absolute-path.go

// Copyright 2020 tools authors
//
// 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 tools

import (
	"os"
	"os/exec"
	"path/filepath"
	"sync"
)

// EnsureAbs prepends the WorkDir to the given path if it is not an absolute path.
func EnsureAbs(path string) string {
	if filepath.IsAbs(path) {
		return path
	}
	return filepath.Join(WorkDir(), path)
}

var (
	workDir     string
	workDirOnce sync.Once
)

// WorkDir returns the absolute path of work directory. It reads the value of envrionment
// variable GOGS_WORK_DIR. When not set, it uses the directory where the application's
// binary is located.
func WorkDir() string {
	workDirOnce.Do(func() {
		workDir = filepath.Dir(AppPath())
	})

	return workDir
}

var (
	appPath     string
	appPathOnce sync.Once
)

// AppPath returns the absolute path of the application's binary.
func AppPath() string {
	appPathOnce.Do(func() {
		var err error
		appPath, err = exec.LookPath(os.Args[0])
		if err != nil {
			panic("look executable path: " + err.Error())
		}
		appPath, err = filepath.Abs(appPath)
		if err != nil {
			panic("get absolute executable path: " + err.Error())
		}
	})

	return appPath
}