transmission/libtransmission/makemeta.cc

378 lines
10 KiB
C++

// This file Copyright © 2010-2023 Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.
#include <algorithm>
#include <cerrno> // for ENOENT
#include <cmath>
#include <ctime> // time()
#include <iterator>
#include <optional>
#include <set>
#include <string>
#include <string_view>
#include <utility>
#include <vector>
#include <fmt/core.h>
#include "libtransmission/transmission.h"
#include "libtransmission/block-info.h" // tr_block_info
#include "libtransmission/crypto-utils.h"
#include "libtransmission/error.h"
#include "libtransmission/file.h"
#include "libtransmission/log.h"
#include "libtransmission/makemeta.h"
#include "libtransmission/quark.h" // TR_KEY_length, TR_KEY_a...
#include "libtransmission/session.h" // TR_NAME
#include "libtransmission/torrent-files.h"
#include "libtransmission/tr-assert.h"
#include "libtransmission/tr-strbuf.h" // tr_pathbuf
#include "libtransmission/utils.h" // for _()
#include "libtransmission/variant.h"
#include "libtransmission/version.h"
using namespace std::literals;
namespace
{
namespace find_files_helpers
{
struct TorrentFile
{
TorrentFile(std::string_view subpath, size_t size)
: subpath_{ subpath }
, lowercase_{ tr_strlower(subpath) }
, size_{ size }
{
}
[[nodiscard]] auto operator<(TorrentFile const& that) const noexcept
{
return lowercase_ < that.lowercase_;
}
std::string subpath_;
std::string lowercase_;
uint64_t size_ = 0;
};
void walkTree(std::string_view const top, std::string_view const subpath, std::set<TorrentFile>& files)
{
TR_ASSERT(!std::empty(top));
TR_ASSERT(!std::empty(subpath));
if (std::empty(top) || std::empty(subpath))
{
return;
}
auto path = tr_pathbuf{ top, '/', subpath };
tr_sys_path_native_separators(std::data(path));
tr_error* error = nullptr;
auto const info = tr_sys_path_get_info(path, 0, &error);
if (error != nullptr)
{
tr_logAddWarn(fmt::format(
_("Skipping '{path}': {error} ({error_code})"),
fmt::arg("path", path),
fmt::arg("error", error->message),
fmt::arg("error_code", error->code)));
tr_error_free(error);
}
if (!info)
{
return;
}
switch (info->type)
{
case TR_SYS_PATH_IS_DIRECTORY:
for (auto const& name : tr_sys_dir_get_files(path))
{
if (!std::empty(subpath))
{
walkTree(top, tr_pathbuf{ subpath, '/', name }, files);
}
else
{
walkTree(top, name, files);
}
}
break;
case TR_SYS_PATH_IS_FILE:
files.emplace(subpath, info->size);
break;
default:
break;
}
}
} // namespace find_files_helpers
tr_torrent_files findFiles(std::string_view const top, std::string_view const subpath)
{
using namespace find_files_helpers;
auto tmp = std::set<TorrentFile>{};
walkTree(top, subpath, tmp);
auto files = tr_torrent_files{};
for (auto const& file : tmp)
{
files.add(file.subpath_, file.size_);
}
return files;
}
} // namespace
tr_metainfo_builder::tr_metainfo_builder(std::string_view single_file_or_parent_directory)
: top_{ single_file_or_parent_directory }
{
files_ = findFiles(tr_sys_path_dirname(top_), tr_sys_path_basename(top_));
block_info_ = tr_block_info{ files_.totalSize(), default_piece_size(files_.totalSize()) };
}
bool tr_metainfo_builder::set_piece_size(uint32_t piece_size) noexcept
{
if (!is_legal_piece_size(piece_size))
{
return false;
}
block_info_ = tr_block_info{ files_.totalSize(), piece_size };
return true;
}
bool tr_metainfo_builder::blocking_make_checksums(tr_error** error)
{
checksum_piece_ = 0;
cancel_ = false;
if (total_size() == 0U)
{
tr_error_set_from_errno(error, ENOENT);
return false;
}
auto hashes = std::vector<std::byte>(std::size(tr_sha1_digest_t{}) * piece_count());
auto* walk = std::data(hashes);
auto sha = tr_sha1::create();
auto file_index = tr_file_index_t{ 0U };
auto piece_index = tr_piece_index_t{ 0U };
auto total_remain = total_size();
auto off = uint64_t{ 0U };
auto buf = std::vector<char>(piece_size());
auto const parent = tr_sys_path_dirname(top_);
auto fd = tr_sys_file_open(
tr_pathbuf{ parent, '/', path(file_index) },
TR_SYS_FILE_READ | TR_SYS_FILE_SEQUENTIAL,
0,
error);
if (fd == TR_BAD_SYS_FILE)
{
return false;
}
while (!cancel_ && (total_remain > 0U))
{
checksum_piece_ = piece_index;
TR_ASSERT(piece_index < piece_count());
auto const piece_size = block_info_.piece_size(piece_index);
buf.resize(piece_size);
auto* bufptr = std::data(buf);
auto left_in_piece = piece_size;
while (left_in_piece > 0U)
{
