move Backend interface to backend package

internal/restic/backend.go

@@ -1,112 +0,0 @@
-package restic
-
-import (
-	"context"
-	"hash"
-	"io"
-)
-
-// Backend is used to store and access data.
-//
-// Backend operations that return an error will be retried when a Backend is
-// wrapped in a RetryBackend. To prevent that from happening, the operations
-// should return a github.com/cenkalti/backoff/v4.PermanentError. Errors from
-// the context package need not be wrapped, as context cancellation is checked
-// separately by the retrying logic.
-type Backend interface {
-	// Location returns a string that describes the type and location of the
-	// repository.
-	Location() string
-
-	// Connections returns the maxmimum number of concurrent backend operations.
-	Connections() uint
-
-	// Hasher may return a hash function for calculating a content hash for the backend
-	Hasher() hash.Hash
-
-	// HasAtomicReplace returns whether Save() can atomically replace files
-	HasAtomicReplace() bool
-
-	// Remove removes a File described  by h.
-	Remove(ctx context.Context, h Handle) error
-
-	// Close the backend
-	Close() error
-
-	// Save stores the data from rd under the given handle.
-	Save(ctx context.Context, h Handle, rd RewindReader) error
-
-	// Load runs fn with a reader that yields the contents of the file at h at the
-	// given offset. If length is larger than zero, only a portion of the file
-	// is read.
-	//
-	// The function fn may be called multiple times during the same Load invocation
-	// and therefore must be idempotent.
-	//
-	// Implementations are encouraged to use util.DefaultLoad
-	Load(ctx context.Context, h Handle, length int, offset int64, fn func(rd io.Reader) error) error
-
-	// Stat returns information about the File identified by h.
-	Stat(ctx context.Context, h Handle) (FileInfo, error)
-
-	// List runs fn for each file in the backend which has the type t. When an
-	// error occurs (or fn returns an error), List stops and returns it.
-	//
-	// The function fn is called exactly once for each file during successful
-	// execution and at most once in case of an error.
-	//
-	// The function fn is called in the same Goroutine that List() is called
-	// from.
-	List(ctx context.Context, t FileType, fn func(FileInfo) error) error
-
-	// IsNotExist returns true if the error was caused by a non-existing file
-	// in the backend.
-	//
-	// The argument may be a wrapped error. The implementation is responsible
-	// for unwrapping it.
-	IsNotExist(err error) bool
-
-	// Delete removes all data in the backend.
-	Delete(ctx context.Context) error
-}
-
-type BackendUnwrapper interface {
-	// Unwrap returns the underlying backend or nil if there is none.
-	Unwrap() Backend
-}
-
-func AsBackend[B Backend](b Backend) B {
-	for b != nil {
-		if be, ok := b.(B); ok {
-			return be
-		}
-
-		if be, ok := b.(BackendUnwrapper); ok {
-			b = be.Unwrap()
-		} else {
-			// not the backend we're looking for
-			break
-		}
-	}
-	var be B
-	return be
-}
-
-type FreezeBackend interface {
-	Backend
-	// Freeze blocks all backend operations except those on lock files
-	Freeze()
-	// Unfreeze allows all backend operations to continue
-	Unfreeze()
-}
-
-// FileInfo is contains information about a file in the backend.
-type FileInfo struct {
-	Size int64
-	Name string
-}
-
-// ApplyEnvironmenter fills in a backend configuration from the environment
-type ApplyEnvironmenter interface {
-	ApplyEnvironment(prefix string)
-}

internal/restic/backend_find.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 
+	"github.com/restic/restic/internal/backend"
 	"github.com/restic/restic/internal/debug"
 )
 
