syncthing/lib/model/tempname.go

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// Copyright (C) 2015 The Syncthing Authors.
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//
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// 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/.
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package model
import (
"crypto/md5"
"fmt"
"path/filepath"
"runtime"
"strings"
)
type tempNamer struct {
prefix string
}
var defTempNamer tempNamer
// 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(".syncthing.") - len(".tmp")
func init() {
if runtime.GOOS == "windows" {
defTempNamer = tempNamer{"~syncthing~"}
} else {
defTempNamer = tempNamer{".syncthing."}
}
}
func (t tempNamer) IsTemporary(name string) bool {
return strings.HasPrefix(filepath.Base(name), t.prefix)
}
func (t tempNamer) TempName(name 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", t.prefix, tbase)
return filepath.Join(tdir, tname)
}