Python extension module segmentation fault

[Rolf Wester]

Hi,

I' trying to make an extension module that passes Numeric arrays. The
wrapper function is (swig generated and modified by myself):

static PyObject *_wrap_my_func(PyObject *self, PyObject *args) {
PyObject * resultobj = 0 ;
PyObject * obj0 = 0 ;
PyArrayObject * mat = 0 ;

std::cout << __FILE__ << " " << __LINE__ << std::endl;
if(!PyArg_ParseTuple(args,(char *)"O:my_func",&obj0)) goto fail;
std::cout << __FILE__ << " " << __LINE__ << " " << obj0 << std::endl;
mat = (PyArrayObject *) PyArray_ContiguousFromObject(obj0,
PyArray_DOUBLE, 1, 1);
std::cout << __FILE__ << " " << __LINE__ << " " << mat << std::endl;

Py_INCREF(Py_None); resultobj = Py_None;
return resultobj;
fail:
return NULL;
}

The shared object is build with:

g++ -c -g -fPIC -I./ -I/usr/local/include/python2.4
-I/usr/local/include/python2.4/Numeric mytest_wrap.cpp -o mytest_wrap.o

g++ -shared -L/usr/local/lib/python2.4/config/ mytest_wrap.o
-lpython2.4 -lm -o _mytest.so


the Python file reads:

import _mytest
from Numeric import *
mat = ones(100,Float64)
print _mytest.my_func(mat)

When running this I get the output:

mytest_wrap.cpp 1499
mytest_wrap.cpp 1502 0x402b55e8
Speicherzugriffsfehler (segmentation fault)

I also ran this with valgrind. Part of valgrinds output is:

==15792== Reading syms from
/mnt/pubdsk/A31/2003/DOKUMENTATION/WESTER/pr3/OPT/opt2.0/test/_mytest.so
(0x1BE7E000)
==15792== Reading syms from
/usr/local/lib/python2.4/site-packages/Numeric/multiarray.so (0x1B90F000)
==15792== Reading syms from
/usr/local/lib/python2.4/site-packages/Numeric/_numpy.so (0x1BFDB000)
==15792== Reading syms from
/usr/local/lib/python2.4/site-packages/Numeric/umath.so (0x1BFF1000)
==15792== Reading syms from
/usr/local/lib/python2.4/lib-dynload/strop.so (0x1B91A000)
==15792== Reading syms from /usr/local/lib/python2.4/lib-dynload/math.so
(0x1C103000)
==15792== Reading syms from
/usr/local/lib/python2.4/lib-dynload/struct.so (0x1C209000)
==15792== Reading syms from
/usr/local/lib/python2.4/lib-dynload/binascii.so (0x1C210000)
==15792== Reading syms from
/usr/local/lib/python2.4/lib-dynload/cStringIO.so (0x1C216000)
mytest_wrap.cpp 1499
mytest_wrap.cpp 1502 0x1bca7610
==15792== Invalid read of size 4
==15792== at 0x1BECE794: _wrap_my_func (mytest_wrap.cpp:1503)
==15792== by 0x811E685: PyCFunction_Call (methodobject.c:93)
==15792== by 0x80C708F: PyEval_EvalFrame (ceval.c:1499)
==15792== by 0x80C8933: PyEval_EvalCodeEx (ceval.c:2736)
==15792== by 0x80C8B64: PyEval_EvalCode (ceval.c:484)
==15792== by 0x80F74A7: PyRun_SimpleFileExFlags (pythonrun.c:1265)
==15792== by 0x80558D6: Py_Main (main.c:484)
==15792== by 0x8054F86: main (python.c:23)
==15792== Address 0x38 is not stack'd, malloc'd or (recently) free'd
==15792==
==15792== Process terminating with default action of signal 11 (SIGSEGV)
==15792== Access not within mapped region at address 0x38
==15792== at 0x1BECE794: _wrap_my_func (mytest_wrap.cpp:1503)
==15792== by 0x811E685: PyCFunction_Call (methodobject.c:93)
==15792== by 0x80C708F: PyEval_EvalFrame (ceval.c:1499)
==15792== by 0x80C8933: PyEval_EvalCodeEx (ceval.c:2736)
==15792== by 0x80C8B64: PyEval_EvalCode (ceval.c:484)
==15792== by 0x80F74A7: PyRun_SimpleFileExFlags (pythonrun.c:1265)
==15792== by 0x80558D6: Py_Main (main.c:484)
==15792== by 0x8054F86: main (python.c:23)
==15792==
==15792== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 8093 from 7)
==15792==


I would be very appreciative for any help.

With kind regards

Rolf Wester

 

[Robert Kern]

Hi,

I' trying to make an extension module that passes Numeric arrays. The
wrapper function is (swig generated and modified by myself):

static PyObject *_wrap_my_func(PyObject *self, PyObject *args) {
PyObject * resultobj = 0 ;
PyObject * obj0 = 0 ;
PyArrayObject * mat = 0 ;

std::cout << __FILE__ << " " << __LINE__ << std::endl;
if(!PyArg_ParseTuple(args,(char *)"O:my_func",&obj0)) goto fail;
std::cout << __FILE__ << " " << __LINE__ << " " << obj0 << std::endl;
mat = (PyArrayObject *) PyArray_ContiguousFromObject(obj0,
PyArray_DOUBLE, 1, 1);
std::cout << __FILE__ << " " << __LINE__ << " " << mat << std::endl;

Py_INCREF(Py_None); resultobj = Py_None;
return resultobj;
fail:
return NULL;
}

The shared object is build with:

g++ -c -g -fPIC -I./ -I/usr/local/include/python2.4
-I/usr/local/include/python2.4/Numeric mytest_wrap.cpp -o mytest_wrap.o

g++ -shared -L/usr/local/lib/python2.4/config/ mytest_wrap.o
-lpython2.4 -lm -o _mytest.so


the Python file reads:

import _mytest
from Numeric import *
mat = ones(100,Float64)
print _mytest.my_func(mat)

When running this I get the output:

mytest_wrap.cpp 1499
mytest_wrap.cpp 1502 0x402b55e8
Speicherzugriffsfehler (segmentation fault)

Did you call import_array() in init_mytest()?

--
Robert Kern
(e-mail address removed)

"In the fields of hell where the grass grows high
Are the graves of dreams allowed to die."
-- Richard Harter

 

[Rolf Wester]

Did you call import_array() in init_mytest()?

No I didn't. Thank you very much for your help. Now it works.

With kind regards

Rolf Wester