label: check parttypes identity type

parttypes can be either:

- A code for MBR/DOS
- An UUID for GPT

User needs a label instance before using a parttype getter. If checking
for a parttype using a code, check if the current label support that
kind of parttype identification before retrieving it. Same applies for
UUID based parttypes.

If wrong identity type is used, raise an exception. Errors regarding
parttype are more informative this way.

label.c

@@ -59,15 +59,23 @@ static int Label_init(LabelObject *self, PyObject *args, PyObject *kwds)
 	"Search for partition type in label-specific table."
 static PyObject *Label_get_parttype_from_code(LabelObject *self, PyObject *args, PyObject *kwds)
 {
+	struct fdisk_label *label = self->lb;
 	struct fdisk_parttype *ptype;
 	unsigned int ptype_code;
+	const char *name;
 
 	if (!PyArg_ParseTuple(args, "I", &ptype_code)) {
 		PyErr_SetString(PyExc_TypeError, ARG_ERR);
 		return NULL;
 	}
 
-	ptype = fdisk_label_get_parttype_from_code(self->lb, ptype_code);
+	if (!fdisk_label_has_code_parttypes(label)) {
+		name = fdisk_label_get_name(label);
+		PyErr_Format(PyExc_RuntimeError, "Current label %s has no code parttypes", name);
+		return NULL;
+	}
+
+	ptype = fdisk_label_get_parttype_from_code(label, ptype_code);
 	if (!ptype) {
 		PyErr_Format(PyExc_RuntimeError, "No match for parttype with code: %d", ptype_code);
 		return NULL;
@@ -80,7 +88,9 @@ static PyObject *Label_get_parttype_from_code(LabelObject *self, PyObject *args,
 	"Search by string for partition type in label-specific table."
 static PyObject *Label_get_parttype_from_string(LabelObject *self, PyObject *args, PyObject *kwds)
 {
+	struct fdisk_label *label = self->lb;
 	struct fdisk_parttype *ptype = NULL;
+	const char *name;
 	char *str;
 
 	if (!PyArg_ParseTuple(args, "s", &str)) {
@@ -88,7 +98,13 @@ static PyObject *Label_get_parttype_from_string(LabelObject *self, PyObject *arg
 		return NULL;
 	}
 
-	ptype = fdisk_label_get_parttype_from_string(self->lb, str);
+	if (fdisk_label_has_code_parttypes(label)) {
+		name = fdisk_label_get_name(label);
+		PyErr_Format(PyExc_RuntimeError, "Current label %s has no string parttypes", name);
+		return NULL;
+	}
+
+	ptype = fdisk_label_get_parttype_from_string(label, str);
 	if (!ptype) {
 		PyErr_Format(PyExc_RuntimeError, "No match for parttype with string: %s", str);
 		return NULL;