Signal error when reading an empty byte-code object (Bug#15405)

* lread.c (read1): signal error
* alloc.c (make_byte_code): eassert header size
(sweep_vectors): change an int to size_t

1 files changed, 3 insertions, 1 deletions

diff --git a/src/alloc.c b/src/alloc.c
index ca21ba2469b..2d9828ffa79 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -2889,7 +2889,7 @@ sweep_vectors (void)
                 free_this_block = 1;
               else
                 {
-                  int tmp;
+                  size_t tmp;
                   SETUP_ON_FREE_LIST (vector, total_bytes, tmp);
                 }
             }
@@ -3132,6 +3132,8 @@ usage: (vector &rest OBJECTS)  */)
 void
 make_byte_code (struct Lisp_Vector *v)
 {
+  /* Don't allow the global zero_vector to become a byte code object. */
+  eassert(0 < v->header.size);
   if (v->header.size > 1 && STRINGP (v->u.contents[1])
       && STRING_MULTIBYTE (v->u.contents[1]))
     /* BYTECODE-STRING must have been produced by Emacs 20.2 or the