1// Copyright 2018 The Wuffs Authors. 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// https://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14 15package wuffsroot 16 17import ( 18 "errors" 19 "go/build" 20 "os" 21 "path/filepath" 22 "sync" 23) 24 25var cache struct { 26 mu sync.Mutex 27 value string 28} 29 30func Value() (string, error) { 31 cache.mu.Lock() 32 value := cache.value 33 cache.mu.Unlock() 34 35 if value != "" { 36 return value, nil 37 } 38 39 // TODO: look for a WUFFSROOT environment variable? Also check that 40 // wuffs-root-directory.txt exists? 41 for _, p := range filepath.SplitList(build.Default.GOPATH) { 42 p = filepath.Join(p, "src", "github.com", "google", "wuffs") 43 if o, err := os.Stat(p); err == nil && o.IsDir() { 44 cache.mu.Lock() 45 cache.value = p 46 cache.mu.Unlock() 47 48 return p, nil 49 } 50 } 51 return "", errors.New("could not find Wuffs root directory") 52} 53