auto const n_this_pass = std::min(file_size(file_index) - off, uint64_t{ left_in_piece });
auto n_read = uint64_t{};
(void)tr_sys_file_read(fd, bufptr, n_this_pass, &n_read, error);
bufptr += n_read;
off += n_read;
left_in_piece -= n_read;
if (off == file_size(file_index))
{
off = 0;
tr_sys_file_close(fd);
fd = TR_BAD_SYS_FILE;
if (++file_index < file_count())
{
fd = tr_sys_file_open(
tr_pathbuf{ parent, '/', path(file_index) },
TR_SYS_FILE_READ | TR_SYS_FILE_SEQUENTIAL,
0,
error);
if (fd == TR_BAD_SYS_FILE)
{
return false;
}
}
}
}
TR_ASSERT(bufptr - std::data(buf) == (int)piece_size);
TR_ASSERT(left_in_piece == 0);
sha->add(std::data(buf), std::size(buf));
auto const digest = sha->finish();
walk = std::copy(std::begin(digest), std::end(digest), walk);
sha->clear();
total_remain -= piece_size;
++piece_index;
}
TR_ASSERT(cancel_ || size_t(walk - std::data(hashes)) == std::size(hashes));
TR_ASSERT(cancel_ || total_remain == 0U);
if (fd != TR_BAD_SYS_FILE)
{
tr_sys_file_close(fd);
}
if (cancel_)
{
tr_error_set_from_errno(error, ECANCELED);
return false;
}
piece_hashes_ = std::move(hashes);
return true;
}
std::string tr_metainfo_builder::benc(tr_error** error) const
{
TR_ASSERT_MSG(!std::empty(piece_hashes_), "did you forget to call makeChecksums() first?");
auto const anonymize = this->anonymize();
auto const& comment = this->comment();
auto const& source = this->source();
auto const& webseeds = this->webseeds();
if (total_size() == 0)
{
tr_error_set_from_errno(error, ENOENT);
return {};
}
auto top = tr_variant::Map{ 8U };
// add the announce URLs
announce_list().add_to_map(top);
// add the webseeds
if (auto const n_webseeds = std::size(webseeds); n_webseeds > 0U)
{
auto webseeds_vec = tr_variant::Vector{};
webseeds_vec.reserve(n_webseeds);
std::copy_n(std::cbegin(webseeds), n_webseeds, std::back_inserter(webseeds_vec));
top.try_emplace(TR_KEY_url_list, std::move(webseeds_vec));
}
// add the comment
if (!std::empty(comment))
{
top.try_emplace(TR_KEY_comment, comment);
}
// maybe add some optional metainfo
if (!anonymize)
{
top.try_emplace(TR_KEY_created_by, TR_NAME "/" LONG_VERSION_STRING);
top.try_emplace(TR_KEY_creation_date, time(nullptr));
}
top.try_emplace(TR_KEY_encoding, "UTF-8"sv);
auto info_dict = tr_variant::Map{ 8U };
auto const base = tr_sys_path_basename(top_);
// "There is also a key `length` or a key `files`, but not both or neither.
// If length is present then the download represents a single file,
// otherwise it represents a set of files which go in a directory structure."
if (file_count() == 1U && !tr_strv_contains(path(0), '/'))
{
info_dict.try_emplace(TR_KEY_length, file_size(0));
}
else
{
auto const n_files = file_count();
auto file_vec = tr_variant::Vector{};
file_vec.reserve(n_files);
for (tr_file_index_t i = 0U; i < n_files; ++i)
{
auto file_map = tr_variant::Map{ 2U };
file_map.try_emplace(TR_KEY_length, file_size(i));
auto subpath = std::string_view{ path(i) };
if (!std::empty(base))
{
subpath.remove_prefix(std::size(base) + std::size("/"sv));
}
auto path_vec = tr_variant::Vector{};
auto token = std::string_view{};
while (tr_strv_sep(&subpath, &token, '/'))
{
path_vec.emplace_back(token);
}
file_map.try_emplace(TR_KEY_path, std::move(path_vec));
file_vec.emplace_back(std::move(file_map));
}
info_dict.try_emplace(TR_KEY_files, std::move(file_vec));
}
if (!std::empty(base))
{
info_dict.try_emplace(TR_KEY_name, base);
}
info_dict.try_emplace(TR_KEY_piece_length, piece_size());
info_dict.try_emplace(TR_KEY_pieces, tr_variant::make_raw(std::data(piece_hashes_), std::size(piece_hashes_)));
if (is_private_)
{
info_dict.try_emplace(TR_KEY_private, 1);
}
if (!std::empty(source))
{
info_dict.try_emplace(TR_KEY_source, source_);
}
top.try_emplace(TR_KEY_info, std::move(info_dict));
return tr_variant_serde::benc().to_string(tr_variant{ std::move(top) });
}
uint32_t tr_metainfo_builder::default_piece_size(uint64_t total_size) noexcept
{
TR_ASSERT(total_size != 0);
// Ideally, we want approximately 2^10 = 1024 pieces, give or take a few hundred pieces.
// So we subtract 10 from the log2 of total size.
// The ideal number of pieces is up for debate.
auto exp = std::log2(total_size) - 10;
// We want a piece size between 16KiB (2^14 bytes) and 16MiB (2^24 bytes) for maximum compatibility
exp = std::clamp(exp, 14., 24.);
return uint32_t{ 1U } << std::lround(exp);
}