vikunja-api/vendor/honnef.co/go/tools/internal/cache/default.go

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// Copyright 2017 The Go 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 cache
import (
"fmt"
"io/ioutil"
"log"
"os"
"path/filepath"
"sync"
)
// Default returns the default cache to use.
func Default() (*Cache, error) {
defaultOnce.Do(initDefaultCache)
return defaultCache, defaultDirErr
}
var (
defaultOnce sync.Once
defaultCache *Cache
)
// cacheREADME is a message stored in a README in the cache directory.
// Because the cache lives outside the normal Go trees, we leave the
// README as a courtesy to explain where it came from.
const cacheREADME = `This directory holds cached build artifacts from staticcheck.
`
// initDefaultCache does the work of finding the default cache
// the first time Default is called.
func initDefaultCache() {
dir := DefaultDir()
if err := os.MkdirAll(dir, 0777); err != nil {
log.Fatalf("failed to initialize build cache at %s: %s\n", dir, err)
}
if _, err := os.Stat(filepath.Join(dir, "README")); err != nil {
// Best effort.
ioutil.WriteFile(filepath.Join(dir, "README"), []byte(cacheREADME), 0666)
}
c, err := Open(dir)
if err != nil {
log.Fatalf("failed to initialize build cache at %s: %s\n", dir, err)
}
defaultCache = c
}
var (
defaultDirOnce sync.Once
defaultDir string
defaultDirErr error
)
// DefaultDir returns the effective STATICCHECK_CACHE setting.
func DefaultDir() string {
// Save the result of the first call to DefaultDir for later use in
// initDefaultCache. cmd/go/main.go explicitly sets GOCACHE so that
// subprocesses will inherit it, but that means initDefaultCache can't
// otherwise distinguish between an explicit "off" and a UserCacheDir error.
defaultDirOnce.Do(func() {
defaultDir = os.Getenv("STATICCHECK_CACHE")
if filepath.IsAbs(defaultDir) {
return
}
if defaultDir != "" {
defaultDirErr = fmt.Errorf("STATICCHECK_CACHE is not an absolute path")
return
}
// Compute default location.
dir, err := os.UserCacheDir()
if err != nil {
defaultDirErr = fmt.Errorf("STATICCHECK_CACHE is not defined and %v", err)
return
}
defaultDir = filepath.Join(dir, "staticcheck")
})
return defaultDir
}