135 lines
4.5 KiB
C++
135 lines
4.5 KiB
C++
/*
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Copyright (c) 2014-2018, Arvid Norberg
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the distribution.
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* Neither the name of the author nor the names of its
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "libtorrent/resolve_links.hpp"
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#include "libtorrent/torrent_info.hpp"
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#include "libtorrent/aux_/numeric_cast.hpp"
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namespace libtorrent {
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#ifndef TORRENT_DISABLE_MUTABLE_TORRENTS
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resolve_links::resolve_links(std::shared_ptr<torrent_info> ti)
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: m_torrent_file(ti)
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{
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TORRENT_ASSERT(ti);
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int piece_size = ti->piece_length();
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file_storage const& fs = ti->files();
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m_file_sizes.reserve(aux::numeric_cast<std::size_t>(fs.num_files()));
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for (auto const i : fs.file_range())
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{
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// don't match pad-files, and don't match files that aren't aligned to
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// pieces. Files are matched by comparing piece hashes, so pieces must
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// be aligned and the same size
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if (fs.pad_file_at(i)) continue;
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if ((fs.file_offset(i) % piece_size) != 0) continue;
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m_file_sizes.insert(std::make_pair(fs.file_size(i), i));
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}
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m_links.resize(m_torrent_file->num_files());
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}
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void resolve_links::match(std::shared_ptr<const torrent_info> const& ti
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, std::string const& save_path)
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{
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if (!ti) return;
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// only torrents with the same piece size
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if (ti->piece_length() != m_torrent_file->piece_length()) return;
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int piece_size = ti->piece_length();
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file_storage const& fs = ti->files();
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m_file_sizes.reserve(aux::numeric_cast<std::size_t>(fs.num_files()));
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for (auto const i : fs.file_range())
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{
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// for every file in the other torrent, see if we have one that match
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// it in m_torrent_file
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// if the file base is not aligned to pieces, we're not going to match
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// it anyway (we only compare piece hashes)
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if ((fs.file_offset(i) % piece_size) != 0) continue;
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if (fs.pad_file_at(i)) continue;
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std::int64_t const file_size = fs.file_size(i);
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auto const range = m_file_sizes.equal_range(file_size);
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for (auto iter = range.first; iter != range.second; ++iter)
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{
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TORRENT_ASSERT(iter->second >= file_index_t(0));
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TORRENT_ASSERT(iter->second < m_torrent_file->files().end_file());
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// if we already have found a duplicate for this file, no need
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// to keep looking
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if (m_links[iter->second].ti) continue;
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// files are aligned and have the same size, now start comparing
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// piece hashes, to see if the files are identical
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// the pieces of the incoming file
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piece_index_t their_piece = fs.map_file(i, 0, 0).piece;
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// the pieces of "this" file (from m_torrent_file)
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piece_index_t our_piece = m_torrent_file->files().map_file(
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iter->second, 0, 0).piece;
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int num_pieces = int((file_size + piece_size - 1) / piece_size);
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bool match = true;
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for (int p = 0; p < num_pieces; ++p, ++their_piece, ++our_piece)
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{
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if (m_torrent_file->hash_for_piece(our_piece)
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!= ti->hash_for_piece(their_piece))
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{
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match = false;
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break;
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}
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}
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if (!match) continue;
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m_links[iter->second].ti = ti;
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m_links[iter->second].save_path = save_path;
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m_links[iter->second].file_idx = i;
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// since we have a duplicate for this file, we may as well remove
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// it from the file-size map, so we won't find it again.
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m_file_sizes.erase(iter);
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break;
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}
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}
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}
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#endif // TORRENT_DISABLE_MUTABLE_TORRENTS
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} // namespace libtorrent
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