C Wrapper Function, crashing Python?

[Java and Swing]

static PyObject *wrap_doStuff(P yObject *self, PyObject *args) {
// this will store the result in a Python object
PyObject *finalResult;

// get arguments from Python
char *result = 0;
char *in= 0;
char *aString = 0;
char *bString = 0;
MY_NUM *a;
MY_NUM *b;
int ok = PyArg_ParseTupl e(args, "sss", &in, &aString, &bString);
if (!ok) return 0;

// do work to get a and b
// count - returns an int; GetVal - returns a char *
a = GetVal(aString, count(aString, ","));
b = GetVal(bString, count(bString, ","));

// make function call, which returns a char *
result = doStuff(in, a, b);

// save result in Python string
finalResult = PyString_FromSt ring(result);

// free memory
PyMem_Free(resu lt);
PyMem_Free(a);
PyMem_Free(b);

// return the result as a Python string
return finalResult;
}

....from python I can call this function 4 times...works fine. WHen I
call it for the fifth time python.exe crashes. im thinking some memory
problem in the wrapper function perhaps...but I am not sure. The
actually C function, doStuff can be called 5, 6,7...N times without a
problem
so i know its gotta be my wrapper.

Any ideas? Thanks!

[Java and Swing]

update:
if I use C's free(result), free(a) free(b) instead of PyMem_Free...I
only get one successfuly use/call of doStuff.

i.e.
// this works
doStuff(...)

// python crashes here
doStuff(...)

Java and Swing wrote:

static PyObject *wrap_doStuff(P yObject *self, PyObject *args) {
// this will store the result in a Python object
PyObject *finalResult;

// get arguments from Python
char *result = 0;
char *in= 0;
char *aString = 0;
char *bString = 0;
MY_NUM *a;
MY_NUM *b;
int ok = PyArg_ParseTupl e(args, "sss", &in, &aString, &bString);
if (!ok) return 0;

// do work to get a and b
// count - returns an int; GetVal - returns a char *
a = GetVal(aString, count(aString, ","));
b = GetVal(bString, count(bString, ","));

// make function call, which returns a char *
result = doStuff(in, a, b);

// save result in Python string
finalResult = PyString_FromSt ring(result);

// free memory
PyMem_Free(resu lt);
PyMem_Free(a);
PyMem_Free(b);

// return the result as a Python string
return finalResult;
}

...from python I can call this function 4 times...works fine. WHen I
call it for the fifth time python.exe crashes. im thinking some memory
problem in the wrapper function perhaps...but I am not sure. The
actually C function, doStuff can be called 5, 6,7...N times without a
problem
so i know its gotta be my wrapper.

Any ideas? Thanks!

[Java and Swing]

one more update...

if I remove PyMem_Free and free(...) ...so no memory clean up...I can
still only call doStuff 4 times, the 5th attemp crashes Python.

Java and Swing wrote:

update:
if I use C's free(result), free(a) free(b) instead of PyMem_Free...I
only get one successfuly use/call of doStuff.

i.e.
// this works
doStuff(...)

// python crashes here
doStuff(...)

Java and Swing wrote:

static PyObject *wrap_doStuff(P yObject *self, PyObject *args) {
// this will store the result in a Python object
PyObject *finalResult;

// get arguments from Python
char *result = 0;
char *in= 0;
char *aString = 0;
char *bString = 0;
MY_NUM *a;
MY_NUM *b;
int ok = PyArg_ParseTupl e(args, "sss", &in, &aString, &bString);
if (!ok) return 0;

// do work to get a and b
// count - returns an int; GetVal - returns a char *
a = GetVal(aString, count(aString, ","));
b = GetVal(bString, count(bString, ","));

// make function call, which returns a char *
result = doStuff(in, a, b);

// save result in Python string
finalResult = PyString_FromSt ring(result);

// free memory
PyMem_Free(resu lt);
PyMem_Free(a);
PyMem_Free(b);

// return the result as a Python string
return finalResult;
}

...from python I can call this function 4 times...works fine. WHen I
call it for the fifth time python.exe crashes. im thinking some memory
problem in the wrapper function perhaps...but I am not sure. The
actually C function, doStuff can be called 5, 6,7...N times without a
problem
so i know its gotta be my wrapper.

Any ideas? Thanks!

