Modified function error handling after calling python function in py_…

src/luainpython.c

@@ -20,6 +20,7 @@
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
 */
+#define PY_SSIZE_T_CLEAN
 #include <Python.h>
 
 /* need this to build with Lua 5.2: enables lua_strlen() macro */
@@ -110,7 +111,12 @@ static PyObject *LuaCall(lua_State *L, PyObject *args)
 {
     PyObject *ret = NULL;
     PyObject *arg;
-    int nargs, rc, i;
+#ifdef PY_SSIZE_T_CLEAN
+    Py_ssize_t nargs, i;
+#else
+    int nargs, i;
+#endif
+    int rc;
 
     if (!PyTuple_Check(args)) {
         PyErr_SetString(PyExc_TypeError, "tuple expected");
@@ -358,7 +364,7 @@ static PyObject* LuaObject_richcmp(PyObject *lhs, PyObject *rhs, int op)
     PyErr_SetString(PyExc_RuntimeError, lua_tostring(LuaState, -1));
     return NULL;
   }
-  return lua_toboolean(LuaState, -1) ? Py_True : Py_False;
+  return LuaConvert(LuaState, -1);
 }
 
 static PyObject *LuaObject_call(PyObject *obj, PyObject *args)
@@ -396,9 +402,17 @@ static PyObject *LuaObject_iternext(LuaObject *obj)
     return ret;
 }
 
+#ifdef PY_SSIZE_T_CLEAN
+static Py_ssize_t LuaObject_length(LuaObject *obj)
+#else
 static int LuaObject_length(LuaObject *obj)
+#endif
 {
+#ifdef PY_SSIZE_T_CLEAN
+    Py_ssize_t len;
+#else
     int len;
+#endif
     lua_rawgeti(LuaState, LUA_REGISTRYINDEX, ((LuaObject*)obj)->ref);
     len = luaL_len(LuaState, -1);
     lua_settop(LuaState, 0);
@@ -428,54 +442,35 @@ static PyMappingMethods LuaObject_as_mapping = {
 
 PyTypeObject LuaObject_Type = {
     PyVarObject_HEAD_INIT(NULL, 0)
-    "lua.custom",             /*tp_name*/
-    sizeof(LuaObject),        /*tp_basicsize*/
-    0,                        /*tp_itemsize*/
-    (destructor)LuaObject_dealloc, /*tp_dealloc*/
-    0,                        /*tp_print*/
-    0,                        /*tp_getattr*/
-    0,                        /*tp_setattr*/
-    0,                        /*tp_compare*/
-    LuaObject_str,            /*tp_repr*/
-    0,                        /*tp_as_number*/
-    0,                        /*tp_as_sequence*/
-    &LuaObject_as_mapping,    /*tp_as_mapping*/
-    0,                        /*tp_hash*/
-    (ternaryfunc)LuaObject_call,     /*tp_call*/
-    LuaObject_str,            /*tp_str*/
-    LuaObject_getattr,       /*tp_getattro*/
-    LuaObject_setattr,        /*tp_setattro*/
-    0,                        /*tp_as_buffer*/
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
-    "custom lua object",      /*tp_doc*/
-    0,                        /*tp_traverse*/
-    0,                        /*tp_clear*/
-    LuaObject_richcmp,        /*tp_richcompare*/
-    0,                        /*tp_weaklistoffset*/
-    PyObject_SelfIter,        /*tp_iter*/
-    (iternextfunc)LuaObject_iternext, /*tp_iternext*/
-    0,                        /*tp_methods*/
-    0,                        /*tp_members*/
-    0,                        /*tp_getset*/
-    0,                        /*tp_base*/
-    0,                        /*tp_dict*/
-    0,                        /*tp_descr_get*/
-    0,                        /*tp_descr_set*/
-    0,                        /*tp_dictoffset*/
-    0,                        /*tp_init*/
-    PyType_GenericAlloc,      /*tp_alloc*/
-    PyType_GenericNew,        /*tp_new*/
-    PyObject_Del,            /*tp_free*/
-    0,                        /*tp_is_gc*/
+    .tp_name = "lua.custom",
+    .tp_basicsize = sizeof(LuaObject),
+    .tp_dealloc = (destructor)LuaObject_dealloc,
+    .tp_repr = LuaObject_str,
+    .tp_as_mapping = &LuaObject_as_mapping,
+    .tp_call = (ternaryfunc)LuaObject_call,
+    .tp_str = LuaObject_str,
+    .tp_getattro = LuaObject_getattr,
+    .tp_setattro = LuaObject_setattr,
+    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+    .tp_doc = "custom lua object",
+    .tp_richcompare = LuaObject_richcmp,
+    .tp_iter = PyObject_SelfIter,
+    .tp_iternext = (iternextfunc)LuaObject_iternext,
+    .tp_alloc = PyType_GenericAlloc,
+    .tp_new = PyType_GenericNew,
+    .tp_free = PyObject_Del,
 };
 
