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class torrent_info
{
public:
torrent_info();
torrent_info(sha1_hash const& info_hash);
torrent_info(entry const& torrent_file); //从一个文件取读数据后，经过bdecode函数转换成entry，之再转输入到这里
entry create_torrent() const; //根据本对象现存的信息，每成一个entry对象
void set_comment(char const* str); //设置注释
void set_piece_size(int size); //设置piece大小
void set_creator(char const* str); //设置创建程序名称
void set_hash(int index, sha1_hash const& h); //设置某一piece的SHA-1 digest
void add_tracker(std::string const& url, int tier = 0); //添加tracker服务器，tier代表优先级，0最高
void add_file(boost::filesystem::path file, size_type size); //添加一个文件信息
void add_url_seed(std::string const& url); //添加一个url seed地址
typedef std::vector<file_entry>::const_iterator file_iterator;
typedef std::vector<file_entry>::const_reverse_iterator
reverse_file_iterator;
file_iterator begin_files() const; //返回文件信息的迭代器
file_iterator end_files() const;
reverse_file_iterator rbegin_files() const; //返回文件信息的逆向迭代器
reverse_file_iterator rend_files() const;
int num_files() const; //返回文件数量
file_entry const& file_at(int index) const; //根据文件信息录入的序号返回文件信息
std::vector<file_slice> map_block(int piece, size_type offset
, int size) const; //??
peer_request map_file(int file_index, size_type file_offset
, int size) const; //??
std::vector<announce_entry> const& trackers() const; //返回tracker列表
std::vector<std::string> const& url_seeds() const; //返回url seed 列表
size_type total_size() const; //返回所有文件大小的总和
size_type piece_length() const; //返回piece长度
int num_pieces() const; //返回piece数量
sha1_hash const& info_hash() const; //返回.torrent的info_hash
std::string const& name() const; //返回.torrent的name
std::string const& comment() const; //返回注释
std::string const& creator() const; //返回创建程序名称
boost::optional<boost::posix_time::ptime>
creation_date() const; //返回创建时间
void print(std::ostream& os) const; //输出所有信息到标准输出流
size_type piece_size(unsigned int index) const; //返回指定piece的大小，只有最后一个piece的大小不同于其它piece
sha1_hash const& hash_for_piece(unsigned int index) const; //返回指定piece的SHA-1 hash
};
要用代码说明torrent_info如何使用，最好的代码莫过于libtorrent的例子make_torrent.cpp
#include <iostream>
#include <fstream>
#include <iterator>
#include <iomanip>
#include "libtorrent/entry.hpp"
#include "libtorrent/bencode.hpp"
#include "libtorrent/torrent_info.hpp"
#include "libtorrent/file.hpp"
#include "libtorrent/storage.hpp"
#include "libtorrent/hasher.hpp"
#include "libtorrent/file_pool.hpp"
#include <boost/filesystem/operations.hpp>
#include <boost/filesystem/path.hpp>
#include <boost/filesystem/fstream.hpp>
using namespace boost::filesystem;
using namespace libtorrent;
void add_files(
torrent_info& t
, path const& p
, path const& l)
{
if (l.leaf()[0] == '.') return;
path f(p / l);
if (is_directory(f))
{
for (directory_iterator i(f), end; i != end; ++i)
add_files(t, p, l / i->leaf());
}
else
{
std::cerr << "adding \"" << l.string() << "\"\n";
t.add_file(l, file_size(f));
}
}
int main(int argc, char* argv[])
{
using namespace libtorrent;
using namespace boost::filesystem;
path::default_name_check(no_check);
if (argc != 4 && argc != 5)
{
return 1;
}
try
{
torrent_info t;
path full_path = complete(path(argv[3]));
ofstream out(complete(path(argv[1])), std::ios_base::binary);
int piece_size = 256 * 1024;
char const* creator_str = "libtorrent";
add_files(t, full_path.branch_path(), full_path.leaf());
t.set_piece_size(piece_size);
file_pool fp;
storage st(t, full_path.branch_path(), fp);
t.add_tracker(argv[2]);
// calculate the hash for all pieces
int num = t.num_pieces();
std::vector<char> buf(piece_size);
for (int i = 0; i < num; ++i)
{
st.read(&buf[0], i, 0, t.piece_size(i));
hasher h(&buf[0], t.piece_size(i));
t.set_hash(i, h.final());
std::cerr << (i+1) << "/" << num << "\r";
}
t.set_creator(creator_str);
if (argc == 5)
t.add_url_seed(argv[4]);
// create the torrent and print it to out
entry e = t.create_torrent();
libtorrent::bencode(std::ostream_iterator<char>(out), e);
}
catch (std::exception& e)
{
std::cerr << e.what() << "\n";
}
return 0;
}
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