forward port patch to have resume data web seeds override .torrent file web seeds, and a flag to merge them

ChangeLog

@@ -75,6 +75,8 @@
 	* almost completely changed the storage interface (for custom storage)
 	* added support for hashing pieces in multiple threads
 
+	* introduce add_torrent_params flags to merge web seeds with resume data
+	  (similar to trackers)
 	* fix bug where dont_count_slow_torrents could not be disabled
 	* fix fallocate hack on linux (fixes corruption on some architectures)
 	* fix auto-manage bug with announce to tracker/lsd/dht limits

bindings/python/src/session.cpp

@@ -615,6 +615,7 @@ void bind_session()
         .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)
+        .value("flag_merge_resume_http_seeds", add_torrent_params::flag_merge_resume_http_seeds)
     ;
     class_<cache_status>("cache_status")
 #ifndef TORRENT_NO_DEPRECATE

include/libtorrent/add_torrent_params.hpp

@@ -225,7 +225,11 @@ namespace libtorrent
 
 			// defaults to off and specifies whether tracker URLs loaded from
 			// resume data should be added to the trackers in the torrent or
-			// replace the trackers.
+			// replace the trackers. When replacing trackers (i.e. this flag is not
+			// set), any trackers passed in via add_torrent_params are also
+			// replaced by any trackers in the resume data. The default behavior is
+			// to have the resume data override the .torrent file _and_ the
+			// trackers added in add_torrent_params.
 			flag_merge_resume_trackers = 0x100,
 
 			// on by default and means that this torrent will be part of state
@@ -253,6 +257,16 @@ namespace libtorrent
 			// the torrent exempt from loading/unloading management.
 			flag_pinned = 0x2000,
 
+			// defaults to off and specifies whether web seed URLs loaded from
+			// resume data should be added to the ones in the torrent file or
+			// replace them. No distinction is made between the two different kinds
+			// of web seeds (`BEP 17`_ and `BEP 19`_). When replacing web seeds
+			// (i.e. when this flag is not set), any web seeds passed in via
+			// add_torrent_params are also replaced. The default behavior is to
+			// have any web seeds in the resume data take presedence over whatever
+			// is passed in here as well as the .torrent file.
+			flag_merge_resume_http_seeds = 0x2000,
+
 			// internal
 			default_flags = flag_pinned | flag_update_subscribe
 				| flag_auto_managed | flag_paused | flag_apply_ip_filter

include/libtorrent/torrent.hpp

@@ -1695,6 +1695,11 @@ namespace libtorrent
 		// present
 		bool m_use_resume_save_path:1;
 
+		// if set to true, add web seed URLs loaded from resume
+		// data into this torrent instead of replacing the ones from the .torrent
+		// file
+		bool m_merge_resume_http_seeds:1;
+
 #if TORRENT_USE_ASSERTS
 	public:
 		// set to false until we've loaded resume data

src/torrent.cpp

@@ -253,6 +253,7 @@ namespace libtorrent
 		, m_magnet_link(false)
 		, m_apply_ip_filter(p.flags & add_torrent_params::flag_apply_ip_filter)
 		, m_merge_resume_trackers(p.flags & add_torrent_params::flag_merge_resume_trackers)
+		, m_merge_resume_http_seeds(p.flags & add_torrent_params::flag_merge_resume_http_seeds)
 		, m_padding(0)
 		, m_priority(0)
 		, m_incomplete(0xffffff)
@@ -316,6 +317,9 @@ namespace libtorrent
 		if (!m_torrent_file)
 			m_torrent_file = (p.ti ? p.ti : boost::make_shared<torrent_info>(info_hash));
 
+		std::vector<web_seed_entry> const& web_seeds = m_torrent_file->web_seeds();
+		m_web_seeds.insert(m_web_seeds.end(), web_seeds.begin(), web_seeds.end());
+
 		// add web seeds from add_torrent_params
 		for (std::vector<std::string>::const_iterator i = p.url_seeds.begin()
 			, end(p.url_seeds.end()); i != end; ++i)
@@ -1945,9 +1949,6 @@ namespace libtorrent
 			update_piece_priorities();
 		}
 
