Merge pull request #13649 from donaldsharp/unlock_the_node_or_else

[mirror_frr.git] / lib / typesafe.c

diff --git a/lib/typesafe.c b/lib/typesafe.c
index f90b59daf0c3a1548093a5793eca9b39b53e41e2..c0774479852da261af67d70572da58b55f2c77fa 100644 (file)
--- a/lib/typesafe.c
+++ b/lib/typesafe.c
@@ -1,17 +1,6 @@
+// SPDX-License-Identifier: ISC
 /*
  * Copyright (c) 2019  David Lamparter, for NetDEF, Inc.
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
 #ifdef HAVE_CONFIG_H
@@ -20,6 +9,7 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <assert.h>
 
 #include "typesafe.h"
 #include "memory.h"
@@ -95,6 +85,15 @@ void typesafe_hash_grow(struct thash_head *head)
        uint32_t newsize = head->count, i, j;
        uint8_t newshift, delta;
 
+       /* note hash_grow is called after head->count++, so newsize is
+        * guaranteed to be >= 1.  So the minimum argument to builtin_ctz
+        * below is 2, which returns 1, and that makes newshift >= 2.
+        *
+        * Calling hash_grow with a zero head->count would result in a
+        * malformed hash table that has tabshift == 1.
+        */
+       assert(head->count > 0);
+
        hash_consistency_check(head);
 
        newsize |= newsize >> 1;