libtorrent/test/test_storage.cpp

/*

Copyright (c) 2005, 2007-2010, 2012-2022, Arvid Norberg
Copyright (c) 2016, 2018, 2021, Alden Torres
Copyright (c) 2016, Andrei Kurushin
Copyright (c) 2016-2018, Steven Siloti
Copyright (c) 2016, 2025, Vladimir Golovnev (glassez)
Copyright (c) 2018, d-komarov
All rights reserved.

You may use, distribute and modify this code under the terms of the BSD license,
see LICENSE file.
*/

#include "test.hpp"
#include "disk_io_test.hpp"
#include "setup_transfer.hpp"
#include "test_utils.hpp"
#include "settings.hpp"

#include "libtorrent/aux_/mmap_storage.hpp"
#include "libtorrent/aux_/posix_storage.hpp"
#include "libtorrent/aux_/pread_storage.hpp"
#include "libtorrent/aux_/file_view_pool.hpp"
#include "libtorrent/aux_/file_pool.hpp"
#include "libtorrent/hasher.hpp"
#include "libtorrent/session.hpp"
#include "libtorrent/session_params.hpp"
#include "libtorrent/alert_types.hpp"
#include "libtorrent/create_torrent.hpp"
#include "libtorrent/torrent_info.hpp"
#include "libtorrent/read_resume_data.hpp"
#include "libtorrent/write_resume_data.hpp"
#include "libtorrent/aux_/path.hpp"
#include "libtorrent/aux_/storage_utils.hpp"
#include "libtorrent/aux_/session_settings.hpp"
#include "libtorrent/aux_/stat_cache.hpp"
#include "libtorrent/aux_/random.hpp"
#include "libtorrent/mmap_disk_io.hpp"
#include "libtorrent/posix_disk_io.hpp"
#include "libtorrent/pread_disk_io.hpp"
#include "libtorrent/flags.hpp"
#include "libtorrent/aux_/readwrite.hpp"
#include "libtorrent/load_torrent.hpp"

#include <memory>
#include <functional> // for bind
#include <fstream>
#include <iostream>

using namespace std::placeholders;
using namespace lt;

namespace {

#if TORRENT_HAVE_MMAP || TORRENT_HAVE_MAP_VIEW_OF_FILE
using lt::aux::mmap_storage;
#endif
using lt::aux::posix_storage;
using lt::aux::pread_storage;

constexpr int piece_size = 16 * 1024 * 16;
constexpr int half = piece_size / 2;

void delete_dirs(std::string path)
{
	path = complete(path);
	error_code ec;
	remove_all(path, ec);
	if (ec && ec != boost::system::errc::no_such_file_or_directory)
	{
		std::printf("remove_all \"%s\": %s\n"
			, path.c_str(), ec.message().c_str());
	}
	TEST_CHECK(!exists(path));
}

void on_check_resume_data(lt::status_t const status, storage_error const& error, bool* done, bool* oversized)
{
	std::cout << time_now_string() << " on_check_resume_data ret: "
		<< int(static_cast<std::uint8_t>(status));

	if (status & lt::disk_status::oversized_file)
	{
		std::cout << " oversized file(s) - ";
		*oversized = true;
	}
	else
	{
		*oversized = false;
	}

	if (status & lt::disk_status::fatal_disk_error)
	{
		std::cout << " disk error: " << error.ec.message()
			<< " file: " << error.file() << std::endl;
	}
	else if (status & lt::disk_status::need_full_check)
	{
		std::cout << " need full check" << std::endl;
	}
	else if (status & lt::disk_status::file_exist)
	{
		std::cout << " file exist" << std::endl;
	}
	else
	{
		std::cout << " success" << std::endl;
	}
	std::cout << std::endl;
	*done = true;
}

void on_piece_checked(piece_index_t, sha1_hash const&
	, storage_error const& error, bool* done)
{
	std::cout << time_now_string() << " on_piece_checked err: "
		<< error.ec.message() << '\n';
	*done = true;
}

void print_error(char const* call, int ret, storage_error const& ec)
{
	std::printf("%s: %s() returned: %d error: \"%s\" in file: %d operation: %s\n"
		, time_now_string().c_str(), call, ret, ec.ec.message().c_str()
		, static_cast<int>(ec.file()), operation_name(ec.operation));
}

void run_until(io_context& ios, bool const& done)
{
	while (!done)
	{
		ios.restart();
		ios.run_one_for(lt::milliseconds(100));
		std::cout << time_now_string() << " done: " << done << std::endl;
	}
}

lt::aux::torrent_info_ptr setup_torrent_info(std::vector<char>& buf)
{
	std::vector<lt::create_file_entry> fs;
	fs.emplace_back(combine_path("temp_storage", "test1.tmp"), 0x8000);
	fs.emplace_back(combine_path("temp_storage", combine_path("folder1", "test2.tmp")), 0x8000);
	fs.emplace_back(combine_path("temp_storage", combine_path("folder2", "test3.tmp")), 0);
	fs.emplace_back(combine_path("temp_storage", combine_path("_folder3", "test4.tmp")), 0);
	fs.emplace_back(combine_path("temp_storage", combine_path("_folder3", combine_path("subfolder", "test5.tmp"))), 0x8000);
	lt::create_torrent t(std::move(fs), 0x4000);

	sha1_hash h = hasher(std::vector<char>(0x4000, 0)).final();
	for (piece_index_t i(0); i < 6_piece; ++i) t.set_hash(i, h);

	buf = bencode(t.generate());
	return load_torrent_buffer(buf).ti;
}

// file_pool_type is a meta function returning the file pool type for a specific
// StorageType
// maybe this would be easier to follow if it was all bundled up in a
// traits class
template <typename StorageType>
struct file_pool_type {};

#if TORRENT_HAVE_MMAP || TORRENT_HAVE_MAP_VIEW_OF_FILE
template <>
struct file_pool_type<mmap_storage>
{
	using type = aux::file_view_pool;
};
#endif

template <>
struct file_pool_type<posix_storage>
{
	using type = int;
};

template <>
struct file_pool_type<pread_storage>
{
	using type = aux::file_pool;
};

template <typename StorageType>
std::shared_ptr<StorageType> make_storage(storage_params const& p
	, typename file_pool_type<StorageType>::type& fp);

#if TORRENT_HAVE_MMAP || TORRENT_HAVE_MAP_VIEW_OF_FILE
template <>
std::shared_ptr<mmap_storage> make_storage(storage_params const& p
	, aux::file_view_pool& fp)
{
	return std::make_shared<mmap_storage>(p, fp);
}
#endif

template <>
std::shared_ptr<posix_storage> make_storage(storage_params const& p
	, int&)
{
	return std::make_shared<posix_storage>(p);
}

template <>
std::shared_ptr<pread_storage> make_storage(storage_params const& p
	, aux::file_pool& fp)
{
	return std::make_shared<pread_storage>(p, fp);
}

template <typename StorageType, typename FilePool>
std::pair<std::shared_ptr<StorageType>, std::shared_ptr<torrent_info const>>
setup_torrent(
	FilePool& fp
	, std::vector<char>& buf
	, std::string const& test_path
	, aux::session_settings& set)
{
	auto info = setup_torrent_info(buf);

	aux::vector<download_priority_t, file_index_t> priorities;
	renamed_files rf;
	storage_params p{
		info->layout(),
		rf,
		test_path,
		{},
		storage_mode_allocate,
		priorities,
		sha1_hash{},
		info->v1(),
		info->v2()
	};
	auto s = make_storage<StorageType>(p, fp);

	// allocate the files and create the directories
	storage_error se;
	s->initialize(set, se);
	if (se)
	{
		TEST_ERROR(se.ec.message().c_str());
		std::printf("mmap_storage::initialize %s: %d\n"
			, se.ec.message().c_str(), static_cast<int>(se.file()));
		throw system_error(se.ec);
	}

	return {s, info};
}

#if TORRENT_HAVE_MMAP || TORRENT_HAVE_MAP_VIEW_OF_FILE
int write(std::shared_ptr<mmap_storage> s
	, aux::session_settings const& sett
	, span<char> buf
	, piece_index_t const piece, int const offset
	, aux::open_mode_t const mode
	, storage_error& error)
{
	return s->write(sett, buf, piece, offset, mode, disk_job_flags_t{}, error);
}

int read(std::shared_ptr<mmap_storage> s
	, aux::session_settings const& sett
	, span<char> buf
	, piece_index_t piece
	, int const offset
	, aux::open_mode_t mode
	, storage_error& ec)
{
	return s->read(sett, buf, piece, offset, mode, disk_job_flags_t{}, ec);
}

void release_files(std::shared_ptr<mmap_storage> s, storage_error& ec)
{
	s->release_files(ec);
}
#endif

int write(std::shared_ptr<posix_storage> s
	, aux::session_settings const& sett
	, span<char> buf
	, piece_index_t const piece
	, int const offset
	, aux::open_mode_t
	, storage_error& error)
{
	return s->write(sett, buf, piece, offset, error);
}

int read(std::shared_ptr<posix_storage> s
	, aux::session_settings const& sett
	, span<char> buf
	, piece_index_t piece
	, int offset
	, aux::open_mode_t
	, storage_error& ec)
{
	return s->read(sett, buf, piece, offset, ec);
}

void release_files(std::shared_ptr<posix_storage>, storage_error&) {}

int write(std::shared_ptr<pread_storage> s
	, aux::session_settings const& sett
	, span<char> buf
	, piece_index_t const piece
	, int const offset
	, aux::open_mode_t mode
	, storage_error& error)
{
	return s->write(sett, buf, piece, offset, mode, disk_job_flags_t{}, error);
}

int read(std::shared_ptr<pread_storage> s
	, aux::session_settings const& sett
	, span<char> buf
	, piece_index_t piece
	, int offset
	, aux::open_mode_t mode
	, storage_error& ec)
{
	return s->read(sett, buf, piece, offset, mode, disk_job_flags_t{}, ec);
}

void release_files(std::shared_ptr<pread_storage> s, storage_error& ec)
{
	s->release_files(ec);
}

std::vector<char> new_piece(std::size_t const size)
{
	std::vector<char> ret(size);
	aux::random_bytes(ret);
	return ret;
}

template <typename StorageType>
void run_storage_tests(std::shared_ptr<torrent_info const> info
	, lt::storage_mode_t storage_mode)
{
	lt::file_storage const& fs = info->layout();
	TORRENT_ASSERT(fs.num_files() > 0);
	{
	error_code ec;
	create_directory(complete("temp_storage"), ec);
	if (ec) std::cout << "create_directory '" << complete("temp_storage")
		<< "': " << ec.message() << std::endl;
	}
	int const num_pieces = fs.num_pieces();
	TEST_EQUAL(info->num_pieces(), num_pieces);

	std::vector<char> piece0 = new_piece(piece_size);
	std::vector<char> piece1 = new_piece(piece_size);
	std::vector<char> piece2 = new_piece(piece_size);

	aux::session_settings set;

	std::vector<char> piece(piece_size);

