[libgpiod] bindings: python: fix segfault when calling Line.request()

[Joel Savitz <jsavitz@redhat.com>]

When Line.request() is called without the required 'consumer=value'
argument, the module attempts access an empty dictionary object
resulting in a segfault. This patch avoids such access when the
dictionary is empty and maintains the current design where the
LineBulk object is responsible for validation of arguments.

Signed-off-by: Joel Savitz <jsavitz@redhat.com>
---
 bindings/python/gpiodmodule.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/bindings/python/gpiodmodule.c b/bindings/python/gpiodmodule.c
index 2f6ef51..ae7e1cc 100644
--- a/bindings/python/gpiodmodule.c
+++ b/bindings/python/gpiodmodule.c
@@ -434,8 +434,12 @@ static PyObject *gpiod_Line_request(gpiod_LineObject *self,
 	gpiod_LineBulkObject *bulk_obj;
 	int rv;
 
-	def_val = PyDict_GetItemString(kwds, "default_val");
-	def_vals = PyDict_GetItemString(kwds, "default_vals");
+	if (PyDict_Size(kwds) > 0) {
+		def_val = PyDict_GetItemString(kwds, "default_val");
+		def_vals = PyDict_GetItemString(kwds, "default_vals");
+	} else {
+		def_val = def_vals = NULL;
+	}
 
 	if (def_val && def_vals) {
 		PyErr_SetString(PyExc_TypeError,
-- 
2.23.0