tailscale: update tailfs file and package names (#11590)

This change updates the tailfs file and package names to their new
naming convention.

Updates #tailscale/corp#16827

Signed-off-by: Charlotte Brandhorst-Satzkorn <charlotte@tailscale.com>

drive/driveimpl/dirfs/openfile.go

@@ -0,0 +1,63 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package dirfs
+
+import (
+	"context"
+	"io/fs"
+	"os"
+
+	"github.com/tailscale/xnet/webdav"
+	"tailscale.com/drive/driveimpl/shared"
+)
+
+// OpenFile implements interface webdav.Filesystem.
+func (dfs *FS) OpenFile(ctx context.Context, name string, flag int, perm os.FileMode) (webdav.File, error) {
+	_, isStaticRoot := dfs.trimStaticRoot(name)
+	if !isStaticRoot && !shared.IsRoot(name) {
+		// Show a folder with no children to represent the requested child. In
+		// practice, the children of this folder are never read, we just need
+		// to give webdav a file here which it uses to call file.Stat(). So,
+		// even though the Child may in fact have its own children, it doesn't
+		// matter here.
+		return &shared.DirFile{
+			Info: shared.ReadOnlyDirInfo(name, dfs.now()),
+			LoadChildren: func() ([]fs.FileInfo, error) {
+				return nil, nil
+			},
+		}, nil
+	}
+
+	di, err := dfs.Stat(ctx, name)
+	if err != nil {
+		return nil, err
+	}
+
+	if dfs.StaticRoot != "" && !isStaticRoot {
+		// Show a folder with a single subfolder that is the static root.
+		return &shared.DirFile{
+			Info: di,
+			LoadChildren: func() ([]fs.FileInfo, error) {
+				return []fs.FileInfo{
+					shared.ReadOnlyDirInfo(dfs.StaticRoot, dfs.now()),
+				}, nil
+			},
+		}, nil
+	}
+
+	// Show a folder with one subfolder for each Child of this FS.
+	return &shared.DirFile{
+		Info: di,
+		LoadChildren: func() ([]fs.FileInfo, error) {
+			childInfos := make([]fs.FileInfo, 0, len(dfs.Children))
+			for _, c := range dfs.Children {
+				if c.isAvailable() {
+					childInfo := shared.ReadOnlyDirInfo(c.Name, dfs.now())
+					childInfos = append(childInfos, childInfo)
+				}
+			}
+			return childInfos, nil
+		},
+	}, nil
+}