	{
	// avoid having two storages use the same files
	typename file_pool_type<StorageType>::type fp;
	boost::asio::io_context ios;
	aux::vector<download_priority_t, file_index_t> priorities;
	std::string const cwd = current_working_directory();
	renamed_files rf;
	storage_params p{
		fs,
		rf,
		cwd,
		{},
		storage_mode,
		priorities,
		sha1_hash{},
		info->v1(),
		info->v2(),
	};
	auto s = make_storage<StorageType>(p, fp);

	storage_error ec;
	s->initialize(set, ec);
	TEST_CHECK(!ec);
	if (ec) print_error("initialize", 0, ec);

	int ret = 0;

	// write piece 1 (in slot 0)
	span<char> iov = span<char>(piece1).first(half);

	ret = write(s, set, iov, 0_piece, 0, aux::open_mode::write, ec);
	TEST_EQUAL(ret, int(iov.size()));
	if (ret != int(iov.size())) print_error("write", ret, ec);

	iov = span<char>(piece1).last(half);
	ret = write(s, set, iov, 0_piece, half, aux::open_mode::write, ec);
	TEST_EQUAL(ret, int(iov.size()));
	if (ret != int(iov.size())) print_error("write", ret, ec);

	// test unaligned read (where the bytes are aligned)
	iov = span<char>(piece).subspan(3, piece_size - 9);
	ret = read(s, set, iov, 0_piece, 3, aux::open_mode::write, ec);
	TEST_EQUAL(ret, int(iov.size()));
	if (ret != int(iov.size())) print_error("read",ret, ec);
	TEST_CHECK(iov == span<char>(piece1).subspan(3, piece_size - 9));

	// test unaligned read (where the bytes are not aligned)
	iov = span<char>(piece).first(piece_size - 9);
	ret = read(s, set, iov, 0_piece, 3, aux::open_mode::write, ec);
	TEST_EQUAL(ret, int(iov.size()));
	if (ret != int(iov.size())) print_error("read", ret, ec);
	TEST_CHECK(iov == span<char>(piece1).subspan(3, piece_size - 9));

	// verify piece 1
	iov = piece;
	ret = read(s, set, iov, 0_piece, 0, aux::open_mode::write, ec);
	TEST_EQUAL(ret, int(iov.size()));
	if (ret != int(iov.size())) print_error("read", ret, ec);
	TEST_CHECK(piece == piece1);

	// do the same with piece 0 and 2 (in slot 1 and 2)
	iov = piece0;
	ret = write(s, set, iov, 1_piece, 0, aux::open_mode::write, ec);
	TEST_EQUAL(ret, int(iov.size()));
	if (ret != int(iov.size())) print_error("write", ret, ec);

	iov = piece2;
	ret = write(s, set, iov, 2_piece, 0, aux::open_mode::write, ec);
	TEST_EQUAL(ret, int(iov.size()));
	if (ret != int(iov.size())) print_error("write", ret, ec);

	// verify piece 0 and 2
	iov = piece;
	ret = read(s, set, iov, 1_piece, 0, aux::open_mode::write, ec);
	TEST_EQUAL(ret, int(iov.size()));
	if (ret != int(iov.size())) print_error("read", ret, ec);
	TEST_CHECK(piece == piece0);

	iov = piece;
	ret = read(s, set, iov, 2_piece, 0, aux::open_mode::write, ec);
	TEST_EQUAL(ret, int(iov.size()));
	if (ret != int(piece_size)) print_error("read", ret, ec);
	TEST_CHECK(piece == piece2);

	release_files(s, ec);
	}
}

template <typename StorageType>
void test_remove(std::string const& test_path)
{
	delete_dirs("temp_storage");

	std::vector<char> buf;
	typename file_pool_type<StorageType>::type fp;
	io_context ios;

	aux::session_settings set;
	auto [s, info] = setup_torrent<StorageType>(fp, buf, test_path, set);

	// directories are not created up-front, unless they contain
	// an empty file (all of which are created up-front, along with
	// all required directories)
	// files are created on first write
	TEST_CHECK(!exists(combine_path(test_path, combine_path("temp_storage"
		, combine_path("_folder3", combine_path("subfolder", "test5.tmp"))))));

	// this directory and file is created up-front because it's an empty file
	TEST_CHECK(exists(combine_path(test_path, combine_path("temp_storage"
		, combine_path("folder2", "test3.tmp")))));

	// this isn't
	TEST_CHECK(!exists(combine_path(test_path, combine_path("temp_storage"
		, combine_path("folder1", "test2.tmp")))));

	buf.resize(0x4000);
	span<char> b = {&buf[0], 0x4000};
	storage_error se;
	write(s, set, b, 2_piece, 0, aux::open_mode::write, se);

	TEST_CHECK(exists(combine_path(test_path, combine_path("temp_storage"
		, combine_path("folder1", "test2.tmp")))));
	TEST_CHECK(!exists(combine_path(test_path, combine_path("temp_storage"
		, combine_path("_folder3", combine_path("subfolder", "test5.tmp"))))));
	file_status st;
	error_code ec;
	stat_file(combine_path(test_path, combine_path("temp_storage"
		, combine_path("folder1", "test2.tmp"))), &st, ec);

	// if the storage truncates the file to the full size, it's 8, otherwise it's
	// 4
	TEST_CHECK(st.file_size == 0x8000 || st.file_size == 0x4000);

	write(s, set, b, 0_piece, 0, aux::open_mode::write, se);

	TEST_CHECK(exists(combine_path(test_path, combine_path("temp_storage"
		, combine_path("_folder3", combine_path("subfolder", "test5.tmp"))))));
	stat_file(combine_path(test_path, combine_path("temp_storage"
		, combine_path("_folder3", "test5.tmp"))), &st, ec);

	// if the storage truncates the file to the full size, it's 8, otherwise it's
	// 4
	TEST_CHECK(st.file_size == 0x8000 || st.file_size == 0x4000);

	s->delete_files(session::delete_files, se);
	if (se) print_error("delete_files", 0, se);

	if (se)
	{
		TEST_ERROR(se.ec.message().c_str());
		std::printf("mmap_storage::delete_files %s: %d\n"
			, se.ec.message().c_str(), static_cast<int>(se.file()));
	}

	TEST_CHECK(!exists(combine_path(test_path, "temp_storage")));
}

template <typename StorageType>
void test_rename(std::string const& test_path)
{
	delete_dirs("temp_storage");

	std::vector<char> buf;
	typename file_pool_type<StorageType>::type fp;
	io_context ios;
	aux::session_settings set;

	auto [s, info] = setup_torrent<StorageType>(fp, buf, test_path, set);
	file_storage const& fs = info->layout();

	// directories are not created up-front, unless they contain
	// an empty file
	std::string first_file = fs.file_path(0_file);
	for (auto const i : fs.file_range())
	{
		TEST_CHECK(!exists(combine_path(test_path, combine_path("temp_storage"
			, fs.file_path(i)))));
	}

	storage_error se;
	s->rename_file(0_file, "new_filename", se);
	if (se.ec)
	{
		std::printf("mmap_storage::rename_file failed: %s\n"
			, se.ec.message().c_str());
	}
	TEST_CHECK(!se.ec);

	TEST_EQUAL(s->names().file_path(0_file), "new_filename");
}

#if TORRENT_HAVE_MMAP || TORRENT_HAVE_MAP_VIEW_OF_FILE
namespace {
std::int64_t file_size_on_disk(std::string const& path)
{
#ifdef TORRENT_WINDOWS
	native_path_string f = convert_to_native_path_string(path);
	// in order to open a directory, we need the FILE_FLAG_BACKUP_SEMANTICS
	HANDLE h = CreateFileW(f.c_str(), 0, FILE_SHARE_DELETE | FILE_SHARE_READ
		| FILE_SHARE_WRITE, nullptr, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, nullptr);
	TEST_CHECK(h != INVALID_HANDLE_VALUE);
	FILE_STANDARD_INFO Standard;
	TEST_CHECK(GetFileInformationByHandleEx(h, FILE_INFO_BY_HANDLE_CLASS::FileStandardInfo, &Standard, sizeof(FILE_STANDARD_INFO)));
	CloseHandle(h);
	return Standard.AllocationSize.QuadPart;
#else
	struct ::stat st{};
	TEST_EQUAL(::stat(path.c_str(), &st), 0);
	return std::int64_t(st.st_blocks) * 512;
#endif
}
}

template <typename StorageType>
void test_pre_allocate()
{
	std::string const test_path = complete("pre_allocate_test_path");
	delete_dirs(combine_path(test_path, "temp_storage"));

	bool const supports_prealloc = fs_supports_prealloc();
	std::vector<char> buf;
	typename file_pool_type<StorageType>::type fp;
	io_context ios;

	aux::session_settings set;
	std::shared_ptr<torrent_info const> info = setup_torrent_info(buf);
	file_storage const& fs = info->layout();

	aux::vector<download_priority_t, file_index_t> priorities{
		lt::dont_download,
		lt::default_priority,
		lt::default_priority,
		lt::default_priority,
		lt::default_priority,
	};
	renamed_files rf;
	storage_params p{
		info->layout(),
		rf,
		test_path,
		{},
		storage_mode_allocate,
		priorities,
		sha1_hash{},
		info->v1(),
		info->v2()
	};
	auto s = make_storage<StorageType>(p, fp);

	// allocate the files and create the directories
	storage_error se;
	s->initialize(set, se);
	if (se)
	{
		TEST_ERROR(se.ec.message().c_str());
		std::printf("storage::initialize %s: %d\n"
			, se.ec.message().c_str(), static_cast<int>(se.file()));
		throw system_error(se.ec);
	}

	std::vector<char> piece1 = new_piece(0x4000);
	span<char> iov = span<char>(piece1);

