syncthing/internal/scanner/walk.go

396 lines
11 KiB
Go

// Copyright (C) 2014 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 http://mozilla.org/MPL/2.0/.
package scanner
import (
"errors"
"os"
"path/filepath"
"runtime"
"strings"
"time"
"unicode/utf8"
"github.com/syncthing/protocol"
"github.com/syncthing/syncthing/internal/ignore"
"github.com/syncthing/syncthing/internal/osutil"
"github.com/syncthing/syncthing/internal/symlinks"
"golang.org/x/text/unicode/norm"
)
var maskModePerm os.FileMode
func init() {
if runtime.GOOS == "windows" {
// There is no user/group/others in Windows' read-only
// attribute, and all "w" bits are set in os.FileInfo
// if the file is not read-only. Do not send these
// group/others-writable bits to other devices in order to
// avoid unexpected world-writable files on other platforms.
maskModePerm = os.ModePerm & 0755
} else {
maskModePerm = os.ModePerm
}
}
type Walker struct {
// Dir is the base directory for the walk
Dir string
// Limit walking to these paths within Dir, or no limit if Sub is empty
Subs []string
// BlockSize controls the size of the block used when hashing.
BlockSize int
// If Matcher is not nil, it is used to identify files to ignore which were specified by the user.
Matcher *ignore.Matcher
// If TempNamer is not nil, it is used to ignore temporary files when walking.
TempNamer TempNamer
// Number of hours to keep temporary files for
TempLifetime time.Duration
// If CurrentFiler is not nil, it is queried for the current file before rescanning.
CurrentFiler CurrentFiler
// If IgnorePerms is true, changes to permission bits will not be
// detected. Scanned files will get zero permission bits and the
// NoPermissionBits flag set.
IgnorePerms bool
// When AutoNormalize is set, file names that are in UTF8 but incorrect
// normalization form will be corrected.
AutoNormalize bool
// Number of routines to use for hashing
Hashers int
// Our vector clock id
ShortID uint64
}
type TempNamer interface {
// Temporary returns a temporary name for the filed referred to by filepath.
TempName(path string) string
// IsTemporary returns true if path refers to the name of temporary file.
IsTemporary(path string) bool
}
type CurrentFiler interface {
// CurrentFile returns the file as seen at last scan.
CurrentFile(name string) (protocol.FileInfo, bool)
}
// Walk returns the list of files found in the local folder by scanning the
// file system. Files are blockwise hashed.
func (w *Walker) Walk() (chan protocol.FileInfo, error) {
if debug {
l.Debugln("Walk", w.Dir, w.Subs, w.BlockSize, w.Matcher)
}
err := checkDir(w.Dir)
if err != nil {
return nil, err
}
files := make(chan protocol.FileInfo)
hashedFiles := make(chan protocol.FileInfo)
newParallelHasher(w.Dir, w.BlockSize, w.Hashers, hashedFiles, files)
go func() {
hashFiles := w.walkAndHashFiles(files)
if len(w.Subs) == 0 {
filepath.Walk(w.Dir, hashFiles)
} else {
for _, sub := range w.Subs {
filepath.Walk(filepath.Join(w.Dir, sub), hashFiles)
}
}
close(files)
}()
return hashedFiles, nil
}
func (w *Walker) walkAndHashFiles(fchan chan protocol.FileInfo) filepath.WalkFunc {
now := time.Now()
return func(p string, info os.FileInfo, err error) error {
// Return value used when we are returning early and don't want to
// process the item. For directories, this means do-not-descend.
