From: Matt Joiner <anacrolix@gmail.com>
Date: Thu, 23 Jan 2020 02:56:39 +0000 (+1100)
Subject: Use CopyN to ensure early io.EOF isn't ignored when hashing pieces
X-Git-Tag: v1.12.0~1
X-Git-Url: http://www.git.stargrave.org/?a=commitdiff_plain;h=913f6df80d4eac2c18980e4b0f10d746427e2ecf;p=btrtrc.git

Use CopyN to ensure early io.EOF isn't ignored when hashing pieces
---

diff --git a/torrent.go b/torrent.go
index f7f518f8..0f4a6810 100644
--- a/torrent.go
+++ b/torrent.go
@@ -769,7 +769,8 @@ func (t *Torrent) hashPiece(piece pieceIndex) (ret metainfo.Hash, copyErr error)
 	p.waitNoPendingWrites()
 	ip := t.info.Piece(int(piece))
 	pl := ip.Length()
-	_, copyErr = io.Copy(hash, io.NewSectionReader(t.pieces[piece].Storage(), 0, pl))
+	_, copyErr = io.CopyN( // Return no error iff pl bytes are copied.
+		hash, io.NewSectionReader(t.pieces[piece].Storage(), 0, pl), pl)
 	missinggo.CopyExact(&ret, hash.Sum(nil))
 	return
 }