@@ -26,13 +27,13 @@ func (e *NoIDByPrefixError) Error() string {
 // Find loads the list of all files of type t and searches for names which
 // start with prefix. If none is found, nil and ErrNoIDPrefixFound is returned.
 // If more than one is found, nil and ErrMultipleIDMatches is returned.
-func Find(ctx context.Context, be Lister, t FileType, prefix string) (ID, error) {
+func Find(ctx context.Context, be backend.Lister, t FileType, prefix string) (ID, error) {
 	match := ID{}
 
 	ctx, cancel := context.WithCancel(ctx)
 	defer cancel()
 
-	err := be.List(ctx, t, func(fi FileInfo) error {
+	err := be.List(ctx, t, func(fi backend.FileInfo) error {
 		// ignore filename which are not an id
 		id, err := ParseID(fi.Name)
 		if err != nil {

internal/restic/backend_find_test.go

@@ -4,13 +4,15 @@ import (
 	"context"
 	"strings"
 	"testing"
+
+	"github.com/restic/restic/internal/backend"
 )
 
 type mockBackend struct {
-	list func(context.Context, FileType, func(FileInfo) error) error
+	list func(context.Context, FileType, func(backend.FileInfo) error) error
 }
 
-func (m mockBackend) List(ctx context.Context, t FileType, fn func(FileInfo) error) error {
+func (m mockBackend) List(ctx context.Context, t FileType, fn func(backend.FileInfo) error) error {
 	return m.list(ctx, t, fn)
 }
 
@@ -29,9 +31,9 @@ func TestFind(t *testing.T) {
 	list := samples
 
 	m := mockBackend{}
-	m.list = func(ctx context.Context, t FileType, fn func(FileInfo) error) error {
+	m.list = func(ctx context.Context, t FileType, fn func(backend.FileInfo) error) error {
 		for _, id := range list {
-			err := fn(FileInfo{Name: id.String()})
+			err := fn(backend.FileInfo{Name: id.String()})
 			if err != nil {
 				return err
 			}

internal/restic/backend_test.go

@@ -1,38 +0,0 @@
-package restic_test
-
-import (
-	"testing"
-
-	"github.com/restic/restic/internal/restic"
-	"github.com/restic/restic/internal/test"
-)
-
-type testBackend struct {
-	restic.Backend
-}
-
-func (t *testBackend) Unwrap() restic.Backend {
-	return nil
-}
-
-type otherTestBackend struct {
-	restic.Backend
-}
-
-func (t *otherTestBackend) Unwrap() restic.Backend {
-	return t.Backend
-}
-
-func TestAsBackend(t *testing.T) {
-	other := otherTestBackend{}
-	test.Assert(t, restic.AsBackend[*testBackend](other) == nil, "otherTestBackend is not a testBackend backend")
-
-	testBe := &testBackend{}
-	test.Assert(t, restic.AsBackend[*testBackend](testBe) == testBe, "testBackend was not returned")
-
-	wrapper := &otherTestBackend{Backend: testBe}
-	test.Assert(t, restic.AsBackend[*testBackend](wrapper) == testBe, "failed to unwrap testBackend backend")
-
-	wrapper.Backend = other
-	test.Assert(t, restic.AsBackend[*testBackend](wrapper) == nil, "a wrapped otherTestBackend is not a testBackend")
-}

