fs: implement fs::get_temp_dir() (Win32)

Trying to workaround issues with sparse files (#10231)

Utilities/File.cpp

@@ -1729,6 +1729,32 @@ const std::string& fs::get_cache_dir()
 	return s_dir;
 }
 
+const std::string& fs::get_temp_dir()
+{
+	static const std::string s_dir = []
+	{
+		std::string dir;
+
+#ifdef _WIN32
+		wchar_t buf[MAX_PATH + 2]{};
+		if (GetTempPathW(MAX_PATH + 1, buf) - 1 > MAX_PATH)
+		{
+			MessageBoxA(nullptr, fmt::format("GetTempPath() failed: error %u.", GetLastError()).c_str(), "fs::get_temp_dir()", MB_ICONERROR);
+			return dir; // empty
+		}
+
+		to_utf8(dir, buf);
+#else
+		// TODO
+		dir = get_cache_dir();
+#endif
+
+		return dir;
+	}();
+
+	return s_dir;
+}
+
 bool fs::remove_all(const std::string& path, bool remove_root)
 {
 	if (const auto root_dir = dir(path))

Utilities/File.h

@@ -636,6 +636,9 @@ namespace fs
 	// Get common cache directory
 	const std::string& get_cache_dir();
 
+	// Temporary directory
+	const std::string& get_temp_dir();
+
 	// Unique pending file creation destined to be renamed to the destination file
 	struct pending_file
 	{

rpcs3/Emu/Memory/vm.cpp

@@ -1128,7 +1128,7 @@ namespace vm
 		if (flags & page_size_4k || flags & preallocated)
 		{
 			// Special path for whole-allocated areas allowing 4k granularity
-			m_common = std::make_shared<utils::shm>(size, fs::get_cache_dir() + std::to_string(utils::get_unique_tsc()));
+			m_common = std::make_shared<utils::shm>(size);
 			m_common->map_critical(vm::base(addr), utils::protection::no);
 			m_common->map_critical(vm::get_super_ptr(addr));
 		}
@@ -1632,7 +1632,7 @@ namespace vm
 
 	inline namespace ps3_
 	{
-		static utils::shm s_hook{0x800000000, fs::get_cache_dir() + "hook.dat"};
+		static utils::shm s_hook{0x800000000, fmt::format("%s/rpcs3_vm_hook_%s", fs::get_temp_dir(), fmt::base57(utils::get_unique_tsc()))};
 
 		void init()
 		{