[Pyobjc-dev] strange problem using NSWorkspace/NSTask to start PyObjC apps

[Robert K. <rob...@gm...>]

Hey all,

I'm running into a strange problem with PyObjC-based apps.

The situation: I'm working on a .mailbundle (a plug-in for Apple Mail). From that plug-in, I want to start a PyObjC-based application. No matter what, this fails: the application gets a SIGSEGV (I'll post some more information below).

I've used pretty much all methods of starting the application (NSWorkspace, NSTask, even executing "open -a APP" from the Python subprocess module), and it keeps failing. Of course, the app works without problems when started manually. Starting the app from a Python-shell using [NSWorkspace launchApplication:] works, too. Just not from within the plug-in.

Even the simplest 'app' fails:
-snip-
from Foundation import *

class MyTestClass(NSObject): pass
-snip-

Same thing: SIGSEGV.

Starting other apps (like Safari) isn't a problem, so it doesn't seem to be some sandbox-type blocking.

Below is the relevant part of the crashlog. All I've been able to find out is that objc_msgSend_vtable3 is an Objective-C runtime shortcut for getting 'self'. It smells like a memory issue, but I'd be grateful if anyone could help me out.

-snip-
Process:         App1 [797]
Path:            /Users/USER/*/App1.app/Contents/MacOS/App1
Identifier:      name.klep.app1
Version:         0.0.0 (0.0.0)
Code Type:       X86-64 (Native)
Parent Process:  launchd [301]

Date/Time:       2011-11-21 06:49:06.394 +0100
OS Version:      Mac OS X 10.7.2 (11C74)
Report Version:  9

Crashed Thread:  0  Dispatch queue: com.apple.main-thread

Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x00007fc2dac50c60

VM Regions Near 0x7fc2dac50c60:
    MALLOC_TINY            0000000104e00000-0000000104f00000 [ 1024K] rw-/rwx SM=PRV  
--> 
    STACK GUARD            00007fff5bc00000-00007fff5f400000 [ 56.0M] ---/rwx SM=NUL  stack guard for thread 0

Application Specific Information:
objc_msgSend() selector name: self
objc[797]: garbage collection is OFF

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   libobjc.A.dylib                 0x00007fff8c84c0cd objc_msgSend_vtable3 + 13
1   _objc.so                        0x0000000101ba5a71 pythonify_c_value + 573
2   _objc.so                        0x0000000101b9d92e 0x101b80000 + 121134
3   org.python.python               0x0000000101a87b58 PyEval_EvalFrameEx + 13318
4   org.python.python               0x0000000101a8acd8 PyEval_EvalCodeEx + 1996
5   org.python.python               0x0000000101a8ae6c PyEval_EvalCode + 341
6   org.python.python               0x0000000101a87e0a PyEval_EvalFrameEx + 14008
7   org.python.python               0x0000000101a8acd8 PyEval_EvalCodeEx + 1996
8   org.python.python               0x0000000101a28abf PyClassMethod_New + 1378
9   org.python.python               0x0000000101a07d32 PyObject_Call + 97
10  org.python.python               0x0000000101a83c40 PyEval_CallObjectWithKeywords + 180
11  _objc.so                        0x0000000101ba0bd3 0x101b80000 + 134099
12  org.python.python               0x0000000101a4cafa PyType_Modified + 891
13  org.python.python               0x0000000101a07d32 PyObject_Call + 97
14  org.python.python               0x0000000101a07eed PyObject_CallFunctionObjArgs + 178
15  org.python.python               0x0000000101a8576b PyEval_EvalFrameEx + 4121
16  org.python.python               0x0000000101a8acd8 PyEval_EvalCodeEx + 1996
17  org.python.python               0x0000000101a8ad4d PyEval_EvalCode + 54
18  org.python.python               0x0000000101aa208f Py_CompileString + 62
19  org.python.python               0x0000000101aa214f PyRun_FileExFlags + 157
20  org.python.python               0x0000000101a801f6 _PyBuiltin_Init + 4630
21  org.python.python               0x0000000101a87d77 PyEval_EvalFrameEx + 13861
22  org.python.python               0x0000000101a8acd8 PyEval_EvalCodeEx + 1996
23  org.python.python               0x0000000101a8ae6c PyEval_EvalCode + 341
24  org.python.python               0x0000000101a87e0a PyEval_EvalFrameEx + 14008
25  org.python.python               0x0000000101a8acd8 PyEval_EvalCodeEx + 1996
26  org.python.python               0x0000000101a8ad4d PyEval_EvalCode + 54
27  org.python.python               0x0000000101aa208f Py_CompileString + 62
28  org.python.python               0x0000000101aa214f PyRun_FileExFlags + 157
29  org.python.python               0x0000000101aa32a2 PyRun_SimpleFileExFlags + 392
30  name.klep.app1                  0x0000000100004476 start + 12854
31  name.klep.app1                  0x0000000100004a96 main + 1465
32  name.klep.app1                  0x0000000100001274 start + 52
-snip-

-- robert