Open fewer files concurrently at load time

For `MultiFileLoader` and `LoadMultipleCl2Sheet`, we now open one file
at a time.

This can help on platforms that limit the number of concurrently open
files, such as the PS2.

Source/engine/assets.hpp

@@ -212,12 +212,27 @@ struct AssetHandle {
 };
 #endif
 
+[[noreturn]] inline void FailedToOpenFileError(const char *path, const char *error)
+{
+	app_fatal(StrCat("Failed to open file:\n", path, "\n\n", error));
+}
+
+inline bool ValidatAssetRef(const char *path, const AssetRef &ref)
+{
+	if (ref.ok())
+		return true;
+	if (!HeadlessMode) {
+		FailedToOpenFileError(path, ref.error());
+	}
+	return false;
+}
+
 inline bool ValidateHandle(const char *path, const AssetHandle &handle)
 {
 	if (handle.ok())
 		return true;
 	if (!HeadlessMode) {
-		app_fatal(StrCat("Failed to open file:\n", path, "\n\n", handle.error()));
+		FailedToOpenFileError(path, handle.error());
 	}
 	return false;
 }

Source/engine/load_cl2.hpp

@@ -1,12 +1,15 @@
 #pragma once
 
+#include <array>
 #include <cstdint>
+#include <cstring>
 
 #include <function_ref.hpp>
 
 #include "appfat.h"
 #include "engine/clx_sprite.hpp"
 #include "engine/load_file.hpp"
+#include "mpq/mpq_common.hpp"
 #include "utils/cl2_to_clx.hpp"
 #include "utils/endian.hpp"
 #include "utils/pointer_value_union.hpp"
@@ -26,17 +29,23 @@ OwnedClxSpriteListOrSheet LoadCl2ListOrSheet(const char *pszName, PointerOrValue
 template <size_t MaxCount>
 OwnedClxSpriteSheet LoadMultipleCl2Sheet(tl::function_ref<const char *(size_t)> filenames, size_t count, uint16_t width)
 {
-	StaticVector<AssetHandle, MaxCount> files;
+	StaticVector<std::array<char, MaxMpqPathSize>, MaxCount> paths;
+	StaticVector<AssetRef, MaxCount> files;
 	StaticVector<size_t, MaxCount> fileSizes;
 	const size_t sheetHeaderSize = 4 * count;
 	size_t totalSize = sheetHeaderSize;
 	for (size_t i = 0; i < count; ++i) {
-		const char *filename = filenames(i);
-		size_t size;
-		files.emplace_back(OpenAsset(filename, size));
+		{
+			const char *path = filenames(i);
+			paths.emplace_back();
+			memcpy(paths.back().data(), path, strlen(path) + 1);
+		}
+		const char *path = paths.back().data();
+		files.emplace_back(FindAsset(path));
 		if (!files.back().ok()) {
-			app_fatal(StrCat("Failed to open file:\n", filename, "\n\n", files.back().error()));
+			FailedToOpenFileError(path, files.back().error());
 		}
+		const size_t size = files.back().size();
 		fileSizes.emplace_back(size);
 		totalSize += size;
 	}
@@ -47,8 +56,10 @@ OwnedClxSpriteSheet LoadMultipleCl2Sheet(tl::function_ref<const char *(size_t)>
 	size_t accumulatedSize = sheetHeaderSize;
 	for (size_t i = 0; i < count; ++i) {
 		const size_t size = fileSizes[i];
-		if (!files[i].read(&data[accumulatedSize], size))
-			app_fatal(StrCat("Read failed:\n", files[i].error()));
+		AssetHandle handle = OpenAsset(std::move(files[i]));
+		if (!handle.ok() || !handle.read(&data[accumulatedSize], size)) {
+			FailedToOpenFileError(paths[i].data(), handle.error());
+		}
 		WriteLE32(&data[i * 4], accumulatedSize);
 #ifndef UNPACKED_MPQS
 		[[maybe_unused]] const uint16_t numLists = Cl2ToClx(&data[accumulatedSize], size, frameWidth);

Source/engine/load_file.hpp

@@ -3,6 +3,7 @@
 #include <array>
 #include <cstddef>
 #include <cstdint>
+#include <cstring>
 #include <memory>
 
 #include <fmt/core.h>
@@ -10,6 +11,7 @@
 #include "appfat.h"
 #include "diablo.h"
 #include "engine/assets.hpp"
+#include "mpq/mpq_common.hpp"
 #include "utils/static_vector.hpp"
 #include "utils/stdcompat/cstddef.hpp"
 #include "utils/str_cat.hpp"
@@ -99,18 +101,24 @@ struct MultiFileLoader {
 	[[nodiscard]] std::unique_ptr<byte[]> operator()(size_t numFiles, PathFn &&pathFn, uint32_t *outOffsets,
 	    FilterFn filterFn = DefaultFilterFn {})
 	{
-		StaticVector<AssetHandle, MaxFiles> files;
+		StaticVector<std::array<char, MaxMpqPathSize>, MaxFiles> paths;
+		StaticVector<AssetRef, MaxFiles> files;
 		StaticVector<uint32_t, MaxFiles> sizes;
 		size_t totalSize = 0;
 		for (size_t i = 0, j = 0; i < numFiles; ++i) {
 			if (!filterFn(i))
 				continue;
-			size_t size;
-			const char *path = pathFn(i);
-			files.emplace_back(OpenAsset(path, size));
-			if (!ValidateHandle(path, files.back()))
+			{
+				const char *path = pathFn(i);
+				paths.emplace_back();
+				memcpy(paths.back().data(), path, strlen(path) + 1);
+			}
+			const char *path = paths.back().data();
+			files.emplace_back(FindAsset(path));
+			if (!ValidatAssetRef(path, files.back()))
 				return nullptr;
 
+			const size_t size = files.back().size();
 			sizes.emplace_back(static_cast<uint32_t>(size));
 			outOffsets[j] = static_cast<uint32_t>(totalSize);
 			totalSize += size;
@@ -121,7 +129,10 @@ struct MultiFileLoader {
 		for (size_t i = 0, j = 0; i < numFiles; ++i) {
 			if (!filterFn(i))
 				continue;
-			files[j].read(&buf[outOffsets[j]], sizes[j]);
+			AssetHandle handle = OpenAsset(std::move(files[j]));
+			if (!handle.ok() || !handle.read(&buf[outOffsets[j]], sizes[j])) {
+				FailedToOpenFileError(paths[j].data(), handle.error());
+			}
 			++j;
 		}
 		return buf;