Fix issue #96

In the native file-based storage, mark pieces incomplete if the necessary file data is missing, or there's a read error on a piece.

storage/file.go

@@ -26,6 +26,7 @@ func NewFile(baseDir string) Client {
 func (fs *fileStorage) OpenTorrent(info *metainfo.InfoEx) (Torrent, error) {
 	return &fileTorrentStorage{
 		fs,
+		&info.Info,
 		pieceCompletionForDir(fs.baseDir),
 	}, nil
 }
@@ -33,15 +34,13 @@ func (fs *fileStorage) OpenTorrent(info *metainfo.InfoEx) (Torrent, error) {
 // File-based torrent storage, not yet bound to a Torrent.
 type fileTorrentStorage struct {
 	fs         *fileStorage
+	info       *metainfo.Info
 	completion pieceCompletion
 }
 
 func (fts *fileTorrentStorage) Piece(p metainfo.Piece) Piece {
 	// Create a view onto the file-based torrent storage.
-	_io := &fileStorageTorrent{
-		p.Info,
-		fts.fs.baseDir,
-	}
+	_io := fileStorageTorrent{fts}
 	// Return the appropriate segments of this.
 	return &fileStoragePiece{
 		fts,
@@ -56,31 +55,14 @@ func (fs *fileTorrentStorage) Close() error {
 	return nil
 }
 
-type fileStoragePiece struct {
-	*fileTorrentStorage
-	p metainfo.Piece
-	io.WriterAt
-	io.ReaderAt
-}
-
-func (fs *fileStoragePiece) GetIsComplete() bool {
-	return fs.completion.Get(fs.p)
-}
-
-func (fs *fileStoragePiece) MarkComplete() error {
-	fs.completion.Set(fs.p, true)
-	return nil
-}
-
 // Exposes file-based storage of a torrent, as one big ReadWriterAt.
 type fileStorageTorrent struct {
-	info    *metainfo.InfoEx
-	baseDir string
+	fts *fileTorrentStorage
 }
 
 // Returns EOF on short or missing file.
 func (fst *fileStorageTorrent) readFileAt(fi metainfo.FileInfo, b []byte, off int64) (n int, err error) {
-	f, err := os.Open(fst.fileInfoName(fi))
+	f, err := os.Open(fst.fts.fileInfoName(fi))
 	if os.IsNotExist(err) {
 		// File missing is treated the same as a short file.
 		err = io.EOF
@@ -108,8 +90,8 @@ func (fst *fileStorageTorrent) readFileAt(fi metainfo.FileInfo, b []byte, off in
 }
 
 // Only returns EOF at the end of the torrent. Premature EOF is ErrUnexpectedEOF.
-func (fst *fileStorageTorrent) ReadAt(b []byte, off int64) (n int, err error) {
-	for _, fi := range fst.info.UpvertedFiles() {
+func (fst fileStorageTorrent) ReadAt(b []byte, off int64) (n int, err error) {
+	for _, fi := range fst.fts.info.UpvertedFiles() {
 		for off < fi.Length {
 			n1, err1 := fst.readFileAt(fi, b, off)
 			n += n1
@@ -136,8 +118,8 @@ func (fst *fileStorageTorrent) ReadAt(b []byte, off int64) (n int, err error) {
 	return
 }
 
-func (fst *fileStorageTorrent) WriteAt(p []byte, off int64) (n int, err error) {
-	for _, fi := range fst.info.UpvertedFiles() {
+func (fst fileStorageTorrent) WriteAt(p []byte, off int64) (n int, err error) {
+	for _, fi := range fst.fts.info.UpvertedFiles() {
 		if off >= fi.Length {
 			off -= fi.Length
 			continue
@@ -146,7 +128,7 @@ func (fst *fileStorageTorrent) WriteAt(p []byte, off int64) (n int, err error) {
 		if int64(n1) > fi.Length-off {
 			n1 = int(fi.Length - off)
 		}
-		name := fst.fileInfoName(fi)
+		name := fst.fts.fileInfoName(fi)
 		os.MkdirAll(filepath.Dir(name), 0770)
 		var f *os.File
 		f, err = os.OpenFile(name, os.O_WRONLY|os.O_CREATE, 0660)
@@ -168,6 +150,6 @@ func (fst *fileStorageTorrent) WriteAt(p []byte, off int64) (n int, err error) {
 	return
 }
 