	// ensure all files, except the first one, have been allocated
	for (auto i : fs.file_range())
	{
		if (fs.file_size(i) > 0)
		{
			int ret = write(s, set, iov, fs.piece_index_at_file(i), 0, aux::open_mode::write, se);
			TEST_EQUAL(ret, int(iov.size()));
			TEST_CHECK(!se.ec);
		}

		error_code ec;
		file_status st;
		std::string const path = fs.file_path(i, test_path);
		stat_file(path, &st, ec);
		if (i == file_index_t{0})
		{
			// the first file has priority 0, and so should not be created
			TEST_EQUAL(ec, boost::system::errc::no_such_file_or_directory);
		}
		else
		{
			TEST_CHECK(!ec);
			std::cerr << "error: " << ec.message() << std::endl;
			TEST_EQUAL(st.file_size, fs.file_size(i));

			if (supports_prealloc || fs.file_size(i) == 0)
			{
				TEST_CHECK(file_size_on_disk(path) >= fs.file_size(i));
			}
			else
			{
				TEST_CHECK(file_size_on_disk(path) <= fs.file_size(i));
			}
		}
	}

	std::cerr << "set file priority" << std::endl;
	// set priority of file 0 to non-zero, and make sure we create the file now
	priorities[0_file] = lt::default_priority;
	s->set_file_priority(set, priorities, se);
	TEST_CHECK(!se.ec);

	for (auto i : fs.file_range())
	{
		error_code ec;
		file_status st;
		std::string const path = fs.file_path(i, test_path);
		stat_file(path, &st, ec);
		std::cerr << "error: " << ec.message() << std::endl;
		TEST_CHECK(!ec);

		if (supports_prealloc || fs.file_size(i) == 0)
		{
			TEST_CHECK(file_size_on_disk(path) >= fs.file_size(i));
		}
		else
		{
			TEST_CHECK(file_size_on_disk(path) <= fs.file_size(i));
		}
	}
}
#endif // TORRENT_HAVE_MMAP || TORRENT_HAVE_MAP_VIEW_OF_FILE

using lt::operator""_bit;
using check_files_flag_t = lt::flags::bitfield_flag<std::uint64_t, struct check_files_flag_type_tag>;

constexpr check_files_flag_t sparse = 0_bit;
constexpr check_files_flag_t test_oversized = 1_bit;
constexpr check_files_flag_t zero_prio = 2_bit;

void test_check_files(check_files_flag_t const flags,
	lt::disk_io_constructor_type const disk_constructor,
	int const aio_threads = 1,
	int const hashing_threads = 0)
{
	std::string const test_path = current_working_directory();

	error_code ec;
	constexpr int piece_size_check = 16 * 1024;
	delete_dirs("temp_storage");

	std::vector<lt::create_file_entry> fs;
	fs.emplace_back("temp_storage/test1.tmp", piece_size_check);
	fs.emplace_back("temp_storage/test2.tmp", piece_size_check * 2);
	fs.emplace_back("temp_storage/test3.tmp", piece_size_check);

	std::vector<char> piece0 = new_piece(piece_size_check);
	std::vector<char> piece2 = new_piece(piece_size_check);

	lt::create_torrent t(std::move(fs), piece_size_check);
	t.set_hash(0_piece, hasher(piece0).final());
	t.set_hash(1_piece, sha1_hash::max());
	t.set_hash(2_piece, sha1_hash::max());
	t.set_hash(3_piece, hasher(piece2).final());

	create_directory(combine_path(test_path, "temp_storage"), ec);
	if (ec) std::cout << "create_directory: " << ec.message() << std::endl;

	if (flags & test_oversized)
		piece2.push_back(0x42);

	ofstream(combine_path(test_path, combine_path("temp_storage", "test1.tmp")).c_str())
		.write(piece0.data(), std::streamsize(piece0.size()));
	ofstream(combine_path(test_path, combine_path("temp_storage", "test3.tmp")).c_str())
		.write(piece2.data(), std::streamsize(piece2.size()));

	std::shared_ptr<torrent_info const> info = load_torrent_buffer(bencode(t.generate())).ti;

	aux::session_settings set;
	boost::asio::io_context ios;
	counters cnt;

	aux::session_settings sett;
	sett.set_int(settings_pack::aio_threads, aio_threads);
	sett.set_int(settings_pack::hashing_threads, hashing_threads);
	std::unique_ptr<disk_interface> io = disk_constructor(ios, sett, cnt);

	aux::vector<download_priority_t, file_index_t> priorities;

	if (flags & zero_prio)
		priorities.resize(std::size_t(info->num_files()), download_priority_t{});

	renamed_files rf;
	storage_params p{
		info->layout(),
		rf,
		test_path,
		{},
		(flags & sparse) ? storage_mode_sparse : storage_mode_allocate,
		priorities,
		sha1_hash{},
		info->v1(),
		info->v2()
	};

	auto st = io->new_torrent(std::move(p), std::shared_ptr<void>());

	bool done = false;
	bool oversized = false;
	add_torrent_params frd;
	aux::vector<std::string, file_index_t> links;
	io->async_check_files(st, &frd, links
		, std::bind(&on_check_resume_data, _1, _2, &done, &oversized));
	io->submit_jobs();
	ios.restart();
	run_until(ios, done);

	TEST_EQUAL(oversized, bool(flags & test_oversized));

	for (auto const i : info->piece_range())
	{
		done = false;
		io->async_hash(st, i, {}
			, disk_interface::sequential_access | disk_interface::volatile_read | disk_interface::v1_hash
			, std::bind(&on_piece_checked, _1, _2, _3, &done));
		io->submit_jobs();
		ios.restart();
		run_until(ios, done);
	}

	int outstanding = 3;
	int hashes_done = 0;
	bool release_done = false;
	sha1_hash const expected_hash = hasher(piece0).final();
	auto hash_handler =
		[&](piece_index_t const piece, sha1_hash const& hash, storage_error const& error) {
			TEST_EQUAL(piece, 0_piece);
			TEST_CHECK(!error);
			TEST_EQUAL(hash, expected_hash);
			++hashes_done;
			--outstanding;
		};

	io->async_hash(st,
		0_piece,
		{},
		disk_interface::sequential_access | disk_interface::volatile_read | disk_interface::v1_hash,
		hash_handler);
	io->async_release_files(st, [&] {
		release_done = true;
		--outstanding;
	});
	io->async_hash(st,
		0_piece,
		{},
		disk_interface::sequential_access | disk_interface::volatile_read | disk_interface::v1_hash,
		hash_handler);
	io->submit_jobs();

	time_point const end_time = clock_type::now() + seconds(10);
	while (outstanding > 0 && clock_type::now() < end_time)
	{
		ios.run_one_for(milliseconds(100));
		ios.restart();
	}

	TEST_EQUAL(outstanding, 0);
	TEST_EQUAL(hashes_done, 2);
	TEST_CHECK(release_done);

	io->abort(true);
}

// TODO: 2 split this test up into smaller parts
template <typename StorageType>
void run_test()
{
	std::string const test_path = current_working_directory();
	std::cout << "\n=== " << test_path << " ===\n" << std::endl;

	std::vector<char> piece0 = new_piece(piece_size);
	std::vector<char> piece1 = new_piece(piece_size);
	std::vector<char> piece2 = new_piece(piece_size);
	std::vector<char> piece3 = new_piece(piece_size);

	delete_dirs("temp_storage");

	std::vector<lt::create_file_entry> fs;
	fs.emplace_back("temp_storage/test1.tmp", 17);
	fs.emplace_back("temp_storage/test2.tmp", 612);
	fs.emplace_back("temp_storage/test3.tmp", 0);
	fs.emplace_back("temp_storage/test4.tmp", 0);
	fs.emplace_back("temp_storage/test5.tmp", 3253);
	fs.emplace_back("temp_storage/test6.tmp", 841);
	int const last_file_size = 4 * int(piece_size) - (17 + 612 + 3253 + 841);
	fs.emplace_back("temp_storage/test7.tmp", last_file_size);

	// File layout
	// +-+--+++-------+-------+----------------------------------------------------------------------------------------+
	// |1| 2||| file5 | file6 | file7                                                                                  |
	// +-+--+++-------+-------+----------------------------------------------------------------------------------------+
	// |                           |                           |                           |                           |
	// | piece 0                   | piece 1                   | piece 2                   | piece 3                   |

	lt::create_torrent t(std::move(fs), piece_size, create_torrent::v1_only);
	TEST_CHECK(t.num_pieces() == 4);
	t.set_hash(0_piece, hasher(piece0).final());
	t.set_hash(1_piece, hasher(piece1).final());
	t.set_hash(2_piece, hasher(piece2).final());
	t.set_hash(3_piece, hasher(piece3).final());

	std::shared_ptr<torrent_info const> info = load_torrent_buffer(bencode(t.generate())).ti;

	for (auto storage_mode : { storage_mode_sparse, storage_mode_allocate })
	{
		// run_storage_tests writes piece 0, 1 and 2. not 3
		run_storage_tests<StorageType>(info, storage_mode);

		// make sure the files have the correct size
		std::string const base = complete("temp_storage");

		// these files should have been allocated as 0 size
		TEST_CHECK(exists(combine_path(base, "test3.tmp")));
		TEST_CHECK(exists(combine_path(base, "test4.tmp")));

		delete_dirs("temp_storage");
	}
}

namespace {
	void test_check_files_all_threads(
		check_files_flag_t const flags, lt::disk_io_constructor_type disk_io)
	{
		test_check_files(flags, disk_io);
		// posix_disk_io is single-threaded; the thread-count variants are redundant
		if (is_single_threaded_disk_io(disk_io)) return;
		test_check_files(flags, disk_io, 0, 1);
		test_check_files(flags, disk_io, 0, 2);
	}
} // anonymous namespace

TORRENT_TEST_DISK_IO(check_files_sparse)
{
	test_check_files_all_threads(sparse | zero_prio, disk_io);
}

TORRENT_TEST_DISK_IO(check_files_oversized_zero_prio)
{
	test_check_files_all_threads(sparse | zero_prio | test_oversized, disk_io);
}

TORRENT_TEST_DISK_IO(check_files_oversized)
{
	test_check_files_all_threads(sparse | test_oversized, disk_io);
}

TORRENT_TEST_DISK_IO(check_files_allocate) { test_check_files_all_threads(zero_prio, disk_io); }

#if TORRENT_HAVE_MMAP || TORRENT_HAVE_MAP_VIEW_OF_FILE
TORRENT_TEST(test_pre_allocate_mmap) { test_pre_allocate<mmap_storage>(); }
#endif

