From 13cdb5eaf7451dfcd5ed409b60eb2a89b90477d9 Mon Sep 17 00:00:00 2001
From: Martin Holst Swende <martin@swende.se>
Date: Thu, 5 Oct 2023 11:10:25 +0200
Subject: [PATCH] trie: implement trie-write filter-function

---
 trie/stackproof.go | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/trie/stackproof.go b/trie/stackproof.go
index c5b4eace9e..118c1dc387 100644
--- a/trie/stackproof.go
+++ b/trie/stackproof.go
@@ -394,3 +394,29 @@ func VerifyRangeProofWithStack(rootHash common.Hash, firstKey []byte, keys [][]b
 	// hasRightElement is true if the hashes we inserted are non-0
 	return len(hps) > 0, nil
 }
+
+// wrarpWriteFunction returns a NodeWriteFunc which filters away writes that are
+// on the boundary: parents of first/last.
+func wrapWriteFunction(origin, first, last []byte, w NodeWriteFunc) NodeWriteFunc {
+	if w == nil {
+		return nil
+	}
+	var originBorder = keybytesToHex(origin)
+	var leftBorder = keybytesToHex(first)
+	var rightBorder = keybytesToHex(last)
+	return func(origin common.Hash, path []byte, hash common.Hash, blob []byte) {
+		if bytes.HasPrefix(originBorder, path) {
+			//fmt.Printf("path %x  tainted left (parent to %x)\n", path, leftBorder)
+			return
+		}
+		if bytes.HasPrefix(leftBorder, path) {
+			//fmt.Printf("path %x  tainted left (parent to %x)\n", path, leftBorder)
+			return
+		}
+		if bytes.HasPrefix(rightBorder, path) {
+			//fmt.Printf("path %x  tainted right (parent to %x)\n", path, rightBorder)
+			return
+		}
+		w(origin, path, hash, blob)
+	}
+}