back-port fix adding empty file as torrent

src/session_impl.cpp

@@ -4929,6 +4929,12 @@ retry:
 			params.ti = t;
 		}
 
+		if (params.ti && !params.ti->is_valid())
+		{
+			ec = errors::no_metadata;
+			return ptr_t();
+		}
+
 		if (params.ti && params.ti->is_valid() && params.ti->num_files() == 0)
 		{
 			ec = errors::no_files_in_torrent;

test/test_session.cpp

@@ -40,6 +40,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/performance_counters.hpp"
 #include "libtorrent/bdecode.hpp"
 #include "libtorrent/bencode.hpp"
+#include "libtorrent/torrent_info.hpp"
 
 using namespace libtorrent;
 namespace lt = libtorrent;
@@ -59,7 +60,6 @@ TORRENT_TEST(session)
 	// verify that we get the appropriate performance warning because
 	// we're allowing a larger queue than we have cache.
 
-
 	alert const* a;
 	for (;;)
 	{
@@ -93,6 +93,23 @@ TORRENT_TEST(session)
 	// the session object
 }
 
+TORRENT_TEST(load_empty_file)
+{
+	settings_pack p;
+	p.set_int(settings_pack::alert_mask, ~0);
+	lt::session ses(p);
+
+	add_torrent_params atp;
+	error_code ignore_errors;
+	atp.ti = boost::make_shared<torrent_info>("", 0, ignore_errors);
+	atp.save_path = ".";
+	error_code ec;
+	torrent_handle h = ses.add_torrent(atp, ec);
+
+	TEST_CHECK(!h.is_valid());
+	TEST_CHECK(ec == error_code(errors::no_metadata))
+}
+
 TORRENT_TEST(session_stats)
 {
 	std::vector<stats_metric> stats = session_stats_metrics();
@@ -107,6 +124,7 @@ TORRENT_TEST(session_stats)
 		TEST_EQUAL(stats[i].value_index, i);
 	}
 }
+
 #if __cplusplus >= 201103L
 
 template <typename Set, typename Save, typename Default, typename Load>

test/test_torrent_info.cpp

@@ -854,6 +854,26 @@ TORRENT_TEST(resolve_duplicates)
 		test_resolve_duplicates(i);
 }
 
+TORRENT_TEST(empty_file)
+{
+	error_code ec;
+	boost::shared_ptr<torrent_info> ti = boost::make_shared<torrent_info>("", 0, ec);
+	TEST_CHECK(ec);
+}
+
+TORRENT_TEST(empty_file2)
+{
+	try
+	{
+		boost::shared_ptr<torrent_info> ti = boost::make_shared<torrent_info>("", 0);
+		TEST_ERROR("expected exception thrown");
+	}
+	catch (libtorrent_exception& e)
+	{
+		printf("Expected error: %s\n", e.error().message().c_str());
+	}
+}
+
 TORRENT_TEST(copy)
 {
 	using namespace libtorrent;