Add walk for trees, restructure

walk.go

@@ -0,0 +1,55 @@
+package restic
+
+import (
+	"path/filepath"
+
+	"github.com/restic/restic/backend"
+	"github.com/restic/restic/debug"
+)
+
+type WalkTreeJob struct {
+	Path  string
+	Error error
+
+	Node *Node
+	Tree *Tree
+}
+
+func walkTree(s Server, path string, id backend.ID, done chan struct{}, jobCh chan<- WalkTreeJob) {
+	debug.Log("walkTree", "start on %q (%v)", path, id.Str())
+	// load tree
+	t, err := LoadTree(s, id)
+	if err != nil {
+		jobCh <- WalkTreeJob{Path: path, Error: err}
+		return
+	}
+
+	for _, node := range t.Nodes {
+		p := filepath.Join(path, node.Name)
+		if node.Type == "dir" {
+			blob, err := t.Map.FindID(node.Subtree)
+			if err != nil {
+				jobCh <- WalkTreeJob{Path: p, Error: err}
+				continue
+			}
+			walkTree(s, p, blob.Storage, done, jobCh)
+		} else {
+			jobCh <- WalkTreeJob{Path: p, Node: node}
+		}
+	}
+
+	if path != "" {
+		jobCh <- WalkTreeJob{Path: filepath.Join(path), Tree: t}
+	}
+	debug.Log("walkTree", "done for %q (%v)", path, id.Str())
+}
+
+// WalkTree walks the tree specified by ID recursively and sends a job for each
+// file and directory it finds. When the channel done is closed, processing
+// stops.
+func WalkTree(server Server, id backend.ID, done chan struct{}, jobCh chan<- WalkTreeJob) {
+	debug.Log("WalkTree", "start on %v", id.Str())
+	walkTree(server, "", id, done, jobCh)
+	close(jobCh)
+	debug.Log("WalkTree", "done", id.Str())
+}