fix bug in auto disk cache size logic

Author: arvidn

ChangeLog

@@ -1,3 +1,4 @@
+	* fix bug in auto disk cache size logic
 	* fix issue with outgoing_interfaces setting, where bind() would be called twice
 	* add build option to disable share-mode
 	* support validation of HTTPS trackers

include/libtorrent/settings_pack.hpp

@@ -78,6 +78,7 @@ namespace aux {
 		, aux::session_settings_single_thread& sett
 		, std::vector<void(aux::session_impl::*)()>* callbacks = nullptr);
 	TORRENT_EXTRA_EXPORT void run_all_updates(aux::session_impl& ses);
+	TORRENT_EXTRA_EXPORT int default_int_value(int const name);
 
 	// converts a setting integer (from the enums string_types, int_types or
 	// bool_types) to a string, and vice versa.

src/disk_buffer_pool.cpp

@@ -292,7 +292,7 @@ namespace libtorrent {
 		if (cache_size < 0)
 		{
 			std::int64_t phys_ram = total_physical_ram();
-			if (phys_ram == 0) m_max_use = 1024;
+			if (phys_ram == 0) m_max_use = default_int_value(settings_pack::cache_size);
 			else
 			{
 				// this is the logic to calculate the automatic disk cache size

src/platform_util.cpp

@@ -112,7 +112,7 @@ namespace libtorrent {
 		MEMORYSTATUSEX ms;
 		ms.dwLength = sizeof(MEMORYSTATUSEX);
 		if (GlobalMemoryStatusEx(&ms))
-			ret = int(ms.ullTotalPhys);
+			ret = ms.ullTotalPhys;
 		else
 			ret = 0;
 #elif defined TORRENT_LINUX

src/settings_pack.cpp

@@ -531,6 +531,12 @@ constexpr int CLOSE_FILE_INTERVAL = 0;
 		return ret;
 	}
 
+	int default_int_value(int const name)
+	{
+		TORRENT_ASSERT((name & settings_pack::type_mask) == settings_pack::int_type_base);
+		return int_settings[name - settings_pack::int_type_base].default_value;
+	}
+
 	void apply_pack(settings_pack const* pack, aux::session_settings& sett
 		, aux::session_impl* ses)
 	{