Fsyncing the file has a small performance penalty and seems unnecessary. The file will be fsynced anyway, when the changes are commited to the database. GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3749
206 lines
5.5 KiB
Go
206 lines
5.5 KiB
Go
// Copyright (C) 2014 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 http://mozilla.org/MPL/2.0/.
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// Package osutil implements utilities for native OS support.
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package osutil
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import (
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"errors"
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"fmt"
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"io"
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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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"github.com/calmh/du"
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"github.com/syncthing/syncthing/lib/sync"
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)
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var ErrNoHome = errors.New("No home directory found - set $HOME (or the platform equivalent).")
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// Try to keep this entire operation atomic-like. We shouldn't be doing this
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// often enough that there is any contention on this lock.
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var renameLock = sync.NewMutex()
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// TryRename renames a file, leaving source file intact in case of failure.
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// Tries hard to succeed on various systems by temporarily tweaking directory
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// permissions and removing the destination file when necessary.
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func TryRename(from, to string) error {
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renameLock.Lock()
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defer renameLock.Unlock()
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return withPreparedTarget(from, to, func() error {
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return os.Rename(from, to)
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})
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}
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// Rename moves a temporary file to it's final place.
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// Will make sure to delete the from file if the operation fails, so use only
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// for situations like committing a temp file to it's final location.
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// Tries hard to succeed on various systems by temporarily tweaking directory
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// permissions and removing the destination file when necessary.
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func Rename(from, to string) error {
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// Don't leave a dangling temp file in case of rename error
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if !(runtime.GOOS == "windows" && strings.EqualFold(from, to)) {
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defer os.Remove(from)
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}
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return TryRename(from, to)
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}
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// Copy copies the file content from source to destination.
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// Tries hard to succeed on various systems by temporarily tweaking directory
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// permissions and removing the destination file when necessary.
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func Copy(from, to string) (err error) {
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return withPreparedTarget(from, to, func() error {
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return copyFileContents(from, to)
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})
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}
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// InWritableDir calls fn(path), while making sure that the directory
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// containing `path` is writable for the duration of the call.
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func InWritableDir(fn func(string) error, path string) error {
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dir := filepath.Dir(path)
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info, err := os.Stat(dir)
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if err != nil {
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return err
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}
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if !info.IsDir() {
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return errors.New("Not a directory: " + path)
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}
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if info.Mode()&0200 == 0 {
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// A non-writeable directory (for this user; we assume that's the
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// relevant part). Temporarily change the mode so we can delete the
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// file or directory inside it.
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err = os.Chmod(dir, 0755)
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if err == nil {
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defer func() {
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err = os.Chmod(dir, info.Mode())
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if err != nil {
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// We managed to change the permission bits like a
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// millisecond ago, so it'd be bizarre if we couldn't
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// change it back.
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panic(err)
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}
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}()
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}
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}
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return fn(path)
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}
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func ExpandTilde(path string) (string, error) {
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if path == "~" {
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return getHomeDir()
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}
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path = filepath.FromSlash(path)
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if !strings.HasPrefix(path, fmt.Sprintf("~%c", os.PathSeparator)) {
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return path, nil
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}
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home, err := getHomeDir()
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if err != nil {
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return "", err
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}
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return filepath.Join(home, path[2:]), nil
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}
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func getHomeDir() (string, error) {
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var home string
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switch runtime.GOOS {
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case "windows":
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home = filepath.Join(os.Getenv("HomeDrive"), os.Getenv("HomePath"))
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if home == "" {
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home = os.Getenv("UserProfile")
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}
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default:
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home = os.Getenv("HOME")
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}
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if home == "" {
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return "", ErrNoHome
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}
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return home, nil
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}
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// Tries hard to succeed on various systems by temporarily tweaking directory
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// permissions and removing the destination file when necessary.
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func withPreparedTarget(from, to string, f func() error) error {
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// Make sure the destination directory is writeable
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toDir := filepath.Dir(to)
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if info, err := os.Stat(toDir); err == nil && info.IsDir() && info.Mode()&0200 == 0 {
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os.Chmod(toDir, 0755)
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defer os.Chmod(toDir, info.Mode())
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}
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// On Windows, make sure the destination file is writeable (or we can't delete it)
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if runtime.GOOS == "windows" {
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os.Chmod(to, 0666)
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if !strings.EqualFold(from, to) {
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err := os.Remove(to)
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if err != nil && !os.IsNotExist(err) {
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return err
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}
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}
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}
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return f()
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}
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// copyFileContents copies the contents of the file named src to the file named
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// by dst. The file will be created if it does not already exist. If the
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// destination file exists, all it's contents will be replaced by the contents
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// of the source file.
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func copyFileContents(src, dst string) (err error) {
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in, err := os.Open(src)
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if err != nil {
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return
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}
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defer in.Close()
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out, err := os.Create(dst)
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if err != nil {
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return
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}
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defer func() {
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cerr := out.Close()
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if err == nil {
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err = cerr
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}
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}()
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_, err = io.Copy(out, in)
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return
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}
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var execExts map[string]bool
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func init() {
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// PATHEXT contains a list of executable file extensions, on Windows
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pathext := filepath.SplitList(os.Getenv("PATHEXT"))
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// We want the extensions in execExts to be lower case
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execExts = make(map[string]bool, len(pathext))
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for _, ext := range pathext {
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execExts[strings.ToLower(ext)] = true
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}
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}
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// IsWindowsExecutable returns true if the given path has an extension that is
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// in the list of executable extensions.
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func IsWindowsExecutable(path string) bool {
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return execExts[strings.ToLower(filepath.Ext(path))]
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}
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func DiskFreeBytes(path string) (free int64, err error) {
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u, err := du.Get(path)
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return u.FreeBytes, err
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}
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func DiskFreePercentage(path string) (freePct float64, err error) {
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u, err := du.Get(path)
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return (float64(u.FreeBytes) / float64(u.TotalBytes)) * 100, err
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}
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