// posix_storage is meant to only use the most portable API for disk I/O, and so
// doesn't support pre-allocating files
/*
TORRENT_TEST(test_pre_allocate_posix)
{
	test_pre_allocate<posix_storage>();
}
*/

#if TORRENT_HAVE_MMAP || TORRENT_HAVE_MAP_VIEW_OF_FILE
TORRENT_TEST(rename_mmap_disk_io)
{
	test_rename<mmap_storage>(current_working_directory());
}

TORRENT_TEST(remove_mmap_disk_io)
{
	test_remove<mmap_storage>(current_working_directory());
}
#endif

TORRENT_TEST(rename_posix_disk_io)
{
	test_rename<posix_storage>(current_working_directory());
}

TORRENT_TEST(remove_posix_disk_io)
{
	test_remove<posix_storage>(current_working_directory());
}

TORRENT_TEST(rename_pread_disk_io)
{
	test_rename<pread_storage>(current_working_directory());
}

TORRENT_TEST(remove_pread_disk_io)
{
	test_remove<pread_storage>(current_working_directory());
}


void test_fastresume(bool const test_deprecated)
{
	std::string test_path = current_working_directory();
	error_code ec;
	std::cout << "\n\n=== test fastresume ===" << std::endl;
	delete_dirs("tmp1");

	create_directory(combine_path(test_path, "tmp1"), ec);
	if (ec) std::cout << "create_directory '" << combine_path(test_path, "tmp1")
		<< "': " << ec.message() << std::endl;
	ofstream file(combine_path(test_path, "tmp1/temporary").c_str());
	add_torrent_params atp = ::create_torrent(&file);
	file.close();
	TEST_CHECK(exists(complete("tmp1/temporary")));
	if (!exists(complete("tmp1/temporary")))
		return;

	entry resume;
	{
		settings_pack pack = settings();
		lt::session ses(pack);

		add_torrent_params p = atp;
		p.save_path = combine_path(test_path, "tmp1");
		p.storage_mode = storage_mode_sparse;
		error_code ignore;
		torrent_handle h = ses.add_torrent(std::move(p), ignore);

		torrent_status s = h.status();
		TEST_CHECK(exists(combine_path(s.save_path, "temporary")));
		if (!exists(combine_path(s.save_path, "temporary")))
			return;

		for (int i = 0; i < 50; ++i)
		{
			print_alerts(ses, "ses");
			s = h.status();
			std::cout << "progress: " << s.progress << std::endl;
			if (s.progress == 1.0f)
			{
				std::cout << "progress: 1.0f" << std::endl;
				break;
			}
			std::this_thread::sleep_for(lt::milliseconds(100));
		}

		// the whole point of the test is to have a resume
		// data which expects the file to exist in full. If
		// we failed to do that, we might as well abort
		TEST_EQUAL(int(s.progress * 1000), 1000);
		if (s.progress != 1.0f)
			return;

		h.save_resume_data();
		alert const* ra = wait_for_alert(ses, save_resume_data_alert::alert_type);
		TEST_CHECK(ra);
		if (ra) resume = write_resume_data(alert_cast<save_resume_data_alert>(ra)->params);
		ses.remove_torrent(h, lt::session::delete_files);
		alert const* da = wait_for_alert(ses, torrent_deleted_alert::alert_type);
		TEST_CHECK(da);
	}
	TEST_CHECK(!exists(combine_path(test_path, combine_path("tmp1", "temporary"))));
	if (exists(combine_path(test_path, combine_path("tmp1", "temporary"))))
		return;

	std::cout << resume.to_string() << "\n";

	// make sure the fast resume check fails! since we removed the file
	{
		settings_pack pack = settings();
		lt::session ses(pack);

		std::vector<char> const resume_data = bencode(resume);

		add_torrent_params p;
		TORRENT_UNUSED(test_deprecated);
#if TORRENT_ABI_VERSION == 1
		if (test_deprecated)
		{
			p.resume_data = resume_data;
		}
		else
#endif
		{
			p = read_resume_data(resume_data);
		}

		p.flags &= ~torrent_flags::paused;
		p.flags &= ~torrent_flags::auto_managed;
		p.ti = atp.ti;
		p.save_path = combine_path(test_path, "tmp1");
		p.storage_mode = storage_mode_sparse;
		torrent_handle h = ses.add_torrent(std::move(p), ec);

		std::printf("expecting fastresume to be rejected because the files were removed");
		alert const* a = wait_for_alert(ses, fastresume_rejected_alert::alert_type
			, "ses");
		// we expect the fast resume to be rejected because the files were removed
		TEST_CHECK(alert_cast<fastresume_rejected_alert>(a) != nullptr);
	}
	delete_dirs("tmp1");
}

} // anonymous namespace

TORRENT_TEST(fastresume)
{
	test_fastresume(false);
}

#if TORRENT_ABI_VERSION == 1
TORRENT_TEST(fastresume_deprecated)
{
	test_fastresume(true);
}
#endif

TORRENT_TEST(fastresume_spanning_piece_missing_file)
{
	int const resume_piece_size = 0x4000;
	std::string const save_path = complete("temp_storage_spanning_resume");
	delete_dirs(save_path);

	file_storage fs;
	fs.add_file(combine_path("test", "first"), resume_piece_size / 2);
	fs.add_file(combine_path("test", "missing"), resume_piece_size / 2);
	fs.add_file(combine_path("test", "unchecked"), resume_piece_size);
	fs.set_piece_length(resume_piece_size);
	fs.set_num_pieces(aux::calc_num_pieces(fs));

	error_code ec;
	create_directories(combine_path(save_path, "test"), ec);
	TEST_CHECK(!ec);

	std::ofstream file(fs.file_path(0_file, save_path).c_str());
	file.write("x", 1);
	file.close();

	add_torrent_params rd;
	rd.have_pieces.resize(fs.num_pieces(), false);
	rd.have_pieces.set_bit(0_piece);

	aux::vector<std::string, file_index_t> links;
	aux::vector<download_priority_t, file_index_t> priorities;
	aux::stat_cache stat;
	storage_error se;
	lt::renamed_files const rf;
	lt::filenames const fn(fs, rf);
	bool const valid = aux::verify_resume_data(rd, links, fn, priorities, stat, save_path, se);

	TEST_CHECK(!valid);
	TEST_EQUAL(se.ec, error_code(errors::mismatching_file_size));
	TEST_EQUAL(static_cast<int>(se.file()), 1);

	delete_dirs(save_path);
}

namespace {

bool got_file_rename_alert(alert const* a)
{
	return alert_cast<lt::file_renamed_alert>(a)
		|| alert_cast<lt::file_rename_failed_alert>(a);
}

} // anonymous namespace

TORRENT_TEST(rename_file)
{
	std::vector<char> buf;
	auto info = setup_torrent_info(buf);

	file_storage const& fs = info->layout();

	settings_pack pack = settings();
	pack.set_bool(settings_pack::disable_hash_checks, true);
	lt::session ses(pack);

	add_torrent_params p;
	p.ti = info;
	p.save_path = ".";
	error_code ec;
	torrent_handle h = ses.add_torrent(std::move(p), ec);

	// prevent race conditions of adding pieces while checking
	lt::torrent_status st = h.status();
	for (int i = 0; i < 40; ++i)
	{
		print_alerts(ses, "ses", true, true);
		st = h.status();
		if (st.state != torrent_status::checking_files
			&& st.state != torrent_status::checking_resume_data)
			break;
		std::this_thread::sleep_for(lt::milliseconds(100));
	}

	// make it a seed
	std::vector<char> tmp(std::size_t(info->piece_length()));
	for (auto const i : fs.piece_range())
		h.add_piece(i, &tmp[0]);

	// wait for the files to have been written

	for (int i = 0; i < info->num_pieces(); ++i)
	{
		alert const* pf = wait_for_alert(ses, piece_finished_alert::alert_type
			, "ses", pop_alerts::cache_alerts);
		TEST_CHECK(pf);
	}

	// now rename them. This is the test
	for (auto const i : fs.file_range())
	{
		std::string name = fs.file_path(i);
		h.rename_file(i, "temp_storage__" + name.substr(12));
	}

	// wait for the files to have been renamed
	for (int i = 0; i < info->num_files(); ++i)
	{
		alert const* fra = wait_for_alert(ses, file_renamed_alert::alert_type
			, "ses", pop_alerts::cache_alerts);
		TEST_CHECK(fra);
	}

	TEST_CHECK(exists(info->name() + "__"));

	// verify get_renamed_files() reflects all renames synchronously
	lt::renamed_files const rf = h.get_renamed_files();
	lt::filenames fn(fs, rf);
	for (auto const i : fs.file_range())
	{
		std::string name = fs.file_path(i);
		TEST_EQUAL(fn.file_path(i), "temp_storage__" + name.substr(12));
	}

	h.save_resume_data();
	alert const* ra = wait_for_alert(ses, save_resume_data_alert::alert_type);
	TEST_CHECK(ra);
	if (!ra) return;
	add_torrent_params resume = alert_cast<save_resume_data_alert>(ra)->params;

	auto const files = resume.renamed_files;
	for (auto const& i : files)
	{
		TEST_EQUAL(i.second.substr(0, 14), "temp_storage__");
	}
}

namespace {

void test_rename_file_fastresume(bool test_deprecated)
{
	std::string test_path = current_working_directory();
	error_code ec;
	std::cout << "\n\n=== test rename file in fastresume ===" << std::endl;
	delete_dirs("tmp2");
	create_directory(combine_path(test_path, "tmp2"), ec);
	if (ec) std::cout << "create_directory: " << ec.message() << std::endl;
	ofstream file(combine_path(test_path, "tmp2/temporary").c_str());
	add_torrent_params atp = ::create_torrent(&file);
	file.close();
	TEST_CHECK(exists(combine_path(test_path, "tmp2/temporary")));

	add_torrent_params resume;
	{
		settings_pack pack = settings();
		lt::session ses(pack);

		add_torrent_params p;
		p.ti = atp.ti;
		p.save_path = combine_path(test_path, "tmp2");
		p.storage_mode = storage_mode_sparse;
		torrent_handle h = ses.add_torrent(std::move(p), ec);

		h.rename_file(0_file, "testing_renamed_files");
		std::cout << "renaming file" << std::endl;
		bool renamed = false;
		for (int i = 0; i < 30; ++i)
		{
			if (print_alerts(ses, "ses", true, true, &got_file_rename_alert)) renamed = true;
			torrent_status s = h.status();
			if (s.state == torrent_status::seeding && renamed) break;
			std::this_thread::sleep_for(lt::milliseconds(100));
		}
		std::cout << "stop loop" << std::endl;
		torrent_status s = h.status();
		TEST_CHECK(s.state == torrent_status::seeding);

		h.save_resume_data();
		alert const* ra = wait_for_alert(ses, save_resume_data_alert::alert_type);
		TEST_CHECK(ra);
		if (ra) resume = alert_cast<save_resume_data_alert>(ra)->params;
		ses.remove_torrent(h);
	}
	TEST_CHECK(!exists(combine_path(test_path, "tmp2/temporary")));
	TEST_CHECK(exists(combine_path(test_path, "tmp2/testing_renamed_files")));
	TEST_CHECK(!resume.renamed_files.empty());

	entry resume_ent = write_resume_data(resume);

	std::cout << resume_ent.to_string() << "\n";