-
 PyObject *Lua_run(PyObject *args, int eval)
 {
     PyObject *ret;
     char *buf = NULL;
     char *s;
+#ifdef PY_SSIZE_T_CLEAN
+    Py_ssize_t len;
+#else
     int len;
+#endif
 
     if (!PyArg_ParseTuple(args, "s#", &s, &len))
         return NULL;

src/pythoninlua.c

@@ -20,6 +20,7 @@
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
 */
+
 #include <Python.h>
 #if defined(__linux__)
 #   include <dlfcn.h>
@@ -183,8 +184,51 @@ static int py_object_call(lua_State *L)
         ret = py_convert(L, value);
         Py_DECREF(value);
     } else {
-        PyErr_Print();
-        luaL_error(L, "error calling python function");
+        char s_exc[1024] = {0};
+        char s_traceback[1024] = {0};
+
+        PyObject *exc_type, *exc_value, *exc_traceback;
+        PyErr_Fetch(&exc_type, &exc_value, &exc_traceback);
+        PyErr_NormalizeException(&exc_type, &exc_value, &exc_traceback);
+
+        PyObject *exc_str = PyObject_Str(exc_value);
+
+        // Need not be garbage collected as per documentation of PyUnicode_AsUTF8
+        const char *exc_cstr = (exc_str)?PyUnicode_AsUTF8(exc_str):"";
+        strncpy(s_exc, (!(exc_cstr)?"UNKNOWN ERROR\n":exc_cstr), 1023);
+
+        if (exc_value != NULL && exc_traceback != NULL) {
+            PyObject *traceback_module = PyImport_ImportModule("traceback");
+            if (traceback_module != NULL) {
+                PyObject *traceback_list = PyObject_CallMethod(traceback_module,
+                        "format_exception", "OOO", exc_type, exc_value, exc_traceback);
+                if (traceback_list != NULL) {
+                    PyObject *traceback_str = PyUnicode_Join(PyUnicode_FromString(""), traceback_list);
+                    if (traceback_str != NULL) {
+                        // Need not be garbage collected as per documentation of PyUnicode_AsUTF8
+                        const char *traceback_cstr = PyUnicode_AsUTF8(traceback_str);
+                        if (traceback_cstr != NULL) {
+                            strncpy(s_traceback, traceback_cstr, 1023);
+                        }
+                        Py_XDECREF(traceback_str);
+                    }
+                    Py_XDECREF(traceback_list);
+                }
+                Py_XDECREF(traceback_module);
+            }
+        }
+        Py_XDECREF(exc_type);
+        Py_XDECREF(exc_value);
+        Py_XDECREF(exc_traceback);
+        Py_XDECREF(exc_str);
+
+        if (*s_traceback == '\0') {
+            luaL_error(L, "error calling python function:\nException: %s", s_exc);
+        }
+        else {
+            luaL_error(L, "error calling python function:\nException: %s", s_traceback);
+        }
+
     }
 
     return ret;

tests/test_py.lua

@@ -40,3 +40,28 @@ bar = 2
 
 assert(python.globals().foo == 1)
 assert(python.globals().bar == 2)
+
+python.execute
+[[
+def throw_exc():
+    raise Exception("THIS EXCEPTION")
+]]
+
+local status, exc = pcall(python.globals().throw_exc)
+assert(status == false)
+assert(exc ==
+[[error calling python function:
+Exception: Traceback (most recent call last):
+  File "<string>", line 2, in throw_exc
+Exception: THIS EXCEPTION
+]], exc)
+
+local b, e = string.find(exc, "Exception: ", 1);
+local ob, oe = b, e;
+while (b ~= nil) do
+    ob, oe = b, e
+    b, e = string.find(exc, "Exception: ", e+1)
+end
+local exc_s = (string.sub(exc, oe+1))
+--assert((require "pl.stringx").strip(exc_s) == "THIS EXCEPTION");
+