/usr/share/gocode/src/github.com/spf13/fsync/fsync.go is in golang-github-spf13-fsync-dev 0.0~git20161130.0.cb2da33-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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// Copyright (C) 2014-5 Steve Francia
// package fsync keeps two files or directories in sync.
//
// err := fsync.Sync("~/dst", ".")
//
// After the above code, if err is nil, every file and directory in the current
// directory is copied to ~/dst and has the same permissions. Consequent calls
// will only copy changed or new files.
//
// SyncTo is a helper function which helps you sync a groups of files or
// directories into a single destination. For instance, calling
//
// SyncTo("public", "build/app.js", "build/app.css", "images", "fonts")
//
// is equivalent to calling
//
// Sync("public/app.js", "build/app.js")
// Sync("public/app.css", "build/app.css")
// Sync("public/images", "images")
// Sync("public/fonts", "fonts")
//
// Actually, this is how SyncTo is implemented: consequent calls to Sync.
//
// By default, sync code ignores extra files in the destination that don’t have
// identicals in the source. Setting Delete field of a Syncer to true changes
// this behavior and deletes these extra files.
package fsync
import (
"bytes"
"errors"
"io"
"os"
"path/filepath"
"runtime"
"github.com/spf13/afero"
)
var (
ErrFileOverDir = errors.New(
"fsync: trying to overwrite a non-empty directory with a file")
)
// Sync copies files and directories inside src into dst.
func Sync(dst, src string) error {
return NewSyncer().Sync(dst, src)
}
// SyncTo syncs srcs files and directories into to directory.
func SyncTo(to string, srcs ...string) error {
return NewSyncer().SyncTo(to, srcs...)
}
// Type Syncer provides functions for syncing files.
type Syncer struct {
// Set this to true to delete files in the destination that don't exist
// in the source.
Delete bool
// By default, modification times are synced. This can be turned off by
// setting this to true.
NoTimes bool
// NoChmod disables permission mode syncing.
NoChmod bool
// TODO add options for not checking content for equality
SrcFs afero.Fs
DestFs afero.Fs
}
// NewSyncer creates a new instance of Syncer with default options.
func NewSyncer() *Syncer {
return &Syncer{SrcFs: new(afero.OsFs), DestFs: new(afero.OsFs)}
}
// Sync copies files and directories inside src into dst.
func (s *Syncer) Sync(dst, src string) error {
// make sure src exists
if _, err := s.SrcFs.Stat(src); err != nil {
return err
}
// return error instead of replacing a non-empty directory with a file
if b, err := s.checkDir(dst, src); err != nil {
return err
} else if b {
return ErrFileOverDir
}
return s.syncRecover(dst, src)
}
// SyncTo syncs srcs files or directories into to directory.
func (s *Syncer) SyncTo(to string, srcs ...string) error {
for _, src := range srcs {
dst := filepath.Join(to, filepath.Base(src))
if err := s.Sync(dst, src); err != nil {
return err
}
}
return nil
}
// syncRecover handles errors and calls sync
func (s *Syncer) syncRecover(dst, src string) (err error) {
defer func() {
if r := recover(); r != nil {
if _, ok := r.(runtime.Error); ok {
panic(r)
}
err = r.(error)
}
}()
s.sync(dst, src)
return nil
}
// sync updates dst to match with src, handling both files and directories.
