webdav/file.go - net - Git at Google

 // Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package webdav

 import (
 	"io"
 	"net/http"
 	"os"
 	"path"
 	"path/filepath"
 	"strings"
 	"sync"
 	"time"
 )

 // A FileSystem implements access to a collection of named files. The elements
 // in a file path are separated by slash ('/', U+002F) characters, regardless
 // of host operating system convention.
 //
 // Each method has the same semantics as the os package's function of the same
 // name.
 type FileSystem interface {
 	Mkdir(name string, perm os.FileMode) error
 	OpenFile(name string, flag int, perm os.FileMode) (File, error)
 	RemoveAll(name string) error
 	Stat(name string) (os.FileInfo, error)
 }

 // A File is returned by a FileSystem's OpenFile method and can be served by a
 // Handler.
 type File interface {
 	http.File
 	io.Writer
 }

 // A Dir implements FileSystem using the native file system restricted to a
 // specific directory tree.
 //
 // While the FileSystem.OpenFile method takes '/'-separated paths, a Dir's
 // string value is a filename on the native file system, not a URL, so it is
 // separated by filepath.Separator, which isn't necessarily '/'.
 //
 // An empty Dir is treated as ".".
 type Dir string

 func (d Dir) resolve(name string) string {
 	// This implementation is based on Dir.Open's code in the standard net/http package.
 	if filepath.Separator != '/' && strings.IndexRune(name, filepath.Separator) >= 0 ||
 		strings.Contains(name, "\x00") {
 		return ""
 	}
 	dir := string(d)
 	if dir == "" {
 		dir = "."
 	}
 	return filepath.Join(dir, filepath.FromSlash(path.Clean("/"+name)))
 }

 func (d Dir) Mkdir(name string, perm os.FileMode) error {
 	if name = d.resolve(name); name == "" {
 		return os.ErrNotExist
 	}
 	return os.Mkdir(name, perm)
 }

 func (d Dir) OpenFile(name string, flag int, perm os.FileMode) (File, error) {
 	if name = d.resolve(name); name == "" {
 		return nil, os.ErrNotExist
 	}
 	return os.OpenFile(name, flag, perm)
 }

 func (d Dir) RemoveAll(name string) error {
 	if name = d.resolve(name); name == "" {
 		return os.ErrNotExist
 	}
 	if name == filepath.Clean(string(d)) {
 		// Prohibit removing the virtual root directory.
 		return os.ErrInvalid
 	}
 	return os.RemoveAll(name)
 }

 func (d Dir) Stat(name string) (os.FileInfo, error) {
 	if name = d.resolve(name); name == "" {
 		return nil, os.ErrNotExist
 	}
 	return os.Stat(name)
 }

 // NewMemFS returns a new in-memory FileSystem implementation.
 func NewMemFS() FileSystem {
 	return &memFS{
 		root: memFSNode{
 			children: make(map[string]*memFSNode),
 			mode:     0660 | os.ModeDir,
 			modTime:  time.Now(),
 		},
 	}
 }

 // A memFS implements FileSystem, storing all metadata and actual file data
 // in-memory. No limits on filesystem size are used, so it is not recommended
 // this be used where the clients are untrusted.
 //
 // Concurrent access is permitted. The tree structure is protected by a mutex,
 // and each node's contents and metadata are protected by a per-node mutex.
 //
 // TODO: Enforce file permissions.
 type memFS struct {
 	mu   sync.Mutex
 	root memFSNode
 }

 // walk walks the directory tree for the fullname, calling f at each step. If f
 // returns an error, the walk will be aborted and return that same error.
 //
 // Each walk is atomic: fs's mutex is held for the entire operation, including
 // all calls to f.
 //
 // dir is the directory at that step, frag is the name fragment, and final is
 // whether it is the final step. For example, walking "/foo/bar/x" will result
 // in 3 calls to f:
 //   - "/", "foo", false
 //   - "/foo/", "bar", false
 //   - "/foo/bar/", "x", true
 func (fs *memFS) walk(op, fullname string, f func(dir *memFSNode, frag string, final bool) error) error {
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

 	original := fullname
 	fullname = path.Clean("/" + fullname)

