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Debugging a crash in a python native library on Android (ex, kivy)

I'm trying to debug a crash in a python extension (cythonized) from pyjnius. The crash signature is as follows:


06-05 18:41:46.111 3631-3631/com.jventura.pyapp I/System.out: + java:invoke(, public abstract void android.text.TextWatcher.beforeTextChanged(java.lang.CharSequence,int,int,int), [Ljava.lang.Object;@c30cd5c)
06-05 18:41:46.113 3631-3631/com.jventura.pyapp I/pybridge: beforeTextChanged called
06-05 18:41:46.114 3631-3631/com.jventura.pyapp A/libc: Fatal signal 11 (SIGSEGV), code 1, fault addr 0x0 in tid 3631 (.jventura.pyapp)
                                                        
                                                        [ 06-05 18:41:46.114   151:  151 W/         ]
                                                        debuggerd: handling request: pid=3631 uid=10103 gid=10103 tid=3631
06-05 18:41:46.112 4374-4374/? W/debuggerd: type=1400 audit(0.0:1696): avc: denied { search } for name="com.jventura.pyapp" dev="dm-0" ino=130503 scontext=u:r:debuggerd:s0 tcontext=u:object_r:app_data_file:s0:c512,c768 tclass=dir permissive=0
06-05 18:41:46.112 4374-4374/? W/debuggerd: type=1400 audit(0.0:1697): avc: denied { search } for name="com.jventura.pyapp" dev="dm-0" ino=130503 scontext=u:r:debuggerd:s0 tcontext=u:object_r:app_data_file:s0:c512,c768 tclass=dir permissive=0
06-05 18:41:46.112 4374-4374/? W/debuggerd: type=1400 audit(0.0:1698): avc: denied { search } for name="com.jventura.pyapp" dev="dm-0" ino=130503 scontext=u:r:debuggerd:s0 tcontext=u:object_r:app_data_file:s0:c512,c768 tclass=dir permissive=0
06-05 18:41:46.112 4374-4374/? W/debuggerd: type=1400 audit(0.0:1699): avc: denied { search } for name="com.jventura.pyapp" dev="dm-0" ino=130503 scontext=u:r:debuggerd:s0 tcontext=u:object_r:app_data_file:s0:c512,c768 tclass=dir permissive=0
06-05 18:41:46.112 4374-4374/? W/debuggerd: type=1400 audit(0.0:1700): avc: denied { search } for name="com.jventura.pyapp" dev="dm-0" ino=130503 scontext=u:r:debuggerd:s0 tcontext=u:object_r:app_data_file:s0:c512,c768 tclass=dir permissive=0
06-05 18:41:46.112 4374-4374/? W/debuggerd: type=1400 audit(0.0:1701): avc: denied { search } for name="com.jventura.pyapp" dev="dm-0" ino=130503 scontext=u:r:debuggerd:s0 tcontext=u:object_r:app_data_file:s0:c512,c768 tclass=dir permissive=0
06-05 18:41:46.112 4374-4374/? W/debuggerd: type=1400 audit(0.0:1702): avc: denied { search } for name="com.jventura.pyapp" dev="dm-0" ino=130503 scontext=u:r:debuggerd:s0 tcontext=u:object_r:app_data_file:s0:c512,c768 tclass=dir permissive=0
06-05 18:41:46.112 4374-4374/? W/debuggerd: type=1400 audit(0.0:1703): avc: denied { search } for name="com.jventura.pyapp" dev="dm-0" ino=130503 scontext=u:r:debuggerd:s0 tcontext=u:object_r:app_data_file:s0:c512,c768 tclass=dir permissive=0
06-05 18:41:46.193 4374-4374/? A/DEBUG: *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
06-05 18:41:46.193 4374-4374/? A/DEBUG: LineageOS Version: '14.1-20170502-NIGHTLY-hammerhead'
06-05 18:41:46.193 4374-4374/? A/DEBUG: Build fingerprint: 'google/hammerhead/hammerhead:6.0.1/M4B30Z/3437181:user/release-keys'
06-05 18:41:46.193 4374-4374/? A/DEBUG: Revision: '11'
06-05 18:41:46.193 4374-4374/? A/DEBUG: ABI: 'arm'
06-05 18:41:46.194 4374-4374/? A/DEBUG: pid: 3631, tid: 3631, name: .jventura.pyapp  >>> com.jventura.pyapp <<<
06-05 18:41:46.194 4374-4374/? A/DEBUG: signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x0
06-05 18:41:46.194 4374-4374/? A/DEBUG:     r0 00000000  r1 3fffffff  r2 b516737c  r3 98bed684
06-05 18:41:46.194 4374-4374/? A/DEBUG:     r4 00000000  r5 00000000  r6 00000000  r7 b2c17770
06-05 18:41:46.194 4374-4374/? A/DEBUG:     r8 96fb22d0  r9 b42a3230  sl 989d0db4  fp 98d85d30
06-05 18:41:46.194 4374-4374/? A/DEBUG:     ip 98ba2c88  sp beef7148  lr 989fdd3f  pc b50f2b68  cpsr 600f0030
06-05 18:41:46.199 4374-4374/? A/DEBUG: backtrace:
06-05 18:41:46.199 4374-4374/? A/DEBUG:     #00 pc 0001db68  /system/lib/libc.so (sem_post+11)
06-05 18:41:46.199 4374-4374/? A/DEBUG:     #01 pc 00028d3b  /data/app/com.jventura.pyapp-2/lib/arm/libpython2.7.so (PyThread_release_lock+2)
06-05 18:41:46.199 4374-4374/? A/DEBUG:     #02 pc 0003b48d  /data/data/com.jventura.pyapp/assets/python/site-packages/jnius/jnius.so
                                        
                                        
                                        [ 06-05 18:41:46.621   151:  151 W/         ]
                                        debuggerd: resuming target 3631

It occurs any time after callback is invoked when using a PythonJavaClass.  In order to figure out where in jnius.so this is occuring I had to use the following command:


~/Android/Crystax/crystax-ndk/toolchains/arm-linux-androideabi-5/prebuilt/linux-x86_64/bin/arm-linux-androideabi-addr2line -f -e ~/.local/share/python-for-android/build/other_builds/pyjnius-genericndkbuild-python2crystax/armeabi-v7a/pyjnius/build/lib.linux-x86_64-2.7/jnius/jnius.so 0003a9bd
__pyx_f_5jnius_invoke0
~/.local/share/python-for-android/build/other_builds/pyjnius-genericndkbuild-python2crystax/armeabi-v7a/pyjnius/jnius/jnius.c:32226

Which shows how to use addr2line to get the source line of the cythonized file that was leading to the crash.  Nice!

Note, if using p4a, you must make sure that the debug symbols are NOT stripped (in recipes.py) as it is done by default.

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