276 lines
8.0 KiB
C++
276 lines
8.0 KiB
C++
// This file Copyright © Mnemosyne LLC.
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// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
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// or any future license endorsed by Mnemosyne LLC.
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// License text can be found in the licenses/ folder.
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#include <algorithm>
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#include <array>
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#include <cerrno>
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#include <cstddef>
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#include <optional>
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#include <string_view>
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#include <fmt/core.h>
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#include "libtransmission/transmission.h"
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#include "libtransmission/block-info.h" // tr_block_info
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#include "libtransmission/crypto-utils.h"
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#include "libtransmission/error.h"
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#include "libtransmission/file.h"
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#include "libtransmission/inout.h"
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#include "libtransmission/session.h"
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#include "libtransmission/torrent.h"
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#include "libtransmission/torrent-files.h"
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#include "libtransmission/tr-assert.h"
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#include "libtransmission/tr-macros.h" // tr_sha1_digest_t
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#include "libtransmission/tr-strbuf.h" // tr_pathbuf
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#include "libtransmission/utils.h"
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using namespace std::literals;
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namespace
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{
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bool read_entire_buf(tr_sys_file_t const fd, uint64_t file_offset, uint8_t* buf, uint64_t buflen, tr_error& error)
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{
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while (buflen > 0U)
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{
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auto n_read = uint64_t{};
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if (!tr_sys_file_read_at(fd, buf, buflen, file_offset, &n_read, &error))
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{
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return false;
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}
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buf += n_read;
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buflen -= n_read;
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file_offset += n_read;
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}
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return true;
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}
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bool write_entire_buf(tr_sys_file_t const fd, uint64_t file_offset, uint8_t const* buf, uint64_t buflen, tr_error& error)
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{
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while (buflen > 0U)
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{
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auto n_written = uint64_t{};
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if (!tr_sys_file_write_at(fd, buf, buflen, file_offset, &n_written, &error))
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{
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return false;
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}
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buf += n_written;
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buflen -= n_written;
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file_offset += n_written;
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}
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return true;
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}
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[[nodiscard]] std::optional<tr_sys_file_t> get_fd(
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tr_session& session,
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tr_open_files& open_files,
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tr_torrent const& tor,
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bool const writable,
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tr_file_index_t const file_index,
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tr_error& error)
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{
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auto const tor_id = tor.id();
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// is the file already open in the fd pool?
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if (auto const fd = open_files.get(tor_id, file_index, writable); fd)
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{
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return fd;
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}
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// does the file exist?
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auto const file_size = tor.file_size(file_index);
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auto const prealloc = writable && tor.file_is_wanted(file_index) ? session.preallocationMode() :
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tr_open_files::Preallocation::None;
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if (auto const found = tor.find_file(file_index); found)
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{
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return open_files.get(tor_id, file_index, writable, found->filename(), prealloc, file_size);
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}
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// do we want to create it?
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auto err = ENOENT;
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if (writable)
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{
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auto const base = tor.current_dir();
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auto const suffix = session.isIncompleteFileNamingEnabled() ? tr_torrent_files::PartialFileSuffix : ""sv;
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auto const filename = tr_pathbuf{ base, '/', tor.file_subpath(file_index), suffix };
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if (auto const fd = open_files.get(tor_id, file_index, writable, filename, prealloc, file_size); fd)
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{
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// make a note that we just created a file
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session.add_file_created();
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return fd;
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}
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err = errno;
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}
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error.set(
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err,
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fmt::format(
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_("Couldn't get '{path}': {error} ({error_code})"),
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fmt::arg("path", tor.file_subpath(file_index)),
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fmt::arg("error", tr_strerror(err)),
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fmt::arg("error_code", err)));
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return {};
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}
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void read_or_write_bytes(
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tr_session& session,
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tr_open_files& open_files,
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tr_torrent const& tor,
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bool const writable,
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tr_file_index_t const file_index,
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uint64_t const file_offset,
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uint8_t* const buf,
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uint64_t const buflen,
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tr_error& error)
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{
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TR_ASSERT(file_index < tor.file_count());
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auto const file_size = tor.file_size(file_index);
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TR_ASSERT(file_size == 0U || file_offset < file_size);
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TR_ASSERT(file_offset + buflen <= file_size);
