Start adding SD card support

src/core/fs/archive_sdmc.cpp

@@ -1,6 +1,8 @@
 #include "fs/archive_sdmc.hpp"
 #include <memory>
 
+namespace fs = std::filesystem;
+
 HorizonResult SDMCArchive::createFile(const FSPath& path, u64 size) {
 	Helpers::panic("[SDMC] CreateFile not yet supported");
 	return Result::Success;
@@ -12,13 +14,48 @@ HorizonResult SDMCArchive::deleteFile(const FSPath& path) {
 }
 
 FileDescriptor SDMCArchive::openFile(const FSPath& path, const FilePerms& perms) {
-	printf("SDMCArchive::OpenFile: Failed");
+	if (path.type == PathType::ASCII) {
+		if (!isPathSafe<PathType::ASCII>(path)) {
+			Helpers::panic("Unsafe path in SaveData::OpenFile");
+		}
+
+		if (perms.raw == 0 || (perms.create() && !perms.write())) {
+			Helpers::panic("[SaveData] Unsupported flags for OpenFile");
+		}
+
+		fs::path p = IOFile::getAppData() / "SDMC";
+		p += fs::path(path.string).make_preferred();
+
+		const char* permString = perms.write() ? "r+b" : "rb";
+
+		if (fs::exists(p)) {  // Return file descriptor if the file exists
+			IOFile file(p.string().c_str(), permString);
+			return file.isOpen() ? file.getHandle() : FileError;
+		} else {
+			// If the file is not found, create it if the create flag is on
+			if (perms.create()) {
+				IOFile file(p.string().c_str(), "wb");  // Create file
+				file.close();                           // Close it
+
+				file.open(p.string().c_str(), permString);  // Reopen with proper perms
+				return file.isOpen() ? file.getHandle() : FileError;
+			} else {
+				return FileError;
+			}
+		}
+	}
+
+	Helpers::panic("SDMCArchive::OpenFile: Failed");
 	return FileError;
 }
 
 Rust::Result<ArchiveBase*, HorizonResult> SDMCArchive::openArchive(const FSPath& path) {
-	printf("SDMCArchive::OpenArchive: Failed\n");
-	return Err(Result::FS::NotFormatted);
+	// TODO: Fail here if the SD is disabled in the connfig.
+	if (path.type != PathType::Empty) {
+		Helpers::panic("Unimplemented path type for SDMC::OpenArchive");
+	}
+
+	return Ok((ArchiveBase*)this);
 }
 
 std::optional<u32> SDMCArchive::readFile(FileSession* file, u64 offset, u32 size, u32 dataPointer) {