syncthing/lib/fs/basicfs.go
Simon Frei 486230768e lib/fs, lib/model: Add error channel to Watch to avoid panics (fixes #5697) (#5734)
* lib/fs, lib/model: Add error channel to Watch to avoid panics (fixes #5697)

* forgot unsupported watch

* and more non(-standard)-unixy fixes

* and windows test

* review
2019-05-25 20:08:26 +01:00

348 lines
8.4 KiB
Go

// Copyright (C) 2016 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
package fs
import (
"errors"
"fmt"
"os"
"path/filepath"
"runtime"
"strings"
"time"
"github.com/calmh/du"
)
var (
ErrInvalidFilename = errors.New("filename is invalid")
ErrNotRelative = errors.New("not a relative path")
)
// The BasicFilesystem implements all aspects by delegating to package os.
// All paths are relative to the root and cannot (should not) escape the root directory.
type BasicFilesystem struct {
root string
}
func newBasicFilesystem(root string) *BasicFilesystem {
// The reason it's done like this:
// C: -> C:\ -> C:\ (issue that this is trying to fix)
// C:\somedir -> C:\somedir\ -> C:\somedir
// C:\somedir\ -> C:\somedir\\ -> C:\somedir
// This way in the tests, we get away without OS specific separators
// in the test configs.
sep := string(filepath.Separator)
root = filepath.Dir(root + sep)
// Attempt tilde expansion; leave unchanged in case of error
if path, err := ExpandTilde(root); err == nil {
root = path
}
// Attempt absolutification; leave unchanged in case of error
if !filepath.IsAbs(root) {
// Abs() looks like a fairly expensive syscall on Windows, while
// IsAbs() is a whole bunch of string mangling. I think IsAbs() may be
// somewhat faster in the general case, hence the outer if...
if path, err := filepath.Abs(root); err == nil {
root = path
}
}
// Attempt to enable long filename support on Windows. We may still not
// have an absolute path here if the previous steps failed.
if runtime.GOOS == "windows" {
root = longFilenameSupport(root)
}
return &BasicFilesystem{root}
}
// rooted expands the relative path to the full path that is then used with os
// package. If the relative path somehow causes the final path to escape the root
// directory, this returns an error, to prevent accessing files that are not in the
// shared directory.
func (f *BasicFilesystem) rooted(rel string) (string, error) {
return rooted(rel, f.root)
}
func rooted(rel, root string) (string, error) {
// The root must not be empty.
if root == "" {
return "", ErrInvalidFilename
}
var err error
// Takes care that rel does not try to escape
rel, err = Canonicalize(rel)
if err != nil {
return "", err
}
return filepath.Join(root, rel), nil
}
func (f *BasicFilesystem) unrooted(path string) string {
return rel(path, f.root)
}
func (f *BasicFilesystem) Chmod(name string, mode FileMode) error {
name, err := f.rooted(name)
if err != nil {
return err
}
return os.Chmod(name, os.FileMode(mode))
}
func (f *BasicFilesystem) Lchown(name string, uid, gid int) error {
name, err := f.rooted(name)
if err != nil {
return err
}
return os.Lchown(name, uid, gid)
}
func (f *BasicFilesystem) Chtimes(name string, atime time.Time, mtime time.Time) error {
name, err := f.rooted(name)
if err != nil {
return err
}
return os.Chtimes(name, atime, mtime)
}
func (f *BasicFilesystem) Mkdir(name string, perm FileMode) error {
name, err := f.rooted(name)
if err != nil {
return err
}
return os.Mkdir(name, os.FileMode(perm))
}
// MkdirAll creates a directory named path, along with any necessary parents,
// and returns nil, or else returns an error.
// The permission bits perm are used for all directories that MkdirAll creates.
// If path is already a directory, MkdirAll does nothing and returns nil.
func (f *BasicFilesystem) MkdirAll(path string, perm FileMode) error {
path, err := f.rooted(path)
if err != nil {
return err
}
return f.mkdirAll(path, os.FileMode(perm))
}
func (f *BasicFilesystem) Lstat(name string) (FileInfo, error) {
name, err := f.rooted(name)
if err != nil {
return nil, err
}
fi, err := underlyingLstat(name)
if err != nil {
return nil, err
}
return basicFileInfo{fi}, err
}
func (f *BasicFilesystem) Remove(name string) error {
name, err := f.rooted(name)
if err != nil {
return err
}
return os.Remove(name)
}
func (f *BasicFilesystem) RemoveAll(name string) error {
