1 files changed, 57 insertions, 0 deletions

diff --git a/lib/libc/stdlib/twalk.c b/lib/libc/stdlib/twalk.c
new file mode 100644
index 000000000000..eab71df638ca
--- /dev/null
+++ b/lib/libc/stdlib/twalk.c
@@ -0,0 +1,57 @@
+/*	$NetBSD: twalk.c,v 1.1 1999/02/22 10:33:16 christos Exp $	*/
+/* $FreeBSD$ */
+
+/*
+ * Tree search generalized from Knuth (6.2.2) Algorithm T just like
+ * the AT&T man page says.
+ *
+ * The node_t structure is for internal use only, lint doesn't grok it.
+ *
+ * Written by reading the System V Interface Definition, not the code.
+ *
+ * Totally public domain.
+ */
+
+#include <sys/cdefs.h>
+#if defined(LIBC_SCCS) && !defined(lint)
+__RCSID("$NetBSD: twalk.c,v 1.1 1999/02/22 10:33:16 christos Exp $");
+#endif /* LIBC_SCCS and not lint */
+
+#include <assert.h>
+#define _SEARCH_PRIVATE
+#include <search.h>
+#include <stdlib.h>
+
+static void trecurse __P((const node_t *,
+    void  (*action)(const void *, VISIT, int), int level));
+
+/* Walk the nodes of a tree */
+static void
+trecurse(root, action, level)
+	const node_t *root;	/* Root of the tree to be walked */
+	void (*action) __P((const void *, VISIT, int));
+	int level;
+{
+
+	if (root->llink == NULL && root->rlink == NULL)
+		(*action)(root, leaf, level);
+	else {
+		(*action)(root, preorder, level);
+		if (root->llink != NULL)
+			trecurse(root->llink, action, level + 1);
+		(*action)(root, postorder, level);
+		if (root->rlink != NULL)
+			trecurse(root->rlink, action, level + 1);
+		(*action)(root, endorder, level);
+	}
+}
+
+/* Walk the nodes of a tree */
+void
+twalk(vroot, action)
+	const void *vroot;	/* Root of the tree to be walked */
+	void (*action) __P((const void *, VISIT, int));
+{
+	if (vroot != NULL && action != NULL)
+		trecurse(vroot, action, 0);
+}