1 // Copyright (C) The Arvados Authors. All rights reserved.
3 // SPDX-License-Identifier: AGPL-3.0
19 "git.curoverse.com/arvados.git/sdk/go/arvados"
21 "golang.org/x/net/context"
22 "golang.org/x/net/webdav"
26 lockPrefix string = uuid()
27 nextLockSuffix int64 = prand.Int63()
28 errReadOnly = errors.New("read-only filesystem")
31 // webdavFS implements a webdav.FileSystem by wrapping an
32 // arvados.CollectionFilesystem.
34 // Collections don't preserve empty directories, so Mkdir is
35 // effectively a no-op, and we need to make parent dirs spring into
36 // existence automatically so sequences like "mkcol foo; put foo/bar"
38 type webdavFS struct {
39 collfs arvados.CollectionFileSystem
44 func (fs *webdavFS) makeparents(name string) {
45 dir, name := path.Split(name)
46 if dir == "" || dir == "/" {
49 dir = dir[:len(dir)-1]
51 fs.collfs.Mkdir(dir, 0755)
54 func (fs *webdavFS) Mkdir(ctx context.Context, name string, perm os.FileMode) error {
58 name = strings.TrimRight(name, "/")
60 return fs.collfs.Mkdir(name, 0755)
63 func (fs *webdavFS) OpenFile(ctx context.Context, name string, flag int, perm os.FileMode) (f webdav.File, err error) {
64 writing := flag&(os.O_WRONLY|os.O_RDWR) != 0
68 f, err = fs.collfs.OpenFile(name, flag, perm)
70 // webdav module returns 404 on all OpenFile errors,
71 // but returns 405 Method Not Allowed if OpenFile()
72 // succeeds but Write() or Close() fails. We'd rather
74 f = writeFailer{File: f, err: errReadOnly}
77 // webdav PROPFIND reads the first few bytes of each
78 // file whose filename extension isn't recognized,
79 // which is prohibitively expensive: we end up
80 // fetching multiple 64MiB blocks. Avoid this by
81 // returning EOF on all reads when handling a
88 func (fs *webdavFS) RemoveAll(ctx context.Context, name string) error {
89 return fs.collfs.RemoveAll(name)
92 func (fs *webdavFS) Rename(ctx context.Context, oldName, newName string) error {
96 fs.makeparents(newName)
97 return fs.collfs.Rename(oldName, newName)
100 func (fs *webdavFS) Stat(ctx context.Context, name string) (os.FileInfo, error) {
104 return fs.collfs.Stat(name)
107 type writeFailer struct {
112 func (wf writeFailer) Write([]byte) (int, error) {
116 func (wf writeFailer) Close() error {
120 type readEOF struct {
124 func (readEOF) Read(p []byte) (int, error) {
128 // noLockSystem implements webdav.LockSystem by returning success for
129 // every possible locking operation, even though it has no side
130 // effects such as actually locking anything. This works for a
131 // read-only webdav filesystem because webdav locks only apply to
134 // This is more suitable than webdav.NewMemLS() for two reasons:
135 // First, it allows keep-web to use one locker for all collections
136 // even though coll1.vhost/foo and coll2.vhost/foo have the same path
137 // but represent different resources. Additionally, it returns valid
138 // tokens (rfc2518 specifies that tokens are represented as URIs and
139 // are unique across all resources for all time), which might improve
140 // client compatibility.
142 // However, it does also permit impossible operations, like acquiring
143 // conflicting locks and releasing non-existent locks. This might
144 // confuse some clients if they try to probe for correctness.
146 // Currently this is a moot point: the LOCK and UNLOCK methods are not
147 // accepted by keep-web, so it suffices to implement the
148 // webdav.LockSystem interface.
149 type noLockSystem struct{}
151 func (*noLockSystem) Confirm(time.Time, string, string, ...webdav.Condition) (func(), error) {
155 func (*noLockSystem) Create(now time.Time, details webdav.LockDetails) (token string, err error) {
156 return fmt.Sprintf("opaquelocktoken:%s-%x", lockPrefix, atomic.AddInt64(&nextLockSuffix, 1)), nil
159 func (*noLockSystem) Refresh(now time.Time, token string, duration time.Duration) (webdav.LockDetails, error) {
160 return webdav.LockDetails{}, nil
163 func (*noLockSystem) Unlock(now time.Time, token string) error {
169 // Return a version 1 variant 4 UUID, meaning all bits are random
170 // except the ones indicating the version and variant.
173 if _, err := rand.Read(data[:]); err != nil {
177 data[8] = data[8]&0x3f | 0x80
179 data[6] = data[6]&0x0f | 0x40
180 return fmt.Sprintf("%x-%x-%x-%x-%x", data[0:4], data[4:6], data[6:8], data[8:10], data[10:])