restic/cache.go

248 lines
5.1 KiB
Go

package restic
import (
"errors"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"github.com/restic/restic/backend"
"github.com/restic/restic/debug"
"github.com/restic/restic/server"
)
type Cache struct {
base string
}
func NewCache(be backend.Identifier) (c *Cache, err error) {
// try to get explicit cache dir from environment
dir := os.Getenv("RESTIC_CACHE")
// otherwise try OS specific default
if dir == "" {
dir, err = GetCacheDir()
if err != nil {
return nil, err
}
}
basedir := filepath.Join(dir, be.ID())
debug.Log("Cache.New", "opened cache at %v", basedir)
return &Cache{base: basedir}, nil
}
func (c *Cache) Has(t backend.Type, subtype string, id backend.ID) (bool, error) {
// try to open file
filename, err := c.filename(t, subtype, id)
if err != nil {
return false, err
}
fd, err := os.Open(filename)
defer fd.Close()
if err != nil {
if os.IsNotExist(err) {
debug.Log("Cache.Has", "test for file %v: not cached", filename)
return false, nil
}
debug.Log("Cache.Has", "test for file %v: error %v", filename, err)
return false, err
}
debug.Log("Cache.Has", "test for file %v: is cached", filename)
return true, nil
}
func (c *Cache) Store(t backend.Type, subtype string, id backend.ID) (io.WriteCloser, error) {
filename, err := c.filename(t, subtype, id)
if err != nil {
return nil, err
}
dirname := filepath.Dir(filename)
err = os.MkdirAll(dirname, 0700)
if err != nil {
return nil, err
}
file, err := os.Create(filename)
if err != nil {
debug.Log("Cache.Store", "error creating file %v: %v", filename, err)
return nil, err
}
debug.Log("Cache.Store", "created file %v", filename)
return file, nil
}
func (c *Cache) Load(t backend.Type, subtype string, id backend.ID) (io.ReadCloser, error) {
// try to open file
filename, err := c.filename(t, subtype, id)
if err != nil {
return nil, err
}
return os.Open(filename)
}
func (c *Cache) Purge(t backend.Type, subtype string, id backend.ID) error {
filename, err := c.filename(t, subtype, id)
if err != nil {
return err
}
err = os.Remove(filename)
debug.Log("Cache.Purge", "Remove file %v: %v", filename, err)
if err != nil && os.IsNotExist(err) {
return nil
}
return err
}
func (c *Cache) Clear(s *server.Server) error {
list, err := c.List(backend.Snapshot)
if err != nil {
return err
}
for _, entry := range list {
debug.Log("Cache.Clear", "found entry %v", entry)
if ok, err := s.Test(backend.Snapshot, entry.ID.String()); !ok || err != nil {
debug.Log("Cache.Clear", "snapshot %v doesn't exist any more, removing %v", entry.ID, entry)
err = c.Purge(backend.Snapshot, entry.Subtype, entry.ID)
if err != nil {
return err
}
}
}
return nil
}
type CacheEntry struct {
ID backend.ID
Subtype string
}
func (c CacheEntry) String() string {
if c.Subtype != "" {
return c.ID.Str() + "." + c.Subtype
}
return c.ID.Str()
}
func (c *Cache) List(t backend.Type) ([]CacheEntry, error) {
var dir string
switch t {
case backend.Snapshot:
dir = filepath.Join(c.base, "snapshots")
default:
return nil, fmt.Errorf("cache not supported for type %v", t)
}
fd, err := os.Open(dir)
if err != nil {
if os.IsNotExist(err) {
return []CacheEntry{}, nil
}
return nil, err
}
defer fd.Close()
fis, err := fd.Readdir(-1)
if err != nil {
return nil, err
}
entries := make([]CacheEntry, 0, len(fis))
for _, fi := range fis {
parts := strings.SplitN(fi.Name(), ".", 2)
id, err := backend.ParseID(parts[0])
// ignore invalid cache entries for now
if err != nil {
debug.Log("Cache.List", "unable to parse name %v as id: %v", parts[0], err)
continue
}
e := CacheEntry{ID: id}
if len(parts) == 2 {
e.Subtype = parts[1]
}
entries = append(entries, e)
}
return entries, nil
}
// Construct file name for given Type.
func (c *Cache) filename(t backend.Type, subtype string, id backend.ID) (string, error) {
filename := id.String()
if subtype != "" {
filename += "." + subtype
}
switch t {
case backend.Snapshot:
return filepath.Join(c.base, "snapshots", filename), nil
}
return "", fmt.Errorf("cache not supported for type %v", t)
}
// high-level functions
// GetCacheDir returns the cache directory according to XDG basedir spec, see
// http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
func GetCacheDir() (string, error) {
xdgcache := os.Getenv("XDG_CACHE_HOME")
home := os.Getenv("HOME")
if xdgcache == "" && home == "" {
return "", errors.New("unable to locate cache directory (XDG_CACHE_HOME and HOME unset)")
}
cachedir := ""
if xdgcache != "" {
cachedir = filepath.Join(xdgcache, "restic")
} else if home != "" {
cachedir = filepath.Join(home, ".cache", "restic")
}
fi, err := os.Stat(cachedir)
if os.IsNotExist(err) {
err = os.MkdirAll(cachedir, 0700)
if err != nil {
return "", err
}
fi, err = os.Stat(cachedir)
debug.Log("getCacheDir", "create cache dir %v", cachedir)
}
if err != nil {
return "", err
}
if !fi.IsDir() {
return "", fmt.Errorf("cache dir %v is not a directory", cachedir)
}
return cachedir, nil
}
// TODO: implement RefreshIndex()