syncthing/scanner/walk.go

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package scanner
import (
"bytes"
"errors"
"io/ioutil"
"os"
"path/filepath"
"runtime"
"strings"
"time"
"github.com/calmh/syncthing/lamport"
"github.com/calmh/syncthing/protocol"
)
type Walker struct {
// Dir is the base directory for the walk
Dir string
// BlockSize controls the size of the block used when hashing.
BlockSize int
// If IgnoreFile is not empty, it is the name used for the file that holds ignore patterns.
IgnoreFile string
// If TempNamer is not nil, it is used to ignore tempory files when walking.
TempNamer TempNamer
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// If CurrentFiler is not nil, it is queried for the current file before rescanning.
CurrentFiler CurrentFiler
// If Suppressor is not nil, it is queried for supression of modified files.
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// Suppressed files will be returned with empty metadata and the Suppressed flag set.
// Requires CurrentFiler to be set.
Suppressor Suppressor
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// If IgnorePerms is true, changes to permission bits will not be
// detected. Scanned files will get zero permission bits and the
// NoPermissionBits flag set.
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IgnorePerms bool
}
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 Suppressor interface {
// Supress returns true if the update to the named file should be ignored.
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Suppress(name string, fi os.FileInfo) (bool, bool)
}
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type CurrentFiler interface {
// CurrentFile returns the file as seen at last scan.
CurrentFile(name string) File
}
// Walk returns the list of files found in the local repository by scanning the
// file system. Files are blockwise hashed.
func (w *Walker) Walk() (files []File, ignore map[string][]string, err error) {
if debug {
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l.Debugln("Walk", w.Dir, w.BlockSize, w.IgnoreFile)
}
err = checkDir(w.Dir)
if err != nil {
return
}
t0 := time.Now()
ignore = make(map[string][]string)
hashFiles := w.walkAndHashFiles(&files, ignore)
filepath.Walk(w.Dir, w.loadIgnoreFiles(w.Dir, ignore))
filepath.Walk(w.Dir, hashFiles)
if debug {
t1 := time.Now()
d := t1.Sub(t0).Seconds()
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l.Debugf("Walk in %.02f ms, %.0f files/s", d*1000, float64(len(files))/d)
}
err = checkDir(w.Dir)
return
}
// CleanTempFiles removes all files that match the temporary filename pattern.
func (w *Walker) CleanTempFiles() {
filepath.Walk(w.Dir, w.cleanTempFile)
}
func (w *Walker) loadIgnoreFiles(dir string, ign map[string][]string) filepath.WalkFunc {
return func(p string, info os.FileInfo, err error) error {
if err != nil {
return nil
}
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rn, err := filepath.Rel(dir, p)
if err != nil {
return nil
}
if pn, sn := filepath.Split(rn); sn == w.IgnoreFile {
pn := strings.Trim(pn, "/")
bs, _ := ioutil.ReadFile(p)
lines := bytes.Split(bs, []byte("\n"))
var patterns []string
for _, line := range lines {
if len(line) > 0 {
patterns = append(patterns, string(line))
}
}
ign[pn] = patterns
}
return nil
}
}
func (w *Walker) walkAndHashFiles(res *[]File, ign map[string][]string) filepath.WalkFunc {
return func(p string, info os.FileInfo, err error) error {
if err != nil {
if debug {
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l.Debugln("error:", p, info, err)
}
return nil
}
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rn, err := filepath.Rel(w.Dir, p)
if err != nil {
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if debug {
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l.Debugln("rel error:", p, err)
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}
return nil
}
if rn == "." {
return nil
}
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if w.TempNamer != nil && w.TempNamer.IsTemporary(rn) {
// A temporary file
if debug {
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l.Debugln("temporary:", rn)
}
return nil
}
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if sn := filepath.Base(rn); sn == w.IgnoreFile || sn == ".stversions" || w.ignoreFile(ign, rn) {