[Antoon Pardon]

Op 2005-10-12, Java and Swing schreef <co*******@gmai l.com>:

static PyObject *wrap_doStuff(P yObject *self, PyObject *args) {
// this will store the result in a Python object
PyObject *finalResult;

// get arguments from Python
char *result = 0;
char *in= 0;
char *aString = 0;
char *bString = 0;
MY_NUM *a;
MY_NUM *b;
int ok = PyArg_ParseTupl e(args, "sss", &in, &aString, &bString);
if (!ok) return 0;

// do work to get a and b
// count - returns an int; GetVal - returns a char *
a = GetVal(aString, count(aString, ","));
b = GetVal(bString, count(bString, ","));

// make function call, which returns a char *
result = doStuff(in, a, b);

// save result in Python string
finalResult = PyString_FromSt ring(result);

// free memory
PyMem_Free(resu lt);
PyMem_Free(a);
PyMem_Free(b);

// return the result as a Python string
return finalResult;
}

...from python I can call this function 4 times...works fine. WHen I
call it for the fifth time python.exe crashes. im thinking some memory
problem in the wrapper function perhaps...but I am not sure. The
actually C function, doStuff can be called 5, 6,7...N times without a
problem
so i know its gotta be my wrapper.

Any ideas? Thanks!

Well assuming your doStuff is a C function that knows nothing of python.
it might be the PyMem_Free(resu lt).
http://docs.python.org/api/memoryInterface.html says the following:

void PyMem_Free(void *p)
Frees the memory block pointed to by p, which must have been
returned by a previous call to PyMem_Malloc() or PyMem_Realloc() .
Otherwise, or if PyMem_Free(p) has been called before, undefined
behavior occurs. If p is NULL, no operation is performed.

But your result wasn't allocated by a PyMem_Malloc, it was returned
to you by a C function.

--
Antoon Pardon

[Java and Swing]

Antoon,
I just saw that to. I updated the code like so...

static PyObject *wrap_doStuff(P yObject *self, PyObject *args) {
// this will store the result in a Python object
PyObject *finalResult;

// get arguments from Python
char *result = 0;
char *in= 0;
char *aString = 0;
char *bString = 0;
MY_NUM *a = (MY_NUM *) PyMem_Malloc((2 0 * sizeof(MY_NUM) + 1); //
the array will be 20 long
MY_NUM *b = (MY_NUM *) PyMem_Malloc((2 0 * sizeof(MY_NUM) + 1); //
the array will be 20 long
int ok = PyArg_ParseTupl e(args, "sss", &in, &aString, &bString);
if (!ok) return 0;

// do work to get a and b
// count - returns an int; GetVal - returns a MY_NUM * (a pointer
to a MY_NUM array)
a = GetVal(aString, count(aString, ","));
b = GetVal(bString, count(bString, ","));

// make function call, which returns a char *
result = doStuff(in, a, b);

// save result in Python string
finalResult = PyString_FromSt ring(result);

// free memory
PyMem_Free(a);
PyMem_Free(b);
free(aString);
free(bString);
free(result);

// return the result as a Python string
return finalResult;
}

...as you can see, i malloc'ed memory, and free'd the memory. However,
I still have python crashing (after only 3 successful calls to
doStuff). And yes, doStuff is a plain C function...noth ing related to
Python.
Antoon Pardon wrote:

Op 2005-10-12, Java and Swing schreef <co*******@gmai l.com>:

static PyObject *wrap_doStuff(P yObject *self, PyObject *args) {
// this will store the result in a Python object
PyObject *finalResult;

// get arguments from Python
char *result = 0;
char *in= 0;
char *aString = 0;
char *bString = 0;
MY_NUM *a;
MY_NUM *b;
int ok = PyArg_ParseTupl e(args, "sss", &in, &aString, &bString);
if (!ok) return 0;

// do work to get a and b
// count - returns an int; GetVal - returns a char *
a = GetVal(aString, count(aString, ","));
b = GetVal(bString, count(bString, ","));

// make function call, which returns a char *
result = doStuff(in, a, b);

// save result in Python string
finalResult = PyString_FromSt ring(result);

// free memory
PyMem_Free(resu lt);
PyMem_Free(a);
PyMem_Free(b);

// return the result as a Python string
return finalResult;
}

...from python I can call this function 4 times...works fine. WHen I
call it for the fifth time python.exe crashes. im thinking some memory
problem in the wrapper function perhaps...but I am not sure. The
actually C function, doStuff can be called 5, 6,7...N times without a
problem
so i know its gotta be my wrapper.

