1// SPDX-License-Identifier: BSD-3-Clause
 2
 3// Copyright (C) 2017-2024 SUSE LLC. All rights reserved.
 4// Use of this source code is governed by a BSD-style
 5// license that can be found in the LICENSE file.
 6
 7package securejoin
 8
 9import "os"
10
11// In future this should be moved into a separate package, because now there
12// are several projects (umoci and go-mtree) that are using this sort of
13// interface.
14
15// VFS is the minimal interface necessary to use [SecureJoinVFS]. A nil VFS is
16// equivalent to using the standard [os].* family of functions. This is mainly
17// used for the purposes of mock testing, but also can be used to otherwise use
18// [SecureJoinVFS] with VFS-like system.
19type VFS interface {
20	// Lstat returns an [os.FileInfo] describing the named file. If the
21	// file is a symbolic link, the returned [os.FileInfo] describes the
22	// symbolic link. Lstat makes no attempt to follow the link.
23	// The semantics are identical to [os.Lstat].
24	Lstat(name string) (os.FileInfo, error)
25
26	// Readlink returns the destination of the named symbolic link.
27	// The semantics are identical to [os.Readlink].
28	Readlink(name string) (string, error)
29}
30
31// osVFS is the "nil" VFS, in that it just passes everything through to the os
32// module.
33type osVFS struct{}
34
35func (o osVFS) Lstat(name string) (os.FileInfo, error) { return os.Lstat(name) }
36
37func (o osVFS) Readlink(name string) (string, error) { return os.Readlink(name) }