syncthing/lib/fs/basicfs.go

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// 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/shirou/gopsutil/v3/disk"
)
var (
errInvalidFilenameEmpty = errors.New("name is invalid, must not be empty")
errInvalidFilenameWindowsSpacePeriod = errors.New("name is invalid, must not end in space or period on Windows")
errInvalidFilenameWindowsReservedName = errors.New("name is invalid, contains Windows reserved name (NUL, COM1, etc.)")
errInvalidFilenameWindowsReservedChar = errors.New("name is invalid, contains Windows reserved character (?, *, etc.)")
errNotRelative = errors.New("not a relative path")
)
func WithJunctionsAsDirs() Option {
return Option{
apply: func(fs Filesystem) {
if basic, ok := fs.(*BasicFilesystem); !ok {
l.Warnln("WithJunctionsAsDirs must only be used with FilesystemTypeBasic")
} else {
basic.junctionsAsDirs = true
}
},
id: "junctionsAsDirs",
}
}
// 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
junctionsAsDirs bool
}
func newBasicFilesystem(root string, opts ...Option) *BasicFilesystem {
if root == "" {
root = "." // Otherwise "" becomes "/" below
}
// 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)
}
fs := &BasicFilesystem{
root: root,
}
for _, opt := range opts {
opt.apply(fs)
}
return fs
}
// 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 "", errInvalidFilenameEmpty
}
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 := f.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 := disk.Usage(name)
if err != nil {
return Usage{}, err
}
return Usage{
Free: u.Free,
Total: u.Total,
}, nil
}
func (f *BasicFilesystem) Type() FilesystemType {
return FilesystemTypeBasic
}
func (f *BasicFilesystem) URI() string {
return strings.TrimPrefix(f.root, `\\?\`)
}
lib/scanner: Fix UTF-8 normalization on ZFS (fixes #4649) It turns out that ZFS doesn't do any normalization when storing files, but does do normalization "as part of any comparison process". In practice, this seems to mean that if you LStat a normalized filename, ZFS will return the FileInfo for the un-normalized version of that filename. This meant that our test to see whether a separate file with a normalized version of the filename already exists was failing, as we were detecting the same file. The fix is to use os.SameFile, to see whether we're getting the same FileInfo from the normalized and un-normalized versions of the same filename. One complication is that ZFS also seems to apply its magic to os.Rename, meaning that we can't use it to rename an un-normalized file to its normalized filename. Instead we have to move via a temporary object. If the move to the temporary object fails, that's OK, we can skip it and move on. If the move from the temporary object fails however, I'm not sure of the best approach: the current one is to leave the temporary file name as-is, and get Syncthing to syncronize it, so at least we don't lose the file. I'm not sure if there are any implications of this however. As part of reworking normalizePath, I spotted that it appeared to be returning the wrong thing: the doc and the surrounding code expecting it to return the normalized filename, but it was returning the un-normalized one. I fixed this, but it seems suspicious that, if the previous behaviour was incorrect, noone ever ran afoul of it. Maybe all filesystems will do some searching and give you a normalized filename if you request an unnormalized one. As part of this, I found that TestNormalization was broken: it was passing, when in fact one of the files it should have verified was present was missing. Maybe this was related to the above issue with normalizePath's return value, I'm not sure. Fixed en route. Kindly tested by @khinsen on the forum, and it appears to work. GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4646
2018-01-05 18:11:09 +00:00
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)
lib/scanner: Fix UTF-8 normalization on ZFS (fixes #4649) It turns out that ZFS doesn't do any normalization when storing files, but does do normalization "as part of any comparison process". In practice, this seems to mean that if you LStat a normalized filename, ZFS will return the FileInfo for the un-normalized version of that filename. This meant that our test to see whether a separate file with a normalized version of the filename already exists was failing, as we were detecting the same file. The fix is to use os.SameFile, to see whether we're getting the same FileInfo from the normalized and un-normalized versions of the same filename. One complication is that ZFS also seems to apply its magic to os.Rename, meaning that we can't use it to rename an un-normalized file to its normalized filename. Instead we have to move via a temporary object. If the move to the temporary object fails, that's OK, we can skip it and move on. If the move from the temporary object fails however, I'm not sure of the best approach: the current one is to leave the temporary file name as-is, and get Syncthing to syncronize it, so at least we don't lose the file. I'm not sure if there are any implications of this however. As part of reworking normalizePath, I spotted that it appeared to be returning the wrong thing: the doc and the surrounding code expecting it to return the normalized filename, but it was returning the un-normalized one. I fixed this, but it seems suspicious that, if the previous behaviour was incorrect, noone ever ran afoul of it. Maybe all filesystems will do some searching and give you a normalized filename if you request an unnormalized one. As part of this, I found that TestNormalization was broken: it was passing, when in fact one of the files it should have verified was present was missing. Maybe this was related to the above issue with normalizePath's return value, I'm not sure. Fixed en route. Kindly tested by @khinsen on the forum, and it appears to work. GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4646
2018-01-05 18:11:09 +00:00
if !ok1 || !ok2 {
return false
}
return os.SameFile(f1.osFileInfo(), f2.osFileInfo())
lib/scanner: Fix UTF-8 normalization on ZFS (fixes #4649) It turns out that ZFS doesn't do any normalization when storing files, but does do normalization "as part of any comparison process". In practice, this seems to mean that if you LStat a normalized filename, ZFS will return the FileInfo for the un-normalized version of that filename. This meant that our test to see whether a separate file with a normalized version of the filename already exists was failing, as we were detecting the same file. The fix is to use os.SameFile, to see whether we're getting the same FileInfo from the normalized and un-normalized versions of the same filename. One complication is that ZFS also seems to apply its magic to os.Rename, meaning that we can't use it to rename an un-normalized file to its normalized filename. Instead we have to move via a temporary object. If the move to the temporary object fails, that's OK, we can skip it and move on. If the move from the temporary object fails however, I'm not sure of the best approach: the current one is to leave the temporary file name as-is, and get Syncthing to syncronize it, so at least we don't lose the file. I'm not sure if there are any implications of this however. As part of reworking normalizePath, I spotted that it appeared to be returning the wrong thing: the doc and the surrounding code expecting it to return the normalized filename, but it was returning the un-normalized one. I fixed this, but it seems suspicious that, if the previous behaviour was incorrect, noone ever ran afoul of it. Maybe all filesystems will do some searching and give you a normalized filename if you request an unnormalized one. As part of this, I found that TestNormalization was broken: it was passing, when in fact one of the files it should have verified was present was missing. Maybe this was related to the above issue with normalizePath's return value, I'm not sure. Fixed en route. Kindly tested by @khinsen on the forum, and it appears to work. GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4646
2018-01-05 18:11:09 +00:00
}
// 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 string, roots []string) *ErrWatchEventOutsideRoot {
return &ErrWatchEventOutsideRoot{fmt.Sprintf("Watching for changes encountered an event outside of the filesystem root: f.root==%v, roots==%v, path==%v. This should never happen, please report this message to forum.syncthing.net.", f.root, roots, absPath)}
}