syncthing/lib/fs/tempname.go
2019-02-02 11:02:28 +01:00

64 lines
1.6 KiB
Go

// Copyright (C) 2015 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 (
"crypto/md5"
"fmt"
"path/filepath"
"runtime"
"strings"
)
const (
WindowsTempPrefix = "~syncthing~"
UnixTempPrefix = ".syncthing."
)
var TempPrefix string
// Real filesystems usually handle 255 bytes. encfs has varying and
// confusing file name limits. We take a safe way out and switch to hashing
// quite early.
const maxFilenameLength = 160 - len(UnixTempPrefix) - len(".tmp")
func init() {
if runtime.GOOS == "windows" {
TempPrefix = WindowsTempPrefix
} else {
TempPrefix = UnixTempPrefix
}
}
// IsTemporary is true if the file name has the temporary prefix. Regardless
// of the normally used prefix, the standard Windows and Unix temp prefixes
// are always recognized as temp files.
func IsTemporary(name string) bool {
name = filepath.Base(name)
if strings.HasPrefix(name, WindowsTempPrefix) ||
strings.HasPrefix(name, UnixTempPrefix) {
return true
}
return false
}
func TempNameWithPrefix(name, prefix string) string {
tdir := filepath.Dir(name)
tbase := filepath.Base(name)
if len(tbase) > maxFilenameLength {
hash := md5.New()
_, _ = hash.Write([]byte(name))
tbase = fmt.Sprintf("%x", hash.Sum(nil))
}
tname := fmt.Sprintf("%s%s.tmp", prefix, tbase)
return filepath.Join(tdir, tname)
}
func TempName(name string) string {
return TempNameWithPrefix(name, TempPrefix)
}