Merge pull request #1436 from restic/remove-old-cache

Remove old cache directories

internal/cache/cache.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"strconv"
+	"time"
 
 	"github.com/pkg/errors"
 	"github.com/restic/restic/internal/debug"
@@ -84,10 +85,12 @@ func writeCachedirTag(dir string) error {
 // performReadahead returns true.
 func New(id string, basedir string) (c *Cache, err error) {
 	if basedir == "" {
-		basedir, err = defaultCacheDir()
-		if err != nil {
-			return nil, err
-		}
+		basedir, err = DefaultDir()
+	}
+
+	err = mkdirCacheDir(basedir)
+	if err != nil {
+		return nil, err
 	}
 
 	// create base dir and tag it as a cache directory
@@ -112,6 +115,12 @@ func New(id string, basedir string) (c *Cache, err error) {
 		return nil, err
 	}
 
+	// update the timestamp so that we can detect old cache dirs
+	err = updateTimestamp(cachedir)
+	if err != nil {
+		return nil, err
+	}
+
 	if v < cacheVersion {
 		err = ioutil.WriteFile(filepath.Join(cachedir, "version"), []byte(fmt.Sprintf("%d", cacheVersion)), 0644)
 		if err != nil {
@@ -137,6 +146,53 @@ func New(id string, basedir string) (c *Cache, err error) {
 	return c, nil
 }
 
+// updateTimestamp sets the modification timestamp (mtime and atime) for the
+// directory d to the current time.
+func updateTimestamp(d string) error {
+	t := time.Now()
+	return fs.Chtimes(d, t, t)
+}
+
+const maxCacheAge = 30 * 24 * time.Hour
+
+// Old returns a list of cache directories with a modification time of more
+// than 30 days ago.
+func Old(basedir string) ([]string, error) {
+	var oldCacheDirs []string
+
+	f, err := fs.Open(basedir)
+	if err != nil {
+		return nil, err
+	}
+
+	entries, err := f.Readdir(-1)
+	if err != nil {
+		return nil, err
+	}
+
+	oldest := time.Now().Add(-maxCacheAge)
+	for _, fi := range entries {
+		if !fi.IsDir() {
+			continue
+		}
+
+		if !fi.ModTime().Before(oldest) {
+			continue
+		}
+
+		oldCacheDirs = append(oldCacheDirs, fi.Name())
+	}
+
+	err = f.Close()
+	if err != nil {
+		return nil, err
+	}
+
+	debug.Log("%d old cache dirs found", len(oldCacheDirs))
+
+	return oldCacheDirs, nil
+}
+
 // errNoSuchFile is returned when a file is not cached.
 type errNoSuchFile struct {
 	Type string

internal/cache/dir.go

@@ -49,29 +49,25 @@ func darwinCacheDir() (string, error) {
 	return filepath.Join(home, "Library", "Caches", "restic"), nil
 }
 
-// defaultCacheDir determines and creates the default cache directory for this
-// system.
-func defaultCacheDir() (string, error) {
-	var cachedir string
-	var err error
+// DefaultDir returns the default cache directory for the current OS.
+func DefaultDir() (cachedir string, err error) {
 	switch runtime.GOOS {
 	case "darwin":
 		cachedir, err = darwinCacheDir()
 	case "windows":
 		cachedir, err = windowsCacheDir()
-	default:
-		// Default to XDG for Linux and any other OSes.
-		cachedir, err = xdgCacheDir()
-	}
-	if err != nil {
-		return "", err
 	}
 
+	// Default to XDG for Linux and any other OSes.
+	return xdgCacheDir()
+}
+
+func mkdirCacheDir(cachedir string) error {
 	fi, err := fs.Stat(cachedir)
 	if os.IsNotExist(errors.Cause(err)) {
 		err = fs.MkdirAll(cachedir, 0700)
 		if err != nil {
-			return "", errors.Wrap(err, "MkdirAll")
+			return errors.Wrap(err, "MkdirAll")
 		}
 
 		fi, err = fs.Stat(cachedir)
@@ -79,12 +75,12 @@ func defaultCacheDir() (string, error) {
 	}
 
 	if err != nil {
-		return "", errors.Wrap(err, "Stat")
+		return errors.Wrap(err, "Stat")
 	}
 
 	if !fi.IsDir() {
-		return "", errors.Errorf("cache dir %v is not a directory", cachedir)
+		return errors.Errorf("cache dir %v is not a directory", cachedir)
 	}
 
-	return cachedir, nil
+	return nil
 }

internal/fs/file.go

@@ -4,6 +4,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"time"
 )
 
 // File is an open file on a file system.
@@ -120,3 +121,12 @@ func RemoveIfExists(filename string) error {
 	}
 	return err
 }
+
+// Chtimes changes the access and modification times of the named file,
+// similar to the Unix utime() or utimes() functions.
+//
+// The underlying filesystem may truncate or round the values to a less
+// precise time unit. If there is an error, it will be of type *PathError.
+func Chtimes(name string, atime time.Time, mtime time.Time) error {
+	return os.Chtimes(fixpath(name), atime, mtime)
+}