internal/restic/file.go

@@ -1,79 +0,0 @@
-package restic
-
-import (
-	"fmt"
-
-	"github.com/restic/restic/internal/errors"
-)
-
-// FileType is the type of a file in the backend.
-type FileType uint8
-
-// These are the different data types a backend can store.
-const (
-	PackFile FileType = 1 + iota
-	KeyFile
-	LockFile
-	SnapshotFile
-	IndexFile
-	ConfigFile
-)
-
-func (t FileType) String() string {
-	s := "invalid"
-	switch t {
-	case PackFile:
-		// Spelled "data" instead of "pack" for historical reasons.
-		s = "data"
-	case KeyFile:
-		s = "key"
-	case LockFile:
-		s = "lock"
-	case SnapshotFile:
-		s = "snapshot"
-	case IndexFile:
-		s = "index"
-	case ConfigFile:
-		s = "config"
-	}
-	return s
-}
-
-// Handle is used to store and access data in a backend.
-type Handle struct {
-	Type       FileType
-	IsMetadata bool
-	Name       string
-}
-
-func (h Handle) String() string {
-	name := h.Name
-	if len(name) > 10 {
-		name = name[:10]
-	}
-	return fmt.Sprintf("<%s/%s>", h.Type, name)
-}
-
-// Valid returns an error if h is not valid.
-func (h Handle) Valid() error {
-	switch h.Type {
-	case PackFile:
-	case KeyFile:
-	case LockFile:
-	case SnapshotFile:
-	case IndexFile:
-	case ConfigFile:
-	default:
-		return errors.Errorf("invalid Type %d", h.Type)
-	}
-
-	if h.Type == ConfigFile {
-		return nil
-	}
-
-	if h.Name == "" {
-		return errors.New("invalid Name")
-	}
-
-	return nil
-}

internal/restic/file_test.go

@@ -1,36 +0,0 @@
-package restic
-
-import (
-	"testing"
-
-	rtest "github.com/restic/restic/internal/test"
-)
-
-func TestHandleString(t *testing.T) {
-	rtest.Equals(t, "<data/foobar>", Handle{Type: PackFile, Name: "foobar"}.String())
-	rtest.Equals(t, "<lock/1>", Handle{Type: LockFile, Name: "1"}.String())
-}
-
-func TestHandleValid(t *testing.T) {
-	var handleTests = []struct {
-		h     Handle
-		valid bool
-	}{
-		{Handle{Name: "foo"}, false},
-		{Handle{Type: 0}, false},
-		{Handle{Type: ConfigFile, Name: ""}, true},
-		{Handle{Type: PackFile, Name: ""}, false},
-		{Handle{Type: LockFile, Name: "010203040506"}, true},
-	}
-
-	for i, test := range handleTests {
-		err := test.h.Valid()
-		if err != nil && test.valid {
-			t.Errorf("test %v failed: error returned for valid handle: %v", i, err)
-		}
-
-		if !test.valid && err == nil {
-			t.Errorf("test %v failed: expected error for invalid handle not found", i)
-		}
-	}
-}

internal/restic/lock.go

@@ -12,6 +12,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/restic/restic/internal/backend"
 	"github.com/restic/restic/internal/errors"
 
 	"github.com/restic/restic/internal/debug"
@@ -213,7 +214,7 @@ func (l *Lock) Unlock() error {
 		return nil
 	}
 
-	return l.repo.Backend().Remove(context.TODO(), Handle{Type: LockFile, Name: l.lockID.String()})
+	return l.repo.Backend().Remove(context.TODO(), backend.Handle{Type: LockFile, Name: l.lockID.String()})
 }
 
 var StaleLockTimeout = 30 * time.Minute
@@ -273,7 +274,7 @@ func (l *Lock) Refresh(ctx context.Context) error {
 	oldLockID := l.lockID
 	l.lockID = &id
 
-	return l.repo.Backend().Remove(context.TODO(), Handle{Type: LockFile, Name: oldLockID.String()})
+	return l.repo.Backend().Remove(context.TODO(), backend.Handle{Type: LockFile, Name: oldLockID.String()})
 }
 
 // RefreshStaleLock is an extended variant of Refresh that can also refresh stale lock files.
@@ -302,13 +303,13 @@ func (l *Lock) RefreshStaleLock(ctx context.Context) error {
 	exists, err = l.checkExistence(ctx)
 	if err != nil {
 		// cleanup replacement lock
-		_ = l.repo.Backend().Remove(context.TODO(), Handle{Type: LockFile, Name: id.String()})
+		_ = l.repo.Backend().Remove(context.TODO(), backend.Handle{Type: LockFile, Name: id.String()})
 		return err
 	}
 
 	if !exists {
 		// cleanup replacement lock
-		_ = l.repo.Backend().Remove(context.TODO(), Handle{Type: LockFile, Name: id.String()})
+		_ = l.repo.Backend().Remove(context.TODO(), backend.Handle{Type: LockFile, Name: id.String()})
 		return ErrRemovedLock
 	}
 
