swarm/api: support mounting manifests via FUSE (#3690)

vendor/bazil.org/fuse/fs/tree.go

@@ -0,0 +1,99 @@
+// FUSE directory tree, for servers that wish to use it with the service loop.
+
+package fs
+
+import (
+	"os"
+	pathpkg "path"
+	"strings"
+
+	"golang.org/x/net/context"
+)
+
+import (
+	"bazil.org/fuse"
+)
+
+// A Tree implements a basic read-only directory tree for FUSE.
+// The Nodes contained in it may still be writable.
+type Tree struct {
+	tree
+}
+
+func (t *Tree) Root() (Node, error) {
+	return &t.tree, nil
+}
+
+// Add adds the path to the tree, resolving to the given node.
+// If path or a prefix of path has already been added to the tree,
+// Add panics.
+//
+// Add is only safe to call before starting to serve requests.
+func (t *Tree) Add(path string, node Node) {
+	path = pathpkg.Clean("/" + path)[1:]
+	elems := strings.Split(path, "/")
+	dir := Node(&t.tree)
+	for i, elem := range elems {
+		dt, ok := dir.(*tree)
+		if !ok {
+			panic("fuse: Tree.Add for " + strings.Join(elems[:i], "/") + " and " + path)
+		}
+		n := dt.lookup(elem)
+		if n != nil {
+			if i+1 == len(elems) {
+				panic("fuse: Tree.Add for " + path + " conflicts with " + elem)
+			}
+			dir = n
+		} else {
+			if i+1 == len(elems) {
+				dt.add(elem, node)
+			} else {
+				dir = &tree{}
+				dt.add(elem, dir)
+			}
+		}
+	}
+}
+
+type treeDir struct {
+	name string
+	node Node
+}
+
+type tree struct {
+	dir []treeDir
+}
+
+func (t *tree) lookup(name string) Node {
+	for _, d := range t.dir {
+		if d.name == name {
+			return d.node
+		}
+	}
+	return nil
+}
+
+func (t *tree) add(name string, n Node) {
+	t.dir = append(t.dir, treeDir{name, n})
+}
+
+func (t *tree) Attr(ctx context.Context, a *fuse.Attr) error {
+	a.Mode = os.ModeDir | 0555
+	return nil
+}
+
+func (t *tree) Lookup(ctx context.Context, name string) (Node, error) {
+	n := t.lookup(name)
+	if n != nil {
+		return n, nil
+	}
+	return nil, fuse.ENOENT
+}
+
+func (t *tree) ReadDirAll(ctx context.Context) ([]fuse.Dirent, error) {
+	var out []fuse.Dirent
+	for _, d := range t.dir {
+		out = append(out, fuse.Dirent{Name: d.name})
+	}
+	return out, nil
+}