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tempname.go
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tempname.go
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// 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 (
"fmt"
"path/filepath"
"strings"
"github.com/syncthing/syncthing/lib/build"
"github.com/syncthing/syncthing/lib/sha256"
)
const (
WindowsTempPrefix = "~syncthing~"
UnixTempPrefix = ".syncthing."
)
func tempPrefix() string {
if build.IsWindows {
return WindowsTempPrefix
} else {
return UnixTempPrefix
}
}
// 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")
// 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)
return strings.HasPrefix(name, WindowsTempPrefix) ||
strings.HasPrefix(name, UnixTempPrefix)
}
func TempNameWithPrefix(name, prefix string) string {
tdir := filepath.Dir(name)
tbase := filepath.Base(name)
var tname string
if len(tbase) > maxFilenameLength {
tname = fmt.Sprintf("%s%x.tmp", prefix, sha256.Sum256([]byte(tbase)))
} else {
tname = prefix + tbase + ".tmp"
}
return filepath.Join(tdir, tname)
}
func TempName(name string) string {
return TempNameWithPrefix(name, tempPrefix())
}