 	// Strip any leading "/"s to make fullname a relative path, as the walk
 	// starts at fs.root.
 	if fullname[0] == '/' {
 		fullname = fullname[1:]
 	}
 	dir := &fs.root

 	for {
 		frag, remaining := fullname, ""
 		i := strings.IndexRune(fullname, '/')
 		final := i < 0
 		if !final {
 			frag, remaining = fullname[:i], fullname[i+1:]
 		}
 		if err := f(dir, frag, final); err != nil {
 			return &os.PathError{
 				Op:   op,
 				Path: original,
 				Err:  err,
 			}
 		}
 		if final {
 			break
 		}
 		child := dir.children[frag]
 		if child == nil {
 			return &os.PathError{
 				Op:   op,
 				Path: original,
 				Err:  os.ErrNotExist,
 			}
 		}
 		if !child.IsDir() {
 			return &os.PathError{
 				Op:   op,
 				Path: original,
 				Err:  os.ErrInvalid,
 			}
 		}
 		dir, fullname = child, remaining
 	}
 	return nil
 }

 func (fs *memFS) Mkdir(name string, perm os.FileMode) error {
 	return fs.walk("mkdir", name, func(dir *memFSNode, frag string, final bool) error {
 		if !final {
 			return nil
 		}
 		if frag == "" {
 			return os.ErrInvalid
 		}
 		if _, ok := dir.children[frag]; ok {
 			return os.ErrExist
 		}
 		dir.children[frag] = &memFSNode{
 			name:     frag,
 			children: make(map[string]*memFSNode),
 			mode:     perm.Perm() | os.ModeDir,
 			modTime:  time.Now(),
 		}
 		return nil
 	})
 }

 func (fs *memFS) OpenFile(name string, flag int, perm os.FileMode) (File, error) {
 	var ret *memFile
 	err := fs.walk("open", name, func(dir *memFSNode, frag string, final bool) error {
 		if !final {
 			return nil
 		}
 		if frag == "" {
 			return os.ErrInvalid
 		}
 		if flag&(os.O_SYNC|os.O_APPEND) != 0 {
 			return os.ErrInvalid
 		}
 		n := dir.children[frag]
 		if flag&os.O_CREATE != 0 {
 			if flag&os.O_EXCL != 0 && n != nil {
 				return os.ErrExist
 			}
 			if n == nil {
 				n = &memFSNode{
 					name: frag,
 					mode: perm.Perm(),
 				}
 				dir.children[frag] = n
 			}
 		}
 		if n == nil {
 			return os.ErrNotExist
 		}
 		if flag&(os.O_WRONLY|os.O_RDWR) != 0 && flag&os.O_TRUNC != 0 {
 			n.mu.Lock()
 			n.data = nil
 			n.mu.Unlock()
 		}

 		children := make([]os.FileInfo, 0, len(n.children))
 		for _, c := range n.children {
 			children = append(children, c)
 		}
 		ret = &memFile{
 			n:        n,
 			children: children,
 		}
 		return nil
 	})
 	if err != nil {
 		return nil, err
 	}
 	return ret, nil
 }

 func (fs *memFS) RemoveAll(name string) error {
 	return fs.walk("remove", name, func(dir *memFSNode, frag string, final bool) error {
 		if !final {
 			return nil
 		}
 		if frag == "" {
 			return os.ErrInvalid
 		}
 		if _, ok := dir.children[frag]; !ok {
 			return os.ErrNotExist
 		}
 		delete(dir.children, frag)
 		return nil
 	})
 }

 func (fs *memFS) Stat(name string) (os.FileInfo, error) {
 	var n *memFSNode
 	err := fs.walk("stat", name, func(dir *memFSNode, frag string, final bool) error {
 		if !final {
 			return nil
 		}
 		if frag == "" {
 			return os.ErrInvalid
 		}
 		n = dir.children[frag]
 		if n == nil {
 			return os.ErrNotExist
 		}
 		return nil
 	})
 	if err != nil {
 		return nil, err
 	}
 	return n, nil
 }

 // A memFSNode represents a single entry in the in-memory filesystem and also
 // implements os.FileInfo.
 type memFSNode struct {
 	name string

 	mu       sync.Mutex
 	modTime  time.Time
 	mode     os.FileMode
 	children map[string]*memFSNode
 	data     []byte
 }

 func (n *memFSNode) Name() string {
 	return n.name
 }

 func (n *memFSNode) Size() int64 {
 	n.mu.Lock()
 	defer n.mu.Unlock()
 	return int64(len(n.data))
 }

 func (n *memFSNode) Mode() os.FileMode {
 	n.mu.Lock()
 	defer n.mu.Unlock()
 	return n.mode
 }

 func (n *memFSNode) ModTime() time.Time {
 	n.mu.Lock()
 	defer n.mu.Unlock()
 	return n.modTime
 }

