util.go

// Copyright 2016 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package agent

import (
	"os"
	"runtime"
)

func openToAppend(fpath string) (*os.File, error) {
	f, err := os.OpenFile(fpath, os.O_RDWR|os.O_APPEND|os.O_CREATE, 0777)
	if err != nil {
		return nil, err
	}
	return f, nil
}

func openToOverwrite(fpath string) (*os.File, error) {
	f, err := os.OpenFile(fpath, os.O_RDWR|os.O_TRUNC|os.O_CREATE, 0777)
	if err != nil {
		return nil, err
	}
	return f, nil
}

func toFile(txt, fpath string) error {
	f, err := openToOverwrite(fpath)
	if err != nil {
		f, err = os.Create(fpath)
		if err != nil {
			return err
		}
	}
	defer f.Close()
	_, err = f.WriteString(txt)
	return err
}

func homeDir() string {
	if runtime.GOOS == "windows" {
		home := os.Getenv("HOMEDRIVE") + os.Getenv("HOMEPATH")
		if home == "" {
			home = os.Getenv("USERPROFILE")
		}
		return home
	}
	return os.Getenv("HOME")
}

// exist returns true if the file or directory exists.
func exist(fpath string) bool {
	st, err := os.Stat(fpath)
	if err != nil {
		if os.IsNotExist(err) {
			return false
		}
	}
	if st.IsDir() {
		return true
	}
	if _, err := os.Stat(fpath); err != nil {
		if os.IsNotExist(err) {
			return false
		}
	}
	return true
}