var skip error // nil
// info nil when error is not nil
if info != nil && info.IsDir() {
skip = filepath.SkipDir
}
if err != nil {
if debug {
l.Debugln("error:", p, info, err)
}
return skip
}
rn, err := filepath.Rel(w.Dir, p)
if err != nil {
if debug {
l.Debugln("rel error:", p, err)
}
return skip
}
if rn == "." {
return nil
}
if w.TempNamer != nil && w.TempNamer.IsTemporary(rn) {
// A temporary file
if debug {
l.Debugln("temporary:", rn)
}
if info.Mode().IsRegular() && info.ModTime().Add(w.TempLifetime).Before(now) {
os.Remove(p)
if debug {
l.Debugln("removing temporary:", rn, info.ModTime())
}
}
return nil
}
if sn := filepath.Base(rn); sn == ".stignore" || sn == ".stfolder" ||
strings.HasPrefix(rn, ".stversions") || w.Matcher.Match(rn) {
// An ignored file
if debug {
l.Debugln("ignored:", rn)
}
return skip
}
if !utf8.ValidString(rn) {
l.Warnf("File name %q is not in UTF8 encoding; skipping.", rn)
return skip
}
var normalizedRn string
if runtime.GOOS == "darwin" {
// Mac OS X file names should always be NFD normalized.
normalizedRn = norm.NFD.String(rn)
} else {
// Every other OS in the known universe uses NFC or just plain
// doesn't bother to define an encoding. In our case *we* do care,
// so we enforce NFC regardless.
normalizedRn = norm.NFC.String(rn)
}
if rn != normalizedRn {
// The file name was not normalized.
if !w.AutoNormalize {
// We're not authorized to do anything about it, so complain and skip.
l.Warnf("File name %q is not in the correct UTF8 normalization form; skipping.", rn)
return skip
}
// We will attempt to normalize it.
normalizedPath := filepath.Join(w.Dir, normalizedRn)
if _, err := osutil.Lstat(normalizedPath); os.IsNotExist(err) {
// Nothing exists with the normalized filename. Good.
if err = os.Rename(p, normalizedPath); err != nil {
l.Infof(`Error normalizing UTF8 encoding of file "%s": %v`, rn, err)
return skip
}
l.Infof(`Normalized UTF8 encoding of file name "%s".`, rn)
} else {
// There is something already in the way at the normalized
// file name.
l.Infof(`File "%s" has UTF8 encoding conflict with another file; ignoring.`, rn)
return skip
}
rn = normalizedRn
}
var cf protocol.FileInfo
var ok bool
// Index wise symlinks are always files, regardless of what the target
// is, because symlinks carry their target path as their content.
if info.Mode()&os.ModeSymlink == os.ModeSymlink {
// If the target is a directory, do NOT descend down there. This
// will cause files to get tracked, and removing the symlink will
// as a result remove files in their real location.
if !symlinks.Supported {
return skip
}
// We always rehash symlinks as they have no modtime or
// permissions. We check if they point to the old target by
// checking that their existing blocks match with the blocks in
// the index.
target, flags, err := symlinks.Read(p)
flags = flags & protocol.SymlinkTypeMask
if err != nil {
if debug {
l.Debugln("readlink error:", p, err)
}
return skip
}
blocks, err := Blocks(strings.NewReader(target), w.BlockSize, 0)
if err != nil {
if debug {
l.Debugln("hash link error:", p, err)
}
return skip
}
if w.CurrentFiler != nil {
// A symlink is "unchanged", if
// - it exists
// - it wasn't deleted (because it isn't now)
// - it was a symlink
// - it wasn't invalid
// - the symlink type (file/dir) was the same
// - the block list (i.e. hash of target) was the same
cf, ok = w.CurrentFiler.CurrentFile(rn)
if ok && !cf.IsDeleted() && cf.IsSymlink() && !cf.IsInvalid() && SymlinkTypeEqual(flags, cf.Flags) && BlocksEqual(cf.Blocks, blocks) {
return skip
}
}
f := protocol.FileInfo{
Name: rn,
Version: cf.Version.Update(w.ShortID),
Flags: protocol.FlagSymlink | flags | protocol.FlagNoPermBits | 0666,
Modified: 0,
