Fix Windows gdb build failure with python support
Commit Message
Hi,
GDB fails to build for Windows host with python support enabled due to
python_file's second argument being of type char * and being passed a
string litteral. This patch takes the conservative assumptions that the
function might indeed modify the character string and use a local char
array to pass the mode instead.
ChangeLog entry is as follows:
*** gdb/ChangeLog ***
2017-04-06 Thomas Preud'homme <thomas.preudhomme@arm.com>
* python/python.c (python_run_simple_file): Pass mode as a char
pointer using local char array.
Testing: build for Windows with python support succeed with this patch and fails
without.
Is this ok to commit to master?
Best regards,
Thomas
Comments
On 04/06/2017 03:28 PM, Thomas Preudhomme wrote:
>
>
> GDB fails to build for Windows host with python support enabled due to
Uppercase "Python", and would be a good idea to mention that this is
Python 2.
> python_file's second argument
It's actually PyFile_FromString's second parameter, not python_file's.
"python_file" is a reference that is being initialized from the result
of PyFile_FromString.
> being of type char * and being passed a
> string litteral.
Typo "literal".
> This patch takes the conservative assumptions that the
> function might indeed modify the character string and use a local char
> array to pass the mode instead.
The Python API is notoriously buggy wrt to const-correctness when
it comes to string parameters.
Note that in gdb/python/python-internal.h, we have fixups for all of:
PyObject_GetAttrString
PyObject_HasAttrString
PyObject_CallMethod
PyErr_NewException
PySys_GetObject
PySys_SetPath
PyGetSetDef
PyArg_ParseTupleAndKeywords
Over the years it's been getting better.
A few of those were added just yesterday, but I didn't build Windows
with Python so I missed this one.
Now, this API in particular seems to have been removed completely
in Python 3, so there's no "it was fixed in 3.x" that we could put
in a comment. Anyway, since this is just one single place, let's just
not bother with anything fancy.
Please just add a cast instead (and update the commit log accordingly):
PyFile_FromString (full_path.get (), (char *) "r")
OK with that change.
Thanks,
Pedro Alves
@@ -348,11 +348,12 @@ python_run_simple_file (FILE *file, const char *filename)
PyRun_SimpleFile (file, filename);
#else /* _WIN32 */
+ char mode[] = "r";
/* Because we have a string for a filename, and are using Python to
open the file, we need to expand any tilde in the path first. */
gdb::unique_xmalloc_ptr<char> full_path (tilde_expand (filename));
- gdbpy_ref<> python_file (PyFile_FromString (full_path.get (), "r"));
+ gdbpy_ref<> python_file (PyFile_FromString (full_path.get (), mode));
if (python_file == NULL)
{
gdbpy_print_stack ();