103 lines
2.2 KiB
Go
103 lines
2.2 KiB
Go
package storage
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import (
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"io"
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"os"
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"github.com/anacrolix/missinggo/v2"
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"github.com/anacrolix/torrent/metainfo"
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)
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type Client struct {
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ci ClientImpl
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}
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func NewClient(cl ClientImpl) *Client {
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return &Client{cl}
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}
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func (cl Client) OpenTorrent(info *metainfo.Info, infoHash metainfo.Hash) (*Torrent, error) {
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t, err := cl.ci.OpenTorrent(info, infoHash)
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if err != nil {
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return nil, err
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}
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return &Torrent{t}, nil
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}
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type Torrent struct {
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TorrentImpl
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}
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func (t Torrent) Piece(p metainfo.Piece) Piece {
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return Piece{t.TorrentImpl.Piece(p), p}
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}
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type Piece struct {
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PieceImpl
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mip metainfo.Piece
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}
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var _ io.WriterTo = Piece{}
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// Why do we have this wrapper? Well PieceImpl doesn't implement io.Reader, so we can't let io.Copy
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// and friends check for io.WriterTo and fallback for us since they expect an io.Reader.
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func (p Piece) WriteTo(w io.Writer) (int64, error) {
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if i, ok := p.PieceImpl.(io.WriterTo); ok {
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return i.WriteTo(w)
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}
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n := p.mip.Length()
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r := io.NewSectionReader(p, 0, n)
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return io.CopyN(w, r, n)
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}
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func (p Piece) WriteAt(b []byte, off int64) (n int, err error) {
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// Callers should not be writing to completed pieces, but it's too
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// expensive to be checking this on every single write using uncached
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// completions.
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// c := p.Completion()
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// if c.Ok && c.Complete {
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// err = errors.New("piece already completed")
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// return
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// }
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if off+int64(len(b)) > p.mip.Length() {
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panic("write overflows piece")
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}
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b = missinggo.LimitLen(b, p.mip.Length()-off)
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return p.PieceImpl.WriteAt(b, off)
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}
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func (p Piece) ReadAt(b []byte, off int64) (n int, err error) {
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if off < 0 {
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err = os.ErrInvalid
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return
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}
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if off >= p.mip.Length() {
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err = io.EOF
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return
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}
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b = missinggo.LimitLen(b, p.mip.Length()-off)
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if len(b) == 0 {
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return
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}
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n, err = p.PieceImpl.ReadAt(b, off)
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if n > len(b) {
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panic(n)
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}
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if n == 0 && err == nil {
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panic("io.Copy will get stuck")
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}
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off += int64(n)
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// Doing this here may be inaccurate. There's legitimate reasons we may fail to read while the
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// data is still there, such as too many open files. There should probably be a specific error
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// to return if the data has been lost.
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if off < p.mip.Length() {
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if err == io.EOF {
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p.MarkNotComplete()
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}
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}
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return
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}
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