@@ -319,7 +320,7 @@ func (l *Lock) RefreshStaleLock(ctx context.Context) error {
 	oldLockID := l.lockID
 	l.lockID = &id
 
-	return l.repo.Backend().Remove(context.TODO(), Handle{Type: LockFile, Name: oldLockID.String()})
+	return l.repo.Backend().Remove(context.TODO(), backend.Handle{Type: LockFile, Name: oldLockID.String()})
 }
 
 func (l *Lock) checkExistence(ctx context.Context) (bool, error) {
@@ -328,7 +329,7 @@ func (l *Lock) checkExistence(ctx context.Context) (bool, error) {
 
 	exists := false
 
-	err := l.repo.Backend().List(ctx, LockFile, func(fi FileInfo) error {
+	err := l.repo.Backend().List(ctx, LockFile, func(fi backend.FileInfo) error {
 		if fi.Name == l.lockID.String() {
 			exists = true
 		}
@@ -387,7 +388,7 @@ func RemoveStaleLocks(ctx context.Context, repo Repository) (uint, error) {
 		}
 
 		if lock.Stale() {
-			err = repo.Backend().Remove(ctx, Handle{Type: LockFile, Name: id.String()})
+			err = repo.Backend().Remove(ctx, backend.Handle{Type: LockFile, Name: id.String()})
 			if err == nil {
 				processed++
 			}
@@ -403,7 +404,7 @@ func RemoveStaleLocks(ctx context.Context, repo Repository) (uint, error) {
 func RemoveAllLocks(ctx context.Context, repo Repository) (uint, error) {
 	var processed uint32
 	err := ParallelList(ctx, repo.Backend(), LockFile, repo.Connections(), func(ctx context.Context, id ID, size int64) error {
-		err := repo.Backend().Remove(ctx, Handle{Type: LockFile, Name: id.String()})
+		err := repo.Backend().Remove(ctx, backend.Handle{Type: LockFile, Name: id.String()})
 		if err == nil {
 			atomic.AddUint32(&processed, 1)
 		}

internal/restic/lock_test.go

@@ -8,6 +8,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/restic/restic/internal/backend"
 	"github.com/restic/restic/internal/backend/mem"
 	"github.com/restic/restic/internal/repository"
 	"github.com/restic/restic/internal/restic"
@@ -53,10 +54,10 @@ func TestMultipleLock(t *testing.T) {
 }
 
 type failLockLoadingBackend struct {
-	restic.Backend
+	backend.Backend
 }
 
-func (be *failLockLoadingBackend) Load(ctx context.Context, h restic.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
+func (be *failLockLoadingBackend) Load(ctx context.Context, h backend.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
 	if h.Type == restic.LockFile {
 		return fmt.Errorf("error loading lock")
 	}
@@ -130,7 +131,7 @@ func createFakeLock(repo restic.Repository, t time.Time, pid int) (restic.ID, er
 }
 
 func removeLock(repo restic.Repository, id restic.ID) error {
-	h := restic.Handle{Type: restic.LockFile, Name: id.String()}
+	h := backend.Handle{Type: restic.LockFile, Name: id.String()}
 	return repo.Backend().Remove(context.TODO(), h)
 }
 
@@ -191,7 +192,7 @@ func TestLockStale(t *testing.T) {
 }
 
 func lockExists(repo restic.Repository, t testing.TB, id restic.ID) bool {
-	h := restic.Handle{Type: restic.LockFile, Name: id.String()}
+	h := backend.Handle{Type: restic.LockFile, Name: id.String()}
 	_, err := repo.Backend().Stat(context.TODO(), h)
 	if err != nil && !repo.Backend().IsNotExist(err) {
 		t.Fatal(err)
@@ -317,7 +318,7 @@ func TestLockRefreshStaleMissing(t *testing.T) {
 	lockID := checkSingleLock(t, repo)
 
