1 // Copyright (C) The Arvados Authors. All rights reserved.
3 // SPDX-License-Identifier: Apache-2.0
21 ErrReadOnlyFile = errors.New("read-only file")
22 ErrNegativeOffset = errors.New("cannot seek to negative offset")
23 ErrFileExists = errors.New("file exists")
24 ErrInvalidOperation = errors.New("invalid operation")
25 ErrInvalidArgument = errors.New("invalid argument")
26 ErrDirectoryNotEmpty = errors.New("directory not empty")
27 ErrWriteOnlyMode = errors.New("file is O_WRONLY")
28 ErrSyncNotSupported = errors.New("O_SYNC flag is not supported")
29 ErrIsDirectory = errors.New("cannot rename file to overwrite existing directory")
30 ErrNotADirectory = errors.New("not a directory")
31 ErrPermission = os.ErrPermission
32 DebugLocksPanicMode = false
35 type syncer interface {
39 func debugPanicIfNotLocked(l sync.Locker) {
40 if !DebugLocksPanicMode {
51 panic("bug: caller-must-have-lock func called, but nobody has lock")
55 // A File is an *os.File-like interface for reading and writing files
63 Readdir(int) ([]os.FileInfo, error)
64 Stat() (os.FileInfo, error)
69 // A FileSystem is an http.Filesystem plus Stat() and support for
70 // opening writable files. All methods are safe to call from multiple
72 type FileSystem interface {
78 // filesystem-wide lock: used by Rename() to prevent deadlock
79 // while locking multiple inodes.
82 // throttle for limiting concurrent background writers
85 // create a new node with nil parent.
86 newNode(name string, perm os.FileMode, modTime time.Time) (node inode, err error)
88 // analogous to os.Stat()
89 Stat(name string) (os.FileInfo, error)
91 // analogous to os.Create(): create/truncate a file and open it O_RDWR.
92 Create(name string) (File, error)
94 // Like os.OpenFile(): create or open a file or directory.
96 // If flag&os.O_EXCL==0, it opens an existing file or
97 // directory if one exists. If flag&os.O_CREATE!=0, it creates
98 // a new empty file or directory if one does not already
101 // When creating a new item, perm&os.ModeDir determines
102 // whether it is a file or a directory.
104 // A file can be opened multiple times and used concurrently
105 // from multiple goroutines. However, each File object should
106 // be used by only one goroutine at a time.
107 OpenFile(name string, flag int, perm os.FileMode) (File, error)
109 Mkdir(name string, perm os.FileMode) error
110 Remove(name string) error
111 RemoveAll(name string) error
112 Rename(oldname, newname string) error
114 // Write buffered data from memory to storage, returning when
115 // all updates have been saved to persistent storage.
118 // Write buffered data from memory to storage, but don't wait
119 // for all writes to finish before returning. If shortBlocks
120 // is true, flush everything; otherwise, if there's less than
121 // a full block of buffered data at the end of a stream, leave
122 // it buffered in memory in case more data can be appended. If
123 // path is "", flush all dirs/streams; otherwise, flush only
124 // the specified dir/stream.
125 Flush(path string, shortBlocks bool) error
127 // Estimate current memory usage.
131 type inode interface {
132 SetParent(parent inode, name string)
135 Read([]byte, filenodePtr) (int, filenodePtr, error)
136 Write([]byte, filenodePtr) (int, filenodePtr, error)
137 Truncate(int64) error
139 Readdir() ([]os.FileInfo, error)
141 FileInfo() os.FileInfo
143 // Child() performs lookups and updates of named child nodes.
145 // (The term "child" here is used strictly. This means name is
146 // not "." or "..", and name does not contain "/".)
148 // If replace is non-nil, Child calls replace(x) where x is
149 // the current child inode with the given name. If possible,
150 // the child inode is replaced with the one returned by
153 // If replace(x) returns an inode (besides x or nil) that is
154 // subsequently returned by Child(), then Child()'s caller
155 // must ensure the new child's name and parent are set/updated
156 // to Child()'s name argument and its receiver respectively.