Any ideas? Thanks!

Well assuming your doStuff is a C function that knows nothing of python.
it might be the PyMem_Free(resu lt).
http://docs.python.org/api/memoryInterface.html says the following:

void PyMem_Free(void *p)
Frees the memory block pointed to by p, which must have been
returned by a previous call to PyMem_Malloc() or PyMem_Realloc() .
Otherwise, or if PyMem_Free(p) has been called before, undefined
behavior occurs. If p is NULL, no operation is performed.

But your result wasn't allocated by a PyMem_Malloc, it was returned
to you by a C function.

--
Antoon Pardon

[Java and Swing]

Antoon,
I just saw that to. I updated the code like so...

static PyObject *wrap_doStuff(P yObject *self, PyObject *args) {
// this will store the result in a Python object
PyObject *finalResult;

// get arguments from Python
char *result = 0;
char *in= 0;
char *aString = 0;
char *bString = 0;
MY_NUM *a = (MY_NUM *) PyMem_Malloc((2 0 * sizeof(MY_NUM) + 1); //
the array will be 20 long
MY_NUM *b = (MY_NUM *) PyMem_Malloc((2 0 * sizeof(MY_NUM) + 1); //
the array will be 20 long
int ok = PyArg_ParseTupl e(args, "sss", &in, &aString, &bString);
if (!ok) return 0;

// do work to get a and b
// count - returns an int; GetVal - returns a MY_NUM * (a pointer
to a MY_NUM array)
a = GetVal(aString, count(aString, ","));
b = GetVal(bString, count(bString, ","));

// make function call, which returns a char *
result = doStuff(in, a, b);

// save result in Python string
finalResult = PyString_FromSt ring(result);

// free memory
PyMem_Free(a);
PyMem_Free(b);
free(aString);
free(bString);
free(result);

// return the result as a Python string
return finalResult;
}

...as you can see, i malloc'ed memory, and free'd the memory. However,
I still have python crashing (after only 3 successful calls to
doStuff). And yes, doStuff is a plain C function...noth ing related to
Python.
Antoon Pardon wrote:

Op 2005-10-12, Java and Swing schreef <co*******@gmai l.com>:

static PyObject *wrap_doStuff(P yObject *self, PyObject *args) {
// this will store the result in a Python object
PyObject *finalResult;

// get arguments from Python
char *result = 0;
char *in= 0;
char *aString = 0;
char *bString = 0;
MY_NUM *a;
MY_NUM *b;
int ok = PyArg_ParseTupl e(args, "sss", &in, &aString, &bString);
if (!ok) return 0;

// do work to get a and b
// count - returns an int; GetVal - returns a char *
a = GetVal(aString, count(aString, ","));
b = GetVal(bString, count(bString, ","));

// make function call, which returns a char *
result = doStuff(in, a, b);

// save result in Python string
finalResult = PyString_FromSt ring(result);

// free memory
PyMem_Free(resu lt);
PyMem_Free(a);
PyMem_Free(b);

// return the result as a Python string
return finalResult;
}

...from python I can call this function 4 times...works fine. WHen I
call it for the fifth time python.exe crashes. im thinking some memory
problem in the wrapper function perhaps...but I am not sure. The
actually C function, doStuff can be called 5, 6,7...N times without a
problem
so i know its gotta be my wrapper.

Any ideas? Thanks!

Well assuming your doStuff is a C function that knows nothing of python.
it might be the PyMem_Free(resu lt).
http://docs.python.org/api/memoryInterface.html says the following:

void PyMem_Free(void *p)
Frees the memory block pointed to by p, which must have been
returned by a previous call to PyMem_Malloc() or PyMem_Realloc() .
Otherwise, or if PyMem_Free(p) has been called before, undefined
behavior occurs. If p is NULL, no operation is performed.

But your result wasn't allocated by a PyMem_Malloc, it was returned
to you by a C function.

--
Antoon Pardon

[Java and Swing]

Sorry about the double post...

anyhow, after putting in debug statements I found that it was crashing
when it called, free(result)... .so I removed the free(result).

now it crashes when it gets to, b = GetVal(bString, count(bString,
","));

...any ideas?

