From 753a02c15661a650762495257bf3abf1167998a7 Mon Sep 17 00:00:00 2001
From: Fredrik Holmqvist <fredrik.holmqvist@gmail.com>
Date: Sat, 24 Dec 2011 20:51:28 +0100
Subject: [PATCH] Reworked strlen and strnlen to look at four bytes at the
 time. From what I understand this should be safe. Based on info from bit
 twiddling hacks: http://graphics.stanford.edu/~seander/bithacks.html

---
 src/system/libroot/posix/string/strlen.c  | 21 +++++++++++++---
 src/system/libroot/posix/string/strnlen.c | 30 +++++++++++++++++++----
 2 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/src/system/libroot/posix/string/strlen.c b/src/system/libroot/posix/string/strlen.c
index 08e0d9a037..013c278796 100644
--- a/src/system/libroot/posix/string/strlen.c
+++ b/src/system/libroot/posix/string/strlen.c
@@ -3,18 +3,33 @@
 ** Distributed under the terms of the NewOS License.
 */
 
-#include <sys/types.h>
 #include <string.h>
+#include <SupportDefs.h>
 
+// From Bit twiddling hacks: http://graphics.stanford.edu/~seander/bithacks.html
+#define hasZeroByte(value) (value - 0x01010101) & ~value & 0x80808080
 
 size_t
 strlen(char const *s)
 {
 	size_t i = 0;
+	uint32 *value;
 
-	while (s[i]) {
-		i += 1;
+	//Make sure we use aligned access
+	while (((uint32) s + i) & 3) {
+		if (!s[i]) return i;
+		i++;
 	}
 
+	//Check four bytes at once
+	value = (uint32 *) (s + i);
+	while (!(hasZeroByte(*value)))
+		value++;
+
+	//Find the exact length
+	i = ((char *) value) - s;
+	while (s[i])
+		i++;
+
 	return i;
 }
diff --git a/src/system/libroot/posix/string/strnlen.c b/src/system/libroot/posix/string/strnlen.c
index 573b36527e..05a29207b8 100644
--- a/src/system/libroot/posix/string/strnlen.c
+++ b/src/system/libroot/posix/string/strnlen.c
@@ -3,16 +3,36 @@
 ** Distributed under the terms of the NewOS License.
 */
 
-#include <sys/types.h>
 #include <string.h>
+#include <SupportDefs.h>
 
 
+// From Bit twiddling hacks: http://graphics.stanford.edu/~seander/bithacks.html
+#define hasZeroByte(value) (value - 0x01010101) & ~value & 0x80808080
+
 size_t
 strnlen(char const *s, size_t count)
 {
-	const char *sc;
+	size_t i = 0;
+	uint32 *value;
 
-	for (sc = s; count-- && *sc != '\0'; ++sc)
-		;
-	return sc - s;
+	//Make sure we use aligned access
+	while (((uint32) s + i) & 3) {
+		if (i == count || !s[i]) return i;
+		i++;
+	}
+
+
+	const uint32 * end = (uint32 *) s + count;
+	//Check four bytes at once
+	value = (uint32 *) (s + i);
+	while (value < end && !(hasZeroByte(*value)) )
+		value++;
+
+	//Find the exact length
+	i = ((char *) value) - s;
+	while (s[i] && i < count )
+		i++;
+
+	return i;
 }