From: Christian Franke <Christian.Franke@t-online.de>
To: cygwin@cygwin.com
Subject: Re: gcc-6.3.0-1 regression: libstdc++6 DLL breaks exception handling
Date: Tue, 07 Feb 2017 15:27:00 -0000 [thread overview]
Message-ID: <a4c62a64-5570-e39c-a8b5-d659fdbfbc6d@t-online.de> (raw)
In-Reply-To: <dcea951e-96f2-b592-4804-1c58abf84a83@gmail.com>
JonY wrote:
> On 01/26/2017 10:30 AM, Christian Franke wrote:
>> After upgrading to gcc test version 6.3.0-1, C++ exception handling is
>> broken if DLL version of new libstdc++6 is used.
>>
> Noted, I'll consider the test version broken for now.
>
>
Meantime I examined the testcase with gdb: The DLL exports a bogus
address for the symbol "_ZTIi" ('typeinfo for int'). This results in
this more simple testcase:
#include <typeinfo>
int main() {
const std::type_info & ti = typeid(int); // &_ZTIi from DLL
const char * p = ti.name(); // segfaults because &_ZTIi is bogus.
}
And indeed, the export table of the DLL looks 'interesting'. The offsets
of various exported symbols are apparently all 93980000:
$ objdump -p cygstdc++-6.dll
[5142] +base[5143] c6760 Export RVA
[5143] +base[5144] c6768 Export RVA
[5144] +base[5145] 93980000 Export RVA
...
[5151] +base[5152] 93980000 Export RVA
[5152] +base[5153] 93980000 Export RVA
[5153] +base[5154] 93980000 Export RVA
[5154] +base[5155] 93980000 Export RVA
...
[5167] +base[5168] 93980000 Export RVA
[5168] +base[5169] c6780 Export RVA
...
[Ordinal/Name Pointer] Table
...
[5143] _ZTISt9type_info
[5144] _ZTIa
...
[5151] _ZTIh
[5152] _ZTIi
[5153] _ZTIj
[5154] _ZTIl
...
[5167] _ZTSDs
[5168] _ZTSN10__cxxabiv115__forced_unwindE
$ objdump -p cygstdc++-6.dll | grep -cw 93980000
759
Hmm... bug in the (bin)utils used to build the DLL?
Possibly related:
https://cygwin.com/ml/cygwin/2017-01/msg00375.html
Christian
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prev parent reply other threads:[~2017-02-07 15:27 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-26 10:31 Christian Franke
2017-02-07 10:04 ` JonY
2017-02-07 15:27 ` Christian Franke [this message]
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