Java and Swing wrote:

Antoon,
I just saw that to. I updated the code like so...

static PyObject *wrap_doStuff(P yObject *self, PyObject *args) {
// this will store the result in a Python object
PyObject *finalResult;

// get arguments from Python
char *result = 0;
char *in= 0;
char *aString = 0;
char *bString = 0;
MY_NUM *a = (MY_NUM *) PyMem_Malloc((2 0 * sizeof(MY_NUM) + 1); //
the array will be 20 long
MY_NUM *b = (MY_NUM *) PyMem_Malloc((2 0 * sizeof(MY_NUM) + 1); //
the array will be 20 long
int ok = PyArg_ParseTupl e(args, "sss", &in, &aString, &bString);
if (!ok) return 0;

// do work to get a and b
// count - returns an int; GetVal - returns a MY_NUM * (a pointer
to a MY_NUM array)
a = GetVal(aString, count(aString, ","));
b = GetVal(bString, count(bString, ","));

// make function call, which returns a char *
result = doStuff(in, a, b);

// save result in Python string
finalResult = PyString_FromSt ring(result);

// free memory
PyMem_Free(a);
PyMem_Free(b);
free(aString);
free(bString);
free(result);

// return the result as a Python string
return finalResult;
}

..as you can see, i malloc'ed memory, and free'd the memory. However,
I still have python crashing (after only 3 successful calls to
doStuff). And yes, doStuff is a plain C function...noth ing related to
Python.
Antoon Pardon wrote:

Op 2005-10-12, Java and Swing schreef <co*******@gmai l.com>:

static PyObject *wrap_doStuff(P yObject *self, PyObject *args) {
// this will store the result in a Python object
PyObject *finalResult;

// get arguments from Python
char *result = 0;
char *in= 0;
char *aString = 0;
char *bString = 0;
MY_NUM *a;
MY_NUM *b;
int ok = PyArg_ParseTupl e(args, "sss", &in, &aString, &bString);
if (!ok) return 0;

// do work to get a and b
// count - returns an int; GetVal - returns a char *
a = GetVal(aString, count(aString, ","));
b = GetVal(bString, count(bString, ","));

// make function call, which returns a char *
result = doStuff(in, a, b);

// save result in Python string
finalResult = PyString_FromSt ring(result);

// free memory
PyMem_Free(resu lt);
PyMem_Free(a);
PyMem_Free(b);

// return the result as a Python string
return finalResult;
}

...from python I can call this function 4 times...works fine. WHen I
call it for the fifth time python.exe crashes. im thinking some memory
problem in the wrapper function perhaps...but I am not sure. The
actually C function, doStuff can be called 5, 6,7...N times without a
problem
so i know its gotta be my wrapper.

Any ideas? Thanks!

Well assuming your doStuff is a C function that knows nothing of python.
it might be the PyMem_Free(resu lt).
http://docs.python.org/api/memoryInterface.html says the following:

void PyMem_Free(void *p)
Frees the memory block pointed to by p, which must have been
returned by a previous call to PyMem_Malloc() or PyMem_Realloc() .
Otherwise, or if PyMem_Free(p) has been called before, undefined
behavior occurs. If p is NULL, no operation is performed.

But your result wasn't allocated by a PyMem_Malloc, it was returned
to you by a C function.

--
Antoon Pardon

[Java and Swing]

ok, further digging...I found that in the C function GetVal...it is
crashing where I try to malloc some memory. Note, I have no problems
when running this from C..just from Python using my wrapper.

GetVal looks something like..
MY_NUM *GetVal(const char *in, const int x) {
MY_NUM *results, *returnResults;
results = (MY_NUM *) malloc((x * sizeof(MY_NUM) + 1);
returnResults = results;
// ..do more work..
return returnResults;
}

I put in print statements into the C code and found that it is crashing
at the line where I malloc some space for "results".

....any ideas why this is crashing when calling from Python via C
wrapper?

Java and Swing wrote:

Sorry about the double post...

anyhow, after putting in debug statements I found that it was crashing
when it called, free(result)... .so I removed the free(result).

now it crashes when it gets to, b = GetVal(bString, count(bString,
","));

..any ideas?

