mirror of
https://github.com/restic/restic.git
synced 2024-12-25 17:27:25 +00:00
250 lines
5.4 KiB
Go
250 lines
5.4 KiB
Go
package restic
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import (
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"errors"
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"fmt"
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"io"
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"os"
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"path/filepath"
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"strings"
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"github.com/restic/restic/backend"
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"github.com/restic/restic/debug"
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"github.com/restic/restic/server"
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)
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// Cache is used to locally cache items from a server.
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type Cache struct {
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base string
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}
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func NewCache(s *server.Server) (*Cache, error) {
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cacheDir, err := getCacheDir()
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if err != nil {
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return nil, err
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}
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basedir := filepath.Join(cacheDir, s.Config.ID)
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debug.Log("Cache.New", "opened cache at %v", basedir)
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return &Cache{base: basedir}, nil
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}
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// Has checks if the local cache has the id.
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func (c *Cache) Has(t backend.Type, subtype string, id backend.ID) (bool, error) {
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filename, err := c.filename(t, subtype, id)
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if err != nil {
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return false, err
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}
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fd, err := os.Open(filename)
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defer fd.Close()
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if err != nil {
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if os.IsNotExist(err) {
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debug.Log("Cache.Has", "test for file %v: not cached", filename)
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return false, nil
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}
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debug.Log("Cache.Has", "test for file %v: error %v", filename, err)
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return false, err
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}
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debug.Log("Cache.Has", "test for file %v: is cached", filename)
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return true, nil
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}
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// Store returns an io.WriteCloser that is used to save new information to the
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// cache. The returned io.WriteCloser must be closed by the caller after all
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// data has been written.
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func (c *Cache) Store(t backend.Type, subtype string, id backend.ID) (io.WriteCloser, error) {
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filename, err := c.filename(t, subtype, id)
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if err != nil {
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return nil, err
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}
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dirname := filepath.Dir(filename)
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err = os.MkdirAll(dirname, 0700)
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if err != nil {
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return nil, err
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}
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file, err := os.Create(filename)
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if err != nil {
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debug.Log("Cache.Store", "error creating file %v: %v", filename, err)
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return nil, err
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}
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debug.Log("Cache.Store", "created file %v", filename)
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return file, nil
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}
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// Load returns information from the cache. The returned io.ReadCloser must be
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// closed by the caller.
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func (c *Cache) Load(t backend.Type, subtype string, id backend.ID) (io.ReadCloser, error) {
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filename, err := c.filename(t, subtype, id)
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if err != nil {
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return nil, err
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}
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return os.Open(filename)
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}
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func (c *Cache) purge(t backend.Type, subtype string, id backend.ID) error {
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filename, err := c.filename(t, subtype, id)
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if err != nil {
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return err
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}
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err = os.Remove(filename)
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debug.Log("Cache.purge", "Remove file %v: %v", filename, err)
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if err != nil && os.IsNotExist(err) {
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return nil
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}
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return err
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}
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// Clear removes information from the cache that isn't present in the server any more.
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func (c *Cache) Clear(s *server.Server) error {
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list, err := c.list(backend.Snapshot)
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if err != nil {
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return err
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}
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for _, entry := range list {
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debug.Log("Cache.Clear", "found entry %v", entry)
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if ok, err := s.Test(backend.Snapshot, entry.ID.String()); !ok || err != nil {
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debug.Log("Cache.Clear", "snapshot %v doesn't exist any more, removing %v", entry.ID, entry)
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err = c.purge(backend.Snapshot, entry.Subtype, entry.ID)
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if err != nil {
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return err
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}
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}
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}
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return nil
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}
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type cacheEntry struct {
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ID backend.ID
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Subtype string
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}
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func (c cacheEntry) String() string {
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if c.Subtype != "" {
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return c.ID.Str() + "." + c.Subtype
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}
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return c.ID.Str()
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}
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func (c *Cache) list(t backend.Type) ([]cacheEntry, error) {
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var dir string
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switch t {
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case backend.Snapshot:
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dir = filepath.Join(c.base, "snapshots")
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default:
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return nil, fmt.Errorf("cache not supported for type %v", t)
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}
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fd, err := os.Open(dir)
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if err != nil {
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if os.IsNotExist(err) {
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return []cacheEntry{}, nil
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}
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return nil, err
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}
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defer fd.Close()
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fis, err := fd.Readdir(-1)
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if err != nil {
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return nil, err
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}
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entries := make([]cacheEntry, 0, len(fis))
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for _, fi := range fis {
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parts := strings.SplitN(fi.Name(), ".", 2)
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id, err := backend.ParseID(parts[0])
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// ignore invalid cache entries for now
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if err != nil {
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debug.Log("Cache.List", "unable to parse name %v as id: %v", parts[0], err)
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continue
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}
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e := cacheEntry{ID: id}
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if len(parts) == 2 {
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e.Subtype = parts[1]
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}
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entries = append(entries, e)
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}
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return entries, nil
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}
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func (c *Cache) filename(t backend.Type, subtype string, id backend.ID) (string, error) {
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filename := id.String()
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if subtype != "" {
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filename += "." + subtype
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}
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switch t {
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case backend.Snapshot:
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return filepath.Join(c.base, "snapshots", filename), nil
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}
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return "", fmt.Errorf("cache not supported for type %v", t)
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}
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func getCacheDir() (string, error) {
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if dir := os.Getenv("RESTIC_CACHE"); dir != "" {
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return dir, nil
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}
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return getXDGCacheDir()
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}
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// getXDGCacheDir returns the cache directory according to XDG basedir spec, see
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// http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
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func getXDGCacheDir() (string, error) {
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xdgcache := os.Getenv("XDG_CACHE_HOME")
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home := os.Getenv("HOME")
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if xdgcache == "" && home == "" {
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return "", errors.New("unable to locate cache directory (XDG_CACHE_HOME and HOME unset)")
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}
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cachedir := ""
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if xdgcache != "" {
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cachedir = filepath.Join(xdgcache, "restic")
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} else if home != "" {
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cachedir = filepath.Join(home, ".cache", "restic")
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}
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fi, err := os.Stat(cachedir)
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if os.IsNotExist(err) {
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err = os.MkdirAll(cachedir, 0700)
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if err != nil {
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return "", err
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}
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fi, err = os.Stat(cachedir)
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debug.Log("getCacheDir", "create cache dir %v", cachedir)
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}
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if err != nil {
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return "", err
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}
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if !fi.IsDir() {
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return "", fmt.Errorf("cache dir %v is not a directory", cachedir)
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}
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return cachedir, nil
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}
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