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if (file_size == 0U)
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{
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return;
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}
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auto const fd = get_fd(session, open_files, tor, writable, file_index, error);
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if (!fd || error)
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{
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return;
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}
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auto fmtstr = ""sv;
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if (writable)
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{
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fmtstr = _("Couldn't save '{path}': {error} ({error_code})");
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write_entire_buf(*fd, file_offset, buf, buflen, error);
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}
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else
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{
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fmtstr = _("Couldn't read '{path}': {error} ({error_code})");
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read_entire_buf(*fd, file_offset, buf, buflen, error);
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}
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if (error)
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{
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tr_logAddErrorTor(
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&tor,
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fmt::format(
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fmt::runtime(fmtstr),
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fmt::arg("path", tor.file_subpath(file_index)),
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fmt::arg("error", error.message()),
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fmt::arg("error_code", error.code())));
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}
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}
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void read_or_write_piece(
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tr_torrent const& tor,
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bool const writable,
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tr_block_info::Location const loc,
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uint8_t* buf,
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uint64_t buflen,
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tr_error& error)
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{
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if (loc.piece >= tor.piece_count())
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{
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error.set_from_errno(EINVAL);
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return;
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}
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auto [file_index, file_offset] = tor.file_offset(loc);
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auto& session = *tor.session;
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auto& open_files = session.openFiles();
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while (buflen != 0U && !error)
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{
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auto const bytes_this_pass = std::min(buflen, tor.file_size(file_index) - file_offset);
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read_or_write_bytes(session, open_files, tor, writable, file_index, file_offset, buf, bytes_this_pass, error);
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if (buf != nullptr)
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{
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buf += bytes_this_pass;
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}
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buflen -= bytes_this_pass;
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++file_index;
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file_offset = 0U;
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}
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}
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std::optional<tr_sha1_digest_t> recalculate_hash(tr_torrent const& tor, tr_piece_index_t const piece)
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{
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TR_ASSERT(piece < tor.piece_count());
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auto sha = tr_sha1{};
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auto buffer = std::array<uint8_t, tr_block_info::BlockSize>{};
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auto& cache = tor.session->cache;
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auto const [begin_byte, end_byte] = tor.block_info().byte_span_for_piece(piece);
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auto const [begin_block, end_block] = tor.block_span_for_piece(piece);
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[[maybe_unused]] auto n_bytes_checked = size_t{};
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for (auto block = begin_block; block < end_block; ++block)
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{
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auto const block_loc = tor.block_loc(block);
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auto const block_len = tor.block_size(block);
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if (auto const success = cache->read_block(tor, block_loc, block_len, std::data(buffer)) == 0; !success)
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{
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return {};
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}
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auto begin = std::data(buffer);
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auto end = begin + block_len;
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// handle edge case where blocks aren't on piece boundaries:
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if (block == begin_block) // `block` may begin before `piece` does
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{
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begin += (begin_byte - block_loc.byte);
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}
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if (block + 1U == end_block) // `block` may end after `piece` does
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{
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end -= (block_loc.byte + block_len - end_byte);
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}
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sha.add(begin, end - begin);
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n_bytes_checked += (end - begin);
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}
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TR_ASSERT(tor.piece_size(piece) == n_bytes_checked);
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return sha.finish();
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}
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} // namespace
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int tr_ioRead(tr_torrent const& tor, tr_block_info::Location const& loc, size_t const len, uint8_t* const setme)
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{
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auto error = tr_error{};
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read_or_write_piece(tor, false /*writable*/, loc, setme, len, error);
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return error.code();
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}
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int tr_ioWrite(tr_torrent& tor, tr_block_info::Location const& loc, size_t const len, uint8_t const* const writeme)
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{
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auto error = tr_error{};
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read_or_write_piece(tor, true /*writable*/, loc, const_cast<uint8_t*>(writeme), len, error);
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// if IO failed, set torrent's error if not already set
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if (error && tor.error().error_type() != TR_STAT_LOCAL_ERROR)
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{
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tor.error().set_local_error(error.message());
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tr_torrentStop(&tor);
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}
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return error.code();
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}
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bool tr_ioTestPiece(tr_torrent const& tor, tr_piece_index_t const piece)
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{
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auto const hash = recalculate_hash(tor, piece);
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return hash && *hash == tor.piece_hash(piece);
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}
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