Java and Swing wrote:

Antoon,
I just saw that to. I updated the code like so...

static PyObject *wrap_doStuff(P yObject *self, PyObject *args) {
// this will store the result in a Python object
PyObject *finalResult;

// get arguments from Python
char *result = 0;
char *in= 0;
char *aString = 0;
char *bString = 0;
MY_NUM *a = (MY_NUM *) PyMem_Malloc((2 0 * sizeof(MY_NUM) + 1); //
the array will be 20 long
MY_NUM *b = (MY_NUM *) PyMem_Malloc((2 0 * sizeof(MY_NUM) + 1); //
the array will be 20 long
int ok = PyArg_ParseTupl e(args, "sss", &in, &aString, &bString);
if (!ok) return 0;

// do work to get a and b
// count - returns an int; GetVal - returns a MY_NUM * (a pointer
to a MY_NUM array)
a = GetVal(aString, count(aString, ","));
b = GetVal(bString, count(bString, ","));

// make function call, which returns a char *
result = doStuff(in, a, b);

// save result in Python string
finalResult = PyString_FromSt ring(result);

// free memory
PyMem_Free(a);
PyMem_Free(b);
free(aString);
free(bString);
free(result);

// return the result as a Python string
return finalResult;
}

..as you can see, i malloc'ed memory, and free'd the memory. However,
I still have python crashing (after only 3 successful calls to
doStuff). And yes, doStuff is a plain C function...noth ing related to
Python.
Antoon Pardon wrote:

Op 2005-10-12, Java and Swing schreef <co*******@gmai l.com>:
> static PyObject *wrap_doStuff(P yObject *self, PyObject *args) {
> // this will store the result in a Python object
> PyObject *finalResult;
>
> // get arguments from Python
> char *result = 0;
> char *in= 0;
> char *aString = 0;
> char *bString = 0;
> MY_NUM *a;
> MY_NUM *b;
> int ok = PyArg_ParseTupl e(args, "sss", &in, &aString, &bString);
> if (!ok) return 0;
>
> // do work to get a and b
> // count - returns an int; GetVal - returns a char *
> a = GetVal(aString, count(aString, ","));
> b = GetVal(bString, count(bString, ","));
>
> // make function call, which returns a char *
> result = doStuff(in, a, b);
>
> // save result in Python string
> finalResult = PyString_FromSt ring(result);
>
> // free memory
> PyMem_Free(resu lt);
> PyMem_Free(a);
> PyMem_Free(b);
>
> // return the result as a Python string
> return finalResult;
> }
>
> ...from python I can call this function 4 times...works fine. WHen I
> call it for the fifth time python.exe crashes. im thinking some memory
> problem in the wrapper function perhaps...but I am not sure. The
> actually C function, doStuff can be called 5, 6,7...N times without a
> problem
> so i know its gotta be my wrapper.
>
> Any ideas? Thanks!

Well assuming your doStuff is a C function that knows nothing of python.
it might be the PyMem_Free(resu lt).
http://docs.python.org/api/memoryInterface.html says the following:

void PyMem_Free(void *p)
Frees the memory block pointed to by p, which must have been
returned by a previous call to PyMem_Malloc() or PyMem_Realloc() .
Otherwise, or if PyMem_Free(p) has been called before, undefined
behavior occurs. If p is NULL, no operation is performed.

But your result wasn't allocated by a PyMem_Malloc, it was returned
to you by a C function.

--
Antoon Pardon

[Bernhard Herzog]

"Java and Swing" <co*******@gmai l.com> writes:

static PyObject *wrap_doStuff(P yObject *self, PyObject *args) { [...] char *aString = 0;
char *bString = 0; [...] int ok = PyArg_ParseTupl e(args, "sss", &in, &aString, &bString); [...] free(aString);
free(bString);

aString and bString are pointers to memory managed by the strings in
your args tuple. You must not free them! The memory is automatically
managed by Python.

Bernhard

--
Intevation GmbH http://intevation.de/
Skencil http://skencil.org/
Thuban http://thuban.intevation.org/

[Java and Swing]

thanks for the tip, however even when I do not free aString or bString,
i'm still crashing at the malloc in the c function, not the wrapper.
Bernhard Herzog wrote:

"Java and Swing" <co*******@gmai l.com> writes:

static PyObject *wrap_doStuff(P yObject *self, PyObject *args) {

[...]

char *aString = 0;
char *bString = 0;

[...]

int ok = PyArg_ParseTupl e(args, "sss", &in, &aString, &bString);

[...]

free(aString);
free(bString);

aString and bString are pointers to memory managed by the strings in
your args tuple. You must not free them! The memory is automatically
managed by Python.

Bernhard

--
Intevation GmbH http://intevation.de/
Skencil http://skencil.org/
Thuban http://thuban.intevation.org/