 func (n *memFSNode) IsDir() bool {
 	return n.Mode().IsDir()
 }

 func (n *memFSNode) Sys() interface{} {
 	return nil
 }

 // A memFile is a File implementation for a memFSNode. It is a per-file (not
 // per-node) read/write position, and if the node is a directory, a snapshot of
 // that node's children.
 type memFile struct {
 	n        *memFSNode
 	children []os.FileInfo
 	// Changes to pos are guarded by n.mu.
 	pos int
 }

 func (f *memFile) Close() error {
 	return nil
 }

 func (f *memFile) Read(p []byte) (int, error) {
 	if f.n.IsDir() {
 		return 0, os.ErrInvalid
 	}
 	f.n.mu.Lock()
 	defer f.n.mu.Unlock()
 	if f.pos >= len(f.n.data) {
 		return 0, io.EOF
 	}
 	n := copy(p, f.n.data[f.pos:])
 	f.pos += n
 	return n, nil
 }

 func (f *memFile) Readdir(count int) ([]os.FileInfo, error) {
 	if !f.n.IsDir() {
 		return nil, os.ErrInvalid
 	}
 	f.n.mu.Lock()
 	defer f.n.mu.Unlock()
 	old := f.pos
 	if old >= len(f.children) {
 		return nil, io.EOF
 	}
 	if count > 0 {
 		f.pos += count
 		if f.pos > len(f.children) {
 			f.pos = len(f.children)
 		}
 	} else {
 		f.pos = len(f.children)
 		old = 0
 	}
 	return f.children[old:f.pos], nil
 }

 func (f *memFile) Seek(offset int64, whence int) (int64, error) {
 	f.n.mu.Lock()
 	defer f.n.mu.Unlock()
 	npos := f.pos
 	// TODO: How to handle offsets greater than the size of system int?
 	switch whence {
 	case os.SEEK_SET:
 		npos = int(offset)
 	case os.SEEK_CUR:
 		npos += int(offset)
 	case os.SEEK_END:
 		npos = len(f.n.data) + int(offset)
 	default:
 		npos = -1
 	}
 	if npos < 0 {
 		return 0, os.ErrInvalid
 	}
 	f.pos = npos
 	return int64(f.pos), nil
 }

 func (f *memFile) Stat() (os.FileInfo, error) {
 	return f.n, nil
 }

 func (f *memFile) Write(p []byte) (int, error) {
 	f.n.mu.Lock()
 	defer f.n.mu.Unlock()
 	epos := len(p) + f.pos
 	if epos > len(f.n.data) {
 		d := make([]byte, epos)
 		copy(d, f.n.data)
 		f.n.data = d
 	}
 	copy(f.n.data[f.pos:], p)
 	f.n.modTime = time.Now()
 	return len(p), nil
 }
	// Copyright 2014 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package webdav

	import (
	"io"
	"net/http"
	"os"
	"path"
	"path/filepath"
	"strings"
	"sync"
	"time"
	)

	// A FileSystem implements access to a collection of named files. The elements
	// in a file path are separated by slash ('/', U+002F) characters, regardless
	// of host operating system convention.
	//
	// Each method has the same semantics as the os package's function of the same
	// name.
	type FileSystem interface {
	Mkdir(name string, perm os.FileMode) error
	OpenFile(name string, flag int, perm os.FileMode) (File, error)
	RemoveAll(name string) error
	Stat(name string) (os.FileInfo, error)
	}

	// A File is returned by a FileSystem's OpenFile method and can be served by a
	// Handler.
	type File interface {
	http.File
	io.Writer
	}

	// A Dir implements FileSystem using the native file system restricted to a
	// specific directory tree.
	//
	// While the FileSystem.OpenFile method takes '/'-separated paths, a Dir's
	// string value is a filename on the native file system, not a URL, so it is
	// separated by filepath.Separator, which isn't necessarily '/'.
	//
	// An empty Dir is treated as ".".
	type Dir string

	func (d Dir) resolve(name string) string {
	// This implementation is based on Dir.Open's code in the standard net/http package.
	if filepath.Separator != '/' && strings.IndexRune(name, filepath.Separator) >= 0 \|\|
	strings.Contains(name, "\x00") {
	return ""
	}
	dir := string(d)
	if dir == "" {
	dir = "."
	}
	return filepath.Join(dir, filepath.FromSlash(path.Clean("/"+name)))
	}

	func (d Dir) Mkdir(name string, perm os.FileMode) error {
	if name = d.resolve(name); name == "" {
	return os.ErrNotExist
	}
	return os.Mkdir(name, perm)
	}

	func (d Dir) OpenFile(name string, flag int, perm os.FileMode) (File, error) {
	if name = d.resolve(name); name == "" {
	return nil, os.ErrNotExist
	}
	return os.OpenFile(name, flag, perm)
	}

	func (d Dir) RemoveAll(name string) error {
	if name = d.resolve(name); name == "" {
	return os.ErrNotExist
	}
	if name == filepath.Clean(string(d)) {
	// Prohibit removing the virtual root directory.
	return os.ErrInvalid
	}
	return os.RemoveAll(name)
	}

	func (d Dir) Stat(name string) (os.FileInfo, error) {
	if name = d.resolve(name); name == "" {
	return nil, os.ErrNotExist
	}
	return os.Stat(name)
	}

