[RFC, gdb/contrib] Fix gdb/contrib/gdb-add-index.sh for dwz-m-ed execs

[Tom de Vries]

On 12-05-19 21:49, Simon Marchi wrote:
> On 2019-05-07 12:13 p.m., Tom de Vries wrote:
>> [ was: Re: [PATCH][gdb] Write index for dwz -m file ]
>>
>>
>> Hi,
>>
>> This is a follow-up patch for "[gdb] Write index for dwz -m file".
>>
>> Any comments on the updated gdb/contrib/gdb-add-index.sh script?
>>
>> In particular, I'd like some advice on whether I should add shell
>> variables (as I've done for readelf) for grep, tail and sed.
>>
>> Thanks,
>> - Tom
>>
> 
> Hi Tom,
> 
> I think it can be useful to override gdb, readelf and objcopy, as it is likely
> that people will want to use specific versions of these (either newer, or
> specific to their architectures).
> 
> But it's not very likely for grep, tail and sed, as long as we make sure that
> we are compatible with the BSD versions of these tools.  That would mean making
> sure we only use features defined by POSIX.
> 

Ack, thanks for the insight.

> One case that isn't handled correct by GDB and/or the script (with both my and
> your patch applied) is running the script on two executables that share the same
> external dwz file.  It will fail adding the index to the dwz file the second time.
> This use case is kind of important, because the point of having dwz files is to
> share it between multiple executables.
> 
> This is what I get the second time:
> 
> $ GDB="/home/simark/build/binutils-gdb/gdb/gdb --data-directory=/home/simark/build/binutils-gdb/gdb/data-directory" ~/src/binutils-gdb/gdb/contrib/gdb-add-index.sh b
> + objcopy --add-section .gdb_index=shared-debug-info.dwz.gdb-index --set-section-flags .gdb_index=readonly shared-debug-info.dwz shared-debug-info.dwz
> objcopy:std9IdCI: can't add section '.gdb_index': file in wrong format
> 
> I haven't looked in more details for this problem.
> 

That's fixed now.

[ In a way, it's a known problem. Running gdb-add-index twice on the
same (regular, non-dwz-ed) executable, gives the same kind of error. ]

> There's a buglet in the clean up code causing the dwz file's index
> (shared-debug-info.dwz.gdb-index in my case) to be left in the current directory after
> running the script (even successfully).  This fixes it:
> 
> ---
> diff --git a/gdb/contrib/gdb-add-index.sh b/gdb/contrib/gdb-add-index.sh
> index afedce0c848d..2b3af2e84f71 100755
> --- a/gdb/contrib/gdb-add-index.sh
> +++ b/gdb/contrib/gdb-add-index.sh
> @@ -70,7 +70,7 @@ for f in "$file" "$dwz_file"; do
>      if [ "$f" = "" ]; then
>  	continue
>      fi
> -    set_files "$file"
> +    set_files "$f"
>      tmp_files="$tmp_files $index4 $index5 $debugstr $debugstrmerge $debugstrerr"
>  done

Ok, I've incorporated that fix, as well as making the handle_file
$dwz_file conditional on $dwz_file != "".

Updated version attached.

Thanks,
- Tom
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