fixup recent change to piece_size_for_req(). it's a bit more complicated; v1 (and hybrid) torrents still need the full piece size to compute the correct piece hash

Author: arvidn

include/libtorrent/torrent_handle.hpp

@@ -290,9 +290,7 @@ namespace aux {
 		// won't return until the libtorrent thread has copied the data into its
 		// disk write buffer. ``data`` is expected to point to a buffer of as
 		// many bytes as the size of the specified piece.
-		// For v2 torrents, pieces at the end of files may not be full sized.
-		// For backwards compatibility, it's OK to pass a full sized piece as
-		// well.
+		// For v2-only torrents, pieces at the end of files may not be full sized.
 		//
 		// The data in the buffer is copied and passed on to the disk IO thread
 		// to be written at some later point in time.

include/libtorrent/torrent_info.hpp

@@ -506,13 +506,15 @@ TORRENT_VERSION_NAMESPACE_3
 		int piece_size(piece_index_t index) const { return m_files.piece_size(index); }
 
 		// returns the piece size appropriate for computing request lengths.
-		// for v2 torrents, pieces at the end of files may be shorter than
-		// the main piece size. This is the case for hybrid torrents as well.
+		// for v2-only torrents, pieces at the end of files may be shorter than
+		// the main piece size. For v1 and hybrid torrents, piece sizes must be
+		// full (except for the last piece) in order to correctly compute the
+		// piece hash.
 		int piece_size_for_req(piece_index_t index) const
 		{
-			return v2()
-				? m_files.piece_size2(index)
-				: m_files.piece_size(index);
+			return v1()
+				? m_files.piece_size(index)
+				: m_files.piece_size2(index);
 		}
 
 		// ``hash_for_piece()`` takes a piece-index and returns the 20-bytes

src/torrent.cpp

@@ -1371,18 +1371,19 @@ aux::vector<download_priority_t, piece_index_t> file_to_piece_prio(
 	{
 		TORRENT_ASSERT(is_single_thread());
 
+		TORRENT_ASSERT_PRECOND(piece < torrent_file().end_piece());
+		TORRENT_ASSERT_PRECOND(piece >= piece_index_t{0});
+		TORRENT_ASSERT_PRECOND(data.size() == std::size_t(m_torrent_file->piece_size_for_req(piece)));
+
 		// make sure the piece index is correct
 		if (piece >= torrent_file().end_piece())
 			return;
 
 		// make sure the piece size is correct
-		// we check against the v1 piece size as well, for backwards compatibility
-		if (data.size() == std::size_t(m_torrent_file->piece_size_for_req(piece))
-			|| data.size() == std::size_t(m_torrent_file->piece_size(piece)))
-		{
-			data.resize(std::size_t(m_torrent_file->piece_size_for_req(piece)));
-			add_piece(piece, data.data(), flags);
-		}
+		if (data.size() != std::size_t(m_torrent_file->piece_size_for_req(piece)))
+			return;
+
+		add_piece(piece, data.data(), flags);
 	}
 
 	// TODO: 3 there's some duplication between this function and

src/web_peer_connection.cpp

@@ -465,8 +465,7 @@ void web_peer_connection::write_request(peer_request const& r)
 			if (info.orig_files().pad_file_at(f.file_index))
 			{
 				++num_pad_files;
-				if (!info.v2())
-					m_file_requests.push_back(file_req);
+				m_file_requests.push_back(file_req);
 				continue;
 			}