restic/backend/local/local.go

394 lines
8.1 KiB
Go

package local
import (
"crypto/rand"
"crypto/sha256"
"encoding/hex"
"errors"
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"sort"
"strings"
"github.com/restic/restic/backend"
)
var ErrWrongData = errors.New("wrong data returned by backend, checksum does not match")
type Local struct {
p string
ver uint
id string
}
// Open opens the local backend at dir.
func Open(dir string) (*Local, error) {
items := []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),
}
// test if all necessary dirs and files are there
for _, d := range items {
if _, err := os.Stat(d); err != nil {
return nil, fmt.Errorf("%s does not exist", d)
}
}
// read version file
f, err := os.Open(filepath.Join(dir, backend.Paths.Version))
if err != nil {
return nil, fmt.Errorf("unable to read version file: %v\n", err)
}
var version uint
n, err := fmt.Fscanf(f, "%d", &version)
if err != nil {
return nil, err
}
if n != 1 {
return nil, errors.New("could not read version from file")
}
err = f.Close()
if err != nil {
return nil, err
}
// check version
if version != backend.Version {
return nil, fmt.Errorf("wrong version %d", version)
}
// read ID
f, err = os.Open(filepath.Join(dir, backend.Paths.ID))
if err != nil {
return nil, err
}
buf, err := ioutil.ReadAll(f)
if err != nil {
return nil, err
}
err = f.Close()
if err != nil {
return nil, err
}
id := strings.TrimSpace(string(buf))
if err != nil {
return nil, err
}
return &Local{p: dir, ver: version, id: id}, nil
}
// Create creates all the necessary files and directories for a new local
// backend at dir.
func Create(dir string) (*Local, error) {
versionFile := filepath.Join(dir, backend.Paths.Version)
idFile := filepath.Join(dir, backend.Paths.ID)
dirs := []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),
}
// test if files already exist
_, err := os.Lstat(versionFile)
if err == nil {
return nil, errors.New("version file already exists")
}
_, err = os.Lstat(idFile)
if err == nil {
return nil, errors.New("id file already exists")
}
// test if directories already exist
for _, d := range dirs[1:] {
if _, err := os.Stat(d); err == nil {
return nil, fmt.Errorf("dir %s already exists", d)
}
}
// create paths for data, refs and temp
for _, d := range dirs {
err := os.MkdirAll(d, backend.Modes.Dir)
if err != nil {
return nil, err
}
}
// create version file
f, err := os.Create(versionFile)
if err != nil {
return nil, err
}
_, err = fmt.Fprintf(f, "%d\n", backend.Version)
if err != nil {
return nil, err
}
err = f.Close()
if err != nil {
return nil, err
}
// create ID file
id := make([]byte, sha256.Size)
_, err = rand.Read(id)
if err != nil {
return nil, err
}
f, err = os.Create(idFile)
if err != nil {
return nil, err
}
_, err = fmt.Fprintln(f, hex.EncodeToString(id))
if err != nil {
return nil, err
}
err = f.Close()
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
}
// Return temp directory in correct directory for this backend.
func (b *Local) tempFile() (*os.File, error) {
return ioutil.TempFile(filepath.Join(b.p, backend.Paths.Temp), "temp-")
}
type localBlob struct {
f *os.File
size uint
final bool
basedir string
}
func (lb *localBlob) Write(p []byte) (int, error) {
if lb.final {
return 0, errors.New("blob already closed")
}
n, err := lb.f.Write(p)
lb.size += uint(n)
return n, err
}
func (lb *localBlob) Size() uint {
return lb.size
}
func (lb *localBlob) Finalize(t backend.Type, name string) error {
if lb.final {
return errors.New("Already finalized")
}
lb.final = true
err := lb.f.Close()
if err != nil {
return fmt.Errorf("local: file.Close: %v", err)
}
f := filename(lb.basedir, t, name)
// create directories if necessary, ignore errors
if t == backend.Data {
os.MkdirAll(filepath.Dir(f), backend.Modes.Dir)
}
// test if new path already exists
if _, err := os.Stat(f); err == nil {
return fmt.Errorf("Close(): file %v already exists", f)
}
if err := os.Rename(lb.f.Name(), f); err != nil {
return err
}
// set mode to read-only
fi, err := os.Stat(f)
if err != nil {
return err
}
return os.Chmod(f, fi.Mode()&os.FileMode(^uint32(0222)))
}
// Create creates a new Blob. The data is available only after Finalize()
// has been called on the returned Blob.
func (b *Local) Create() (backend.Blob, error) {
// TODO: make sure that tempfile is removed upon error
// create tempfile in backend
file, err := b.tempFile()
if err != nil {
return nil, err
}
blob := localBlob{
f: file,
basedir: b.p,
}
return &blob, nil
}
// Construct path for given Type and name.
func filename(base string, t backend.Type, name string) string {
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)
}
// Get returns a reader that yields the content stored under the given
// name. The reader should be closed after draining it.
func (b *Local) Get(t backend.Type, name string) (io.ReadCloser, error) {
return os.Open(filename(b.p, t, name))
}
// GetReader returns an io.ReadCloser for the Blob with the given name of
// type t at offset and length. If length is 0, the reader reads until EOF.
func (b *Local) GetReader(t backend.Type, name string, offset, length uint) (io.ReadCloser, error) {
f, err := os.Open(filename(b.p, t, name))
if err != nil {
return nil, err
}
_, err = f.Seek(int64(offset), 0)
if err != nil {
return nil, err
}
if length == 0 {
return f, nil
}
return backend.LimitReadCloser(f, int64(length)), 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 {
return os.Remove(filename(b.p, t, name))
}
// List returns a channel that yields all names of blobs of type t. A
// goroutine ist started for this. If the channel done is closed, sending
// stops.
func (b *Local) List(t backend.Type, done <-chan struct{}) <-chan string {
// TODO: use os.Open() and d.Readdirnames() instead of Glob()
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])
}
sort.Strings(matches)
go func() {
defer close(ch)
for _, m := range matches {
if m == "" {
continue
}
select {
case ch <- m:
case <-done:
return
}
}
}()
return ch
}
// Version returns the version of this local backend.
func (b *Local) Version() uint {
return b.ver
}
// ID returns the ID of this local backend.
func (b *Local) ID() string {
return b.id
}
// Delete removes the repository and all files.
func (b *Local) Delete() error { return os.RemoveAll(b.p) }
// Close does nothing
func (b *Local) Close() error { return nil }