-func (fst *fileStorageTorrent) fileInfoName(fi metainfo.FileInfo) string {
-	return filepath.Join(append([]string{fst.baseDir, fst.info.Name}, fi.Path...)...)
+func (fts *fileTorrentStorage) fileInfoName(fi metainfo.FileInfo) string {
+	return filepath.Join(append([]string{fts.fs.baseDir, fts.info.Name}, fi.Path...)...)
 }

storage/file_misc.go

@@ -0,0 +1,29 @@
+package storage
+
+import "github.com/anacrolix/torrent/metainfo"
+
+func extentCompleteRequiredLengths(info *metainfo.Info, off, n int64) (ret []metainfo.FileInfo) {
+	if n == 0 {
+		return
+	}
+	for _, fi := range info.UpvertedFiles() {
+		if off >= fi.Length {
+			off -= fi.Length
+			continue
+		}
+		n1 := n
+		if off+n1 > fi.Length {
+			n1 = fi.Length - off
+		}
+		ret = append(ret, metainfo.FileInfo{
+			Path:   fi.Path,
+			Length: off + n1,
+		})
+		n -= n1
+		if n == 0 {
+			return
+		}
+		off = 0
+	}
+	panic("extent exceeds torrent bounds")
+}

storage/file_misc_test.go

@@ -0,0 +1,40 @@
+package storage
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/anacrolix/torrent/metainfo"
+)
+
+func TestExtentCompleteRequiredLengths(t *testing.T) {
+	info := &metainfo.InfoEx{
+		Info: metainfo.Info{
+			Files: []metainfo.FileInfo{
+				{Path: []string{"a"}, Length: 2},
+				{Path: []string{"b"}, Length: 3},
+			},
+		},
+	}
+	assert.Empty(t, extentCompleteRequiredLengths(&info.Info, 0, 0))
+	assert.EqualValues(t, []metainfo.FileInfo{
+		{Path: []string{"a"}, Length: 1},
+	}, extentCompleteRequiredLengths(&info.Info, 0, 1))
+	assert.EqualValues(t, []metainfo.FileInfo{
+		{Path: []string{"a"}, Length: 2},
+	}, extentCompleteRequiredLengths(&info.Info, 0, 2))
+	assert.EqualValues(t, []metainfo.FileInfo{
+		{Path: []string{"a"}, Length: 2},
+		{Path: []string{"b"}, Length: 1},
+	}, extentCompleteRequiredLengths(&info.Info, 0, 3))
+	assert.EqualValues(t, []metainfo.FileInfo{
+		{Path: []string{"b"}, Length: 2},
+	}, extentCompleteRequiredLengths(&info.Info, 2, 2))
+	assert.EqualValues(t, []metainfo.FileInfo{
+		{Path: []string{"b"}, Length: 3},
+	}, extentCompleteRequiredLengths(&info.Info, 4, 1))
+	assert.Len(t, extentCompleteRequiredLengths(&info.Info, 5, 0), 0)
+	assert.Panics(t, func() { extentCompleteRequiredLengths(&info.Info, 6, 1) })
+
+}

storage/file_storage_piece.go

@@ -0,0 +1,55 @@
+package storage
+
+import (
+	"io"
+	"os"
+
+	"github.com/anacrolix/torrent/metainfo"
+)
+
+type fileStoragePiece struct {
+	*fileTorrentStorage
+	p metainfo.Piece
+	io.WriterAt
+	r io.ReaderAt
+}
+
+func (fs *fileStoragePiece) GetIsComplete() (ret bool) {
+	ret = fs.completion.Get(fs.p)
+	if !ret {
+		return
+	}
+	// If it's allegedly complete, check that its constituent files have the
+	// necessary length.
+	for _, fi := range extentCompleteRequiredLengths(&fs.p.Info.Info, fs.p.Offset(), fs.p.Length()) {
+		s, err := os.Stat(fs.fileInfoName(fi))
+		if err != nil || s.Size() < fi.Length {
+			ret = false
+			break
+		}
+	}
+	if ret {
+		return
+	}
+	// The completion was wrong, fix it.
+	fs.completion.Set(fs.p, false)
+	return
+}
+
+func (fs *fileStoragePiece) MarkComplete() error {
+	fs.completion.Set(fs.p, true)
+	return nil
+}
+
+func (fsp *fileStoragePiece) ReadAt(b []byte, off int64) (n int, err error) {
+	n, err = fsp.r.ReadAt(b, off)
+	if n != 0 {
+		err = nil
+		return
+	}
+	if off < 0 || off >= fsp.p.Length() {
+		return
+	}
+	fsp.completion.Set(fsp.p, false)
+	return
+}

storage/issue96_test.go

@@ -0,0 +1,37 @@
+package storage
+
+import (
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/anacrolix/torrent/metainfo"
+)
+
+func testMarkedCompleteMissingOnRead(t *testing.T, csf func(string) Client) {
+	td, err := ioutil.TempDir("", "")
+	require.NoError(t, err)
+	defer os.RemoveAll(td)
+	cs := csf(td)
+	info := &metainfo.InfoEx{
+		Info: metainfo.Info{
+			PieceLength: 1,
+			Files:       []metainfo.FileInfo{{Path: []string{"a"}, Length: 1}},
+		},
+	}
+	ts, err := cs.OpenTorrent(info)
+	require.NoError(t, err)
+	p := ts.Piece(info.Piece(0))
+	require.NoError(t, p.MarkComplete())
+	require.False(t, p.GetIsComplete())
+	n, err := p.ReadAt(make([]byte, 1), 0)
+	require.Error(t, err)
+	require.EqualValues(t, 0, n)
+	require.False(t, p.GetIsComplete())
+}
+
+func TestMarkedCompleteMissingOnReadFile(t *testing.T) {
+	testMarkedCompleteMissingOnRead(t, NewFile)
+}