github.com/elek/golangci-lint@v1.42.2-0.20211208090441-c05b7fcb3a9a/internal/cache/default.go (about)

     1  // Copyright 2017 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package cache
     6  
     7  import (
     8  	"fmt"
     9  	"io/ioutil"
    10  	"log"
    11  	"os"
    12  	"path/filepath"
    13  	"sync"
    14  )
    15  
    16  // Default returns the default cache to use.
    17  func Default() (*Cache, error) {
    18  	defaultOnce.Do(initDefaultCache)
    19  	return defaultCache, defaultDirErr
    20  }
    21  
    22  var (
    23  	defaultOnce  sync.Once
    24  	defaultCache *Cache
    25  )
    26  
    27  // cacheREADME is a message stored in a README in the cache directory.
    28  // Because the cache lives outside the normal Go trees, we leave the
    29  // README as a courtesy to explain where it came from.
    30  const cacheREADME = `This directory holds cached build artifacts from golangci-lint.
    31  `
    32  
    33  // initDefaultCache does the work of finding the default cache
    34  // the first time Default is called.
    35  func initDefaultCache() {
    36  	dir := DefaultDir()
    37  	if err := os.MkdirAll(dir, 0744); err != nil {
    38  		log.Fatalf("failed to initialize build cache at %s: %s\n", dir, err)
    39  	}
    40  	if _, err := os.Stat(filepath.Join(dir, "README")); err != nil {
    41  		// Best effort.
    42  		if wErr := ioutil.WriteFile(filepath.Join(dir, "README"), []byte(cacheREADME), 0666); wErr != nil {
    43  			log.Fatalf("Failed to write README file to cache dir %s: %s", dir, err)
    44  		}
    45  	}
    46  
    47  	c, err := Open(dir)
    48  	if err != nil {
    49  		log.Fatalf("failed to initialize build cache at %s: %s\n", dir, err)
    50  	}
    51  	defaultCache = c
    52  }
    53  
    54  var (
    55  	defaultDirOnce sync.Once
    56  	defaultDir     string
    57  	defaultDirErr  error
    58  )
    59  
    60  // DefaultDir returns the effective GOLANGCI_LINT_CACHE setting.
    61  func DefaultDir() string {
    62  	// Save the result of the first call to DefaultDir for later use in
    63  	// initDefaultCache. cmd/go/main.go explicitly sets GOCACHE so that
    64  	// subprocesses will inherit it, but that means initDefaultCache can't
    65  	// otherwise distinguish between an explicit "off" and a UserCacheDir error.
    66  
    67  	defaultDirOnce.Do(func() {
    68  		defaultDir = os.Getenv("GOLANGCI_LINT_CACHE")
    69  		if filepath.IsAbs(defaultDir) {
    70  			return
    71  		}
    72  		if defaultDir != "" {
    73  			defaultDirErr = fmt.Errorf("GOLANGCI_LINT_CACHE is not an absolute path")
    74  			return
    75  		}
    76  
    77  		// Compute default location.
    78  		dir, err := os.UserCacheDir()
    79  		if err != nil {
    80  			defaultDirErr = fmt.Errorf("GOLANGCI_LINT_CACHE is not defined and %v", err)
    81  			return
    82  		}
    83  		defaultDir = filepath.Join(dir, "golangci-lint")
    84  	})
    85  
    86  	return defaultDir
    87  }