	// make sure the fast resume check succeeds, even though we renamed the file
	{
		settings_pack pack = settings();
		lt::session ses(pack);

		add_torrent_params p;
		std::vector<char> const resume_data = bencode(resume_ent);
		TORRENT_UNUSED(test_deprecated);
#if TORRENT_ABI_VERSION == 1
		if (test_deprecated)
		{
			p.resume_data = resume_data;
		}
		else
#endif
		{
			p = read_resume_data(resume_data);
		}
		p.ti = atp.ti;
		p.save_path = combine_path(test_path, "tmp2");
		p.storage_mode = storage_mode_sparse;
		torrent_handle h = ses.add_torrent(std::move(p), ec);

		torrent_status stat;
		for (int i = 0; i < 50; ++i)
		{
			stat = h.status();
			print_alerts(ses, "ses");
			if (stat.state == torrent_status::seeding)
				break;
			std::this_thread::sleep_for(lt::milliseconds(100));
		}
		TEST_CHECK(stat.state == torrent_status::seeding);

		h.save_resume_data();
		alert const* ra = wait_for_alert(ses, save_resume_data_alert::alert_type);
		TEST_CHECK(ra);
		if (ra) resume = alert_cast<save_resume_data_alert>(ra)->params;
		ses.remove_torrent(h);
	}
	TEST_CHECK(!resume.renamed_files.empty());

	resume_ent = write_resume_data(resume);
	std::cout << resume_ent.to_string() << "\n";

	remove_all(combine_path(test_path, "tmp2"), ec);
	if (ec && ec != boost::system::errc::no_such_file_or_directory)
		std::cout << "remove_all '" << combine_path(test_path, "tmp2")
		<< "': " << ec.message() << std::endl;
}

} // anonymous namespace

TORRENT_TEST(rename_file_fastresume)
{
	test_rename_file_fastresume(false);
}

#if TORRENT_ABI_VERSION == 1
TORRENT_TEST(rename_file_fastresume_deprecated)
{
	test_rename_file_fastresume(true);
}
#endif

namespace {

void fill_pattern(span<char> buf)
{
	int counter = 0;
	for (char& v : buf)
	{
		v = char(counter & 0xff);
		++counter;
	}
}

void fill_pattern(span<span<char> const> bufs)
{
	int counter = 0;
	for (auto const& buf : bufs)
	{
		for (char& v : buf)
		{
			v = char(counter & 0xff);
			++counter;
		}
	}
}

bool check_pattern(std::vector<char> const& buf, int counter)
{
	unsigned char const* p = reinterpret_cast<unsigned char const*>(buf.data());
	for (int k = 0; k < int(buf.size()); ++k)
	{
		if (p[k] != (counter & 0xff)) return false;
		++counter;
	}
	return true;
}

template <typename Char>
void alloc_iov(span<Char>* iov, int num_bufs)
{
	for (std::size_t i = 0; i < static_cast<size_t>(num_bufs); ++i)
	{
		std::size_t const len = static_cast<std::size_t>(num_bufs) * (i + 1);
		iov[i] = { new char[len], static_cast<std::ptrdiff_t>(len) };
	}
}

// TODO: this should take a span
template <typename Char>
void free_iov(span<Char>* iov, int num_bufs)
{
	for (int i = 0; i < num_bufs; ++i)
	{
		delete[] iov[i].data();
		iov[i] = { nullptr, 0 };
	}
}

} // anonymous namespace

TORRENT_TEST(iovec_advance_bufs)
{
	span<char> iov1[10];
	span<char const> iov2[10];
	alloc_iov(iov1, 10);
	fill_pattern({iov1, 10});

	memcpy(iov2, iov1, sizeof(iov1));

	span<span<char const>> iov = iov2;

	// advance iov 13 bytes. Make sure what's left fits pattern 1 shifted
	// 13 bytes
	iov = aux::advance_bufs(iov, 13);

	// make sure what's in
	int counter = 13;
	for (auto buf : iov)
	{
		for (char v : buf)
		{
			TEST_EQUAL(v, static_cast<char>(counter));
			++counter;
		}
	}

	free_iov(iov1, 10);
}

TORRENT_TEST(iovec_copy_bufs)
{
	span<char> iov1[10];
	span<char> iov2[10];

	alloc_iov(iov1, 10);
	fill_pattern({iov1, 10});

	// copy exactly 106 bytes from iov1 to iov2
	int num_bufs = aux::copy_bufs(span<span<char> const>(iov1), 106, span<span<char>>(iov2));

	// verify that the first 100 bytes is pattern 1
	// and that the remaining bytes are pattern 2

	int counter = 0;
	for (int i = 0; i < num_bufs; ++i)
	{
		for (char v : iov2[i])
		{
			TEST_EQUAL(int(v), (counter & 0xff));
			++counter;
		}
	}
	TEST_EQUAL(counter, 106);

	free_iov(iov1, 10);
}

#if TORRENT_HAVE_MMAP || TORRENT_HAVE_MAP_VIEW_OF_FILE
TORRENT_TEST(mmap_disk_io) { run_test<mmap_storage>(); }
#endif
TORRENT_TEST(posix_disk_io) { run_test<posix_storage>(); }
TORRENT_TEST(pread_disk_io) { run_test<pread_storage>(); }

namespace {

file_storage make_fs()
{
	file_storage fs;
	fs.add_file(combine_path("readwrite", "1"), 3);
	fs.add_file(combine_path("readwrite", "2"), 9);
	fs.add_file(combine_path("readwrite", "3"), 81);
	fs.add_file(combine_path("readwrite", "4"), 6561);
	fs.set_piece_length(0x1000);
	fs.set_num_pieces(aux::calc_num_pieces(fs));
	return fs;
}

struct test_fileop
{
	explicit test_fileop(int stripe_size) : m_stripe_size(stripe_size) {}

	int operator()(file_index_t const file_index, std::int64_t const file_offset
		, span<char> buf, storage_error&)
	{
		std::size_t offset = size_t(file_offset);
		if (file_index >= m_file_data.end_index())
		{
			m_file_data.resize(static_cast<int>(file_index) + 1);
		}

		std::size_t const write_size = std::size_t(std::min(m_stripe_size, int(buf.size())));
		buf = buf.first(int(write_size));

		std::vector<char>& file = m_file_data[file_index];

		if (offset + write_size > file.size())
			file.resize(offset + write_size);

		std::memcpy(&file[offset], buf.data(), write_size);
		return int(write_size);
	}

	int m_stripe_size;
	aux::vector<std::vector<char>, file_index_t> m_file_data;
};

struct test_read_fileop
{
	// EOF after size bytes read
	explicit test_read_fileop(int size) : m_size(size), m_counter(0) {}

	int operator()(file_index_t, std::int64_t /*file_offset*/
		, span<char> buf, storage_error&)
	{
		if (buf.size() > m_size)
			buf = buf.first(m_size);
		for (char& v : buf)
		{
			v = char(m_counter & 0xff);
			++m_counter;
		}
		m_size -= int(buf.size());
		return int(buf.size());
	}

	int m_size;
	int m_counter;
};

struct test_error_fileop
{
	// EOF after size bytes read
	explicit test_error_fileop(file_index_t error_file)
		: m_error_file(error_file) {}

	int operator()(file_index_t const file_index, std::int64_t /*file_offset*/
		, span<char> buf, storage_error& ec)
	{
		if (m_error_file == file_index)
		{
			ec.file(file_index);
			ec.ec.assign(boost::system::errc::permission_denied
				, boost::system::generic_category());
			ec.operation = operation_t::file_read;
			return 0;
		}
		return int(buf.size());
	}

	file_index_t m_error_file;
};

} // anonymous namespace

TORRENT_TEST(readwrite_stripe_1)
{
	file_storage fs = make_fs();
	test_fileop fop(1);
	storage_error ec;

	std::vector<char> buf(std::size_t(fs.total_size()));
	fill_pattern(buf);

	int ret = readwrite(fs, span<char>(buf), 0_piece, 0, ec, std::ref(fop));

	TEST_EQUAL(ret, fs.total_size());
	TEST_EQUAL(fop.m_file_data.size(), 4);
	TEST_EQUAL(fop.m_file_data[0_file].size(), 3);
	TEST_EQUAL(fop.m_file_data[1_file].size(), 9);
	TEST_EQUAL(fop.m_file_data[2_file].size(), 81);
	TEST_EQUAL(fop.m_file_data[3_file].size(), 6561);

	TEST_CHECK(check_pattern(fop.m_file_data[0_file], 0));
	TEST_CHECK(check_pattern(fop.m_file_data[1_file], 3));
	TEST_CHECK(check_pattern(fop.m_file_data[2_file], 3 + 9));
	TEST_CHECK(check_pattern(fop.m_file_data[3_file], 3 + 9 + 81));
}

TORRENT_TEST(readwrite_single_buffer)
{
	file_storage fs = make_fs();
	test_fileop fop(10000000);
	storage_error ec;

	std::vector<char> buf(size_t(fs.total_size()));
	fill_pattern(buf);

	int ret = readwrite(fs, span<char>(buf), 0_piece, 0, ec, std::ref(fop));

	TEST_EQUAL(ret, fs.total_size());
	TEST_EQUAL(fop.m_file_data.size(), 4);
	TEST_EQUAL(fop.m_file_data[0_file].size(), 3);
	TEST_EQUAL(fop.m_file_data[1_file].size(), 9);
	TEST_EQUAL(fop.m_file_data[2_file].size(), 81);
	TEST_EQUAL(fop.m_file_data[3_file].size(), 6561);

