«

static PyObject *wrap_doStuff(PyObject *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_ParseTuple(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_FromString(result);

// free memory
PyMem_Free(result);
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!

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(PyObject *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_ParseTuple(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_FromString(result);
>
> // free memory
> PyMem_Free(result);
> 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!

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(PyObject *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_ParseTuple(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_FromString(result);
> >
> > // free memory
> > PyMem_Free(result);
> > 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!

Op 2005-10-12, Java and Swing schreef <>:
> static PyObject *wrap_doStuff(PyObject *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_ParseTuple(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_FromString(result);
>
> // free memory
> PyMem_Free(result);
> 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(result).
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

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

static PyObject *wrap_doStuff(PyObject *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((20 * sizeof(MY_NUM) + 1); //
the array will be 20 long
MY_NUM *b = (MY_NUM *) PyMem_Malloc((20 * sizeof(MY_NUM) + 1); //
the array will be 20 long
int ok = PyArg_ParseTuple(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_FromString(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...nothing related to
Python.


Antoon Pardon wrote:
> Op 2005-10-12, Java and Swing schreef <>:
> > static PyObject *wrap_doStuff(PyObject *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_ParseTuple(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_FromString(result);
> >
> > // free memory
> > PyMem_Free(result);
> > 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(result).
> 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

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

static PyObject *wrap_doStuff(PyObject *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((20 * sizeof(MY_NUM) + 1); //
the array will be 20 long
MY_NUM *b = (MY_NUM *) PyMem_Malloc((20 * sizeof(MY_NUM) + 1); //
the array will be 20 long
int ok = PyArg_ParseTuple(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_FromString(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...nothing related to
Python.


Antoon Pardon wrote:
> Op 2005-10-12, Java and Swing schreef <>:
> > static PyObject *wrap_doStuff(PyObject *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_ParseTuple(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_FromString(result);
> >
> > // free memory
> > PyMem_Free(result);
> > 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(result).
> 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

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(PyObject *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((20 * sizeof(MY_NUM) + 1); //
> the array will be 20 long
> MY_NUM *b = (MY_NUM *) PyMem_Malloc((20 * sizeof(MY_NUM) + 1); //
> the array will be 20 long
> int ok = PyArg_ParseTuple(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_FromString(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...nothing related to
> Python.
>
>
> Antoon Pardon wrote:
> > Op 2005-10-12, Java and Swing schreef <>:
> > > static PyObject *wrap_doStuff(PyObject *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_ParseTuple(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_FromString(result);
> > >
> > > // free memory
> > > PyMem_Free(result);
> > > 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(result).
> > 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

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(PyObject *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((20 * sizeof(MY_NUM) + 1); //
> > the array will be 20 long
> > MY_NUM *b = (MY_NUM *) PyMem_Malloc((20 * sizeof(MY_NUM) + 1); //
> > the array will be 20 long
> > int ok = PyArg_ParseTuple(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_FromString(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...nothing related to
> > Python.
> >
> >
> > Antoon Pardon wrote:
> > > Op 2005-10-12, Java and Swing schreef <>:
> > > > static PyObject *wrap_doStuff(PyObject *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_ParseTuple(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_FromString(result);
> > > >
> > > > // free memory
> > > > PyMem_Free(result);
> > > > 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(result).
> > > 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" <> writes:

> static PyObject *wrap_doStuff(PyObject *self, PyObject *args) {
[...]
> char *aString = 0;
> char *bString = 0;
[...]
> int ok = PyArg_ParseTuple(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/

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" <> writes:
>
> > static PyObject *wrap_doStuff(PyObject *self, PyObject *args) {
> [...]
> > char *aString = 0;
> > char *bString = 0;
> [...]
> > int ok = PyArg_ParseTuple(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/