mirror of
https://github.com/restic/restic.git
synced 2024-12-25 17:27:25 +00:00
f69a39cff5
This allows identifying a repository regardless if it's accessed over SFTP or locally. Introduced for having a per-repository cache.
445 lines
8.6 KiB
Go
445 lines
8.6 KiB
Go
package backend
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import (
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"crypto/rand"
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"crypto/sha256"
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"errors"
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"path/filepath"
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"strings"
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)
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const (
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dirMode = 0700
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dataPath = "data"
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snapshotPath = "snapshots"
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treePath = "trees"
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lockPath = "locks"
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keyPath = "keys"
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tempPath = "tmp"
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versionFileName = "version"
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idFileName = "id"
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)
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var ErrWrongData = errors.New("wrong data returned by backend, checksum does not match")
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type Local struct {
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p string
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ver uint
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id ID
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}
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// OpenLocal opens the local backend at dir.
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func OpenLocal(dir string) (*Local, error) {
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items := []string{
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dir,
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filepath.Join(dir, dataPath),
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filepath.Join(dir, snapshotPath),
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filepath.Join(dir, treePath),
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filepath.Join(dir, lockPath),
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filepath.Join(dir, keyPath),
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filepath.Join(dir, tempPath),
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}
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// test if all necessary dirs and files are there
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for _, d := range items {
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if _, err := os.Stat(d); err != nil {
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return nil, fmt.Errorf("%s does not exist", d)
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}
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}
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// read version file
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f, err := os.Open(filepath.Join(dir, versionFileName))
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if err != nil {
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return nil, fmt.Errorf("unable to read version file: %v\n", err)
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}
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var version uint
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n, err := fmt.Fscanf(f, "%d", &version)
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if err != nil {
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return nil, err
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}
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if n != 1 {
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return nil, errors.New("could not read version from file")
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}
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err = f.Close()
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if err != nil {
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return nil, err
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}
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// check version
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if version != BackendVersion {
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return nil, fmt.Errorf("wrong version %d", version)
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}
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// read ID
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f, err = os.Open(filepath.Join(dir, idFileName))
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if err != nil {
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return nil, err
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}
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buf, err := ioutil.ReadAll(f)
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if err != nil {
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return nil, err
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}
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err = f.Close()
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if err != nil {
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return nil, err
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}
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id, err := ParseID(strings.TrimSpace(string(buf)))
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if err != nil {
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return nil, err
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}
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return &Local{p: dir, ver: version, id: id}, nil
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}
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// CreateLocal creates all the necessary files and directories for a new local
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// backend at dir.
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func CreateLocal(dir string) (*Local, error) {
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versionFile := filepath.Join(dir, versionFileName)
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idFile := filepath.Join(dir, idFileName)
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dirs := []string{
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dir,
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filepath.Join(dir, dataPath),
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filepath.Join(dir, snapshotPath),
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filepath.Join(dir, treePath),
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filepath.Join(dir, lockPath),
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filepath.Join(dir, keyPath),
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filepath.Join(dir, tempPath),
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}
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// test if files already exist
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_, err := os.Lstat(versionFile)
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if err == nil {
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return nil, errors.New("version file already exists")
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}
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_, err = os.Lstat(idFile)
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if err == nil {
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return nil, errors.New("id file already exists")
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}
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// test if directories already exist
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for _, d := range dirs[1:] {
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if _, err := os.Stat(d); err == nil {
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return nil, fmt.Errorf("dir %s already exists", d)
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}
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}
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// create paths for data, refs and temp
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for _, d := range dirs {
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err := os.MkdirAll(d, dirMode)
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if err != nil {
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return nil, err
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}
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}
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// create version file
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f, err := os.Create(versionFile)
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if err != nil {
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return nil, err
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}
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_, err = fmt.Fprintf(f, "%d\n", BackendVersion)
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if err != nil {
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return nil, err
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}
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err = f.Close()
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if err != nil {
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return nil, err
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}
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// create ID file
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id := make([]byte, sha256.Size)
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_, err = rand.Read(id)
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if err != nil {
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return nil, err
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}
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f, err = os.Create(idFile)
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if err != nil {
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return nil, err
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}
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_, err = fmt.Fprintf(f, "%s\n", ID(id).String())
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if err != nil {
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return nil, err
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}
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err = f.Close()
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if err != nil {
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return nil, err
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}
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// open backend
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return OpenLocal(dir)
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}
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// Location returns this backend's location (the directory name).
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func (b *Local) Location() string {
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return b.p
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}
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// Return temp directory in correct directory for this backend.
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func (b *Local) tempFile() (*os.File, error) {
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return ioutil.TempFile(filepath.Join(b.p, tempPath), "temp-")
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}
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// Rename temp file to final name according to type and ID.
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func (b *Local) renameFile(file *os.File, t Type, id ID) error {
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newname := b.filename(t, id)
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oldname := file.Name()
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if t == Data || t == Tree {
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// create directories if necessary, ignore errors
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os.MkdirAll(filepath.Dir(newname), dirMode)
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}
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return os.Rename(oldname, newname)
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}
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// Construct directory for given Type.