157 // This is not necessarily done before replace(x) returns, but
158 // it must be done before Child()'s caller releases the
161 // Nil represents "no child". replace(nil) signifies that no
162 // child with this name exists yet. If replace() returns nil,
163 // the existing child should be deleted if possible.
165 // An implementation of Child() is permitted to ignore
166 // replace() or its return value. For example, a regular file
167 // inode does not have children, so Child() always returns
170 // Child() returns the child, if any, with the given name: if
171 // a child was added or changed, the new child is returned.
173 // Caller must have lock (or rlock if replace is nil).
174 Child(name string, replace func(inode) (inode, error)) (inode, error)
182 type fileinfo struct {
189 // Name implements os.FileInfo.
190 func (fi fileinfo) Name() string {
194 // ModTime implements os.FileInfo.
195 func (fi fileinfo) ModTime() time.Time {
199 // Mode implements os.FileInfo.
200 func (fi fileinfo) Mode() os.FileMode {
204 // IsDir implements os.FileInfo.
205 func (fi fileinfo) IsDir() bool {
206 return fi.mode&os.ModeDir != 0
209 // Size implements os.FileInfo.
210 func (fi fileinfo) Size() int64 {
214 // Sys implements os.FileInfo.
215 func (fi fileinfo) Sys() interface{} {
219 type nullnode struct{}
221 func (*nullnode) Mkdir(string, os.FileMode) error {
222 return ErrInvalidOperation
225 func (*nullnode) Read([]byte, filenodePtr) (int, filenodePtr, error) {
226 return 0, filenodePtr{}, ErrInvalidOperation
229 func (*nullnode) Write([]byte, filenodePtr) (int, filenodePtr, error) {
230 return 0, filenodePtr{}, ErrInvalidOperation
233 func (*nullnode) Truncate(int64) error {
234 return ErrInvalidOperation
237 func (*nullnode) FileInfo() os.FileInfo {
241 func (*nullnode) IsDir() bool {
245 func (*nullnode) Readdir() ([]os.FileInfo, error) {
246 return nil, ErrInvalidOperation
249 func (*nullnode) Child(name string, replace func(inode) (inode, error)) (inode, error) {
250 return nil, ErrNotADirectory
253 func (*nullnode) MemorySize() int64 {
254 // Types that embed nullnode should report their own size, but
255 // if they don't, we at least report a non-zero size to ensure
256 // a large tree doesn't get reported as 0 bytes.
260 type treenode struct {
263 inodes map[string]inode
269 func (n *treenode) FS() FileSystem {
273 func (n *treenode) SetParent(p inode, name string) {
277 n.fileinfo.name = name
280 func (n *treenode) Parent() inode {
286 func (n *treenode) IsDir() bool {
290 func (n *treenode) Child(name string, replace func(inode) (inode, error)) (child inode, err error) {
291 debugPanicIfNotLocked(n)
292 child = n.inodes[name]
293 if name == "" || name == "." || name == ".." {
294 err = ErrInvalidArgument
300 newchild, err := replace(child)
305 delete(n.inodes, name)
306 } else if newchild != child {
307 n.inodes[name] = newchild
308 n.fileinfo.modTime = time.Now()
314 func (n *treenode) Size() int64 {
315 return n.FileInfo().Size()
318 func (n *treenode) FileInfo() os.FileInfo {
321 n.fileinfo.size = int64(len(n.inodes))
325 func (n *treenode) Readdir() (fi []os.FileInfo, err error) {
328 fi = make([]os.FileInfo, 0, len(n.inodes))
329 for _, inode := range n.inodes {
330 fi = append(fi, inode.FileInfo())
335 func (n *treenode) Sync() error {
338 for _, inode := range n.inodes {
339 syncer, ok := inode.(syncer)
341 return ErrInvalidOperation
351 func (n *treenode) MemorySize() (size int64) {
354 debugPanicIfNotLocked(n)
355 for _, inode := range n.inodes {
356 size += inode.MemorySize()
361 type fileSystem struct {
368 func (fs *fileSystem) rootnode() inode {
372 func (fs *fileSystem) throttle() *throttle {
376 func (fs *fileSystem) locker() sync.Locker {
380 // OpenFile is analogous to os.OpenFile().
