diff -r bc704c9af6d6 user/test/iattr.c
--- a/user/test/iattr.c	Tue Sep 02 10:17:39 2008 -0700
+++ b/user/test/iattr.c	Tue Sep 02 11:00:56 2008 -0700
@@ -32,11 +32,28 @@
 	return need;
 }

+int attr_check(void *attrs, unsigned size)
+{
+	void *limit = attrs + size;
+	unsigned head;
+	while (attrs < limit - 1)
+	{
+		attrs = decode16(attrs, &head);
+		kind = head >> 12;
+		if (kind < ATTR_MINIMUM || kind > ATTR_MAXIMUM)
+			return 0;
+		if (attrs + atsize[kind] > limit)
+			return 0;
+		attrs += atsize[kind];
+	}
+	return 1;
+}
+
 void *encode_attrs(SB, void *attrs, unsigned size, struct inode *inode)
 {
 	//printf("encode %u attr bytes\n", size);
 	void *limit = attrs + size - 3;
-	for (int kind = 0; kind < 32; kind++) {
+	for (int kind = 0; kind < 16; kind++) {
 		if (!(inode->present & (1 << kind)))
 			continue;
 		if (attrs >= limit)
@@ -144,6 +161,12 @@

 #ifndef main
 #ifndef iattr_included_from_ileaf
+
+void test_attrencoding()
+{
+	// do something cool
+}
+
 int main(int argc, char *argv[])
 {
 	SB = &(struct sb){ .version = 0 };
diff -r bc704c9af6d6 user/test/tux3.h
--- a/user/test/tux3.h	Tue Sep 02 10:17:39 2008 -0700
+++ b/user/test/tux3.h	Tue Sep 02 11:00:56 2008 -0700
@@ -231,11 +231,13 @@
 block_t balloc(SB);

 enum atkind {
+	ATTR_MINIMUM = 6,
 	MODE_OWNER_ATTR = 6,
 	DATA_BTREE_ATTR = 7,
 	CTIME_SIZE_ATTR = 8,
 	LINK_COUNT_ATTR = 9,
 	MTIME_ATTR = 10,
+	ATTR_MAXIMUM = 10,
 };

 enum atbit {