1 files changed, 15 insertions, 7 deletions

diff --git a/src/buffer.h b/src/buffer.h
index fd989925976..284cfa7b4a8 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -1088,6 +1088,14 @@ extern void mmap_set_vars (bool);
 extern void restore_buffer (Lisp_Object);
 extern void set_buffer_if_live (Lisp_Object);
 
+/* Return B as a struct buffer pointer, defaulting to the current buffer.  */
+
+INLINE struct buffer *
+decode_buffer (Lisp_Object b)
+{
+  return NILP (b) ? current_buffer : (CHECK_BUFFER (b), XBUFFER (b));
+}
+
 /* Set the current buffer to B.
 
    We previously set windows_or_buffers_changed here to invalidate
@@ -1120,15 +1128,15 @@ record_unwind_current_buffer (void)
 #define GET_OVERLAYS_AT(posn, overlays, noverlays, nextp, chrq)         \
   do {                                                                  \
     ptrdiff_t maxlen = 40;                                              \
-    overlays = alloca (maxlen * sizeof *overlays);                      \
-    noverlays = overlays_at (posn, false, &overlays, &maxlen,           \
-                             nextp, NULL, chrq);                        \
-    if (noverlays > maxlen)                                             \
+    SAFE_NALLOCA (overlays, 1, maxlen);                                 \
+    (noverlays) = overlays_at (posn, false, &(overlays), &maxlen,       \
+                               nextp, NULL, chrq);                      \
+    if ((noverlays) > maxlen)                                           \
       {                                                                 \
         maxlen = noverlays;                                             \
-        overlays = alloca (maxlen * sizeof *overlays);                  \
-        noverlays = overlays_at (posn, false, &overlays, &maxlen,       \
-                                 nextp, NULL, chrq);                    \
+        SAFE_NALLOCA (overlays, 1, maxlen);                             \
+        (noverlays) = overlays_at (posn, false, &(overlays), &maxlen,   \
+                                   nextp, NULL, chrq);                  \
       }                                                                 \
   } while (false)