 	// refresh must fail if lock was removed
-	rtest.OK(t, repo.Backend().Remove(context.TODO(), restic.Handle{Type: restic.LockFile, Name: lockID.String()}))
+	rtest.OK(t, repo.Backend().Remove(context.TODO(), backend.Handle{Type: restic.LockFile, Name: lockID.String()}))
 	time.Sleep(time.Millisecond)
 	err = lock.RefreshStaleLock(context.TODO())
 	rtest.Assert(t, err == restic.ErrRemovedLock, "unexpected error, expected %v, got %v", restic.ErrRemovedLock, err)

internal/restic/parallel.go

@@ -3,11 +3,12 @@ package restic
 import (
 	"context"
 
+	"github.com/restic/restic/internal/backend"
 	"github.com/restic/restic/internal/debug"
 	"golang.org/x/sync/errgroup"
 )
 
-func ParallelList(ctx context.Context, r Lister, t FileType, parallelism uint, fn func(context.Context, ID, int64) error) error {
+func ParallelList(ctx context.Context, r backend.Lister, t FileType, parallelism uint, fn func(context.Context, ID, int64) error) error {
 
 	type FileIDInfo struct {
 		ID
@@ -22,7 +23,7 @@ func ParallelList(ctx context.Context, r Lister, t FileType, parallelism uint, f
 	// send list of index files through ch, which is closed afterwards
 	wg.Go(func() error {
 		defer close(ch)
-		return r.List(ctx, t, func(fi FileInfo) error {
+		return r.List(ctx, t, func(fi backend.FileInfo) error {
 			id, err := ParseID(fi.Name)
 			if err != nil {
 				debug.Log("unable to parse %v as an ID", fi.Name)

internal/restic/repository.go

@@ -3,6 +3,7 @@ package restic
 import (
 	"context"
 
+	"github.com/restic/restic/internal/backend"
 	"github.com/restic/restic/internal/crypto"
 	"github.com/restic/restic/internal/errors"
 	"github.com/restic/restic/internal/ui/progress"
@@ -17,7 +18,7 @@ var ErrInvalidData = errors.New("invalid data returned")
 type Repository interface {
 
 	// Backend returns the backend used by the repository
-	Backend() Backend
+	Backend() backend.Backend
 	// Connections returns the maximum number of concurrent backend operations
 	Connections() uint
 
@@ -56,10 +57,17 @@ type Repository interface {
 	SaveUnpacked(context.Context, FileType, []byte) (ID, error)
 }
 
-// Lister allows listing files in a backend.
-type Lister interface {
-	List(context.Context, FileType, func(FileInfo) error) error
-}
+type FileType = backend.FileType
+
+// These are the different data types a backend can store.
+const (
+	PackFile     FileType = backend.PackFile
+	KeyFile      FileType = backend.KeyFile
+	LockFile     FileType = backend.LockFile
+	SnapshotFile FileType = backend.SnapshotFile
+	IndexFile    FileType = backend.IndexFile
+	ConfigFile   FileType = backend.ConfigFile
+)
 
