added setting to ignore file modification time when loading resume files

ChangeLog

@@ -1,3 +1,4 @@
+	* added setting to ignore file modification time when loading resume files
 	* support more fine-grained torrent states between which peer sources it
 	  announces to
 	* supports calculating sha1 file-hashes when creating torrents

docs/manual.rst

@@ -3872,6 +3872,7 @@ session_settings
 		int default_peer_upload_rate;
 		int default_peer_download_rate;
 		bool broadcast_lsd;
+		bool ignore_resume_timestamps;
 	};
 
 ``user_agent`` this is the client identification to the tracker.
@@ -4503,6 +4504,15 @@ if ``broadcast_lsd`` is set to true, the local peer discovery
 broadcast its messages. This can be useful when running on networks
 that don't support multicast. It's off by default since it's inefficient.
 
+``ignore_resume_timestamps`` determines if the storage, when loading
+resume data files, should verify that the file modification time
+with the timestamps in the resume data. This defaults to false, which
+means timestamps are taken into account, and resume data is less likely
+to accepted (torrents are more likely to be fully checked when loaded).
+It might be useful to set this to true if your network is faster than your
+disk, and it would be faster to redownload potentially missed pieces than
+to go through the whole storage to look for them.
+
 pe_settings
 ===========
 

include/libtorrent/session_settings.hpp

@@ -211,6 +211,7 @@ namespace libtorrent
 			, default_peer_upload_rate(0)
 			, default_peer_download_rate(0)
 			, broadcast_lsd(false)
+			, ignore_resume_timestamps(false)
 		{}
 
 		// this is the user agent that will be sent to the tracker
@@ -810,6 +811,12 @@ namespace libtorrent
 		// default in order to avoid flooding networks for no good reason. If
 		// a network is known not to support multicast, this can be enabled
 		bool broadcast_lsd;
+
+		// when set to true, the file modification time is ignored when loading
+		// resume data. The resume data includes the expected timestamp of each
+		// file and is typically compared to make sure the files haven't changed
+		// since the last session
+		bool ignore_resume_timestamps;
 	};
 
 #ifndef TORRENT_DISABLE_DHT

src/session_impl.cpp

@@ -306,6 +306,7 @@ namespace aux {
 		TORRENT_SETTING(boolean, strict_end_game_mode)
 		TORRENT_SETTING(integer, default_peer_upload_rate)
 		TORRENT_SETTING(integer, default_peer_download_rate)
+		TORRENT_SETTING(boolean, ignore_resume_timestamps)
 	};
 
 #undef TORRENT_SETTING

src/storage.cpp

@@ -187,11 +187,17 @@ namespace libtorrent
 	// resume data. This is because full allocation will not move
 	// pieces, so any older version of the resume data will
 	// still be a correct subset of the actual data on disk.
+	enum flags_t
+	{
+		compact_mode = 1,
+		ignore_timestamps = 2
+	};
+
 	bool match_filesizes(
 		file_storage const& fs
 		, std::string p
 		, std::vector<std::pair<size_type, std::time_t> > const& sizes
-		, bool compact_mode
+		, int flags
 		, error_code& error)
 	{
 		if ((int)sizes.size() != fs.num_files())
@@ -220,17 +226,20 @@ namespace libtorrent
 				time = s.mtime;
 			}
 
-			if ((compact_mode && size != size_iter->first)
+			if (((flags & compact_mode) && size != size_iter->first)
-				|| (!compact_mode && size < size_iter->first))
+				|| (!(flags & compact_mode) && size < size_iter->first))
 			{
 				error = errors::mismatching_file_size;
 				return false;
 			}
+
+			if (flags & ignore_timestamps) continue;
+
 			// allow one second 'slack', because of FAT volumes
 			// in sparse mode, allow the files to be more recent
 			// than the resume data, but only by 5 minutes
-			if ((compact_mode && (time > size_iter->second + 1 || time < size_iter->second - 1)) ||
+			if (((flags & compact_mode) && (time > size_iter->second + 1 || time < size_iter->second - 1)) ||
-				(!compact_mode && (time > size_iter->second + 5 * 60 || time < size_iter->second - 1)))
+				(!(flags & compact_mode) && (time > size_iter->second + 5 * 60 || time < size_iter->second - 1)))
 			{
 				error = errors::mismatching_file_timestamp;
 				return false;
@@ -823,8 +832,10 @@ namespace libtorrent
 				}
 			}
 		}
-		return match_filesizes(files(), m_save_path, file_sizes
+		int flags = (full_allocation_mode ? 0 : compact_mode)
-			, !full_allocation_mode, error);
+			| (settings().ignore_resume_timestamps ? ignore_timestamps : 0);
+
+		return match_filesizes(files(), m_save_path, file_sizes, flags, error);
 
 	}