name, err := f.rooted(name)
if err != nil {
return err
}
return os.RemoveAll(name)
}
func (f *BasicFilesystem) Rename(oldpath, newpath string) error {
oldpath, err := f.rooted(oldpath)
if err != nil {
return err
}
newpath, err = f.rooted(newpath)
if err != nil {
return err
}
return os.Rename(oldpath, newpath)
}
func (f *BasicFilesystem) Stat(name string) (FileInfo, error) {
name, err := f.rooted(name)
if err != nil {
return nil, err
}
fi, err := os.Stat(name)
if err != nil {
return nil, err
}
return basicFileInfo{fi}, err
}
func (f *BasicFilesystem) DirNames(name string) ([]string, error) {
name, err := f.rooted(name)
if err != nil {
return nil, err
}
fd, err := os.OpenFile(name, OptReadOnly, 0777)
if err != nil {
return nil, err
}
defer fd.Close()
names, err := fd.Readdirnames(-1)
if err != nil {
return nil, err
}
return names, nil
}
func (f *BasicFilesystem) Open(name string) (File, error) {
rootedName, err := f.rooted(name)
if err != nil {
return nil, err
}
fd, err := os.Open(rootedName)
if err != nil {
return nil, err
}
return basicFile{fd, name}, err
}
func (f *BasicFilesystem) OpenFile(name string, flags int, mode FileMode) (File, error) {
rootedName, err := f.rooted(name)
if err != nil {
return nil, err
}
fd, err := os.OpenFile(rootedName, flags, os.FileMode(mode))
if err != nil {
return nil, err
}
return basicFile{fd, name}, err
}
func (f *BasicFilesystem) Create(name string) (File, error) {
rootedName, err := f.rooted(name)
if err != nil {
return nil, err
}
fd, err := os.Create(rootedName)
if err != nil {
return nil, err
}
return basicFile{fd, name}, err
}
func (f *BasicFilesystem) Walk(root string, walkFn WalkFunc) error {
// implemented in WalkFilesystem
return errors.New("not implemented")
}
func (f *BasicFilesystem) Glob(pattern string) ([]string, error) {
pattern, err := f.rooted(pattern)
if err != nil {
return nil, err
}
files, err := filepath.Glob(pattern)
unrooted := make([]string, len(files))
for i := range files {
unrooted[i] = f.unrooted(files[i])
}
return unrooted, err
}
func (f *BasicFilesystem) Usage(name string) (Usage, error) {
name, err := f.rooted(name)
if err != nil {
return Usage{}, err
}
u, err := du.Get(name)
return Usage{
Free: u.FreeBytes,
Total: u.TotalBytes,
}, err
}
func (f *BasicFilesystem) Type() FilesystemType {
return FilesystemTypeBasic
}
func (f *BasicFilesystem) URI() string {
return strings.TrimPrefix(f.root, `\\?\`)
}
func (f *BasicFilesystem) SameFile(fi1, fi2 FileInfo) bool {
// Like os.SameFile, we always return false unless fi1 and fi2 were created
// by this package's Stat/Lstat method.
f1, ok1 := fi1.(basicFileInfo)
f2, ok2 := fi2.(basicFileInfo)
if !ok1 || !ok2 {
return false
}
return os.SameFile(f1.FileInfo, f2.FileInfo)
}
// basicFile implements the fs.File interface on top of an os.File
type basicFile struct {
*os.File
name string
}
func (f basicFile) Name() string {
return f.name
}
func (f basicFile) Stat() (FileInfo, error) {
info, err := f.File.Stat()
if err != nil {
return nil, err
}
return basicFileInfo{info}, nil
}
// basicFileInfo implements the fs.FileInfo interface on top of an os.FileInfo.
type basicFileInfo struct {
os.FileInfo
}
func (e basicFileInfo) IsSymlink() bool {
// Must use basicFileInfo.Mode() because it may apply magic.
return e.Mode()&ModeSymlink != 0
}
func (e basicFileInfo) IsRegular() bool {
// Must use basicFileInfo.Mode() because it may apply magic.
return e.Mode()&ModeType == 0
}
// longFilenameSupport adds the necessary prefix to the path to enable long
// filename support on windows if necessary.
// This does NOT check the current system, i.e. will also take effect on unix paths.
func longFilenameSupport(path string) string {
if filepath.IsAbs(path) && !strings.HasPrefix(path, `\\`) {
return `\\?\` + path
}
return path
}
type ErrWatchEventOutsideRoot struct{ msg string }
func (e *ErrWatchEventOutsideRoot) Error() string {
return e.msg
}
func (f *BasicFilesystem) newErrWatchEventOutsideRoot(absPath, root string) *ErrWatchEventOutsideRoot {
return &ErrWatchEventOutsideRoot{fmt.Sprintf("Watching for changes encountered an event outside of the filesystem root: f.root==%v, root==%v, path==%v. This should never happen, please report this message to forum.syncthing.net.", f.root, root, absPath)}
}