tailfs: initial implementation
Add a WebDAV-based folder sharing mechanism that is exposed to local clients at 100.100.100.100:8080 and to remote peers via a new peerapi endpoint at /v0/tailfs. Add the ability to manage folder sharing via the new 'share' CLI sub-command. Updates tailscale/corp#16827 Signed-off-by: Percy Wegmann <percy@tailscale.com>
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Percy Wegmann
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Percy Wegmann
Percy Wegmann
parent
2e404b769d
commit
993acf4475
@@ -0,0 +1,256 @@
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// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// Package webdavfs provides an implementation of webdav.FileSystem backed by
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// a gowebdav.Client.
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package webdavfs
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import (
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"context"
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"errors"
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"fmt"
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"io"
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"io/fs"
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"log"
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"net/http"
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"os"
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"time"
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"github.com/tailscale/gowebdav"
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"github.com/tailscale/xnet/webdav"
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"tailscale.com/tailfs/shared"
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"tailscale.com/tstime"
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"tailscale.com/types/logger"
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)
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const (
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// keep requests from taking too long if the server is down or slow to respond
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opTimeout = 2 * time.Second // TODO(oxtoacart): tune this
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)
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type Options struct {
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// Logf us a logging function to use for debug and error logging.
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Logf logger.Logf
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// URL is the base URL of the remote WebDAV server.
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URL string
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// Transport is the http.Transport to use for connecting to the WebDAV
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// server.
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Transport http.RoundTripper
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// StatRoot, if true, will cause this filesystem to actually stat its own
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// root via the remote server. If false, it will use a static directory
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// info for the root to avoid a round-trip.
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StatRoot bool
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// StatCacheTTL, when greater than 0, enables caching of file metadata
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StatCacheTTL time.Duration
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// Clock, if specified, determines the current time. If not specified, we
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// default to time.Now().
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Clock tstime.Clock
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}
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// webdavFS adapts gowebdav.Client to webdav.FileSystem
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type webdavFS struct {
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logf logger.Logf
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transport http.RoundTripper
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*gowebdav.Client
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now func() time.Time
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statRoot bool
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statCache *statCache
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}
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// New creates a new webdav.FileSystem backed by the given gowebdav.Client.
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// If cacheTTL is greater than zero, the filesystem will cache results from
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// Stat calls for the given duration.
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func New(opts Options) webdav.FileSystem {
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if opts.Logf == nil {
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opts.Logf = log.Printf
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}
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wfs := &webdavFS{
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logf: opts.Logf,
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transport: opts.Transport,
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Client: gowebdav.New(&gowebdav.Opts{URI: opts.URL, Transport: opts.Transport}),
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statRoot: opts.StatRoot,
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}
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if opts.StatCacheTTL > 0 {
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wfs.statCache = newStatCache(opts.StatCacheTTL)
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}
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if opts.Clock != nil {
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wfs.now = opts.Clock.Now
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} else {
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wfs.now = time.Now
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}
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return wfs
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}
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// Mkdir implements webdav.FileSystem.
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func (wfs *webdavFS) Mkdir(ctx context.Context, name string, perm os.FileMode) error {
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ctxWithTimeout, cancel := context.WithTimeout(ctx, opTimeout)
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defer cancel()
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if wfs.statCache != nil {
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wfs.statCache.invalidate()
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}
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return translateWebDAVError(wfs.Client.Mkdir(ctxWithTimeout, name, perm))
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}
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// OpenFile implements webdav.FileSystem.