 // LoaderUnpacked allows loading a blob not stored in a pack file
 type LoaderUnpacked interface {

internal/restic/rewind_reader.go

@@ -1,117 +0,0 @@
-package restic
-
-import (
-	"bytes"
-	"hash"
-	"io"
-
-	"github.com/restic/restic/internal/errors"
-)
-
-// RewindReader allows resetting the Reader to the beginning of the data.
-type RewindReader interface {
-	io.Reader
-
-	// Rewind rewinds the reader so the same data can be read again from the
-	// start.
-	Rewind() error
-
-	// Length returns the number of bytes that can be read from the Reader
-	// after calling Rewind.
-	Length() int64
-
-	// Hash return a hash of the data if requested by the backed.
-	Hash() []byte
-}
-
-// ByteReader implements a RewindReader for a byte slice.
-type ByteReader struct {
-	*bytes.Reader
-	Len  int64
-	hash []byte
-}
-
-// Rewind restarts the reader from the beginning of the data.
-func (b *ByteReader) Rewind() error {
-	_, err := b.Reader.Seek(0, io.SeekStart)
-	return err
-}
-
-// Length returns the number of bytes read from the reader after Rewind is
-// called.
-func (b *ByteReader) Length() int64 {
-	return b.Len
-}
-
-// Hash return a hash of the data if requested by the backed.
-func (b *ByteReader) Hash() []byte {
-	return b.hash
-}
-
-// statically ensure that *ByteReader implements RewindReader.
-var _ RewindReader = &ByteReader{}
-
-// NewByteReader prepares a ByteReader that can then be used to read buf.
-func NewByteReader(buf []byte, hasher hash.Hash) *ByteReader {
-	var hash []byte
-	if hasher != nil {
-		// must never fail according to interface
-		_, err := hasher.Write(buf)
-		if err != nil {
-			panic(err)
-		}
-		hash = hasher.Sum(nil)
-	}
-	return &ByteReader{
-		Reader: bytes.NewReader(buf),
-		Len:    int64(len(buf)),
-		hash:   hash,
-	}
-}
-
-// statically ensure that *FileReader implements RewindReader.
-var _ RewindReader = &FileReader{}
-
-// FileReader implements a RewindReader for an open file.
-type FileReader struct {
-	io.ReadSeeker
-	Len  int64
-	hash []byte
-}
-
-// Rewind seeks to the beginning of the file.
-func (f *FileReader) Rewind() error {
-	_, err := f.ReadSeeker.Seek(0, io.SeekStart)
-	return errors.Wrap(err, "Seek")
-}
-
-// Length returns the length of the file.
-func (f *FileReader) Length() int64 {
-	return f.Len
-}
-
-// Hash return a hash of the data if requested by the backed.
-func (f *FileReader) Hash() []byte {
-	return f.hash
-}
-
-// NewFileReader wraps f in a *FileReader.
-func NewFileReader(f io.ReadSeeker, hash []byte) (*FileReader, error) {
-	pos, err := f.Seek(0, io.SeekEnd)
-	if err != nil {
-		return nil, errors.Wrap(err, "Seek")
-	}
-
-	fr := &FileReader{
-		ReadSeeker: f,
-		Len:        pos,
-		hash:       hash,
-	}
-
-	err = fr.Rewind()
-	if err != nil {
-		return nil, err
-	}
-
-	return fr, nil
-}

