assets.cpp: Switch to C FILE for UNPACKED_MPQS

Eliminates some of the (minor) overhead of fstream.

Source/engine/assets.cpp

@@ -144,7 +144,7 @@ AssetRef FindAsset(const char *filename)
 AssetHandle OpenAsset(AssetRef &&ref, bool threadsafe)
 {
 #ifdef UNPACKED_MPQS
-	return AssetHandle { CreateFileStream(ref.path.c_str(), std::fstream::in | std::fstream::binary) };
+	return AssetHandle { OpenFile(ref.path.c_str(), "rb") };
 #else
 	if (ref.archive != nullptr)
 		return AssetHandle { SDL_RWops_FromMpqFile(*ref.archive, ref.fileNumber, ref.filename, threadsafe) };

Source/engine/assets.hpp

@@ -2,6 +2,7 @@
 
 #include <cstddef>
 #include <cstdint>
+#include <cstdio>
 #include <string>
 
 #include <SDL.h>
@@ -40,23 +41,47 @@ struct AssetRef {
 };
 
 struct AssetHandle {
-	std::optional<std::fstream> handle;
+	FILE *handle = nullptr;
+
+	AssetHandle() = default;
+
+	AssetHandle(FILE *handle)
+	    : handle(handle)
+	{
+	}
+
+	AssetHandle(AssetHandle &&other) noexcept
+	    : handle(other.handle)
+	{
+		other.handle = nullptr;
+	}
+
+	AssetHandle &operator=(AssetHandle &&other) noexcept
+	{
+		handle = other.handle;
+		other.handle = nullptr;
+		return *this;
+	}
+
+	~AssetHandle()
+	{
+		if (handle != nullptr)
+			std::fclose(handle);
+	}
 
 	[[nodiscard]] bool ok() const
 	{
-		return handle && !handle->fail();
+		return handle != nullptr && std::ferror(handle) == 0;
 	}
 
 	bool read(void *buffer, size_t len)
 	{
-		handle->read(static_cast<char *>(buffer), len);
-		return !handle->fail();
+		return std::fread(buffer, len, 1, handle) == 1;
 	}
 
 	bool seek(std::ios::pos_type pos)
 	{
-		handle->seekg(pos);
-		return !handle->fail();
+		return std::fseek(handle, pos, SEEK_SET) == 0;
 	}
 
 	[[nodiscard]] const char *error() const

Source/utils/file_util.cpp

@@ -225,4 +225,20 @@ std::optional<std::fstream> CreateFileStream(const char *path, std::ios::openmod
 #endif
 }
 
+FILE *OpenFile(const char *path, const char *mode)
+{
+#if (defined(_WIN64) || defined(_WIN32)) && !defined(NXDK)
+	std::unique_ptr<wchar_t[]> pathUtf16;
+	std::unique_ptr<wchar_t[]> modeUtf16;
+	if ((pathUtf16 = ToWideChar(path)) == nullptr
+	    || (modeUtf16 = ToWideChar(mode)) == nullptr) {
+		LogError("UTF-8 -> UTF-16 conversion error code {}", ::GetLastError());
+		return {};
+	}
+	return _wfopen(pathUtf16.get(), modeUtf16.get());
+#else
+	return std::fopen(path, mode);
+#endif
+}
+
 } // namespace devilution

Source/utils/file_util.h

@@ -23,6 +23,7 @@ bool GetFileSize(const char *path, std::uintmax_t *size);
 bool ResizeFile(const char *path, std::uintmax_t size);
 void RemoveFile(const char *path);
 std::optional<std::fstream> CreateFileStream(const char *path, std::ios::openmode mode);
+FILE *OpenFile(const char *path, const char *mode);
 
 #if (defined(_WIN64) || defined(_WIN32)) && !defined(NXDK)
 std::unique_ptr<wchar_t[]> ToWideChar(string_view path);