Blocks: blocks,
}
if debug {
l.Debugln("symlink to hash:", p, f)
}
fchan <- f
return skip
}
if info.Mode().IsDir() {
if w.CurrentFiler != nil {
// A directory is "unchanged", if it
// - exists
// - has the same permissions as previously, unless we are ignoring permissions
// - was not marked deleted (since it apparently exists now)
// - was a directory previously (not a file or something else)
// - was not a symlink (since it's a directory now)
// - was not invalid (since it looks valid now)
cf, ok = w.CurrentFiler.CurrentFile(rn)
permUnchanged := w.IgnorePerms || !cf.HasPermissionBits() || PermsEqual(cf.Flags, uint32(info.Mode()))
if ok && permUnchanged && !cf.IsDeleted() && cf.IsDirectory() && !cf.IsSymlink() && !cf.IsInvalid() {
return nil
}
}
flags := uint32(protocol.FlagDirectory)
if w.IgnorePerms {
flags |= protocol.FlagNoPermBits | 0777
} else {
flags |= uint32(info.Mode() & maskModePerm)
}
f := protocol.FileInfo{
Name: rn,
Version: cf.Version.Update(w.ShortID),
Flags: flags,
Modified: info.ModTime().Unix(),
}
if debug {
l.Debugln("dir:", p, f)
}
fchan <- f
return nil
}
if info.Mode().IsRegular() {
curMode := uint32(info.Mode())
if runtime.GOOS == "windows" && osutil.IsWindowsExecutable(rn) {
curMode |= 0111
}
if w.CurrentFiler != nil {
// A file is "unchanged", if it
// - exists
// - has the same permissions as previously, unless we are ignoring permissions
// - was not marked deleted (since it apparently exists now)
// - had the same modification time as it has now
// - was not a directory previously (since it's a file now)
// - was not a symlink (since it's a file now)
// - was not invalid (since it looks valid now)
// - has the same size as previously
cf, ok = w.CurrentFiler.CurrentFile(rn)
permUnchanged := w.IgnorePerms || !cf.HasPermissionBits() || PermsEqual(cf.Flags, curMode)
if ok && permUnchanged && !cf.IsDeleted() && cf.Modified == info.ModTime().Unix() && !cf.IsDirectory() &&
!cf.IsSymlink() && !cf.IsInvalid() && cf.Size() == info.Size() {
return nil
}
if debug {
l.Debugln("rescan:", cf, info.ModTime().Unix(), info.Mode()&os.ModePerm)
}
}
var flags = curMode & uint32(maskModePerm)
if w.IgnorePerms {
flags = protocol.FlagNoPermBits | 0666
}
f := protocol.FileInfo{
Name: rn,
Version: cf.Version.Update(w.ShortID),
Flags: flags,
Modified: info.ModTime().Unix(),
}
if debug {
l.Debugln("to hash:", p, f)
}
fchan <- f
}
return nil
}
}
func checkDir(dir string) error {
if info, err := osutil.Lstat(dir); err != nil {
return err
} else if !info.IsDir() {
return errors.New(dir + ": not a directory")
} else if debug {
l.Debugln("checkDir", dir, info)
}
return nil
}
func PermsEqual(a, b uint32) bool {
switch runtime.GOOS {
case "windows":
// There is only writeable and read only, represented for user, group
// and other equally. We only compare against user.
return a&0600 == b&0600
default:
// All bits count
return a&0777 == b&0777
}
}
func SymlinkTypeEqual(disk, index uint32) bool {
// If the target is missing, Unix never knows what type of symlink it is
// and Windows always knows even if there is no target. Which means that
// without this special check a Unix node would be fighting with a Windows
// node about whether or not the target is known. Basically, if you don't
// know and someone else knows, just accept it. The fact that you don't
// know means you are on Unix, and on Unix you don't really care what the
// target type is. The moment you do know, and if something doesn't match,
// that will propagate through the cluster.
if disk&protocol.FlagSymlinkMissingTarget != 0 && index&protocol.FlagSymlinkMissingTarget == 0 {
return true
}
return disk&protocol.SymlinkTypeMask == index&protocol.SymlinkTypeMask
}