internal/restic/rewind_reader_test.go

@@ -1,175 +0,0 @@
-package restic
-
-import (
-	"bytes"
-	"crypto/md5"
-	"hash"
-	"io"
-	"math/rand"
-	"os"
-	"path/filepath"
-	"testing"
-	"time"
-
-	"github.com/restic/restic/internal/test"
-)
-
-func TestByteReader(t *testing.T) {
-	buf := []byte("foobar")
-	for _, hasher := range []hash.Hash{nil, md5.New()} {
-		fn := func() RewindReader {
-			return NewByteReader(buf, hasher)
-		}
-		testRewindReader(t, fn, buf)
-	}
-}
-
-func TestFileReader(t *testing.T) {
-	buf := []byte("foobar")
-
-	d := test.TempDir(t)
-	filename := filepath.Join(d, "file-reader-test")
-	err := os.WriteFile(filename, buf, 0600)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	f, err := os.Open(filename)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	defer func() {
-		err := f.Close()
-		if err != nil {
-			t.Fatal(err)
-		}
-	}()
-
-	for _, hasher := range []hash.Hash{nil, md5.New()} {
-		fn := func() RewindReader {
-			var hash []byte
-			if hasher != nil {
-				// must never fail according to interface
-				_, err := hasher.Write(buf)
-				if err != nil {
-					panic(err)
-				}
-				hash = hasher.Sum(nil)
-			}
-			rd, err := NewFileReader(f, hash)
-			if err != nil {
-				t.Fatal(err)
-			}
-			return rd
-		}
-
-		testRewindReader(t, fn, buf)
-	}
-}
-
-func testRewindReader(t *testing.T, fn func() RewindReader, data []byte) {
-	seed := time.Now().UnixNano()
-	t.Logf("seed is %d", seed)
-	rnd := rand.New(rand.NewSource(seed))
-
-	type ReaderTestFunc func(t testing.TB, r RewindReader, data []byte)
-	var tests = []ReaderTestFunc{
-		func(t testing.TB, rd RewindReader, data []byte) {
-			if rd.Length() != int64(len(data)) {
-				t.Fatalf("wrong length returned, want %d, got %d", int64(len(data)), rd.Length())
-			}
-
-			buf := make([]byte, len(data))
-			_, err := io.ReadFull(rd, buf)
-			if err != nil {
-				t.Fatal(err)
-			}
-
-			if !bytes.Equal(buf, data) {
-				t.Fatalf("wrong data returned")
-			}
-
-			if rd.Length() != int64(len(data)) {
-				t.Fatalf("wrong length returned, want %d, got %d", int64(len(data)), rd.Length())
-			}
-
-			err = rd.Rewind()
-			if err != nil {
-				t.Fatal(err)
-			}
-
-			if rd.Length() != int64(len(data)) {
-				t.Fatalf("wrong length returned, want %d, got %d", int64(len(data)), rd.Length())
-			}
-
-			buf2 := make([]byte, int64(len(data)))
-			_, err = io.ReadFull(rd, buf2)
-			if err != nil {
-				t.Fatal(err)
-			}
-
-			if !bytes.Equal(buf2, data) {
-				t.Fatalf("wrong data returned")
-			}
-
-			if rd.Length() != int64(len(data)) {
-				t.Fatalf("wrong length returned, want %d, got %d", int64(len(data)), rd.Length())
-			}
-
-			if rd.Hash() != nil {
-				hasher := md5.New()
-				// must never fail according to interface
-				_, _ = hasher.Write(buf2)
-				if !bytes.Equal(rd.Hash(), hasher.Sum(nil)) {
-					t.Fatal("hash does not match data")
-				}
-			}
-		},
-		func(t testing.TB, rd RewindReader, data []byte) {
-			// read first bytes
-			buf := make([]byte, rnd.Intn(len(data)))
-			_, err := io.ReadFull(rd, buf)
-			if err != nil {
-				t.Fatal(err)
-			}
-
-			if !bytes.Equal(buf, data[:len(buf)]) {
-				t.Fatalf("wrong data returned")
-			}
-
-			err = rd.Rewind()
-			if err != nil {
-				t.Fatal(err)
-			}
-
-			buf2 := make([]byte, rnd.Intn(len(data)))
-			_, err = io.ReadFull(rd, buf2)
-			if err != nil {
-				t.Fatal(err)
-			}
-
-			if !bytes.Equal(buf2, data[:len(buf2)]) {
-				t.Fatalf("wrong data returned")
-			}
-
-			// read remainder
-			buf3 := make([]byte, len(data)-len(buf2))
-			_, err = io.ReadFull(rd, buf3)
-			if err != nil {
-				t.Fatal(err)
-			}
-
-			if !bytes.Equal(buf3, data[len(buf2):]) {
-				t.Fatalf("wrong data returned")
-			}
-		},
-	}
-
-	for _, test := range tests {
-		t.Run("", func(t *testing.T) {
-			rd := fn()
-			test(t, rd, data)
-		})
-	}
-}

internal/restic/snapshot.go

@@ -8,6 +8,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/restic/restic/internal/backend"
 	"github.com/restic/restic/internal/debug"
 )
 