381 func (fs *fileSystem) OpenFile(name string, flag int, perm os.FileMode) (File, error) {
382 return fs.openFile(name, flag, perm)
385 func (fs *fileSystem) openFile(name string, flag int, perm os.FileMode) (*filehandle, error) {
386 if flag&os.O_SYNC != 0 {
387 return nil, ErrSyncNotSupported
389 dirname, name := path.Split(name)
390 parent, err := rlookup(fs.root, dirname)
394 var readable, writable bool
395 switch flag & (os.O_RDWR | os.O_RDONLY | os.O_WRONLY) {
404 return nil, fmt.Errorf("invalid flags 0x%x", flag)
406 if !writable && parent.IsDir() {
407 // A directory can be opened via "foo/", "foo/.", or
411 return &filehandle{inode: parent}, nil
413 return &filehandle{inode: parent.Parent()}, nil
416 createMode := flag&os.O_CREATE != 0
419 defer parent.Unlock()
422 defer parent.RUnlock()
424 n, err := parent.Child(name, nil)
429 return nil, os.ErrNotExist
431 n, err = parent.Child(name, func(inode) (repl inode, err error) {
432 repl, err = parent.FS().newNode(name, perm|0755, time.Now())
436 repl.SetParent(parent, name)
442 // Parent rejected new child, but returned no error
443 return nil, ErrInvalidArgument
445 } else if flag&os.O_EXCL != 0 {
446 return nil, ErrFileExists
447 } else if flag&os.O_TRUNC != 0 {
449 return nil, fmt.Errorf("invalid flag O_TRUNC in read-only mode")
450 } else if n.IsDir() {
451 return nil, fmt.Errorf("invalid flag O_TRUNC when opening directory")
452 } else if err := n.Truncate(0); err != nil {
458 append: flag&os.O_APPEND != 0,
464 func (fs *fileSystem) Open(name string) (http.File, error) {
465 return fs.OpenFile(name, os.O_RDONLY, 0)
468 func (fs *fileSystem) Create(name string) (File, error) {
469 return fs.OpenFile(name, os.O_CREATE|os.O_RDWR|os.O_TRUNC, 0)
472 func (fs *fileSystem) Mkdir(name string, perm os.FileMode) error {
473 dirname, name := path.Split(name)
474 n, err := rlookup(fs.root, dirname)
480 if child, err := n.Child(name, nil); err != nil {
482 } else if child != nil {
486 _, err = n.Child(name, func(inode) (repl inode, err error) {
487 repl, err = n.FS().newNode(name, perm|os.ModeDir, time.Now())
491 repl.SetParent(n, name)
497 func (fs *fileSystem) Stat(name string) (os.FileInfo, error) {
498 node, err := rlookup(fs.root, name)
502 return node.FileInfo(), nil
505 func (fs *fileSystem) Rename(oldname, newname string) error {
506 olddir, oldname := path.Split(oldname)
507 if oldname == "" || oldname == "." || oldname == ".." {
508 return ErrInvalidArgument
510 olddirf, err := fs.openFile(olddir+".", os.O_RDONLY, 0)
512 return fmt.Errorf("%q: %s", olddir, err)
514 defer olddirf.Close()
516 newdir, newname := path.Split(newname)
517 if newname == "." || newname == ".." {
518 return ErrInvalidArgument
519 } else if newname == "" {
520 // Rename("a/b", "c/") means Rename("a/b", "c/b")
523 newdirf, err := fs.openFile(newdir+".", os.O_RDONLY, 0)
525 return fmt.Errorf("%q: %s", newdir, err)
527 defer newdirf.Close()
529 // TODO: If the nearest common ancestor ("nca") of olddirf and
530 // newdirf is on a different filesystem than fs, we should
531 // call nca.FS().Rename() instead of proceeding. Until then
532 // it's awkward for filesystems to implement their own Rename
533 // methods effectively: the only one that runs is the one on
534 // the root FileSystem exposed to the caller (webdav, fuse,
537 // When acquiring locks on multiple inodes, avoid deadlock by
538 // locking the entire containing filesystem first.