	TEST_CHECK(check_pattern(fop.m_file_data[0_file], 0));
	TEST_CHECK(check_pattern(fop.m_file_data[1_file], 3));
	TEST_CHECK(check_pattern(fop.m_file_data[2_file], 3 + 9));
	TEST_CHECK(check_pattern(fop.m_file_data[3_file], 3 + 9 + 81));
}

TORRENT_TEST(readwrite_read)
{
	file_storage fs = make_fs();
	test_read_fileop fop(10000000);
	storage_error ec;

	std::vector<char> buf(size_t(fs.total_size()));

	// read everything
	int ret = readwrite(fs, span<char>(buf), 0_piece, 0, ec, std::ref(fop));

	TEST_EQUAL(ret, fs.total_size());
	TEST_CHECK(check_pattern(buf, 0));
}

TORRENT_TEST(readwrite_read_short)
{
	file_storage fs = make_fs();
	test_read_fileop fop(100);
	storage_error ec;

	std::vector<char> buf(size_t(fs.total_size()));

	// read everything
	int ret = readwrite(fs, span<char>(buf), 0_piece, 0, ec, std::ref(fop));

	TEST_EQUAL(static_cast<int>(ec.file()), 3);

	TEST_EQUAL(ret, 100);
	buf.resize(100);
	TEST_CHECK(check_pattern(buf, 0));
}

TORRENT_TEST(readwrite_error)
{
	file_storage fs = make_fs();
	test_error_fileop fop(2_file);
	storage_error ec;

	std::vector<char> buf(size_t(fs.total_size()));

	// read everything
	int ret = readwrite(fs, span<char>(buf), 0_piece, 0, ec, std::ref(fop));

	TEST_EQUAL(ret, 12);
	TEST_EQUAL(static_cast<int>(ec.file()), 2);
	TEST_CHECK(ec.operation == operation_t::file_read);
	TEST_EQUAL(ec.ec, boost::system::errc::permission_denied);
	std::printf("error: %s\n", ec.ec.message().c_str());
}

TORRENT_TEST(readwrite_zero_size_files)
{
	file_storage fs;
	fs.add_file(combine_path("readwrite", "1"), 3);
	fs.add_file(combine_path("readwrite", "2"), 0);
	fs.add_file(combine_path("readwrite", "3"), 81);
	fs.add_file(combine_path("readwrite", "4"), 0);
	fs.add_file(combine_path("readwrite", "5"), 6561);
	fs.set_piece_length(0x1000);
	fs.set_num_pieces(aux::calc_num_pieces(fs));
	test_read_fileop fop(10000000);
	storage_error ec;

	std::vector<char> buf(size_t(fs.total_size()));

	// read everything
	int ret = readwrite(fs, span<char>(buf), 0_piece, 0, ec, std::ref(fop));

	TEST_EQUAL(ret, fs.total_size());
	TEST_CHECK(check_pattern(buf, 0));
}

template <typename StorageType>
void test_move_storage_to_self()
{
	// call move_storage with the path to the existing storage. should be a no-op
	std::string const save_path = current_working_directory();
	std::string const test_path = complete("temp_storage");
	delete_dirs(test_path);

	aux::session_settings set;
	std::vector<char> buf;
	typename file_pool_type<StorageType>::type fp;
	io_context ios;
	auto [s, info] = setup_torrent<StorageType>(fp, buf, save_path, set);

	span<char> const b = {&buf[0], 4};
	storage_error se;
	TEST_EQUAL(se.ec, boost::system::errc::success);
	write(s, set, b, 1_piece, 0, aux::open_mode::write, se);

	TEST_CHECK(exists(combine_path(test_path, combine_path("folder2", "test3.tmp"))));
	TEST_CHECK(exists(combine_path(test_path, combine_path("_folder3", "test4.tmp"))));
	TEST_EQUAL(se.ec, boost::system::errc::success);

	s->move_storage(save_path, move_flags_t::always_replace_files, se);
	TEST_EQUAL(se.ec, boost::system::errc::success);
	std::cerr << "file: " << se.file() << '\n';
	std::cerr << "op: " << int(se.operation) << '\n';
	std::cerr << "ec: " << se.ec.message() << '\n';

	TEST_CHECK(exists(test_path));

	TEST_CHECK(exists(combine_path(test_path, combine_path("folder2", "test3.tmp"))));
	TEST_CHECK(exists(combine_path(test_path, combine_path("_folder3", "test4.tmp"))));
}

template <typename StorageType>
void test_move_storage_into_self()
{
	std::string const save_path = current_working_directory();
	delete_dirs("temp_storage");

	aux::session_settings set;
	std::vector<char> buf;
	typename file_pool_type<StorageType>::type fp;
	io_context ios;
	auto [s, info] = setup_torrent<StorageType>(fp, buf, save_path, set);

	span<char> const b = {&buf[0], 4};
	storage_error se;
	write(s, set, b, 2_piece, 0, aux::open_mode::write, se);

	std::string const test_path = combine_path(save_path, combine_path("temp_storage", "folder1"));
	s->move_storage(test_path, move_flags_t::always_replace_files, se);
	TEST_EQUAL(se.ec, boost::system::errc::success);

	TEST_CHECK(exists(combine_path(test_path, combine_path("temp_storage"
		, combine_path("folder1", "test2.tmp")))));

	// these directories and files are created up-front because they are empty files
	TEST_CHECK(exists(combine_path(test_path, combine_path("temp_storage"
		, combine_path("folder2", "test3.tmp")))));
	TEST_CHECK(exists(combine_path(test_path, combine_path("temp_storage"
		, combine_path("_folder3", "test4.tmp")))));
}

template <typename StorageType>
void test_move_storage_reset(move_flags_t const flags)
{
	std::string const save_path = current_working_directory();
	std::string const test_path = complete("temp_storage2");
	delete_dirs(test_path);

	aux::session_settings set;
	file_storage fs;
	std::vector<char> buf;
	typename file_pool_type<StorageType>::type fp;
	io_context ios;
	auto [s, ifno] = setup_torrent<StorageType>(fp, buf, save_path, set);

	span<char> const b = {&buf[0], 4};
	storage_error se;
	TEST_EQUAL(se.ec, boost::system::errc::success);
	write(s, set, b, 1_piece, 0, aux::open_mode::write, se);

	std::string const root = combine_path(save_path, "temp_storage");
	TEST_CHECK(exists(combine_path(root, combine_path("folder2", "test3.tmp"))));
	TEST_CHECK(exists(combine_path(root, combine_path("_folder3", "test4.tmp"))));
	std::string const root2 = combine_path(test_path, "temp_storage");
	TEST_CHECK(!exists(combine_path(root2, combine_path("folder2", "test3.tmp"))));
	TEST_CHECK(!exists(combine_path(root2, combine_path("_folder3", "test4.tmp"))));
	TEST_EQUAL(se.ec, boost::system::errc::success);

	std::string new_path;
	status_t ret;
	std::tie(ret, new_path) = s->move_storage(test_path, flags, se);
	TEST_EQUAL(new_path, test_path);
	TEST_EQUAL(se.ec, boost::system::errc::success);
	std::cerr << "file: " << se.file() << '\n';
	std::cerr << "op: " << int(se.operation) << '\n';
	std::cerr << "ec: " << se.ec.message() << '\n';

	// the root directory is created, but none of the files are moved
	TEST_CHECK(exists(test_path));
	TEST_CHECK(!exists(combine_path(root2, combine_path("folder2", "test3.tmp"))));
	TEST_CHECK(!exists(combine_path(root2, combine_path("_folder3", "test4.tmp"))));
}

#if TORRENT_HAVE_MMAP || TORRENT_HAVE_MAP_VIEW_OF_FILE
TORRENT_TEST(move_default_storage_to_self)
{
	test_move_storage_to_self<mmap_storage>();
}

TORRENT_TEST(move_default_storage_into_self)
{
	test_move_storage_into_self<mmap_storage>();
}

TORRENT_TEST(move_default_storage_reset)
{
	test_move_storage_reset<mmap_storage>(move_flags_t::reset_save_path);
	test_move_storage_reset<mmap_storage>(move_flags_t::reset_save_path_unchecked);
}
#endif

TORRENT_TEST(move_posix_storage_to_self)
{
	test_move_storage_to_self<posix_storage>();
}

TORRENT_TEST(move_posix_storage_into_self)
{
	test_move_storage_into_self<posix_storage>();
}

TORRENT_TEST(move_posix_storage_reset)
{
	test_move_storage_reset<posix_storage>(move_flags_t::reset_save_path);
	test_move_storage_reset<posix_storage>(move_flags_t::reset_save_path_unchecked);
}

TORRENT_TEST(move_pread_storage_to_self)
{
	test_move_storage_to_self<pread_storage>();
}

TORRENT_TEST(move_pread_storage_into_self)
{
	test_move_storage_into_self<pread_storage>();
}

TORRENT_TEST(move_pread_storage_reset)
{
	test_move_storage_reset<pread_storage>(move_flags_t::reset_save_path);
	test_move_storage_reset<pread_storage>(move_flags_t::reset_save_path_unchecked);
}

TORRENT_TEST(storage_paths_string_pooling)
{
	file_storage file_storage;
	file_storage.add_file(combine_path("test_storage", "root.txt"), 0x4000);
	file_storage.add_file(combine_path("test_storage", combine_path("sub", "test1.txt")), 0x4000);
	file_storage.add_file(combine_path("test_storage", combine_path("sub", "test2.txt")), 0x4000);
	file_storage.add_file(combine_path("test_storage", combine_path("sub", "test3.txt")), 0x4000);

	// "sub" paths should point to same string item, so paths.size() must not grow
	TEST_CHECK(file_storage.paths().size() <= 2);
}

