support storing save_path in resume data

ChangeLog

@@ -1,5 +1,6 @@
 1.0 release
 
+	* support storing save_path in resume data
 	* don't use full allocation on network drives (on windows)
 	* added clear_piece_deadlines() to remove all piece deadlines
 	* improve queuing logic of inactive torrents (dont_count_slow_torrents)

bindings/python/src/session.cpp

@@ -604,6 +604,9 @@ void bind_session()
         .value("flag_duplicate_is_error", add_torrent_params::flag_duplicate_is_error)
         .value("flag_merge_resume_trackers", add_torrent_params::flag_merge_resume_trackers)
         .value("flag_update_subscribe", add_torrent_params::flag_update_subscribe)
+        .value("flag_super_seeding", add_torrent_params::flag_super_seeding)
+        .value("flag_sequential_download", add_torrent_params::flag_sequential_download)
+        .value("flag_use_resume_save_path", add_torrent_params::flag_use_resume_save_path)
     ;
     class_<cache_status>("cache_status")
         .def_readonly("blocks_written", &cache_status::blocks_written)

docs/manual.rst

@@ -354,6 +354,10 @@ The file format is a bencoded dictionary containing the following fields:
 |                          | necessarily complete, but complete enough to be able to send |
 |                          | any piece that we have, indicated by the have bitmask.       |
 +--------------------------+--------------------------------------------------------------+
+| ``save_path``            | string. The save path where this torrent was saved. This is  |
+|                          | especially useful when moving torrents with move_storage()   |
+|                          | since this will be updated.                                  |
++--------------------------+--------------------------------------------------------------+
 | ``peers``                | list of dictionaries. Each dictionary has the following      |
 |                          | layout:                                                      |
 |                          |                                                              |

include/libtorrent/add_torrent_params.hpp

@@ -147,9 +147,9 @@ namespace libtorrent
 			// in there will override the seed mode you set here.
 			flag_seed_mode = 0x001,
 
-			// If ``flag_override_resume_data`` is set, the ``paused`` and
-			// ``auto_managed`` state of the torrent are not loaded from the
-			// resume data, but the states requested by the flags in
+			// If ``flag_override_resume_data`` is set, the ``paused``,
+			// ``auto_managed`` and ``save_path`` of the torrent are not loaded
+			// from the resume data, but the states requested by the flags in
 			// ``add_torrent_params`` will override them.
 			//
 			// If you pass in resume data, the paused state of the torrent when
@@ -244,6 +244,11 @@ namespace libtorrent
 			// the torrent handle immediately after adding it.
 			flag_sequential_download = 0x800,
 
+			// if this flag is set, the save path from the resume data file, if
+			// present, is honored. This defaults to not being set, in which
+			// case the save_path specified in add_torrent_params is always used.
+			flag_use_resume_save_path = 0x1000,
+
 			// internal
 			default_flags = flag_update_subscribe | flag_auto_managed | flag_paused | flag_apply_ip_filter
 #ifndef TORRENT_NO_DEPRECATE
@@ -273,6 +278,11 @@ namespace libtorrent
 		// to the session (if DHT is enabled). The hostname may be an IP address.
 		std::vector<std::pair<std::string, int> > dht_nodes;
 		std::string name;
+
+		// the path where the torrent is or will be stored. Note that this may
+		// alos be stored in resume data. If you which the save path saved in
+		// the resume data to be used, you need to set the
+		// flag_use_resume_save_path flag.
 		std::string save_path;
 
 		// The optional parameter, ``resume_data`` can be given if up to date

include/libtorrent/torrent.hpp

@@ -1420,6 +1420,10 @@ namespace libtorrent
 		// queued, torrent. Every second it's above the threshold
 		boost::int16_t m_inactive_counter;
 
+		// if this is set, accept the save path saved in the resume data, if
+		// present
+		bool m_use_resume_save_path:1;
+
 #if TORRENT_USE_ASSERTS
 	public:
 		// set to false until we've loaded resume data

src/torrent.cpp

@@ -249,6 +249,7 @@ namespace libtorrent
 		, m_interface_index(0)
 		, m_progress_ppm(0)
 		, m_inactive_counter(0)
+		, m_use_resume_save_path(p.flags & add_torrent_params::flag_use_resume_save_path)
 	{
 		// if there is resume data already, we don't need to trigger the initial save
 		// resume data
@@ -1487,6 +1488,17 @@ namespace libtorrent
 			return;
 		}
 
+		// Chicken-and-egg: need to load resume data to get last save_path
+		// before constructing m_owning_storage, but need storage before
+		// loading resume data. So peek ahead in this case.
+		// only do this if the user is willing to have the resume data
+		// settings override the settings set in add_torrent_params
+		if (!m_use_resume_save_path && m_resume_entry.type() == lazy_entry::dict_t)
+		{
+			std::string p = m_resume_entry.dict_find_string_value("save_path");
+			if (!p.empty()) m_save_path = p;
+		}
+
 		// the shared_from_this() will create an intentional
 		// cycle of ownership, se the hpp file for description.
 		m_owning_storage = new piece_manager(shared_from_this(), m_torrent_file
@@ -5197,6 +5209,12 @@ namespace libtorrent
 		m_last_download = rd.dict_find_int_value("last_download", 0);
 		m_last_upload = rd.dict_find_int_value("last_upload", 0);
 
+		if (!m_use_resume_save_path)
+		{
+			std::string p = rd.dict_find_string_value("save_path");
+			if (!p.empty()) m_save_path = p;
+		}
+
 		m_url = rd.dict_find_string_value("url");
 		m_uuid = rd.dict_find_string_value("uuid");
 		m_source_feed_url = rd.dict_find_string_value("feed");
@@ -5396,6 +5414,8 @@ namespace libtorrent
 		ret["last_download"] = m_last_download;
 		ret["last_upload"] = m_last_upload;
 
+		ret["save_path"] = m_save_path;
+
 		if (!m_url.empty()) ret["url"] = m_url;
 		if (!m_uuid.empty()) ret["uuid"] = m_uuid;
 		if (!m_source_feed_url.empty()) ret["feed"] = m_source_feed_url;
@@ -6676,6 +6696,8 @@ namespace libtorrent
 
 			m_save_path = save_path;
 #endif
+			m_need_save_resume_data = true;
+
 			if (alerts().should_post<storage_moved_alert>())
 			{
 				alerts().post_alert(storage_moved_alert(get_handle(), m_save_path));
@@ -6694,6 +6716,7 @@ namespace libtorrent
 			if (alerts().should_post<storage_moved_alert>())
 				alerts().post_alert(storage_moved_alert(get_handle(), j.str));
 			m_save_path = j.str;
+			m_need_save_resume_data = true;
 			if (ret == piece_manager::need_full_check)
 				force_recheck();
 		}