// An ignored file
if debug {
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l.Debugln("ignored:", rn)
}
if info.IsDir() {
return filepath.SkipDir
}
return nil
}
if info.Mode().IsDir() {
if w.CurrentFiler != nil {
cf := w.CurrentFiler.CurrentFile(rn)
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permUnchanged := w.IgnorePerms || !protocol.HasPermissionBits(cf.Flags) || PermsEqual(cf.Flags, uint32(info.Mode()))
if cf.Modified == info.ModTime().Unix() && protocol.IsDirectory(cf.Flags) && permUnchanged {
if debug {
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l.Debugln("unchanged:", cf)
}
*res = append(*res, cf)
} else {
var flags uint32 = protocol.FlagDirectory
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if w.IgnorePerms {
flags |= protocol.FlagNoPermBits | 0777
} else {
flags |= uint32(info.Mode() & os.ModePerm)
}
f := File{
Name: rn,
Version: lamport.Default.Tick(0),
Flags: flags,
Modified: info.ModTime().Unix(),
}
if debug {
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l.Debugln("dir:", cf, f)
}
*res = append(*res, f)
}
return nil
}
}
if info.Mode().IsRegular() {
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if w.CurrentFiler != nil {
cf := w.CurrentFiler.CurrentFile(rn)
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permUnchanged := w.IgnorePerms || !protocol.HasPermissionBits(cf.Flags) || PermsEqual(cf.Flags, uint32(info.Mode()))
if !protocol.IsDeleted(cf.Flags) && cf.Modified == info.ModTime().Unix() && permUnchanged {
if debug {
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l.Debugln("unchanged:", cf)
}
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*res = append(*res, cf)
return nil
}
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if w.Suppressor != nil {
if cur, prev := w.Suppressor.Suppress(rn, info); cur && !prev {
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l.Infof("Changes to %q are being temporarily suppressed because it changes too frequently.", p)
cf.Suppressed = true
cf.Version++
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if debug {
l.Debugln("suppressed:", cf)
}
*res = append(*res, cf)
return nil
} else if prev && !cur {
l.Infof("Changes to %q are no longer suppressed.", p)
}
}
if debug {
l.Debugln("rescan:", cf, info.ModTime().Unix(), info.Mode()&os.ModePerm)
}
}
fd, err := os.Open(p)
if err != nil {
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if debug {
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l.Debugln("open:", p, err)
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}
return nil
}
defer fd.Close()
t0 := time.Now()
blocks, err := Blocks(fd, w.BlockSize)
if err != nil {
if debug {
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l.Debugln("hash error:", rn, err)
}
return nil
}
if debug {
t1 := time.Now()
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l.Debugln("hashed:", rn, ";", len(blocks), "blocks;", info.Size(), "bytes;", int(float64(info.Size())/1024/t1.Sub(t0).Seconds()), "KB/s")
}
var flags = uint32(info.Mode() & os.ModePerm)
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if w.IgnorePerms {
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flags = protocol.FlagNoPermBits | 0666
}
f := File{
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Name: rn,
Version: lamport.Default.Tick(0),
Size: info.Size(),
Flags: flags,
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Modified: info.ModTime().Unix(),
Blocks: blocks,
}
*res = append(*res, f)
}
return nil
}
}
func (w *Walker) cleanTempFile(path string, info os.FileInfo, err error) error {
if err != nil {
return err
}
if info.Mode()&os.ModeType == 0 && w.TempNamer.IsTemporary(path) {
os.Remove(path)
}
return nil
}
func (w *Walker) ignoreFile(patterns map[string][]string, file string) bool {
first, last := filepath.Split(file)
for prefix, pats := range patterns {
if len(prefix) == 0 || prefix == first || strings.HasPrefix(first, prefix+"/") {
for _, pattern := range pats {
if match, _ := filepath.Match(pattern, last); match {
return true
}
}
}
}
return false
}
func checkDir(dir string) error {
if info, err := os.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
}
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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
}
}