1 // Copyright (C) The Arvados Authors. All rights reserved.
3 // SPDX-License-Identifier: AGPL-3.0
18 "git.curoverse.com/arvados.git/sdk/go/arvados"
20 "golang.org/x/net/context"
21 "golang.org/x/net/webdav"
25 lockPrefix string = uuid()
26 nextLockSuffix int64 = prand.Int63()
27 errReadOnly = errors.New("read-only filesystem")
30 // webdavFS implements a webdav.FileSystem by wrapping an
31 // arvados.CollectionFilesystem.
33 // Collections don't preserve empty directories, so Mkdir is
34 // effectively a no-op, and we need to make parent dirs spring into
35 // existence automatically so sequences like "mkcol foo; put foo/bar"
37 type webdavFS struct {
38 collfs arvados.CollectionFileSystem
42 func (fs *webdavFS) makeparents(name string) {
43 dir, name := path.Split(name)
44 if dir == "" || dir == "/" {
47 dir = dir[:len(dir)-1]
49 fs.collfs.Mkdir(dir, 0755)
52 func (fs *webdavFS) Mkdir(ctx context.Context, name string, perm os.FileMode) error {
56 name = strings.TrimRight(name, "/")
58 return fs.collfs.Mkdir(name, 0755)
61 func (fs *webdavFS) OpenFile(ctx context.Context, name string, flag int, perm os.FileMode) (f webdav.File, err error) {
62 writing := flag&(os.O_WRONLY|os.O_RDWR) != 0
66 f, err = fs.collfs.OpenFile(name, flag, perm)
68 // webdav module returns 404 on all OpenFile errors,
69 // but returns 405 Method Not Allowed if OpenFile()
70 // succeeds but Write() or Close() fails. We'd rather
72 f = writeFailer{File: f, err: errReadOnly}
77 func (fs *webdavFS) RemoveAll(ctx context.Context, name string) error {
78 return fs.collfs.RemoveAll(name)
81 func (fs *webdavFS) Rename(ctx context.Context, oldName, newName string) error {
85 fs.makeparents(newName)
86 return fs.collfs.Rename(oldName, newName)
89 func (fs *webdavFS) Stat(ctx context.Context, name string) (os.FileInfo, error) {
93 return fs.collfs.Stat(name)
96 type writeFailer struct {
101 func (wf writeFailer) Write([]byte) (int, error) {
105 func (wf writeFailer) Close() error {
109 // noLockSystem implements webdav.LockSystem by returning success for
110 // every possible locking operation, even though it has no side
111 // effects such as actually locking anything. This works for a
112 // read-only webdav filesystem because webdav locks only apply to
115 // This is more suitable than webdav.NewMemLS() for two reasons:
116 // First, it allows keep-web to use one locker for all collections
117 // even though coll1.vhost/foo and coll2.vhost/foo have the same path
118 // but represent different resources. Additionally, it returns valid
119 // tokens (rfc2518 specifies that tokens are represented as URIs and
120 // are unique across all resources for all time), which might improve
121 // client compatibility.
123 // However, it does also permit impossible operations, like acquiring
124 // conflicting locks and releasing non-existent locks. This might
125 // confuse some clients if they try to probe for correctness.
127 // Currently this is a moot point: the LOCK and UNLOCK methods are not
128 // accepted by keep-web, so it suffices to implement the
129 // webdav.LockSystem interface.
130 type noLockSystem struct{}
132 func (*noLockSystem) Confirm(time.Time, string, string, ...webdav.Condition) (func(), error) {
136 func (*noLockSystem) Create(now time.Time, details webdav.LockDetails) (token string, err error) {
137 return fmt.Sprintf("opaquelocktoken:%s-%x", lockPrefix, atomic.AddInt64(&nextLockSuffix, 1)), nil
140 func (*noLockSystem) Refresh(now time.Time, token string, duration time.Duration) (webdav.LockDetails, error) {
141 return webdav.LockDetails{}, nil
144 func (*noLockSystem) Unlock(now time.Time, token string) error {
150 // Return a version 1 variant 4 UUID, meaning all bits are random
151 // except the ones indicating the version and variant.
154 if _, err := rand.Read(data[:]); err != nil {
158 data[8] = data[8]&0x3f | 0x80
160 data[6] = data[6]&0x0f | 0x40
161 return fmt.Sprintf("%x-%x-%x-%x-%x", data[0:4], data[4:6], data[6:8], data[8:10], data[10:])