Make Caja.OperationHandle usable.

The Caja.OperationHandle.handle property is added: this gives access to the
effective handle taking the form of a non-zero signed integer that can be
stored in a void pointer. Trying to set this property with an invalid value
raises an exception.
Upon update_file_info_full call, the new Caja.OperationHandle is preset with
a "unique" non-null value generated from an atomic counter. When the python
method returns, the handle value is transmitted to Caja whatever it is:
this fixes the problem of Caja expecting a non-null handle when
CAJA_OPERATION_IN_PROGRESS is returned.

Ref: https://github.com/mate-desktop/python-caja/issues/36

2 files changed, 70 insertions, 2 deletions

diff --git a/src/caja-python-object.c b/src/caja-python-object.c
index e2bdf85..fbc5f79 100644
--- a/src/caja-python-object.c
+++ b/src/caja-python-object.c
@@ -411,20 +411,34 @@ caja_python_object_update_file_info (CajaInfoProvider 		*provider,
     CajaOperationResult ret = CAJA_OPERATION_COMPLETE;
     PyObject *py_ret = NULL;
 	PyGILState_STATE state = pyg_gil_state_ensure();
-	PyObject *py_handle = caja_python_boxed_new (_PyCajaOperationHandle_Type, *handle, FALSE);
+	static volatile gssize handle_generator = 1;
 
   	debug_enter();
 
 	CHECK_OBJECT(object);
 
+	*handle = NULL;
+
 	if (PyObject_HasAttrString(object->instance, "update_file_info_full"))
 	{
+        PyObject *py_handle;
+		void *h;
+
+        /* Generate a new handle with a default value. */
+        do {
+            h = (CajaOperationHandle *) g_atomic_pointer_add (&handle_generator, 1);
+        } while (!h);
+        py_handle = caja_python_boxed_new (_PyCajaOperationHandle_Type,
+                                           h, FALSE);
+
+
 		py_ret = PyObject_CallMethod(object->instance,
 									 METHOD_PREFIX "update_file_info_full", "(NNNN)",
 									 pygobject_new((GObject*)provider),
 									 py_handle,
 									 pyg_boxed_new(G_TYPE_CLOSURE, update_complete, TRUE, TRUE),
 									 pygobject_new((GObject*)file));
+		*handle = (void *) ((PyGBoxed *) py_handle)->boxed;
 	}
 	else if (PyObject_HasAttrString(object->instance, "update_file_info"))
 	{
@@ -447,6 +461,9 @@ caja_python_object_update_file_info (CajaInfoProvider 		*provider,
 	}
 
 	ret = INT_ASLONG(py_ret);
+
+    if (!*handle && ret == CAJA_OPERATION_IN_PROGRESS)
+        ret = CAJA_OPERATION_FAILED;
 	
  beach:
  	free_pygobject_data(file, NULL);
diff --git a/src/caja-python.c b/src/caja-python.c
index e9940ab..f609b1e 100644
--- a/src/caja-python.c
+++ b/src/caja-python.c
@@ -22,6 +22,7 @@
 #endif
 
 #include <Python.h>
+#include <structmember.h>
 #include <pygobject.h>
 #include <gmodule.h>
 #include <gtk/gtk.h>
@@ -33,8 +34,12 @@
 
 #if PY_MAJOR_VERSION >= 3
 #define STRING_FROMSTRING(str)	PyUnicode_FromString(str)
+#define INT_FROMSSIZE_T(val)    PyLong_FromSsize_t(val)
+#define INT_ASSSIZE_T(obj)      PyLong_AsSsize_t(obj)
 #else
 #define STRING_FROMSTRING(str)	PyString_FromString(str)
+#define INT_FROMSSIZE_T(val)    PyInt_FromSsize_t(val)
+#define INT_ASSSIZE_T(obj)      PyInt_AsSsize_t(obj)
 #endif
 
 static const GDebugKey caja_python_debug_keys[] = {
@@ -49,6 +54,37 @@ static GArray *all_types = NULL;
 static GList *all_pyfiles = NULL;
 
 
+/* Caja.OperationHandle value access. */
+static PyObject *
+caja_operationhandle_get_handle(PyGBoxed *self, void *closure)
+{
+	return INT_FROMSSIZE_T((Py_ssize_t) (size_t) self->boxed);
+}
+
+static int
+caja_operationhandle_set_handle(PyGBoxed *self, PyObject *value, void *closure)
+{
+	Py_ssize_t val = INT_ASSSIZE_T(value);
+
+	if (!PyErr_Occurred()) {
+		if (val) {
+			self->boxed = (void *) val;
+			return 0;
+		}
+		PyErr_SetString(PyExc_ValueError, "invalid operation handle value");
+	}
+	return -1;
+}
+
+static PyGetSetDef caja_operationhandle_handle = {
+	"handle",
+	(getter) caja_operationhandle_get_handle,
+	(setter) caja_operationhandle_set_handle,
+	"Operation handle value",
+	NULL
+};
+
+
 static inline gboolean 
 np_init_pygobject(void)
 {
@@ -163,7 +199,7 @@ caja_python_load_dir (GTypeModule *module,
 static gboolean
 caja_python_init_python (void)
 {
-	PyObject *gi, *require_version, *args, *caja;
+	PyObject *gi, *require_version, *args, *caja, *descr;
 	GModule *libpython;
 #if PY_MAJOR_VERSION >= 3
 	wchar_t *argv[] = { L"caja", NULL };
@@ -256,6 +292,21 @@ caja_python_init_python (void)
 	IMPORT(OperationHandle, "OperationHandle");
 
 #undef IMPORT
+
+	/* Add the "handle" member to the OperationHandle type. */
+	descr = PyDescr_NewGetSet(_PyCajaOperationHandle_Type,
+							  &caja_operationhandle_handle);
+    if (!descr) {
+		PyErr_Print();
+		return FALSE;
+	}
+	if (PyDict_SetItemString(_PyCajaOperationHandle_Type->tp_dict,
+						     caja_operationhandle_handle.name, descr)) {
+		Py_DECREF(descr);
+		PyErr_Print();
+		return FALSE;
+	}
+	Py_DECREF(descr);
 	
 	return TRUE;
 }