[Python-Dev] Newly Built Python3 Binary Throws Segfault

[Cyd Haselton]

Alternatively, is there a hassle-free way to find out what changed in
obmalloc.c between 2.7.x and 3.4.x?


On Fri, Jan 30, 2015 at 9:29 AM, Cyd Haselton <chaselton at gmail.com> wrote:
> There's a related strdup patch for readline.c, mentioned
> here:http://bugs.python.org/issue21390 and here
> https://github.com/rave-engine/python3-android/issues/2.
> There's a patch, but I'm not sure how to modify it for obmalloc.c, as
> (I think) the functions all belong to Python...they're all prefixed
> with _PyXx
>
> On Fri, Jan 30, 2015 at 9:05 AM, Cyd Haselton <chaselton at gmail.com> wrote:
>> Absolutely.  Good thing I have addr2line on device
>>
>> /bld/python/Python-3.4.2 $ addr2line -C -f -e /lib/libpython3.4m.so.1.0 0008bbc8
>> _PyMem_RawStrdup
>> /bld/python/Python-3.4.2/Objects/obmalloc.c:323
>> /bld/python/Python-3.4.2 $
>>
>>
>>
>> On Thu, Jan 29, 2015 at 8:26 PM, Ryan <rymg19 at gmail.com> wrote:
>>> Could you try the steps at http://stackoverflow.com/a/11369475/2097780? They
>>> allow you to get a better idea of where libc is crashing.
>>>
>>> Cyd Haselton <chaselton at gmail.com> wrote:
>>>>
>>>> Managed to get this out of logcat:
>>>> F(11914) Fatal signal 11 (SIGSEGV) at 0x00000000 (code=1), thread
>>>> 11914 (python)  (libc)
>>>>
>>>> [ 01-29 19:30:55.855 23373:23373 F/libc     ]
>>>> Fatal signal 11 (SIGSEGV) at 0x00000000 (code=1), thread 23373 (python)
>>>>
>>>> Less detail than strace but it seems to be that python is segfaulting
>>>> libc...
>>>>
>>>> On Wed, Jan 28, 2015 at 11:23 AM, Ryan Gonzalez <rymg19 at gmail.com> wrote:
>>>>>
>>>>>  On Wed, Jan 28, 2015 at 10:43 AM, Guido van Rossum <guido at python.org>
>>>>> wrote:
>>>>>>
>>>>>>
>>>>>>  What I see in the strace:
>>>>>>
>>>>>>  ... load libpython3.4m.so.1.0
>>>>>>  ... load libm
>>>>>>  ... open /dev/__properties__ and do something to it
>>>>>> (what?)
>>>>>>  ... get current time
>>>>>>  ... allocate memory
>>>>>>  ... getuid
>>>>>>  ... segfault
>>>>>>
>>>>>>  That's not a lot to go on, but it doesn't look as if it has started to
>>>>>>  load modules yet.
>>>>>>
>>>>>>  Does /dev/__properties__ ring a bell? Not to me.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> https://android.googlesource.com/platform/system/core/+/tools_r22/init/property_service.c
>>>>>  is the code that works with that file.
>>>>>
>>>>>  This explains it a bit (slides 24-29). Looks like something to do with
>>>>>  interprocess communication. Likely has nothing to do with Python itself.
>>>>>
>>>>>  Maybe this would be useful?
>>>>>
>>>>>>
>>>>>>  That stack trace would be really helpful.
>>>>>>
>>>>>>  On Wed, Jan 28, 2015 at 8:34 AM, Cyd Haselton <chaselton at gmail.com>
>>>>>> wrote:
>>>>>>>
>>>>>>>
>>>>>>>  Apologies...I'm not sure what a stack track is, but I do have the
>>>>>>>  strace.  Nearest I can tell, it happens due to an open call, though I
>>>>>>>  am probably wrong.
>>>>>>>  Attaching the strace output to this email.  I'm going to head back to
>>>>>>>  the documentation and to back out of some Android-related changes in
>>>>>>>  _localemodule.c
>>>>>>>
>>>>>>>  On Wed, Jan 28, 2015 at 9:43 AM, Guido van Rossum <guido at python.org>
>>>>>>>  wrote:
>>>>>>>>
>>>>>>>>  There could be a million differences relevant (unicode, ints, ...).
>>>>>>>>  Perhaps
>>>>>>>>  the importlib bootstrap is failing. Perhaps the dynamic loading code
>>>>>>>>  changed. Did you get a stack track? (IIRC strace shows a syscall
>>>>>>>> trace
>>>>>>>>  --
>>>>>>>>  also useful, but doesn't tell you precisely how
>>>>>>>> it segfaulted.)
>>>>>>>>
>>>>>>>>  On Wed, Jan 28, 2015 at 6:43 AM, Cyd Haselton <chaselton at gmail.com>
>>>>>>>>  wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>  All,
>>>>>>>>>  I recently ditched my attempts to port Python 2.7.8 to Android in
>>>>>>>>>  favor of Python 3.4.2.  Unfortunately, after using the same
>>>>>>>>> configure
>>>>>>>>>  options in the same environment, and modifying the setup.py as
>>>>>>>>> needed,
>>>>>>>>>  the newly built binary throws a segfault when the
>>>>>>>>> generate-posix-vars
>>>>>>>>>  portion of the build is reached...and when it is run as well (i.e.
>>>>>>>>>  ./python --help, ./python -E -S -m sysconfig, or similar)
>>>>>>>>>
>>>>>>>>>  I took a strace of ./python, however I'm a bit lost when reviewing
>>>>>>>>> it.
>>>>>>>>>  Any ideas as to what may be going on...i.e. why Python 2.7 works but
>>>>>>>>>  3.x throws a segfault?
>>>>>>>>>
>>>>>>>>>  Thanks in advance,
>>>>>>>>>  Cyd
>>>>>>>>> ________________________________
>>>>>>>>>
>>>>>>>>>  Python-Dev mailing list
>>>>>>>>>
>>>>>>>>> Python-Dev at python.org
>>>>>>>>>  https://mail.python.org/mailman/listinfo/python-dev
>>>>>>>>>  Unsubscribe:
>>>>>>>>>
>>>>>>>>> https://mail.python.org/mailman/options/python-dev/guido%40python.org
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>  --
>>>>>>>>  --Guido van Rossum (python.org/~guido)
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>  --
>>>>>>  --Guido van Rossum (python.org/~guido)
>>>>>>
>>>>>> ________________________________
>>>>>>
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>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>  --
>>>>>  Ryan
>>>>>  If anybody ever asks me why I prefer C++ to C, my answer will be simple:
>>>>>  "It's becauseslejfp23(@#Q*(E*EIdc-SEGFAULT. Wait, I don't think that was
>>>>>  nul-terminated."
>>>>>  Personal reality distortion fields are immune to contradictory evidence.
>>>>> -
>>>>>  srean
>>>>>  Check out my website: http://kirbyfan64.github.io/
>>>
>>>
>>> --
>>> Sent from my Android phone with K-9 Mail. Please excuse my brevity.
>>> Check out my website: http://kirbyfan64.github.io/