func (s *Syncer) sync(dst, src string) {
// sync permissions and modification times after handling content
defer s.syncstats(dst, src)
// read files info
dstat, err := s.DestFs.Stat(dst)
if err != nil && !os.IsNotExist(err) {
panic(err)
}
sstat, err := s.SrcFs.Stat(src)
if err != nil && os.IsNotExist(err) {
return // src was deleted before we could copy it
}
check(err)
if !sstat.IsDir() {
// src is a file
// delete dst if its a directory
if dstat != nil && dstat.IsDir() {
check(s.DestFs.RemoveAll(dst))
}
if !s.equal(dst, src) {
// perform copy
df, err := s.DestFs.Create(dst)
check(err)
defer df.Close()
sf, err := s.SrcFs.Open(src)
if os.IsNotExist(err) {
return
}
check(err)
defer sf.Close()
_, err = io.Copy(df, sf)
if os.IsNotExist(err) {
return
}
check(err)
}
return
}
// src is a directory
// make dst if necessary
if dstat == nil {
// dst does not exist; create directory
check(s.DestFs.MkdirAll(dst, 0755)) // permissions will be synced later
} else if !dstat.IsDir() {
// dst is a file; remove and create directory
check(s.DestFs.Remove(dst))
check(s.DestFs.MkdirAll(dst, 0755)) // permissions will be synced later
}
// go through sf files and sync them
files, err := afero.ReadDir(s.SrcFs, src)
if os.IsNotExist(err) {
return
}
check(err)
// make a map of filenames for quick lookup; used in deletion
// deletion below
m := make(map[string]bool, len(files))
for _, file := range files {
dst2 := filepath.Join(dst, file.Name())
src2 := filepath.Join(src, file.Name())
s.sync(dst2, src2)
m[file.Name()] = true
}
// delete files from dst that does not exist in src
if s.Delete {
files, err = afero.ReadDir(s.DestFs, dst)
check(err)
for _, file := range files {
if !m[file.Name()] {
check(s.DestFs.RemoveAll(filepath.Join(dst, file.Name())))
}
}
}
}
// syncstats makes sure dst has the same pemissions and modification time as src
func (s *Syncer) syncstats(dst, src string) {
// get file infos; return if not exist and panic if error
dstat, err1 := s.DestFs.Stat(dst)
sstat, err2 := s.SrcFs.Stat(src)
if os.IsNotExist(err1) || os.IsNotExist(err2) {
return
}
check(err1)
check(err2)
// update dst's permission bits
if !s.NoChmod {
if dstat.Mode().Perm() != sstat.Mode().Perm() {
check(s.DestFs.Chmod(dst, sstat.Mode().Perm()))
}
}
// update dst's modification time
if !s.NoTimes {
if !dstat.ModTime().Equal(sstat.ModTime()) {
err := s.DestFs.Chtimes(dst, sstat.ModTime(), sstat.ModTime())
check(err)
}
}
}
// equal returns true if both dst and src files are equal
func (s *Syncer) equal(dst, src string) bool {
// get file infos
info1, err1 := s.DestFs.Stat(dst)
info2, err2 := s.SrcFs.Stat(src)
if os.IsNotExist(err1) || os.IsNotExist(err2) {
return false
}
check(err1)
check(err2)
// check sizes
if info1.Size() != info2.Size() {
return false
}
// both have the same size, check the contents
f1, err := s.DestFs.Open(dst)
check(err)
defer f1.Close()
f2, err := s.SrcFs.Open(src)
check(err)
defer f2.Close()
buf1 := make([]byte, 1000)
buf2 := make([]byte, 1000)
for {
// read from both
n1, err := f1.Read(buf1)
if err != nil && err != io.EOF {
panic(err)
}
n2, err := f2.Read(buf2)
if err != nil && err != io.EOF {
panic(err)
}
// compare read bytes
if !bytes.Equal(buf1[:n1], buf2[:n2]) {
return false
}
// end of both files
if n1 == 0 && n2 == 0 {
break
}
}
return true
}
// checkDir returns true if dst is a non-empty directory and src is a file
func (s *Syncer) checkDir(dst, src string) (b bool, err error) {
// read file info
dstat, err := s.DestFs.Stat(dst)
if os.IsNotExist(err) {
return false, nil
} else if err != nil {
return false, err
}
sstat, err := s.SrcFs.Stat(src)
if err != nil {
return false, err
}
// return false is dst is not a directory or src is a directory
if !dstat.IsDir() || sstat.IsDir() {
return false, nil
}
// dst is a directory and src is a file
// check if dst is non-empty
// read dst directory
files, err := afero.ReadDir(s.DestFs, dst)
if err != nil {
return false, err
}
if len(files) > 0 {
return true, nil
}
return false, nil
}
func check(err error) {
if err != nil {
panic(err)
}
}
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