restic/backend/local/local.go

289 lines
6.1 KiB
Go

package local
import (
"errors"
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"github.com/restic/restic/backend"
"github.com/restic/restic/debug"
)
// Local is a backend in a local directory.
type Local struct {
p string
}
func paths(dir string) []string {
return []string{
dir,
filepath.Join(dir, backend.Paths.Data),
filepath.Join(dir, backend.Paths.Snapshots),
filepath.Join(dir, backend.Paths.Index),
filepath.Join(dir, backend.Paths.Locks),
filepath.Join(dir, backend.Paths.Keys),
filepath.Join(dir, backend.Paths.Temp),
}
}
// Open opens the local backend as specified by config.
func Open(dir string) (*Local, error) {
// test if all necessary dirs are there
for _, d := range paths(dir) {
if _, err := os.Stat(d); err != nil {
return nil, fmt.Errorf("%s does not exist", d)
}
}
return &Local{p: dir}, nil
}
// Create creates all the necessary files and directories for a new local
// backend at dir. Afterwards a new config blob should be created.
func Create(dir string) (*Local, error) {
// test if config file already exists
_, err := os.Lstat(filepath.Join(dir, backend.Paths.Config))
if err == nil {
return nil, errors.New("config file already exists")
}
// create paths for data, refs and temp
for _, d := range paths(dir) {
err := os.MkdirAll(d, backend.Modes.Dir)
if err != nil {
return nil, err
}
}
// open backend
return Open(dir)
}
// Location returns this backend's location (the directory name).
func (b *Local) Location() string {
return b.p
}
// Construct path for given Type and name.
func filename(base string, t backend.Type, name string) string {
if t == backend.Config {
return filepath.Join(base, "config")
}
return filepath.Join(dirname(base, t, name), name)
}
// Construct directory for given Type.
func dirname(base string, t backend.Type, name string) string {
var n string
switch t {
case backend.Data:
n = backend.Paths.Data
if len(name) > 2 {
n = filepath.Join(n, name[:2])
}
case backend.Snapshot:
n = backend.Paths.Snapshots
case backend.Index:
n = backend.Paths.Index
case backend.Lock:
n = backend.Paths.Locks
case backend.Key:
n = backend.Paths.Keys
}
return filepath.Join(base, n)
}
// Load returns the data stored in the backend for h at the given offset
// and saves it in p. Load has the same semantics as io.ReaderAt.
func (b *Local) Load(h backend.Handle, p []byte, off int64) (n int, err error) {
if err := h.Valid(); err != nil {
return 0, err
}
f, err := os.Open(filename(b.p, h.Type, h.Name))
if err != nil {
return 0, err
}
defer func() {
e := f.Close()
if err == nil && e != nil {
err = e
}
}()
if off > 0 {
_, err = f.Seek(off, 0)
if err != nil {
return 0, err
}
}
return io.ReadFull(f, p)
}
// writeToTempfile saves p into a tempfile in tempdir.
func writeToTempfile(tempdir string, p []byte) (filename string, err error) {
tmpfile, err := ioutil.TempFile(tempdir, "temp-")
if err != nil {
return "", err
}
n, err := tmpfile.Write(p)
if err != nil {
return "", err
}
if n != len(p) {
return "", errors.New("not all bytes writen")
}
if err = tmpfile.Sync(); err != nil {
return "", err
}
err = tmpfile.Close()
if err != nil {
return "", err
}
return tmpfile.Name(), nil
}
// Save stores data in the backend at the handle.
func (b *Local) Save(h backend.Handle, p []byte) (err error) {
if err := h.Valid(); err != nil {
return err
}
tmpfile, err := writeToTempfile(filepath.Join(b.p, backend.Paths.Temp), p)
debug.Log("local.Save", "saved %v (%d bytes) to %v", h, len(p), tmpfile)
filename := filename(b.p, h.Type, h.Name)
// test if new path already exists
if _, err := os.Stat(filename); err == nil {
return fmt.Errorf("Rename(): file %v already exists", filename)
}
// create directories if necessary, ignore errors
if h.Type == backend.Data {
err = os.MkdirAll(filepath.Dir(filename), backend.Modes.Dir)
if err != nil {
return err
}
}
err = os.Rename(tmpfile, filename)
debug.Log("local.Save", "save %v: rename %v -> %v: %v",
h, filepath.Base(tmpfile), filepath.Base(filename), err)
if err != nil {
return err
}
// set mode to read-only
fi, err := os.Stat(filename)
if err != nil {
return err
}
return setNewFileMode(filename, fi)
}
// Stat returns information about a blob.
func (b *Local) Stat(h backend.Handle) (backend.BlobInfo, error) {
if err := h.Valid(); err != nil {
return backend.BlobInfo{}, err
}
fi, err := os.Stat(filename(b.p, h.Type, h.Name))
if err != nil {
return backend.BlobInfo{}, err
}
return backend.BlobInfo{Size: fi.Size()}, nil
}
// Test returns true if a blob of the given type and name exists in the backend.
func (b *Local) Test(t backend.Type, name string) (bool, error) {
_, err := os.Stat(filename(b.p, t, name))
if err != nil {
if os.IsNotExist(err) {
return false, nil
}
return false, err
}
return true, nil
}
// Remove removes the blob with the given name and type.
func (b *Local) Remove(t backend.Type, name string) error {
fn := filename(b.p, t, name)
// reset read-only flag
err := os.Chmod(fn, 0666)
if err != nil {
return err
}
return os.Remove(fn)
}
// List returns a channel that yields all names of blobs of type t. A
// goroutine is started for this. If the channel done is closed, sending
// stops.
func (b *Local) List(t backend.Type, done <-chan struct{}) <-chan string {
var pattern string
if t == backend.Data {
pattern = filepath.Join(dirname(b.p, t, ""), "*", "*")
} else {
pattern = filepath.Join(dirname(b.p, t, ""), "*")
}
ch := make(chan string)
matches, err := filepath.Glob(pattern)
if err != nil {
close(ch)
return ch
}
for i := range matches {
matches[i] = filepath.Base(matches[i])
}
go func() {
defer close(ch)
for _, m := range matches {
if m == "" {
continue
}
select {
case ch <- m:
case <-done:
return
}
}
}()
return ch
}
// Delete removes the repository and all files.
func (b *Local) Delete() error {
return os.RemoveAll(b.p)
}
// Close closes all open files.
func (b *Local) Close() error {
// this does not need to do anything, all open files are closed within the
// same function.
return nil
}