Load console identity from NAND setting.txt (#164)

runtime/include/nand_settings.h

@@ -0,0 +1,69 @@
+#pragma once
+
+#include <array>
+#include <cstdint>
+#include <filesystem>
+#include <fstream>
+#include <map>
+#include <optional>
+#include <string>
+#include <utility>
+
+namespace RuntimeNandSettings {
+
+using Settings = std::map<std::string, std::string>;
+
+// Wii setting.txt is a 256-byte buffer encrypted with a rotating XOR key.
+inline std::optional<Settings> Read(const std::filesystem::path& nandRoot) {
+    std::ifstream input(nandRoot / "title/00000001/00000002/data/setting.txt",
+                        std::ios::binary);
+    std::array<uint8_t, 256> bytes{};
+    if (!input.read(reinterpret_cast<char*>(bytes.data()), bytes.size())) {
+        return std::nullopt;
+    }
+    uint32_t key = 0x73B5DBFAu;
+    std::string decoded;
+    for (const uint8_t byte : bytes) {
+        const char value = static_cast<char>(byte ^ static_cast<uint8_t>(key));
+        key = (key << 1) | (key >> 31);
+        if (value == '\0') {
+            break;
+        }
+        if (value != '\r') {
+            decoded += value;
+        }
+    }
+    Settings settings;
+    for (size_t start = 0; start < decoded.size();) {
+        const size_t end = decoded.find('\n', start);
+        const std::string line = decoded.substr(start, end - start);
+        const size_t equals = line.find('=');
+        if (equals != std::string::npos && equals != 0) {
+            settings.emplace(line.substr(0, equals), line.substr(equals + 1));
+        }
+        if (end == std::string::npos) {
+            break;
+        }
+        start = end + 1;
+    }
+    return settings;
+}
+
+inline bool HasIdentity(const Settings& settings) {
+    const auto serial = settings.find("SERNO");
+    if (serial == settings.end() || serial->second.empty() || serial->second.size() > 9 ||
+        serial->second.find_first_not_of("0123456789") != std::string::npos ||
+        serial->second.find_first_not_of('0') == std::string::npos) {
+        return false;
+    }
+    for (const auto& field : {std::pair{"CODE", 5u}, {"AREA", 3u}, {"GAME", 2u}}) {
+        const auto value = settings.find(field.first);
+        if (value == settings.end() || value->second.empty() ||
+            value->second.size() > field.second) {
+            return false;
+        }
+    }
+    return true;
+}
+
+} // namespace RuntimeNandSettings