#if TORRENT_HAVE_MMAP || TORRENT_HAVE_MAP_VIEW_OF_FILE
TORRENT_TEST(dont_move_intermingled_files)
{
	std::string const save_path = complete("save_path_1");
	delete_dirs(combine_path(save_path, "temp_storage"));

	std::string const test_path = complete("save_path_2");
	delete_dirs(combine_path(test_path, "temp_storage"));

	aux::session_settings set;
	std::vector<char> buf;
	typename file_pool_type<mmap_storage>::type fp;
	io_context ios;
	auto [s, info] = setup_torrent<mmap_storage>(fp, buf, save_path, set);

	span<char> b = {&buf[0], 4};
	storage_error se;
	s->write(set, b, 2_piece, 0, aux::open_mode::write, disk_job_flags_t{}, se);

	error_code ec;
	create_directory(combine_path(save_path, combine_path("temp_storage"
		, combine_path("_folder3", "alien_folder1"))), ec);
	TEST_EQUAL(ec, boost::system::errc::success);

	ofstream(combine_path(save_path, combine_path("temp_storage", "alien1.tmp")).c_str());
	ofstream(combine_path(save_path, combine_path("temp_storage", combine_path("folder1", "alien2.tmp"))).c_str());

	s->move_storage(test_path, move_flags_t::always_replace_files, se);
	TEST_EQUAL(se.ec, boost::system::errc::success);

	// torrent files moved to new place
	TEST_CHECK(exists(combine_path(test_path, combine_path("temp_storage"
		, combine_path("folder1", "test2.tmp")))));
	// these directories and files are created up-front because they are empty files
	TEST_CHECK(exists(combine_path(test_path, combine_path("temp_storage"
		, combine_path("folder2", "test3.tmp")))));
	TEST_CHECK(exists(combine_path(test_path, combine_path("temp_storage"
		, combine_path("_folder3", "test4.tmp")))));

	// intermingled files and directories are still in old place
	TEST_CHECK(exists(combine_path(save_path, combine_path("temp_storage"
		, "alien1.tmp"))));
	TEST_CHECK(!exists(combine_path(test_path, combine_path("temp_storage"
		, "alien1.tmp"))));
	TEST_CHECK(exists(combine_path(save_path, combine_path("temp_storage"
		, combine_path("folder1", "alien2.tmp")))));
	TEST_CHECK(!exists(combine_path(test_path, combine_path("temp_storage"
		, combine_path("folder1", "alien2.tmp")))));
	TEST_CHECK(exists(combine_path(save_path, combine_path("temp_storage"
		, combine_path("_folder3", "alien_folder1")))));
	TEST_CHECK(!exists(combine_path(test_path, combine_path("temp_storage"
		, combine_path("_folder3", "alien_folder1")))));
}
#endif

namespace {

void sync(lt::io_context& ioc, int& outstanding)
{
	while (outstanding > 0)
	{
		ioc.restart();
		ioc.run_one_for(lt::milliseconds(100));
	}
}

template <typename Fun>
void test_unaligned_read(lt::disk_io_constructor_type constructor, Fun fun)
{
	lt::io_context ioc;
	lt::counters cnt;
	lt::settings_pack pack;
	pack.set_int(lt::settings_pack::aio_threads, 1);
	pack.set_int(lt::settings_pack::file_pool_size, 2);

	std::unique_ptr<lt::disk_interface> disk_io
		= constructor(ioc, pack, cnt);

	lt::file_storage fs;
	fs.add_file("test", lt::default_block_size * 2);
	fs.set_num_pieces(1);
	fs.set_piece_length(lt::default_block_size * 2);

	std::string const save_path = complete("save_path");
	delete_dirs(combine_path(save_path, "test"));

	lt::aux::vector<lt::download_priority_t, lt::file_index_t> prios;
	lt::renamed_files rf;
	lt::storage_params params(fs
		, rf
		, save_path
		, {}
		, lt::storage_mode_sparse
		, prios
		, lt::sha1_hash("01234567890123456789")
		, true // v1-hashes
		, true // v2-hashes
		);

	lt::storage_holder t = disk_io->new_torrent(params, {});

	int outstanding = 0;
	lt::add_torrent_params atp;
	disk_io->async_check_files(t, &atp, lt::aux::vector<std::string, lt::file_index_t>{}
		, [&](lt::status_t, lt::storage_error const&) { --outstanding; });
	++outstanding;
	disk_io->submit_jobs();
	sync(ioc, outstanding);

	fun(disk_io.get(), t, ioc, outstanding);

	t.reset();
	disk_io->abort(true);
}

struct write_handler
{
	write_handler(int& outstanding) : m_out(&outstanding) {}
	void operator()(lt::storage_error const& ec) const
	{
		--(*m_out);
		if (ec) std::cout << "async_write failed " << ec.ec.message() << '\n';
		TEST_CHECK(!ec);
	}
	int* m_out;
};

struct read_handler
{
	// disk_buffer_holder doesn't expose a size, so the caller is
	// responsible for sizing the read to default_block_size and
	// supplying that many expected bytes.
	read_handler(int& outstanding, char const* expected)
		: m_out(&outstanding)
		, m_exp(expected)
	{}
	void operator()(lt::disk_buffer_holder h, lt::storage_error const& ec) const
	{
		--(*m_out);
		if (ec) std::cout << "async_read failed " << ec.ec.message() << '\n';
		TEST_CHECK(!ec);
		TEST_CHECK(lt::span<char const>(m_exp, lt::default_block_size)
			== lt::span<char const>(h.data(), lt::default_block_size));
	}
	int* m_out;
	char const* m_exp;
};

void both_sides_from_store_buffer(lt::disk_interface* disk_io, lt::storage_holder const& t, lt::io_context& ioc, int& outstanding)
{
	std::vector<char> write_buffer(lt::default_block_size * 2);
	aux::random_bytes(write_buffer);

	lt::peer_request const req0{0_piece, 0, lt::default_block_size};
	lt::peer_request const req1{0_piece, lt::default_block_size, lt::default_block_size};

	// this is the unaligned read request
	lt::peer_request const req2{0_piece, lt::default_block_size / 2, lt::default_block_size};

	std::vector<char> const expected_buffer(write_buffer.begin() + req2.start
		, write_buffer.begin() + req2.start + req2.length);

	++outstanding;
	disk_io->async_write(t, req0, write_buffer.data(), {}, write_handler(outstanding));
	++outstanding;
	disk_io->async_write(t, req1, write_buffer.data() + lt::default_block_size, {}, write_handler(outstanding));
	++outstanding;
	disk_io->async_read(t, req2, read_handler(outstanding, expected_buffer.data()));
	disk_io->submit_jobs();
	sync(ioc, outstanding);
}

void first_side_from_store_buffer(lt::disk_interface* disk_io, lt::storage_holder const& t, lt::io_context& ioc, int& outstanding)
{
	std::vector<char> write_buffer(lt::default_block_size * 2);
	aux::random_bytes(write_buffer);

	lt::peer_request const req0{0_piece, 0, lt::default_block_size};
	lt::peer_request const req1{0_piece, lt::default_block_size, lt::default_block_size};

	// this is the unaligned read request
	lt::peer_request const req2{0_piece, lt::default_block_size / 2, lt::default_block_size};

	std::vector<char> const expected_buffer(write_buffer.begin() + req2.start
		, write_buffer.begin() + req2.start + req2.length);

	++outstanding;
	disk_io->async_write(t, req0, write_buffer.data(), {}, write_handler(outstanding));

	disk_io->submit_jobs();
	sync(ioc, outstanding);

	++outstanding;
	disk_io->async_write(t, req1, write_buffer.data() + lt::default_block_size, {}, write_handler(outstanding));
	++outstanding;
	disk_io->async_read(t, req2, read_handler(outstanding, expected_buffer.data()));
	disk_io->submit_jobs();
	sync(ioc, outstanding);
}

void second_side_from_store_buffer(lt::disk_interface* disk_io, lt::storage_holder const& t, lt::io_context& ioc, int& outstanding)
{
	std::vector<char> write_buffer(lt::default_block_size * 2);
	aux::random_bytes(write_buffer);

	lt::peer_request const req0{0_piece, 0, lt::default_block_size};
	lt::peer_request const req1{0_piece, lt::default_block_size, lt::default_block_size};

	// this is the unaligned read request
	lt::peer_request const req2{0_piece, lt::default_block_size / 2, lt::default_block_size};

	std::vector<char> const expected_buffer(write_buffer.begin() + req2.start
		, write_buffer.begin() + req2.start + req2.length);

	++outstanding;
	disk_io->async_write(t, req1, write_buffer.data() + lt::default_block_size, {}, write_handler(outstanding));
	disk_io->submit_jobs();
	sync(ioc, outstanding);

	++outstanding;
	disk_io->async_write(t, req0, write_buffer.data(), {}, write_handler(outstanding));
	++outstanding;
	disk_io->async_read(t, req2, read_handler(outstanding, expected_buffer.data()));
	disk_io->submit_jobs();
	sync(ioc, outstanding);
}

void none_from_store_buffer(lt::disk_interface* disk_io, lt::storage_holder const& t, lt::io_context& ioc, int& outstanding)
{
	std::vector<char> write_buffer(lt::default_block_size * 2);
	aux::random_bytes(write_buffer);

	lt::peer_request const req0{0_piece, 0, lt::default_block_size};
	lt::peer_request const req1{0_piece, lt::default_block_size, lt::default_block_size};

	// this is the unaligned read request
	lt::peer_request const req2{0_piece, lt::default_block_size / 2, lt::default_block_size};

	std::vector<char> const expected_buffer(write_buffer.begin() + req2.start
		, write_buffer.begin() + req2.start + req2.length);

	++outstanding;
	disk_io->async_write(t, req0, write_buffer.data(), {}, write_handler(outstanding));
	++outstanding;
	disk_io->async_write(t, req1, write_buffer.data() + lt::default_block_size, {}, write_handler(outstanding));
	disk_io->submit_jobs();
	sync(ioc, outstanding);

	++outstanding;
	disk_io->async_read(t, req2, read_handler(outstanding, expected_buffer.data()));
	disk_io->submit_jobs();
	sync(ioc, outstanding);
}

}

#if TORRENT_HAVE_MMAP || TORRENT_HAVE_MAP_VIEW_OF_FILE
TORRENT_TEST(mmap_unaligned_read_both_store_buffer)
{
	test_unaligned_read(lt::mmap_disk_io_constructor, both_sides_from_store_buffer);
	test_unaligned_read(lt::mmap_disk_io_constructor, first_side_from_store_buffer);
	test_unaligned_read(lt::mmap_disk_io_constructor, second_side_from_store_buffer);
	test_unaligned_read(lt::mmap_disk_io_constructor, none_from_store_buffer);
}
#endif

TORRENT_TEST(posix_unaligned_read_both_store_buffer)
{
	test_unaligned_read(lt::posix_disk_io_constructor, both_sides_from_store_buffer);
	test_unaligned_read(lt::posix_disk_io_constructor, first_side_from_store_buffer);
	test_unaligned_read(lt::posix_disk_io_constructor, second_side_from_store_buffer);
	test_unaligned_read(lt::posix_disk_io_constructor, none_from_store_buffer);
}

