package storage import ( "fmt" "io" "os" "path/filepath" "github.com/anacrolix/missinggo" "github.com/anacrolix/torrent/common" "github.com/anacrolix/torrent/segments" "github.com/anacrolix/torrent/metainfo" ) // File-based storage for torrents, that isn't yet bound to a particular // torrent. type fileClientImpl struct { baseDir string pathMaker func(baseDir string, info *metainfo.Info, infoHash metainfo.Hash) string pc PieceCompletion } // The Default path maker just returns the current path func defaultPathMaker(baseDir string, info *metainfo.Info, infoHash metainfo.Hash) string { return baseDir } func infoHashPathMaker(baseDir string, info *metainfo.Info, infoHash metainfo.Hash) string { return filepath.Join(baseDir, infoHash.HexString()) } // All Torrent data stored in this baseDir func NewFile(baseDir string) ClientImplCloser { return NewFileWithCompletion(baseDir, pieceCompletionForDir(baseDir)) } func NewFileWithCompletion(baseDir string, completion PieceCompletion) *fileClientImpl { return NewFileWithCustomPathMakerAndCompletion(baseDir, nil, completion) } // File storage with data partitioned by infohash. func NewFileByInfoHash(baseDir string) ClientImplCloser { return NewFileWithCustomPathMaker(baseDir, infoHashPathMaker) } // Allows passing a function to determine the path for storing torrent data. The function is // responsible for sanitizing the info if it uses some part of it (for example sanitizing // info.Name). func NewFileWithCustomPathMaker(baseDir string, pathMaker func(baseDir string, info *metainfo.Info, infoHash metainfo.Hash) string) ClientImplCloser { return NewFileWithCustomPathMakerAndCompletion(baseDir, pathMaker, pieceCompletionForDir(baseDir)) } // Allows passing custom PieceCompletion func NewFileWithCustomPathMakerAndCompletion(baseDir string, pathMaker func(baseDir string, info *metainfo.Info, infoHash metainfo.Hash) string, completion PieceCompletion) *fileClientImpl { if pathMaker == nil { pathMaker = defaultPathMaker } return &fileClientImpl{ baseDir: baseDir, pathMaker: pathMaker, pc: completion, } } func (me *fileClientImpl) Close() error { return me.pc.Close() } func (fs *fileClientImpl) OpenTorrent(info *metainfo.Info, infoHash metainfo.Hash) (_ TorrentImpl, err error) { dir := fs.pathMaker(fs.baseDir, info, infoHash) upvertedFiles := info.UpvertedFiles() files := make([]file, 0, len(upvertedFiles)) for i, fileInfo := range upvertedFiles { var s string s, err = ToSafeFilePath(append([]string{info.Name}, fileInfo.Path...)...) if err != nil { err = fmt.Errorf("file %v has unsafe path %q: %w", i, fileInfo.Path, err) return } f := file{ path: filepath.Join(dir, s), length: fileInfo.Length, } if f.length == 0 { err = CreateNativeZeroLengthFile(f.path) if err != nil { err = fmt.Errorf("creating zero length file: %w", err) return } } files = append(files, f) } t := &fileTorrentImpl{ files, segments.NewIndex(common.LengthIterFromUpvertedFiles(upvertedFiles)), infoHash, fs.pc, } return TorrentImpl{ Piece: t.Piece, Close: t.Close, }, nil } type file struct { // The safe, OS-local file path. path string length int64 } type fileTorrentImpl struct { files []file segmentLocater segments.Index infoHash metainfo.Hash completion PieceCompletion } func (fts *fileTorrentImpl) Piece(p metainfo.Piece) PieceImpl { // Create a view onto the file-based torrent storage. _io := fileTorrentImplIO{fts} // Return the appropriate segments of this. return &filePieceImpl{ fts, p, missinggo.NewSectionWriter(_io, p.Offset(), p.Length()), io.NewSectionReader(_io, p.Offset(), p.Length()), } } func (fs *fileTorrentImpl) Close() error { return nil } // A helper to create zero-length files which won't appear for file-orientated storage since no // writes will ever occur to them (no torrent data is associated with a zero-length file). The // caller should make sure the file name provided is safe/sanitized. func CreateNativeZeroLengthFile(name string) error { os.MkdirAll(filepath.Dir(name), 0777) var f io.Closer f, err := os.Create(name) if err != nil { return err } return f.Close() } // Exposes file-based storage of a torrent, as one big ReadWriterAt. type fileTorrentImplIO struct { fts *fileTorrentImpl } // Returns EOF on short or missing file. func (fst *fileTorrentImplIO) readFileAt(file file, b []byte, off int64) (n int, err error) { f, err := os.Open(file.path) if os.IsNotExist(err) { // File missing is treated the same as a short file. err = io.EOF return } if err != nil { return } defer f.Close() // Limit the read to within the expected bounds of this file. if int64(len(b)) > file.length-off { b = b[:file.length-off] } for off < file.length && len(b) != 0 { n1, err1 := f.ReadAt(b, off) b = b[n1:] n += n1 off += int64(n1) if n1 == 0 { err = err1 break } } return } // Only returns EOF at the end of the torrent. Premature EOF is ErrUnexpectedEOF. func (fst fileTorrentImplIO) ReadAt(b []byte, off int64) (n int, err error) { fst.fts.segmentLocater.Locate(segments.Extent{off, int64(len(b))}, func(i int, e segments.Extent) bool { n1, err1 := fst.readFileAt(fst.fts.files[i], b[:e.Length], e.Start) n += n1 b = b[n1:] err = err1 return err == nil // && int64(n1) == e.Length }) if len(b) != 0 && err == nil { err = io.EOF } return } func (fst fileTorrentImplIO) WriteAt(p []byte, off int64) (n int, err error) { //log.Printf("write at %v: %v bytes", off, len(p)) fst.fts.segmentLocater.Locate(segments.Extent{off, int64(len(p))}, func(i int, e segments.Extent) bool { name := fst.fts.files[i].path os.MkdirAll(filepath.Dir(name), 0777) var f *os.File f, err = os.OpenFile(name, os.O_WRONLY|os.O_CREATE, 0666) if err != nil { return false } var n1 int n1, err = f.WriteAt(p[:e.Length], e.Start) //log.Printf("%v %v wrote %v: %v", i, e, n1, err) closeErr := f.Close() n += n1 p = p[n1:] if err == nil { err = closeErr } if err == nil && int64(n1) != e.Length { err = io.ErrShortWrite } return err == nil }) return }