1 files changed, 130 insertions, 0 deletions
diff --git a/back/cmd/authfs/authfs.go b/back/cmd/authfs/authfs.go
new file mode 100644
index 0000000..e2a8bf9
--- /dev/null
+++ b/back/cmd/authfs/authfs.go
@@ -0,0 +1,130 @@
+package main
+
+import (
+	"fmt"
+	"path"
+	"sync"
+
+	p9 "github.com/Harvey-OS/ninep/protocol"
+
+	"git.samanthony.xyz/buth/back/auth"
+)
+
+const (
+	_ uint64 = iota
+	rootQidPath
+	usersQidPath
+	sessionsQidPath
+)
+
+type File interface {
+	Qid() (p9.QID, error)
+	// TODO
+}
+
+type Dir interface {
+	File
+	// TODO: walk, create
+}
+
+// Authfs is the root p9.NineServer.
+type Authfs struct {
+	*RootDir
+	*UsersDir
+	*SessionsDir
+
+	mu    sync.Mutex // guards below
+	files map[p9.FID]File
+}
+
+func NewAuthfs(rootPath string) (*Authfs, error) {
+	root := NewRootDir()
+	users, err := NewUsersDir(rootPath, root.Version)
+	if err != nil {
+		return nil, err
+	}
+	return &Authfs{
+		root,
+		users,
+		NewSessionsDir(root.Version),
+		sync.Mutex{},
+		make(map[p9.FID]File),
+	}, nil
+}
+
+func (fs *Authfs) Close() {
+	fs.RootDir.Close()
+	fs.UsersDir.Close()
+	fs.SessionsDir.Close()
+}
+
+func (fs *Authfs) Rattach(fid, afid p9.FID, uname, aname string) (p9.QID, error) {
+	if afid != p9.NOFID {
+		return p9.QID{}, fmt.Errorf("authfs: no authentication required")
+	}
+
+	var (
+		f   File
+		err error
+		ok  bool
+	)
+
+	aname = path.Clean(path.Join("/", aname))
+	dir, file := path.Split(aname)
+	switch dir {
+	case "/":
+		switch file {
+		case "":
+			f = fs.RootDir
+		case "users":
+			f = fs.UsersDir
+		case "sessions":
+			f = fs.SessionsDir
+		default:
+			return p9.QID{}, ErrFileNotExist
+		}
+
+	case "/users/":
+		f, err = fs.UsersDir.Walk(file)
+		if err != nil {
+			return p9.QID{}, err
+		}
+
+	case "/sessions/":
+		sessid, err := auth.ParseSessId(file)
+		if err != nil {
+			return p9.QID{}, err
+		}
+		f, ok = fs.SessionsDir.Get(sessid)
+		if !ok {
+			return p9.QID{}, ErrFileNotExist
+		}
+
+	default:
+		return p9.QID{}, ErrFileNotExist
+	}
+	if f == nil {
+		panic("unreachable")
+	}
+
+	qid, err := f.Qid()
+	if err != nil {
+		return p9.QID{}, err
+	}
+	if err := fs.attach(fid, f); err != nil {
+		return p9.QID{}, err
+	}
+	return qid, nil
+}
+
+func (fs *Authfs) attach(fid p9.FID, f File) error {
+	fs.mu.Lock()
+	defer fs.mu.Unlock()
+
+	if _, exists := fs.files[fid]; exists {
+		return ErrFidExist
+	}
+
+	fs.files[fid] = f
+	return nil
+}