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