[Python-Dev] Newly Built Python3 Binary Throws Segfault

Victor Stinner victor.stinner at gmail.com
Fri Jan 30 21:04:16 CET 2015 

Android provides a minimal support of locales. Most functions return a
fake result, do nothing. I'm not sure that it supports any codec. To
support Android, we may force UTF-8 for the filesystem encoding, as
done on Mac OS X.

Victor

2015-01-30 19:04 GMT+01:00 Ryan Gonzalez <rymg19 at gmail.com>:
> No...
>
> ...but I think I found the issue with grep. Try applying the attached patch
> to the Python/frozenmain.c. It comments out the locale handling.
>
> It seems that Python always calls its strdup function on the locale string.
> On Android, this can apparently be null (as seen in the bug report you
> linked to).
>
> On Fri, Jan 30, 2015 at 12:00 PM, Cyd Haselton <chaselton at gmail.com> wrote:
>>
>> I don't have gdb on device; does the following tell you where Python's
>> strdup is called?
>>
>> >> _PyMem_RawStrdup
>> >> /bld/python/Python-3.4.2/Objects/obmalloc.c:323
>>
>> On Fri, Jan 30, 2015 at 11:52 AM, Ryan Gonzalez <rymg19 at gmail.com> wrote:
>> > Is it possible at all to get a stack trace of the crash using gdb? Try
>> > the
>> > steps here.
>> >
>> > That way we can see where Python's own strdup function is getting
>> > called.
>> >
>> > 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)
>> >> >>>>
>> >> >>>> ________________________________
>> >> >>>>
>> >> >>>>  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/rymg19%40gmail.com
>> >> >>>
>> >> >>>
>> >> >>>
>> >> >>>
>> >> >>>
>> >> >>>  --
>> >> >>>  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/
>> >
>> >
>> >
>> >
>> > --
>> > 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/
>
>
>
>
> --
> 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/
>
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