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func (wfs *webdavFS) OpenFile(ctx context.Context, name string, flag int, perm os.FileMode) (webdav.File, error) {
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if hasFlag(flag, os.O_APPEND) {
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return nil, &os.PathError{
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Op: "open",
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Path: name,
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Err: errors.New("mode APPEND not supported"),
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}
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}
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ctxWithTimeout, cancel := context.WithTimeout(ctx, opTimeout)
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defer cancel()
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if hasFlag(flag, os.O_WRONLY) || hasFlag(flag, os.O_RDWR) {
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if wfs.statCache != nil {
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wfs.statCache.invalidate()
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}
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fi, err := wfs.Stat(ctxWithTimeout, name)
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if err != nil && !errors.Is(err, os.ErrNotExist) {
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return nil, err
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}
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if err == nil && fi.IsDir() {
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return nil, &os.PathError{
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Op: "open",
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Path: name,
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Err: errors.New("is a directory"),
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}
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}
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pipeReader, pipeWriter := io.Pipe()
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f := &writeOnlyFile{
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WriteCloser: pipeWriter,
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name: name,
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perm: perm,
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fs: wfs,
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finalError: make(chan error, 1),
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}
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go func() {
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defer pipeReader.Close()
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err := wfs.Client.WriteStream(context.Background(), name, pipeReader, perm)
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f.finalError <- err
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close(f.finalError)
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}()
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return f, nil
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}
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// Assume reading
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fi, err := wfs.Stat(ctxWithTimeout, name)
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if err != nil {
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return nil, translateWebDAVError(err)
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}
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if fi.IsDir() {
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return wfs.dirWithChildren(name, fi), nil
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}
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return &readOnlyFile{
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client: wfs.Client,
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name: name,
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initialFI: fi,
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rewindBuffer: make([]byte, 0, MaxRewindBuffer),
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}, nil
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}
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func (wfs *webdavFS) dirWithChildren(name string, fi fs.FileInfo) webdav.File {
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return &shared.DirFile{
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Info: fi,
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LoadChildren: func() ([]fs.FileInfo, error) {
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ctxWithTimeout, cancel := context.WithTimeout(context.Background(), opTimeout)
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defer cancel()
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dirInfos, err := wfs.Client.ReadDir(ctxWithTimeout, name)
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if err != nil {
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wfs.logf("encountered error reading children of '%v', returning empty list: %v", name, err)
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// We do not return the actual error here because some WebDAV clients
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// will take that as an invitation to retry, hanging in the process.
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return dirInfos, nil
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}
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if wfs.statCache != nil {
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wfs.statCache.set(name, dirInfos)
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}
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return dirInfos, nil
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},
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}
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}
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// RemoveAll implements webdav.FileSystem.
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func (wfs *webdavFS) RemoveAll(ctx context.Context, name string) error {
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ctxWithTimeout, cancel := context.WithTimeout(ctx, opTimeout)
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defer cancel()
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if wfs.statCache != nil {
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wfs.statCache.invalidate()
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}
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return wfs.Client.RemoveAll(ctxWithTimeout, name)
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}
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// Rename implements webdav.FileSystem.
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func (wfs *webdavFS) Rename(ctx context.Context, oldName, newName string) error {
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ctxWithTimeout, cancel := context.WithTimeout(ctx, opTimeout)
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defer cancel()
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if wfs.statCache != nil {
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wfs.statCache.invalidate()
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}
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return wfs.Client.Rename(ctxWithTimeout, oldName, newName, false)
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}
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// Stat implements webdav.FileSystem.
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func (wfs *webdavFS) Stat(ctx context.Context, name string) (fs.FileInfo, error) {
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if wfs.statCache != nil {
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return wfs.statCache.getOrFetch(name, wfs.doStat)
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}
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return wfs.doStat(name)
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}
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// Close implements webdav.FileSystem.
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func (wfs *webdavFS) Close() error {
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if wfs.statCache != nil {
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wfs.statCache.stop()
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}
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tr, ok := wfs.transport.(*http.Transport)
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if ok {
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tr.CloseIdleConnections()
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}
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return nil
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}
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func (wfs *webdavFS) doStat(name string) (fs.FileInfo, error) {
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ctxWithTimeout, cancel := context.WithTimeout(context.Background(), opTimeout)
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defer cancel()
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if !wfs.statRoot && shared.IsRoot(name) {
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// use a static directory info for the root
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// always use now() as the modified time to bust caches
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return shared.ReadOnlyDirInfo(name, wfs.now()), nil
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}
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fi, err := wfs.Client.Stat(ctxWithTimeout, name)
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return fi, translateWebDAVError(err)
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}
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func translateWebDAVError(err error) error {
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if err == nil {
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return nil
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}
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var se gowebdav.StatusError
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if errors.As(err, &se) {
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if se.Status == http.StatusNotFound {
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return os.ErrNotExist
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}
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}
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// Note, we intentionally don't wrap the error because we don't want
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// github.com/tailscale/xnet/webdav to try to interpret the underlying
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// error.
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return fmt.Errorf("unexpected WebDAV error: %v", err)
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}
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func hasFlag(flags int, flag int) bool {
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return (flags & flag) == flag
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}
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