-		std::vector<web_seed_entry> const& web_seeds = m_torrent_file->web_seeds();
-		m_web_seeds.insert(m_web_seeds.end(), web_seeds.begin(), web_seeds.end());
-
 #if TORRENT_USE_ASSERTS
 		m_resume_data_loaded = true;
 #endif
@@ -6914,7 +6915,17 @@ namespace libtorrent
 				prioritize_udp_trackers();
 		}
 
+		// if merge resume http seeds is not set, we need to clear whatever web
+		// seeds we loaded from the .torrent file, because we want whatever's in
+		// the resume file to take precedence. If there aren't even any fields in
+		// the resume data though, keep the ones from the torrent
 		bdecode_node url_list = rd.dict_find_list("url-list");
+		bdecode_node httpseeds = rd.dict_find_list("httpseeds");
+		if ((url_list || httpseeds) && !m_merge_resume_http_seeds)
+		{
+			m_web_seeds.clear();
+		}
+
 		if (url_list)
 		{
 			for (int i = 0; i < url_list.list_size(); ++i)
@@ -6926,7 +6937,6 @@ namespace libtorrent
 			}
 		}
 
-		bdecode_node httpseeds = rd.dict_find_list("httpseeds");
 		if (httpseeds)
 		{
 			for (int i = 0; i < httpseeds.list_size(); ++i)

test/test_resume.cpp

@@ -56,6 +56,7 @@ boost::shared_ptr<torrent_info> generate_torrent()
 	lt::create_torrent t(fs, 128 * 1024, 6);
 
 	t.add_tracker("http://torrent_file_tracker.com/announce");
+	t.add_url_seed("http://torrent_file_url_seed.com/");
 
 	int num = t.num_pieces();
 	TEST_CHECK(num > 0);
@@ -696,4 +697,45 @@ TORRENT_TEST(paused)
 	// and trackers for instance
 }
 
+TORRENT_TEST(url_seed_resume_data)
+{
+	// merge url seeds with resume data
+	fprintf(stderr, "flags: merge_resume_http_seeds\n");
+	lt::session ses;
+	torrent_handle h = test_resume_flags(ses,
+		add_torrent_params::flag_merge_resume_http_seeds);
+	std::set<std::string> us = h.url_seeds();
+	std::set<std::string> ws = h.http_seeds();
+
+	TEST_EQUAL(us.size(), 3);
+	TEST_EQUAL(std::count(us.begin(), us.end()
+		, "http://add_torrent_params_url_seed.com"), 1);
+	TEST_EQUAL(std::count(us.begin(), us.end()
+		, "http://torrent_file_url_seed.com/"), 1);
+	TEST_EQUAL(std::count(us.begin(), us.end()
+		, "http://resume_data_url_seed.com/"), 1);
+
+	TEST_EQUAL(ws.size(), 1);
+	TEST_EQUAL(std::count(ws.begin(), ws.end()
+		, "http://resume_data_http_seed.com"), 1);
+}
+
+TORRENT_TEST(resume_override_torrent)
+{
+	// resume data overrides the .torrent_file
+	fprintf(stderr, "flags: no merge_resume_http_seed\n");
+	lt::session ses;
+	torrent_handle h = test_resume_flags(ses,
+		add_torrent_params::flag_merge_resume_trackers);
+	std::set<std::string> us = h.url_seeds();
+	std::set<std::string> ws = h.http_seeds();
+
+	TEST_EQUAL(ws.size(), 1);
+	TEST_EQUAL(std::count(ws.begin(), ws.end()
+		, "http://resume_data_http_seed.com"), 1);
+
+	TEST_EQUAL(us.size(), 1);
+	TEST_EQUAL(std::count(us.begin(), us.end()
+		, "http://resume_data_url_seed.com/"), 1);
+}