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Re: [PATCH] libdw: fix offset for sig8 lookup in dwarf_formref_die
- From: Jason Leasure <jpleasu at super dot org>
- To: elfutils-devel at lists dot fedorahosted dot org
- Date: Wed, 14 Jan 2015 12:14:47 -0500
- Subject: Re: [PATCH] libdw: fix offset for sig8 lookup in dwarf_formref_die
On 01/14/2015 11:47 AM, Mark Wielaard wrote:
> On Wed, 2015-01-14 at 09:26 -0500, Jason P. Leasure wrote:
>> The type_offset of a type unit header is relative to the beginning
>> of the type unit header.
>>
>> Signed-off-by: Jason P. Leasure <jpleasu@super.org>
>> ---
>> libdw/dwarf_formref_die.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/libdw/dwarf_formref_die.c b/libdw/dwarf_formref_die.c
>> index 63f6697..8b92e22 100644
>> --- a/libdw/dwarf_formref_die.c
>> +++ b/libdw/dwarf_formref_die.c
>> @@ -95,7 +95,7 @@ dwarf_formref_die (attr, result)
>>
>> datap = cu->dbg->sectiondata[IDX_debug_types]->d_buf;
>> size = cu->dbg->sectiondata[IDX_debug_types]->d_size;
>> - offset = cu->type_offset;
>> + offset = cu->start + cu->type_offset;
> Thanks, I believe this is correct. I am surprised we didn't encounter
> this earlier. Do you happen to have a testcase for it?
>
> Cheers,
>
> Mark
Sorry, I don't have a good testcase, but you can generate a binary with
two type units in the debug_types section using:
echo 'struct A{ struct B {} x;};int main(){A a;return 0;}' | g++ -x
c++ -g -fdebug-types-section -
to see the global die offsets:
dwarfdump -Gi ./a.out
Jason