Add belt and braces check of PyString_AsString return.

diff --git a/Modules/_csv.c b/Modules/_csv.c
index 03e715a41b7516970bcc91f8a341a32762715a3f..a433960132db6527c3274c78f4d6af149a384952 100644 (file)
--- a/Modules/_csv.c
+++ b/Modules/_csv.c
@@ -1098,6 +1098,7 @@ static int
 join_append_lineterminator(WriterObj *self)
 {
        int terminator_len;
+       char *terminator;
 
        terminator_len = PyString_Size(self->dialect->lineterminator);
 
@@ -1105,10 +1106,10 @@ join_append_lineterminator(WriterObj *self)
        if (!join_check_rec_size(self, self->rec_len + terminator_len))
                return 0;
 
-       memmove(self->rec + self->rec_len,
-               /* should not be NULL */
-               PyString_AsString(self->dialect->lineterminator), 
-                terminator_len);
+       terminator = PyString_AsString(self->dialect->lineterminator); 
+       if (terminator == NULL)
+               return 0;
+       memmove(self->rec + self->rec_len, terminator, terminator_len);
        self->rec_len += terminator_len;
 
        return 1;