@@ -79,7 +80,7 @@ func SaveSnapshot(ctx context.Context, repo SaverUnpacked, sn *Snapshot) (ID, er
 // If the called function returns an error, this function is cancelled and
 // also returns this error.
 // If a snapshot ID is in excludeIDs, it will be ignored.
-func ForAllSnapshots(ctx context.Context, be Lister, loader LoaderUnpacked, excludeIDs IDSet, fn func(ID, *Snapshot, error) error) error {
+func ForAllSnapshots(ctx context.Context, be backend.Lister, loader LoaderUnpacked, excludeIDs IDSet, fn func(ID, *Snapshot, error) error) error {
 	var m sync.Mutex
 
 	// For most snapshots decoding is nearly for free, thus just assume were only limited by IO

internal/restic/snapshot_find.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/restic/restic/internal/backend"
 	"github.com/restic/restic/internal/errors"
 )
 
@@ -34,7 +35,7 @@ func (f *SnapshotFilter) matches(sn *Snapshot) bool {
 
 // findLatest finds the latest snapshot with optional target/directory,
 // tags, hostname, and timestamp filters.
-func (f *SnapshotFilter) findLatest(ctx context.Context, be Lister, loader LoaderUnpacked) (*Snapshot, error) {
+func (f *SnapshotFilter) findLatest(ctx context.Context, be backend.Lister, loader LoaderUnpacked) (*Snapshot, error) {
 
 	var err error
 	absTargets := make([]string, 0, len(f.Paths))
@@ -90,7 +91,7 @@ func splitSnapshotID(s string) (id, subfolder string) {
 
 // FindSnapshot takes a string and tries to find a snapshot whose ID matches
 // the string as closely as possible.
-func FindSnapshot(ctx context.Context, be Lister, loader LoaderUnpacked, s string) (*Snapshot, string, error) {
+func FindSnapshot(ctx context.Context, be backend.Lister, loader LoaderUnpacked, s string) (*Snapshot, string, error) {
 	s, subfolder := splitSnapshotID(s)
 
 	// no need to list snapshots if `s` is already a full id
@@ -108,7 +109,7 @@ func FindSnapshot(ctx context.Context, be Lister, loader LoaderUnpacked, s strin
 
 // FindLatest returns either the latest of a filtered list of all snapshots
 // or a snapshot specified by `snapshotID`.
-func (f *SnapshotFilter) FindLatest(ctx context.Context, be Lister, loader LoaderUnpacked, snapshotID string) (*Snapshot, string, error) {
+func (f *SnapshotFilter) FindLatest(ctx context.Context, be backend.Lister, loader LoaderUnpacked, snapshotID string) (*Snapshot, string, error) {
 	id, subfolder := splitSnapshotID(snapshotID)
 	if id == "latest" {
 		sn, err := f.findLatest(ctx, be, loader)
@@ -126,7 +127,7 @@ type SnapshotFindCb func(string, *Snapshot, error) error
 var ErrInvalidSnapshotSyntax = errors.New("<snapshot>:<subfolder> syntax not allowed")
 
 // FindAll yields Snapshots, either given explicitly by `snapshotIDs` or filtered from the list of all snapshots.
-func (f *SnapshotFilter) FindAll(ctx context.Context, be Lister, loader LoaderUnpacked, snapshotIDs []string, fn SnapshotFindCb) error {
+func (f *SnapshotFilter) FindAll(ctx context.Context, be backend.Lister, loader LoaderUnpacked, snapshotIDs []string, fn SnapshotFindCb) error {
 	if len(snapshotIDs) != 0 {
 		var err error
 		usedFilter := false