make resume_data_flags type safe

bindings/python/src/converters.cpp

@@ -299,6 +299,7 @@ void bind_converters()
     to_python_converter<lt::file_open_mode_t, from_bitfield_flag<lt::file_open_mode_t>>();
     to_python_converter<lt::picker_flags_t, from_bitfield_flag<lt::picker_flags_t>>();
     to_python_converter<lt::alert_category_t, from_bitfield_flag<lt::alert_category_t>>();
+    to_python_converter<lt::resume_data_flags_t, from_bitfield_flag<lt::resume_data_flags_t>>();
 
     // work-around types
     to_python_converter<lt::aux::noexcept_movable<lt::address>, address_to_tuple<
@@ -348,4 +349,5 @@ void bind_converters()
     to_bitfield_flag<lt::file_open_mode_t>();
     to_bitfield_flag<lt::picker_flags_t>();
     to_bitfield_flag<lt::alert_category_t>();
+    to_bitfield_flag<lt::resume_data_flags_t>();
 }

bindings/python/src/torrent_handle.cpp

@@ -428,6 +428,7 @@ void add_piece(torrent_handle& th, piece_index_t piece, char const *data, int fl
 }
 
 class dummy {};
+class dummy4 {};
 
 using by_value = return_value_policy<return_by_value>;
 void bind_torrent_handle()
@@ -603,11 +604,12 @@ void bind_torrent_handle()
         .value("graceful_pause", torrent_handle::graceful_pause)
     ;
 
-    enum_<torrent_handle::save_resume_flags_t>("save_resume_flags_t")
-        .value("flush_disk_cache", torrent_handle::flush_disk_cache)
-        .value("save_info_dict", torrent_handle::save_info_dict)
-        .value("only_if_modified", torrent_handle::only_if_modified)
-    ;
+    {
+    scope s = class_<dummy4>("save_resume_flags_t");
+    s.attr("flush_disk_cache") = torrent_handle::flush_disk_cache;
+    s.attr("save_info_dict") = torrent_handle::save_info_dict;
+    s.attr("only_if_modified") = torrent_handle::only_if_modified;
+    }
 
     enum_<torrent_handle::deadline_flags>("deadline_flags")
         .value("alert_when_available", torrent_handle::alert_when_available)

include/libtorrent/torrent.hpp

@@ -529,7 +529,7 @@ namespace libtorrent {
 		bool is_paused() const;
 		bool is_torrent_paused() const { return m_paused; }
 		void force_recheck();
-		void save_resume_data(int flags);
+		void save_resume_data(resume_data_flags_t flags);
 
 		bool need_save_resume_data() const { return m_need_save_resume_data; }
 
@@ -1532,7 +1532,7 @@ namespace libtorrent {
 
 		// these are the flags sent in on a call to save_resume_data
 		// we need to save them to check them in write_resume_data
-		std::uint32_t m_save_resume_flags:8;
+		resume_data_flags_t m_save_resume_flags;
 
 // ----
 

include/libtorrent/torrent_handle.hpp

@@ -57,10 +57,12 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/torrent_flags.hpp"
 #include "libtorrent/peer_info.hpp" // for peer_source_flags_t
 
-namespace libtorrent { namespace aux {
+namespace libtorrent {
+namespace aux {
 
-		struct session_impl;
-	}
+	struct session_impl;
+
+}
 
 	class entry;
 	struct open_file_state;
@@ -80,6 +82,9 @@ namespace libtorrent { namespace aux {
 	void TORRENT_NO_RETURN throw_invalid_handle();
 #endif
 
+	struct resume_data_flags_tag;
+	using resume_data_flags_t = flags::bitfield_flag<std::uint8_t, resume_data_flags_tag>;
+
 	// holds the state of a block in a piece. Who we requested
 	// it from and how far along we are at downloading it.
 	struct TORRENT_EXPORT block_info
@@ -611,35 +616,27 @@ namespace libtorrent { namespace aux {
 		// will start connecting to peers again, as normal.
 		void force_recheck() const;
 
-		// flags used in the save_resume_data call to control additional
-		// actions or fields to save.
-		enum save_resume_flags_t
-		{
-			// the disk cache will be flushed before creating the resume data.
-			// This avoids a problem with file timestamps in the resume data in
-			// case the cache hasn't been flushed yet.
-			flush_disk_cache = 1,
+		// the disk cache will be flushed before creating the resume data.
+		// This avoids a problem with file timestamps in the resume data in
+		// case the cache hasn't been flushed yet.
+		static constexpr resume_data_flags_t flush_disk_cache{1};
 
