Check Py{Bytes,String}_AsStringAndSize() for failure

PyBytes_AsStringAndSize() and PyString_AsStringAndSize() were not
being checked for failure.

Closes swig#1349.

Author: ZackerySpytz

Lib/python/pyhead.swg

@@ -43,8 +43,11 @@ SWIG_Python_str_AsChar(PyObject *str)
   if (str) {
     char *cstr;
     Py_ssize_t len;
-    PyBytes_AsStringAndSize(str, &cstr, &len);
+    if (PyBytes_AsStringAndSize(str, &cstr, &len) == -1)
+      return NULL;
     newstr = (char *) malloc(len+1);
+    if (!newstr)
+      return NULL;
     memcpy(newstr, cstr, len+1);
     Py_XDECREF(str);
   }

Lib/python/pystrings.swg

@@ -32,9 +32,11 @@ SWIG_AsCharPtrAndSize(PyObject *obj, char** cptr, size_t* psize, int *alloc)
     if (alloc)
       *alloc = SWIG_NEWOBJ;
 %#endif
-    PyBytes_AsStringAndSize(obj, &cstr, &len);
+    if (PyBytes_AsStringAndSize(obj, &cstr, &len) == -1)
+      return SWIG_TypeError;
 %#else
-    PyString_AsStringAndSize(obj, &cstr, &len);
+    if (PyString_AsStringAndSize(obj, &cstr, &len) == -1)
+      return SWIG_TypeError;
 %#endif
     if (cptr) {
       if (alloc) {