blob: d1a24f075deea935ecb64235b739e8a59cd39142 [file] [log] [blame]
// Copyright 2018 The Wuffs 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
//
// https://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 wuffsroot
import (
"errors"
"go/build"
"os"
"path/filepath"
"sync"
)
var initialWorkingDirectory = ""
func init() {
initialWorkingDirectory, _ = os.Getwd()
}
var cache struct {
mu sync.Mutex
value string
}
func setValue(value string) (string, error) {
cache.mu.Lock()
cache.value = value
cache.mu.Unlock()
return value, nil
}
func Value() (string, error) {
cache.mu.Lock()
value := cache.value
cache.mu.Unlock()
if value != "" {
return value, nil
}
const wrdTxt = "wuffs-root-directory.txt"
// Look for "w-r-d.txt" in the working directory or its ancestors.
for p, q := initialWorkingDirectory, ""; p != q; p, q = filepath.Dir(p), p {
if _, err := os.Stat(filepath.Join(p, wrdTxt)); err == nil {
return setValue(p)
}
}
// Look for "github.com/google/wuffs/w-r-d.txt" in the Go source
// directories.
for _, p := range build.Default.SrcDirs() {
p = filepath.Join(p, "github.com", "google", "wuffs")
if _, err := os.Stat(filepath.Join(p, wrdTxt)); err == nil {
return setValue(p)
}
}
return "", errors.New("could not find Wuffs root directory")
}