539 cfs := olddirf.inode.FS()
541 defer cfs.locker().Unlock()
543 if cfs != newdirf.inode.FS() {
544 // Moving inodes across filesystems is not (yet)
545 // supported. Locking inodes from different
546 // filesystems could deadlock, so we must error out
548 return ErrInvalidArgument
551 // To ensure we can test reliably whether we're about to move
552 // a directory into itself, lock all potential common
553 // ancestors of olddir and newdir.
554 needLock := []sync.Locker{}
555 for _, node := range []inode{olddirf.inode, newdirf.inode} {
556 needLock = append(needLock, node)
557 for node.Parent() != node && node.Parent().FS() == node.FS() {
559 needLock = append(needLock, node)
562 locked := map[sync.Locker]bool{}
563 for i := len(needLock) - 1; i >= 0; i-- {
564 if n := needLock[i]; !locked[n] {
571 _, err = olddirf.inode.Child(oldname, func(oldinode inode) (inode, error) {
573 return oldinode, os.ErrNotExist
575 if locked[oldinode] {
576 // oldinode cannot become a descendant of itself.
577 return oldinode, ErrInvalidArgument
579 if oldinode.FS() != cfs && newdirf.inode != olddirf.inode {
580 // moving a mount point to a different parent
581 // is not (yet) supported.
582 return oldinode, ErrInvalidArgument
584 accepted, err := newdirf.inode.Child(newname, func(existing inode) (inode, error) {
585 if existing != nil && existing.IsDir() {
586 return existing, ErrIsDirectory
591 // Leave oldinode in olddir.
594 accepted.SetParent(newdirf.inode, newname)
600 func (fs *fileSystem) Remove(name string) error {
601 return fs.remove(strings.TrimRight(name, "/"), false)
604 func (fs *fileSystem) RemoveAll(name string) error {
605 err := fs.remove(strings.TrimRight(name, "/"), true)
606 if os.IsNotExist(err) {
607 // "If the path does not exist, RemoveAll returns
608 // nil." (see "os" pkg)
614 func (fs *fileSystem) remove(name string, recursive bool) error {
615 dirname, name := path.Split(name)
616 if name == "" || name == "." || name == ".." {
617 return ErrInvalidArgument
619 dir, err := rlookup(fs.root, dirname)
625 _, err = dir.Child(name, func(node inode) (inode, error) {
627 return nil, os.ErrNotExist
629 if !recursive && node.IsDir() && node.Size() > 0 {
630 return node, ErrDirectoryNotEmpty
637 func (fs *fileSystem) Sync() error {
638 if syncer, ok := fs.root.(syncer); ok {
641 return ErrInvalidOperation
644 func (fs *fileSystem) Flush(string, bool) error {
645 log.Printf("TODO: flush fileSystem")
646 return ErrInvalidOperation
649 func (fs *fileSystem) MemorySize() int64 {
650 return fs.root.MemorySize()
653 // rlookup (recursive lookup) returns the inode for the file/directory
654 // with the given name (which may contain "/" separators). If no such
655 // file/directory exists, the returned node is nil.
656 func rlookup(start inode, path string) (node inode, err error) {
658 for _, name := range strings.Split(path, "/") {
660 if name == "." || name == "" {
668 node, err = func() (inode, error) {
671 return node.Child(name, nil)
673 if node == nil || err != nil {
677 if node == nil && err == nil {
683 func permittedName(name string) bool {
684 return name != "" && name != "." && name != ".." && !strings.Contains(name, "/")