	// NewMemFS returns a new in-memory FileSystem implementation.
	func NewMemFS() FileSystem {
	return &memFS{
	root: memFSNode{
	children: make(map[string]*memFSNode),
	mode: 0660 \| os.ModeDir,
	modTime: time.Now(),
	},
	}
	}

	// A memFS implements FileSystem, storing all metadata and actual file data
	// in-memory. No limits on filesystem size are used, so it is not recommended
	// this be used where the clients are untrusted.
	//
	// Concurrent access is permitted. The tree structure is protected by a mutex,
	// and each node's contents and metadata are protected by a per-node mutex.
	//
	// TODO: Enforce file permissions.
	type memFS struct {
	mu sync.Mutex
	root memFSNode
	}

	// walk walks the directory tree for the fullname, calling f at each step. If f
	// returns an error, the walk will be aborted and return that same error.
	//
	// Each walk is atomic: fs's mutex is held for the entire operation, including
	// all calls to f.
	//
	// dir is the directory at that step, frag is the name fragment, and final is
	// whether it is the final step. For example, walking "/foo/bar/x" will result
	// in 3 calls to f:
	// - "/", "foo", false
	// - "/foo/", "bar", false
	// - "/foo/bar/", "x", true
	func (fs memFS) walk(op, fullname string, f func(dir memFSNode, frag string, final bool) error) error {
	fs.mu.Lock()
	defer fs.mu.Unlock()

	original := fullname
	fullname = path.Clean("/" + fullname)

	// Strip any leading "/"s to make fullname a relative path, as the walk
	// starts at fs.root.
	if fullname[0] == '/' {
	fullname = fullname[1:]
	}
	dir := &fs.root

	for {
	frag, remaining := fullname, ""
	i := strings.IndexRune(fullname, '/')
	final := i < 0
	if !final {
	frag, remaining = fullname[:i], fullname[i+1:]
	}
	if err := f(dir, frag, final); err != nil {
	return &os.PathError{
	Op: op,
	Path: original,
	Err: err,
	}
	}
	if final {
	break
	}
	child := dir.children[frag]
	if child == nil {
	return &os.PathError{
	Op: op,
	Path: original,
	Err: os.ErrNotExist,
	}
	}
	if !child.IsDir() {
	return &os.PathError{
	Op: op,
	Path: original,
	Err: os.ErrInvalid,
	}
	}
	dir, fullname = child, remaining
	}
	return nil
	}

	func (fs *memFS) Mkdir(name string, perm os.FileMode) error {
	return fs.walk("mkdir", name, func(dir *memFSNode, frag string, final bool) error {
	if !final {
	return nil
	}
	if frag == "" {
	return os.ErrInvalid
	}
	if _, ok := dir.children[frag]; ok {
	return os.ErrExist
	}
	dir.children[frag] = &memFSNode{
	name: frag,
	children: make(map[string]*memFSNode),
	mode: perm.Perm() \| os.ModeDir,
	modTime: time.Now(),
	}
	return nil
	})
	}

	func (fs *memFS) OpenFile(name string, flag int, perm os.FileMode) (File, error) {
	var ret *memFile
	err := fs.walk("open", name, func(dir *memFSNode, frag string, final bool) error {
	if !final {
	return nil
	}
	if frag == "" {
	return os.ErrInvalid
	}
	if flag&(os.O_SYNC\|os.O_APPEND) != 0 {
	return os.ErrInvalid
	}
	n := dir.children[frag]
	if flag&os.O_CREATE != 0 {
	if flag&os.O_EXCL != 0 && n != nil {
	return os.ErrExist
	}
	if n == nil {
	n = &memFSNode{
	name: frag,
	mode: perm.Perm(),
	}
	dir.children[frag] = n
	}
	}
	if n == nil {
	return os.ErrNotExist
	}
	if flag&(os.O_WRONLY\|os.O_RDWR) != 0 && flag&os.O_TRUNC != 0 {
	n.mu.Lock()
	n.data = nil
	n.mu.Unlock()
	}