-			// the resume data will contain the metadata from the torrent file as
-			// well. This is default for any torrent that's added without a
-			// torrent file (such as a magnet link or a URL).
-			save_info_dict = 2,
+		// the resume data will contain the metadata from the torrent file as
+		// well. This is default for any torrent that's added without a
+		// torrent file (such as a magnet link or a URL).
+		static constexpr resume_data_flags_t save_info_dict{2};
 
-			// if nothing significant has changed in the torrent since the last
-			// time resume data was saved, fail this attempt. Significant changes
-			// primarily include more data having been downloaded, file or piece
-			// priorities having changed etc. If the resume data doesn't need
-			// saving, a save_resume_data_failed_alert is posted with the error
-			// resume_data_not_modified.
-			only_if_modified = 4
-		};
+		// if nothing significant has changed in the torrent since the last
+		// time resume data was saved, fail this attempt. Significant changes
+		// primarily include more data having been downloaded, file or piece
+		// priorities having changed etc. If the resume data doesn't need
+		// saving, a save_resume_data_failed_alert is posted with the error
+		// resume_data_not_modified.
+		static constexpr resume_data_flags_t only_if_modified{4};
 
 		// ``save_resume_data()`` asks libtorrent to generate fast-resume data for
 		// this torrent.
 		//
-		// The ``flags`` argument is a bitmask of flags ORed together. see
-		// save_resume_flags_t
-		//
 		// This operation is asynchronous, ``save_resume_data`` will return
 		// immediately. The resume data is delivered when it's done through an
 		// save_resume_data_alert.
@@ -760,7 +757,7 @@ namespace libtorrent { namespace aux {
 		//	the alert, but it has not been received yet. Those torrents would
 		//	report that they don't need to save resume data again, and skipped by
 		//	the initial loop, and thwart the counter otherwise.
-		void save_resume_data(int flags = 0) const;
+		void save_resume_data(resume_data_flags_t flags = {}) const;
 
 		// This function returns true if any whole chunk has been downloaded
 		// since the torrent was first loaded or since the last time the resume

src/torrent.cpp

@@ -194,7 +194,7 @@ namespace libtorrent {
 		, m_stop_when_ready(p.flags & torrent_flags::stop_when_ready)
 		, m_need_save_resume_data(p.flags & torrent_flags::need_save_resume)
 		, m_max_uploads((1 << 24) - 1)
-		, m_save_resume_flags(0)
+		, m_save_resume_flags()
 		, m_num_uploads(0)
 		, m_need_connect_boost(true)
 		, m_lsd_seq(0)
@@ -8326,7 +8326,7 @@ namespace libtorrent {
 	// TODO: add a flag to ignore stats, and only care about resume data for
 	// content. For unchanged files, don't trigger a load of the metadata
 	// just to save an empty resume data file
-	void torrent::save_resume_data(int const flags)
+	void torrent::save_resume_data(resume_data_flags_t const flags)
 	{
 		TORRENT_ASSERT(is_single_thread());
 		INVARIANT_CHECK;
@@ -8346,7 +8346,7 @@ namespace libtorrent {
 		}
 
 		m_need_save_resume_data = false;
-		m_save_resume_flags = aux::numeric_cast<std::uint8_t>(flags);
+		m_save_resume_flags = flags;
 		state_updated();
 
 		if ((flags & torrent_handle::flush_disk_cache) && m_storage)

src/torrent_handle.cpp

@@ -58,6 +58,10 @@ using libtorrent::aux::session_impl;
 
 namespace libtorrent {
 
+	constexpr resume_data_flags_t torrent_handle::flush_disk_cache;
+	constexpr resume_data_flags_t torrent_handle::save_info_dict;
+	constexpr resume_data_flags_t torrent_handle::only_if_modified;
+
 #ifndef BOOST_NO_EXCEPTIONS
 	void TORRENT_NO_RETURN throw_invalid_handle()
 	{
@@ -344,7 +348,7 @@ namespace libtorrent {
 #endif
 	}
 
-	void torrent_handle::save_resume_data(int f) const
+	void torrent_handle::save_resume_data(resume_data_flags_t f) const
 	{
 		async_call(&torrent::save_resume_data, f);
 	}