auto import from //depot/cupcake/@135843
diff --git a/lib/strnlen.c b/lib/strnlen.c
new file mode 100644
index 0000000..09ba788
--- /dev/null
+++ b/lib/strnlen.c
@@ -0,0 +1,33 @@
+/* Find the length of STRING, but scan at most MAXLEN characters.
+ Copyright (C) 2005, 2006 Free Software Foundation, Inc.
+ Written by Simon Josefsson.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "strnlen.h"
+
+/* Find the length of STRING, but scan at most MAXLEN characters.
+ If no '\0' terminator is found in that many characters, return MAXLEN. */
+
+size_t
+strnlen (const char *string, size_t maxlen)
+{
+ const char *end = memchr (string, '\0', maxlen);
+ return end ? (size_t) (end - string) : maxlen;
+}