	children := make([]os.FileInfo, 0, len(n.children))
	for _, c := range n.children {
	children = append(children, c)
	}
	ret = &memFile{
	n: n,
	children: children,
	}
	return nil
	})
	if err != nil {
	return nil, err
	}
	return ret, nil
	}

	func (fs *memFS) RemoveAll(name string) error {
	return fs.walk("remove", name, func(dir *memFSNode, frag string, final bool) error {
	if !final {
	return nil
	}
	if frag == "" {
	return os.ErrInvalid
	}
	if _, ok := dir.children[frag]; !ok {
	return os.ErrNotExist
	}
	delete(dir.children, frag)
	return nil
	})
	}

	func (fs *memFS) Stat(name string) (os.FileInfo, error) {
	var n *memFSNode
	err := fs.walk("stat", name, func(dir *memFSNode, frag string, final bool) error {
	if !final {
	return nil
	}
	if frag == "" {
	return os.ErrInvalid
	}
	n = dir.children[frag]
	if n == nil {
	return os.ErrNotExist
	}
	return nil
	})
	if err != nil {
	return nil, err
	}
	return n, nil
	}

	// A memFSNode represents a single entry in the in-memory filesystem and also
	// implements os.FileInfo.
	type memFSNode struct {
	name string

	mu sync.Mutex
	modTime time.Time
	mode os.FileMode
	children map[string]*memFSNode
	data []byte
	}

	func (n *memFSNode) Name() string {
	return n.name
	}

	func (n *memFSNode) Size() int64 {
	n.mu.Lock()
	defer n.mu.Unlock()
	return int64(len(n.data))
	}

	func (n *memFSNode) Mode() os.FileMode {
	n.mu.Lock()
	defer n.mu.Unlock()
	return n.mode
	}

	func (n *memFSNode) ModTime() time.Time {
	n.mu.Lock()
	defer n.mu.Unlock()
	return n.modTime
	}

	func (n *memFSNode) IsDir() bool {
	return n.Mode().IsDir()
	}

	func (n *memFSNode) Sys() interface{} {
	return nil
	}

	// A memFile is a File implementation for a memFSNode. It is a per-file (not
	// per-node) read/write position, and if the node is a directory, a snapshot of
	// that node's children.
	type memFile struct {
	n *memFSNode
	children []os.FileInfo
	// Changes to pos are guarded by n.mu.
	pos int
	}

	func (f *memFile) Close() error {
	return nil
	}

	func (f *memFile) Read(p []byte) (int, error) {
	if f.n.IsDir() {
	return 0, os.ErrInvalid
	}
	f.n.mu.Lock()
	defer f.n.mu.Unlock()
	if f.pos >= len(f.n.data) {
	return 0, io.EOF
	}
	n := copy(p, f.n.data[f.pos:])
	f.pos += n
	return n, nil
	}

	func (f *memFile) Readdir(count int) ([]os.FileInfo, error) {
	if !f.n.IsDir() {
	return nil, os.ErrInvalid
	}
	f.n.mu.Lock()
	defer f.n.mu.Unlock()
	old := f.pos
	if old >= len(f.children) {
	return nil, io.EOF
	}
	if count > 0 {
	f.pos += count
	if f.pos > len(f.children) {
	f.pos = len(f.children)
	}
	} else {
	f.pos = len(f.children)
	old = 0
	}
	return f.children[old:f.pos], nil
	}

	func (f *memFile) Seek(offset int64, whence int) (int64, error) {
	f.n.mu.Lock()
	defer f.n.mu.Unlock()
	npos := f.pos
	// TODO: How to handle offsets greater than the size of system int?
	switch whence {
	case os.SEEK_SET:
	npos = int(offset)
	case os.SEEK_CUR:
	npos += int(offset)
	case os.SEEK_END:
	npos = len(f.n.data) + int(offset)
	default:
	npos = -1
	}
	if npos < 0 {
	return 0, os.ErrInvalid
	}
	f.pos = npos
	return int64(f.pos), nil
	}

	func (f *memFile) Stat() (os.FileInfo, error) {
	return f.n, nil
	}

	func (f *memFile) Write(p []byte) (int, error) {
	f.n.mu.Lock()
	defer f.n.mu.Unlock()
	epos := len(p) + f.pos
	if epos > len(f.n.data) {
	d := make([]byte, epos)
	copy(d, f.n.data)
	f.n.data = d
	}
	copy(f.n.data[f.pos:], p)
	f.n.modTime = time.Now()
	return len(p), nil
	}