TORRENT_TEST(iovec_bufs)
{
	span<char const> iov[10];

	for (int i = 1; i < 10; ++i)
	{
		alloc_iov(iov, i);

		int expected_size = 0;
		for (int k = 0; k < i; ++k) expected_size += i * (k + 1);
		TEST_EQUAL(aux::bufs_size(span<span<char const> const>(&iov[0], i)), expected_size);

		free_iov(iov, i);
	}
}

using part_file_flag_t = lt::flags::bitfield_flag<std::uint64_t, struct test_part_file_flag_type_tag>;

constexpr part_file_flag_t custom_path = 0_bit;

template <typename StorageType>
void test_part_file(lt::storage_mode_t const storage_mode, part_file_flag_t const flags)
{
	static int test_index = 0;

	std::cerr << "test_part_file " << test_index << " " << typeid(StorageType).name() << " storage_mode:" << storage_mode << " " << ((flags & custom_path ) ? " custom_path" : "") << std::endl;

	std::vector<char> piece0 = new_piece(17 + 612);

	delete_dirs("temp_storage");

	std::vector<lt::create_file_entry> fs;
	fs.emplace_back("temp_storage/test1.tmp", 17);
	fs.emplace_back("temp_storage/test2.tmp", 612);

	lt::create_torrent t(std::move(fs), piece_size, create_torrent::v1_only);
	TEST_CHECK(t.num_pieces() == 1);
	t.set_hash(0_piece, hasher(piece0).final());

	std::shared_ptr<torrent_info const> info = load_torrent_buffer(bencode(t.generate())).ti;

	aux::session_settings set;

	// avoid having two storages use the same files
	typename file_pool_type<StorageType>::type fp;
	boost::asio::io_context ios;
	aux::vector<download_priority_t, file_index_t> priorities = {1_pri, 0_pri};
	std::string const cwd = current_working_directory();
	std::string download_dir = combine_path(cwd, "part_file_test_" + std::to_string(test_index));
	std::string const part_file_dir = combine_path(download_dir, "part_file_dir");
	++test_index;

	renamed_files rf;
	storage_params p(
		info->layout(),
		rf,
		download_dir,
		(flags & custom_path) ? "part_file_dir" : "",
		storage_mode,
		priorities,
		sha1_hash{},
		info->v1(),
		info->v2()
	);
	auto s = make_storage<StorageType>(p, fp);

	storage_error ec;
	s->initialize(set, ec);
	TEST_CHECK(!ec);
	if (ec) print_error("initialize", 0, ec);

	int ret = 0;

	// write piece 1
	span<char> iov = span<char>(piece0);

	ret = write(s, set, iov, 0_piece, 0, aux::open_mode::write, ec);
	TEST_EQUAL(ret, int(iov.size()));
	if (ret != int(iov.size())) print_error("write", ret, ec);

	release_files(s, ec);

	// has_any_file should return true since we wrote data
	{
		storage_error haf_ec;
		TEST_CHECK(s->has_any_file(haf_ec));
		TEST_CHECK(!haf_ec);
	}

	// make sure the part file is stored in the expected location
	std::string const part_file_name = "." + aux::to_hex(p.info_hash) + ".parts";
	if (flags & custom_path)
	{
		TEST_CHECK(exists(combine_path(part_file_dir, part_file_name)));
		TEST_CHECK(!exists(combine_path(download_dir, part_file_name)));
	}
	else
	{
		TEST_CHECK(!exists(combine_path(part_file_dir, part_file_name)));
		TEST_CHECK(exists(combine_path(download_dir, part_file_name)));
	}

	// now move the torrent and make sure the part file is where it's expected to be
	std::string const new_download_dir = download_dir + "_new";
	std::string const new_part_file_dir = combine_path(new_download_dir, "part_file_dir");
	storage_error se;
	s->move_storage(new_download_dir, move_flags_t::always_replace_files, se);
	TEST_CHECK(!se);

	if (flags & custom_path)
	{
		TEST_CHECK(exists(combine_path(new_part_file_dir, part_file_name)));
		TEST_CHECK(!exists(combine_path(download_dir, part_file_name)));
		TEST_CHECK(!exists(combine_path(new_download_dir, part_file_name)));
	}
	else
	{
		TEST_CHECK(!exists(combine_path(new_part_file_dir, part_file_name)));
		TEST_CHECK(!exists(combine_path(download_dir, part_file_name)));
		TEST_CHECK(exists(combine_path(new_download_dir, part_file_name)));
	}

	// delete_files should remove the part file from the correct location
	s->delete_files(session::delete_files, se);
	if (se) print_error("delete_files", 0, se);
	TEST_CHECK(!se);

	if (flags & custom_path)
	{
		TEST_CHECK(!exists(combine_path(new_part_file_dir, part_file_name)));
	}
	else
	{
		TEST_CHECK(!exists(combine_path(new_download_dir, part_file_name)));
	}

	// has_any_file should return false after all files have been deleted
	{
		storage_error haf_ec;
		TEST_CHECK(!s->has_any_file(haf_ec));
		TEST_CHECK(!haf_ec);
	}
}

#if TORRENT_HAVE_MMAP || TORRENT_HAVE_MAP_VIEW_OF_FILE
TORRENT_TEST(mmap_disk_io_part_file)
{
	for (auto storage_mode : { storage_mode_sparse, storage_mode_allocate })
	{
		for (auto flags : {part_file_flag_t{}, custom_path})
		{
			test_part_file<mmap_storage>(storage_mode, flags);
		}
	}
}
#endif

TORRENT_TEST(pread_disk_io_part_file)
{
	for (auto storage_mode : { storage_mode_sparse, storage_mode_allocate })
	{
		for (auto flags : {part_file_flag_t{}, custom_path})
		{
			test_part_file<pread_storage>(storage_mode, flags);
		}
	}
}

TORRENT_TEST(posix_disk_io_part_file)
{
	for (auto storage_mode : { storage_mode_sparse, storage_mode_allocate })
	{
		for (auto flags : {part_file_flag_t{}, custom_path})
		{
			test_part_file<posix_storage>(storage_mode, flags);
		}
	}
}

// Test the vec-write path (pread_storage::write(span<span<char const> const>))
// when a piece overlaps a 0-priority file. mmap_storage and posix_storage use
// the single-buffer readwrite() path so this overload is pread_storage-only.
//
// file_defs is a list of (block_count, priority) pairs. All files are packed
// into a single piece so that the write covers all of them at once.
static void test_write_vec_partfile(
	std::vector<std::pair<int, download_priority_t>> const& file_defs
	, lt::storage_mode_t const storage_mode)
{
	int const block = 0x4000; // 16 KiB

	int total_blocks = 0;
	for (auto const& [nblocks, _prio] : file_defs) total_blocks += nblocks;
	int const ps = block * total_blocks; // one piece covers all files

	std::vector<lt::create_file_entry> flist;
	aux::vector<download_priority_t, file_index_t> priorities;
	for (std::size_t i = 0; i < file_defs.size(); ++i)
	{
		auto const [nblocks, prio] = file_defs[i];
		flist.emplace_back("vec_test/f" + std::to_string(i) + ".tmp"
			, std::int64_t(block) * nblocks);
		priorities.push_back(prio);
	}

	lt::create_torrent t(std::move(flist), ps, lt::create_torrent::v1_only);
	TEST_CHECK(t.num_pieces() == 1);

	std::vector<std::vector<char>> blks(static_cast<std::size_t>(total_blocks));
	std::vector<char> full_piece;
	for (auto& b : blks)
	{
		b = new_piece(block);
		full_piece.insert(full_piece.end(), b.begin(), b.end());
	}
	t.set_hash(0_piece, hasher(full_piece).final());

	std::shared_ptr<torrent_info const> info = load_torrent_buffer(bencode(t.generate())).ti;

	aux::session_settings set;
	file_pool_type<pread_storage>::type fp;
	std::string const cwd = current_working_directory();
	std::string const download_dir = combine_path(cwd, "pread_vec_partfile_test");
	delete_dirs(download_dir);
	renamed_files rf;
	storage_params p(
		info->layout(),
		rf,
		download_dir,
		{},
		storage_mode,
		priorities,
		sha1_hash{},
		info->v1(),
		info->v2()
	);
	auto s = make_storage<pread_storage>(p, fp);
	storage_error ec;
	s->initialize(set, ec);
	TEST_CHECK(!ec);
	if (ec) print_error("initialize", 0, ec);

	// write piece 0 as individual block-sized buffers via the vec overload.
	// any 0-priority file spanning more than one block causes bufs.size() > 1
	// in the part-file branch of the write lambda.
	std::vector<span<char const>> buf_spans;
	buf_spans.reserve(std::size_t(total_blocks));
	for (auto const& b : blks) buf_spans.emplace_back(b);
	span<span<char const> const> const vec_bufs(buf_spans.data()
		, static_cast<std::ptrdiff_t>(buf_spans.size()));
	int const wret = s->write(set, vec_bufs, 0_piece, 0
		, aux::open_mode::write, disk_job_flags_t{}, ec);
	TEST_EQUAL(wret, ps);
	TEST_CHECK(!ec);
	if (ec) print_error("write", wret, ec);

	std::vector<char> read_buf(static_cast<std::size_t>(ps));
	int const rret = s->read(set, read_buf, 0_piece, 0
		, aux::open_mode::read_only, disk_job_flags_t{}, ec);
	TEST_EQUAL(rret, ps);
	TEST_CHECK(!ec);
	if (ec) print_error("read", rret, ec);
	TEST_CHECK(read_buf == full_piece);

	s->delete_files(session::delete_files, ec);
	if (ec) print_error("delete_files", 0, ec);
}

TORRENT_TEST(pread_write_vec_partfile_multi_buf)
{
	for (auto const sm : {storage_mode_sparse, storage_mode_allocate})
	{
		// 0-priority file (2 blocks) at the start of the piece
		test_write_vec_partfile({{2, 0_pri}, {2, 1_pri}}, sm);
		// 0-priority file (2 blocks) at the end of the piece
		test_write_vec_partfile({{2, 1_pri}, {2, 0_pri}}, sm);
		// 0-priority file (2 blocks) in the middle, normal files on both sides
		test_write_vec_partfile({{1, 1_pri}, {2, 0_pri}, {1, 1_pri}}, sm);
	}
}