Add 64 KiB head/tail and content-hash duplicate ladder (closes #61) (#62)

trees.go

@@ -13,9 +13,10 @@ import (
 
 // fileSig is a file's duplicate signature; mtime is excluded.
 type fileSig struct {
-	size int64
-	head string
-	tail string
+	size    int64
+	head    string
+	tail    string
+	content string
 }
 
 // treeNode is one directory reconstructed from the scan stream.
@@ -122,7 +123,9 @@ func buildHierarchy(recs []scanRec) (*treeNode, []*treeNode) {
 			node.files = make(map[string]fileSig)
 		}
 
-		sig := fileSig{size: r.size, head: r.head, tail: r.tail}
+		sig := fileSig{
+			size: r.size, head: r.head, tail: r.tail, content: r.content,
+		}
 
 		// An unhashed record (its size was unique when last scanned)
 		// has unknown content: give it a signature no other file can
@@ -188,7 +191,7 @@ func (n *treeNode) compute() {
 	for name, sig := range n.files {
 		entries = append(entries,
 			"f\x00"+name+"\x00"+strconv.FormatInt(sig.size, 10)+
-				"\x00"+sig.head+"\x00"+sig.tail)
+				"\x00"+sig.head+"\x00"+sig.tail+"\x00"+sig.content)
 		n.fileCount++
 		n.totalSize += sig.size
 	}