mirror of
https://github.com/syncthing/syncthing.git
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347 lines
8.4 KiB
Go
347 lines
8.4 KiB
Go
// Copyright (C) 2016 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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// You can obtain one at https://mozilla.org/MPL/2.0/.
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package fs
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import (
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"errors"
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"os"
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"path/filepath"
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"runtime"
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"strings"
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"time"
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"github.com/calmh/du"
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)
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var (
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ErrInvalidFilename = errors.New("filename is invalid")
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ErrNotRelative = errors.New("not a relative path")
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)
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// The BasicFilesystem implements all aspects by delegating to package os.
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// All paths are relative to the root and cannot (should not) escape the root directory.
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type BasicFilesystem struct {
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root string
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}
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func newBasicFilesystem(root string) *BasicFilesystem {
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// The reason it's done like this:
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// C: -> C:\ -> C:\ (issue that this is trying to fix)
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// C:\somedir -> C:\somedir\ -> C:\somedir
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// C:\somedir\ -> C:\somedir\\ -> C:\somedir
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// This way in the tests, we get away without OS specific separators
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// in the test configs.
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root = filepath.Dir(root + string(filepath.Separator))
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// Attempt tilde expansion; leave unchanged in case of error
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if path, err := ExpandTilde(root); err == nil {
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root = path
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}
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// Attempt absolutification; leave unchanged in case of error
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if !filepath.IsAbs(root) {
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// Abs() looks like a fairly expensive syscall on Windows, while
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// IsAbs() is a whole bunch of string mangling. I think IsAbs() may be
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// somewhat faster in the general case, hence the outer if...
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if path, err := filepath.Abs(root); err == nil {
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root = path
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}
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}
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// Attempt to enable long filename support on Windows. We may still not
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// have an absolute path here if the previous steps failed.
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if runtime.GOOS == "windows" {
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if filepath.IsAbs(root) && !strings.HasPrefix(root, `\\`) {
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root = `\\?\` + root
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}
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// If we're not on Windows, we want the path to end with a slash to
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// penetrate symlinks. On Windows, paths must not end with a slash.
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} else if root[len(root)-1] != filepath.Separator {
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root = root + string(filepath.Separator)
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}
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return &BasicFilesystem{
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root: root,
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}
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}
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// rooted expands the relative path to the full path that is then used with os
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// package. If the relative path somehow causes the final path to escape the root
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// directoy, this returns an error, to prevent accessing files that are not in the
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// shared directory.
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func (f *BasicFilesystem) rooted(rel string) (string, error) {
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// The root must not be empty.
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if f.root == "" {
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return "", ErrInvalidFilename
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}
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pathSep := string(PathSeparator)
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// The expected prefix for the resulting path is the root, with a path
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// separator at the end.
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expectedPrefix := filepath.FromSlash(f.root)
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if !strings.HasSuffix(expectedPrefix, pathSep) {
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expectedPrefix += pathSep
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}
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// The relative path should be clean from internal dotdots and similar
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// funkyness.
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rel = filepath.FromSlash(rel)
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if filepath.Clean(rel) != rel {
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return "", ErrInvalidFilename
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}
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// It is not acceptable to attempt to traverse upwards.
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switch rel {
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case "..", pathSep:
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return "", ErrNotRelative
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}
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if strings.HasPrefix(rel, ".."+pathSep) {
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return "", ErrNotRelative
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}
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if strings.HasPrefix(rel, pathSep+pathSep) {
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// The relative path may pretend to be an absolute path within the
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// root, but the double path separator on Windows implies something
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// else. It would get cleaned by the Join below, but it's out of
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// spec anyway.
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return "", ErrNotRelative
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}
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// The supposedly correct path is the one filepath.Join will return, as
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// it does cleaning and so on. Check that one first to make sure no
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// obvious escape attempts have been made.
