Change end to a char and catch missing parsing cases

Author: kesmit13

singlestoredb/mysql/accel.c

@@ -1213,7 +1213,7 @@ static PyObject *read_row_from_packet(
     PyObject *py_result = NULL;
     PyObject *py_item = NULL;
     PyObject *py_str = NULL;
-    char *end = NULL;
+    char end = '\0';
 
     int sign = 1;
     int year = 0;
@@ -1240,7 +1240,7 @@ static PyObject *read_row_from_packet(
     for (unsigned long i = 0; i < py_state->n_cols; i++) {
 
         read_length_coded_string(&data, &data_l, &out, &out_l, &is_null);
-        end = &out[out_l];
+        end = out[out_l];
 
         orig_out = out;
         orig_out_l = out_l;
@@ -1267,10 +1267,6 @@ static PyObject *read_row_from_packet(
 
             // If no converter was passed in, do the default processing.
             else {
-                // Make sure not to overrun
-                char tmp = *end;
-                if (data_l) *end = '\0';
-
                 switch (py_state->type_codes[i]) {
                 case MYSQL_TYPE_NEWDECIMAL:
                 case MYSQL_TYPE_DECIMAL:
@@ -1287,16 +1283,21 @@ static PyObject *read_row_from_packet(
                 case MYSQL_TYPE_LONG:
                 case MYSQL_TYPE_LONGLONG:
                 case MYSQL_TYPE_INT24:
+                    if (data_l) out[out_l] = '\0';
                     if (py_state->flags[i] & MYSQL_FLAG_UNSIGNED) {
                         py_item = PyLong_FromUnsignedLongLong(strtoull(out, NULL, 10));
                     } else {
                         py_item = PyLong_FromLongLong(strtoll(out, NULL, 10));
                     }
+                    if (data_l) out[out_l] = end;
                     if (!py_item) goto error;
                     break;
+
                 case MYSQL_TYPE_FLOAT:
                 case MYSQL_TYPE_DOUBLE:
-                    py_item = PyFloat_FromDouble(strtod(out, &end));
+                    if (data_l) out[out_l] = '\0';
+                    py_item = PyFloat_FromDouble(strtod(out, NULL));
+                    if (data_l) out[out_l] = end;
                     if (!py_item) goto error;
                     break;
 
@@ -1428,8 +1429,10 @@ static PyObject *read_row_from_packet(
                         goto error;
                         break;
                     }
+                    if (data_l) out[out_l] = '\0';
                     year = strtoul(out, NULL, 10);
                     py_item = PyLong_FromLong(year);
+                    if (data_l) out[out_l] = end;
                     if (!py_item) goto error;
                     break;
 
@@ -1469,7 +1472,6 @@ static PyObject *read_row_from_packet(
                                  py_state->type_codes[i], NULL);
                     goto error;
                 }
-                if (data_l) *end = tmp;
             }
         }