Implement reading from RomFS

src/core/filesystem/archive_ncch.cpp

@@ -0,0 +1,62 @@
+#include "fs/archive_ncch.hpp"
+#include <memory>
+
+bool SelfNCCHArchive::openFile(const FSPath& path) {
+	if (path.type != PathType::Binary) {
+		printf("Invalid SelfNCCH path type");
+		return false;
+	}
+
+	// We currently only know how to read from an NCCH's RomFS
+	if (mem.read32(path.pointer) != 0) {
+		Helpers::panic("Read from NCCH's non-RomFS section!");
+	}
+
+	return true;
+}
+
+ArchiveBase* SelfNCCHArchive::openArchive(FSPath& path) {
+	if (path.type != PathType::Empty) {
+		printf("Invalid path type for SelfNCCH archive: %d\n", path.type);
+		return nullptr;
+	}
+
+	return this;
+}
+
+std::optional<u32> SelfNCCHArchive::readFile(FileSession* file, u64 offset, u32 size, u32 dataPointer) {
+	auto cxi = mem.getCXI();
+	if (cxi == nullptr) {
+		Helpers::panic("Tried to read file from non-existent CXI");
+		return std::nullopt;
+	}
+
+	if (!cxi->hasRomFS()) {
+		Helpers::panic("Tried to read from CXI without RomFS");
+	}
+
+	const u32 romFSSize = cxi->romFS.size;
+	const u32 romFSOffset = cxi->romFS.offset;
+	if ((offset >> 32) || (offset >= romFSSize) || (offset + size >= romFSSize)) {
+		Helpers::panic("Tried to read from SelfNCCH with too big of an offset");
+	}
+
+	IOFile& ioFile = mem.CXIFile;
+	if (!ioFile.seek(cxi->fileOffset + romFSOffset + offset)) {
+		Helpers::panic("Failed to seek while reading from RomFS");
+	}
+
+	std::unique_ptr<u8[]> data(new u8[size]);
+	auto [success, bytesRead] = ioFile.readBytes(&data[0], size);
+
+	if (!success) {
+		Helpers::panic("Failed to read from RomFS");
+	}
+
+	for (u64 i = 0; i < bytesRead; i++) {
+		mem.write8(dataPointer + i, data[i]);
+		printf("%x\n", data[i]);
+	}
+
+	return bytesRead;
+}