fixup! erts: Refactor bitstring (binary) handling

erlang · Nov 16, 2023 · af8e9ed · af8e9ed
1 parent abb786e
commit af8e9ed
Showing 1 changed file with 19 additions and 14 deletions.
diff --git a/erts/emulator/beam/erl_iolist.c b/erts/emulator/beam/erl_iolist.c
@@ -129,38 +129,43 @@ enum iolist_action generic_iolist_size(ErtsIOListState *state,
     L_start:
         while (is_list(obj)) {
             Eterm *cell = list_val(obj);
+            Eterm head, tail;
+
             if ((YieldSupport) && --yield_count <= 0) {
                 goto L_yield;
             }
 
-            obj = CAR(cell);
+            /* Note that we don't update `obj` straight away: if we have to
+             * bail on a size overflow, we don't want to return into the main
+             * loop with the raw `head` as that may be a type error. */
+            head = CAR(cell);
+            tail = CDR(cell);
 
-            if (is_byte(obj)) {
+            if (is_byte(head)) {
                 if (ERTS_UNLIKELY(size > (ERTS_UWORD_MAX - 8))) {
-                    ESTACK_PUSH(s, CDR(cell));
                     goto L_overflow;
                 }
                 size += 8;
-            } else if (is_bitstring(obj)) {
-                Uint obj_size = bitstring_size(obj);
-                if ((obj_size % (Unit)) != 0) {
+            } else  if (is_bitstring(head)) {
+                Uint head_size = bitstring_size(head);
+                if ((head_size % (Unit)) != 0) {
                     goto L_type_error;
                 }
-                if (ERTS_UNLIKELY(size > (ERTS_UWORD_MAX - obj_size))) {
-                    ESTACK_PUSH(s, CDR(cell));
+                if (ERTS_UNLIKELY(size > (ERTS_UWORD_MAX - head_size))) {
                     goto L_overflow;
                 }
-                size += obj_size;
-            } else if (is_list(obj)) {
-                /* Deal with the inner list in `obj` first, handling our tail
+                size += head_size;
+            } else if (is_list(head)) {
+                /* Deal with the inner list in `head` first, handling our tail
                  * later */
-                ESTACK_PUSH(s, CDR(cell));
+                ESTACK_PUSH(s, tail);
+                obj = head;
                 continue;
-            } else if (is_not_nil(obj)) {
+            } else if (is_not_nil(head)) {
                 goto L_type_error;
             }
 
-            obj = CDR(cell);
+            obj = tail;
         }
 
         if ((YieldSupport) && --yield_count <= 0) {