[Python-Dev] Newly Built Python3 Binary Throws Segfault

[Cyd Haselton]

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
>>>>>>>> ________________________________
>>>>>>>>
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>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>  --
>>>>>>>  --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/