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joined := filepath.Join(f.root, rel)
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if rel == "." && !strings.HasSuffix(joined, pathSep) {
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joined += pathSep
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}
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if !strings.HasPrefix(joined, expectedPrefix) {
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return "", ErrNotRelative
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}
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return joined, nil
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}
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func (f *BasicFilesystem) unrooted(path string) string {
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return strings.TrimPrefix(strings.TrimPrefix(path, f.root), string(PathSeparator))
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}
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func (f *BasicFilesystem) Chmod(name string, mode FileMode) error {
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name, err := f.rooted(name)
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if err != nil {
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return err
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}
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return os.Chmod(name, os.FileMode(mode))
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}
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func (f *BasicFilesystem) Chtimes(name string, atime time.Time, mtime time.Time) error {
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name, err := f.rooted(name)
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if err != nil {
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return err
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}
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return os.Chtimes(name, atime, mtime)
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}
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func (f *BasicFilesystem) Mkdir(name string, perm FileMode) error {
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name, err := f.rooted(name)
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if err != nil {
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return err
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}
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return os.Mkdir(name, os.FileMode(perm))
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}
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func (f *BasicFilesystem) Lstat(name string) (FileInfo, error) {
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name, err := f.rooted(name)
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if err != nil {
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return nil, err
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}
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fi, err := underlyingLstat(name)
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if err != nil {
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return nil, err
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}
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return fsFileInfo{fi}, err
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}
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func (f *BasicFilesystem) Remove(name string) error {
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name, err := f.rooted(name)
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if err != nil {
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return err
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}
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return os.Remove(name)
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}
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func (f *BasicFilesystem) RemoveAll(name string) error {
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name, err := f.rooted(name)
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if err != nil {
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return err
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}
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return os.RemoveAll(name)
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}
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func (f *BasicFilesystem) Rename(oldpath, newpath string) error {
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oldpath, err := f.rooted(oldpath)
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if err != nil {
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return err
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}
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newpath, err = f.rooted(newpath)
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if err != nil {
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return err
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}
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return os.Rename(oldpath, newpath)
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}
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func (f *BasicFilesystem) Stat(name string) (FileInfo, error) {
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name, err := f.rooted(name)
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if err != nil {
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return nil, err
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}
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fi, err := os.Stat(name)
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if err != nil {
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return nil, err
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}
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return fsFileInfo{fi}, err
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}
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func (f *BasicFilesystem) DirNames(name string) ([]string, error) {
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name, err := f.rooted(name)
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if err != nil {
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return nil, err
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}
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fd, err := os.OpenFile(name, OptReadOnly, 0777)
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if err != nil {
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return nil, err
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}
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defer fd.Close()
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names, err := fd.Readdirnames(-1)
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if err != nil {
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return nil, err
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}
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return names, nil
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}
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func (f *BasicFilesystem) Open(name string) (File, error) {
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rootedName, err := f.rooted(name)
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if err != nil {
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return nil, err
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}
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fd, err := os.Open(rootedName)
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if err != nil {
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return nil, err
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}
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return fsFile{fd, name}, err
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}
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func (f *BasicFilesystem) OpenFile(name string, flags int, mode FileMode) (File, error) {
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rootedName, err := f.rooted(name)
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if err != nil {
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return nil, err
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}
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fd, err := os.OpenFile(rootedName, flags, os.FileMode(mode))
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if err != nil {
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return nil, err
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}
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return fsFile{fd, name}, err
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}
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func (f *BasicFilesystem) Create(name string) (File, error) {
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rootedName, err := f.rooted(name)
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if err != nil {
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return nil, err
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}
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fd, err := os.Create(rootedName)
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if err != nil {
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return nil, err
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}
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return fsFile{fd, name}, err
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}
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func (f *BasicFilesystem) Walk(root string, walkFn WalkFunc) error {
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// implemented in WalkFilesystem
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return errors.New("not implemented")
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}
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func (f *BasicFilesystem) Glob(pattern string) ([]string, error) {
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pattern, err := f.rooted(pattern)
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if err != nil {
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return nil, err
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}
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files, err := filepath.Glob(pattern)
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unrooted := make([]string, len(files))
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for i := range files {
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unrooted[i] = f.unrooted(files[i])
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}
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return unrooted, err
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}
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func (f *BasicFilesystem) Usage(name string) (Usage, error) {
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name, err := f.rooted(name)
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if err != nil {
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return Usage{}, err
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}
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u, err := du.Get(name)
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return Usage{
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Free: u.FreeBytes,
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Total: u.TotalBytes,
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}, err
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}
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func (f *BasicFilesystem) Type() FilesystemType {
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return FilesystemTypeBasic
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}
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func (f *BasicFilesystem) URI() string {
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return strings.TrimPrefix(f.root, `\\?\`)
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}
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// fsFile implements the fs.File interface on top of an os.File
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type fsFile struct {
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*os.File
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name string
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}
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func (f fsFile) Name() string {
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return f.name
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}
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func (f fsFile) Stat() (FileInfo, error) {
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info, err := f.File.Stat()
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if err != nil {
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return nil, err
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}
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return fsFileInfo{info}, nil
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}
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func (f fsFile) Sync() error {
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err := f.File.Sync()
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// On Windows, fsyncing a directory returns a "handle is invalid"
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// So we swallow that and let things go through in order not to have to add
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// a separate way of syncing directories versus files.
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if err != nil && (runtime.GOOS != "windows" || !strings.Contains(err.Error(), "handle is invalid")) {
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return err
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}
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return nil
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}
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// fsFileInfo implements the fs.FileInfo interface on top of an os.FileInfo.
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type fsFileInfo struct {
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os.FileInfo
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}
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func (e fsFileInfo) Mode() FileMode {
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return FileMode(e.FileInfo.Mode())
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}
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func (e fsFileInfo) IsRegular() bool {
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return e.FileInfo.Mode().IsRegular()
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}
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func (e fsFileInfo) IsSymlink() bool {
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return e.FileInfo.Mode()&os.ModeSymlink == os.ModeSymlink
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}
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