Enhance dbm module error messages with descriptive type information

Author: furkanonder

Modules/_dbmmodule.c

@@ -236,8 +236,9 @@ dbm_ass_sub_lock_held(PyObject *self, PyObject *v, PyObject *w)
     dbmobject *dp = dbmobject_CAST(self);
 
     if ( !PyArg_Parse(v, "s#", &krec.dptr, &tmp_size) ) {
-        PyErr_SetString(PyExc_TypeError,
-                        "dbm mappings have bytes or string keys only");
+        PyErr_Format(PyExc_TypeError,
+                     "dbm key returned %.100s for value %R But database keys must be bytes or str, not %.100s",
+                     Py_TYPE(v)->tp_name, v, Py_TYPE(v)->tp_name);
         return -1;
     }
     _dbm_state *state = PyType_GetModuleState(Py_TYPE(dp));
@@ -263,8 +264,9 @@ dbm_ass_sub_lock_held(PyObject *self, PyObject *v, PyObject *w)
         }
     } else {
         if ( !PyArg_Parse(w, "s#", &drec.dptr, &tmp_size) ) {
-            PyErr_SetString(PyExc_TypeError,
-                 "dbm mappings have bytes or string elements only");
+            PyErr_Format(PyExc_TypeError,
+                         "dbm value returned %.100s for value %R But database values must be bytes or str, not %.100s",
+                         Py_TYPE(w)->tp_name, w, Py_TYPE(w)->tp_name);
             return -1;
         }
         drec.dsize = tmp_size;

Modules/_gdbmmodule.c

@@ -248,7 +248,7 @@ parse_datum(PyObject *o, datum *d, const char *failmsg)
     Py_ssize_t size;
     if (!PyArg_Parse(o, "s#", &d->dptr, &size)) {
         if (failmsg != NULL) {
-            PyErr_SetString(PyExc_TypeError, failmsg);
+            PyErr_Format(PyExc_TypeError, failmsg, Py_TYPE(o)->tp_name, o, Py_TYPE(o)->tp_name);
         }
         return 0;
     }
@@ -324,11 +324,12 @@ static int
 gdbm_ass_sub_lock_held(PyObject *op, PyObject *v, PyObject *w)
 {
     datum krec, drec;
-    const char *failmsg = "gdbm mappings have bytes or string indices only";
+    const char *key_failmsg = "dbm key returned %.100s for value %R But database keys must be bytes or str, not %.100s";
+    const char *value_failmsg = "dbm value returned %.100s for value %R But database keys must be bytes or str, not %.100s";
     gdbmobject *dp = _gdbmobject_CAST(op);
     _gdbm_state *state = PyType_GetModuleState(Py_TYPE(dp));
 
-    if (!parse_datum(v, &krec, failmsg)) {
+    if (!parse_datum(v, &krec, key_failmsg)) {
         return -1;
     }
     if (dp->di_dbm == NULL) {
@@ -349,7 +350,7 @@ gdbm_ass_sub_lock_held(PyObject *op, PyObject *v, PyObject *w)
         }
     }
     else {
-        if (!parse_datum(w, &drec, failmsg)) {
+        if (!parse_datum(w, &drec, value_failmsg)) {
             return -1;
         }
         errno = 0;