1// Copyright © 2018 Steve Francia <spf@spf13.com>.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6// http://www.apache.org/licenses/LICENSE-2.0
7//
8// Unless required by applicable law or agreed to in writing, software
9// distributed under the License is distributed on an "AS IS" BASIS,
10// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11// See the License for the specific language governing permissions and
12// limitations under the License.
13
14package afero
15
16import (
17	"errors"
18)
19
20// Symlinker is an optional interface in Afero. It is only implemented by the
21// filesystems saying so.
22// It indicates support for 3 symlink related interfaces that implement the
23// behaviors of the os methods:
24//    - Lstat
25//    - Symlink, and
26//    - Readlink
27type Symlinker interface {
28	Lstater
29	Linker
30	LinkReader
31}
32
33// Linker is an optional interface in Afero. It is only implemented by the
34// filesystems saying so.
35// It will call Symlink if the filesystem itself is, or it delegates to, the os filesystem,
36// or the filesystem otherwise supports Symlink's.
37type Linker interface {
38	SymlinkIfPossible(oldname, newname string) error
39}
40
41// ErrNoSymlink is the error that will be wrapped in an os.LinkError if a file system
42// does not support Symlink's either directly or through its delegated filesystem.
43// As expressed by support for the Linker interface.
44var ErrNoSymlink = errors.New("symlink not supported")
45
46// LinkReader is an optional interface in Afero. It is only implemented by the
47// filesystems saying so.
48type LinkReader interface {
49	ReadlinkIfPossible(name string) (string, error)
50}
51
52// ErrNoReadlink is the error that will be wrapped in an os.Path if a file system
53// does not support the readlink operation either directly or through its delegated filesystem.
54// As expressed by support for the LinkReader interface.
55var ErrNoReadlink = errors.New("readlink not supported")
56