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func (b *Local) dirname(t Type, id ID) string {
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var n string
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switch t {
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case Data:
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n = dataPath
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if id != nil {
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n = filepath.Join(dataPath, fmt.Sprintf("%02x", id[0]))
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}
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case Snapshot:
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n = snapshotPath
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case Tree:
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n = treePath
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if id != nil {
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n = filepath.Join(treePath, fmt.Sprintf("%02x", id[0]))
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}
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case Lock:
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n = lockPath
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case Key:
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n = keyPath
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}
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return filepath.Join(b.p, n)
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}
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type localBlob struct {
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f *os.File
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hw *HashingWriter
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backend *Local
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tpe Type
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id ID
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size uint
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closed bool
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}
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func (lb *localBlob) Close() error {
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if lb.closed {
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return errors.New("Close() called on closed file")
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}
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lb.closed = true
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err := lb.f.Close()
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if err != nil {
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return fmt.Errorf("local: file.Close: %v", err)
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}
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// get ID
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lb.id = ID(lb.hw.Sum(nil))
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// check for duplicate ID
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res, err := lb.backend.Test(lb.tpe, lb.id)
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if err != nil {
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return fmt.Errorf("testing presence of ID %v failed: %v", lb.id, err)
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}
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if res {
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return ErrAlreadyPresent
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}
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// rename file
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err = lb.backend.renameFile(lb.f, lb.tpe, lb.id)
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if err != nil {
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return err
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}
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return nil
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}
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func (lb *localBlob) Write(p []byte) (int, error) {
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n, err := lb.hw.Write(p)
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lb.size += uint(n)
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return n, err
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}
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func (lb *localBlob) ID() (ID, error) {
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if lb.id == nil {
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return nil, errors.New("blob is not closed, ID unavailable")
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}
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return lb.id, nil
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}
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func (lb *localBlob) Size() uint {
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return lb.size
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}
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// Create creates a new blob of type t. Blob implements io.WriteCloser. Once
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// Close() has been called, ID() can be used to retrieve the ID. If the blob is
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// already present, Close() returns ErrAlreadyPresent.
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func (b *Local) Create(t Type) (Blob, error) {
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// TODO: make sure that tempfile is removed upon error
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// create tempfile in backend
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file, err := b.tempFile()
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if err != nil {
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return nil, err
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}
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hw := NewHashingWriter(file, newHash())
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blob := localBlob{
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hw: hw,
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f: file,
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backend: b,
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tpe: t,
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}
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return &blob, nil
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}
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// Construct path for given Type and ID.
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func (b *Local) filename(t Type, id ID) string {
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return filepath.Join(b.dirname(t, id), id.String())
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}
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// Get returns the content stored under the given ID. If the data doesn't match
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// the requested ID, ErrWrongData is returned.
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func (b *Local) Get(t Type, id ID) ([]byte, error) {
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if id == nil {
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return nil, errors.New("unable to load nil ID")
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}
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// try to open file
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file, err := os.Open(b.filename(t, id))
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defer file.Close()
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if err != nil {
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return nil, err
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}
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// read all
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buf, err := ioutil.ReadAll(file)
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if err != nil {
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return nil, err
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}
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// check id
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if !Hash(buf).Equal(id) {
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return nil, ErrWrongData
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}
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return buf, nil
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}
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// GetReader returns a reader that yields the content stored under the given
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// ID. The content is not verified. The reader should be closed after draining
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// it.
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func (b *Local) GetReader(t Type, id ID) (io.ReadCloser, error) {
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if id == nil {
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return nil, errors.New("unable to load nil ID")
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}
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// try to open file
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file, err := os.Open(b.filename(t, id))
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if err != nil {
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return nil, err
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}
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return file, nil
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}
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// Test returns true if a blob of the given type and ID exists in the backend.
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func (b *Local) Test(t Type, id ID) (bool, error) {
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// try to open file
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file, err := os.Open(b.filename(t, id))
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defer func() {
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file.Close()
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}()
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if err != nil {
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if os.IsNotExist(err) {
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return false, nil
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}
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return false, err
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}
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return true, nil
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}
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// Remove removes the content stored at ID.
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func (b *Local) Remove(t Type, id ID) error {
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return os.Remove(b.filename(t, id))
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}
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// List lists all objects of a given type.
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func (b *Local) List(t Type) (IDs, error) {
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// TODO: use os.Open() and d.Readdirnames() instead of Glob()
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var pattern string
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if t == Data || t == Tree {
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pattern = filepath.Join(b.dirname(t, nil), "*", "*")
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} else {
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pattern = filepath.Join(b.dirname(t, nil), "*")
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}
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matches, err := filepath.Glob(pattern)
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if err != nil {
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return nil, err
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}
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ids := make(IDs, 0, len(matches))
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for _, m := range matches {
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base := filepath.Base(m)
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if base == "" {
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continue
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}
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id, err := ParseID(base)
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if err != nil {
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continue
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}
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ids = append(ids, id)
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}
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return ids, nil
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}
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// Version returns the version of this local backend.
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func (b *Local) Version() uint {
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return b.ver
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}
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// ID returns the ID of this local backend.
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func (b *Local) ID() ID {
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return b.id
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}
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// Close closes the backend
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func (b *Local) Close() error {
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return nil
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}
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// Delete removes the repository and all files.
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func (b *Local) Delete() error {
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return os.RemoveAll(b.p)
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}
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