> index 8125c64e1b6..f49989dc536 100644
> --- a/binutils/dwarf.c
> +++ b/binutils/dwarf.c
> @@ -7971,6 +7971,14 @@ display_debug_str_offsets (struct dwarf_section *section,
>  	  entries_end = end;
>  	  debug_str_offsets_hdr_len = 0;
>  
> +	  /* FIXME: We assume 32-bit dwarf here.  According to
> +	     https://gcc.gnu.org/wiki/DebugFission:
> +	     The size of each entry is 4 bytes for DWARF-32 compilation units,
> +	     or 8 bytes for DWARF-64 compilation units, as determined by the
> +	     unit_length field of the compilation unit header in the
> +	     .debug_info.dwo section.  */
> +	  entry_length = 4;
> +
>  	  printf (_("    Length: %#" PRIx64 "\n"), length);
>  	  printf (_("       Index   Offset [String]\n"));
>  	}
> -- 
> 2.35.3

I don't see the need for this patch.  If length is zero we already
have entry_length of four.

-- 
Alan Modra