tailscale/atomicfile/atomicfile.go

29 lines
849 B
Go

// Copyright 2019 Tailscale & AUTHORS. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package atomicfile contains code related to writing to filesystems
// atomically.
//
// This package should be considered internal; its API is not stable.
package atomicfile // import "tailscale.com/atomicfile"
import (
"fmt"
"io/ioutil"
"os"
)
// WriteFile writes data to filename+some suffix, then renames it
// into filename.
func WriteFile(filename string, data []byte, perm os.FileMode) error {
tmpname := filename + ".new.tmp"
if err := ioutil.WriteFile(tmpname, data, perm); err != nil {
return fmt.Errorf("%#v: %v", tmpname, err)
}
if err := os.Rename(tmpname, filename); err != nil {
return fmt.Errorf("%#v->%#v: %v", tmpname, filename, err)
}
return nil
}