csnum fix

runtime/CMakeLists.txt

@@ -289,6 +289,11 @@ target_include_directories(mkw_nand_settings_tests PRIVATE "${CMAKE_CURRENT_LIST
 target_compile_features(mkw_nand_settings_tests PRIVATE cxx_std_17)
 add_test(NAME mkw_nand_settings_tests COMMAND mkw_nand_settings_tests)
 
+add_executable(mkw_sc_serial_tests "${CMAKE_CURRENT_LIST_DIR}/tests/sc_serial_tests.cpp")
+target_include_directories(mkw_sc_serial_tests PRIVATE "${CMAKE_CURRENT_LIST_DIR}/include")
+target_compile_features(mkw_sc_serial_tests PRIVATE cxx_std_17)
+add_test(NAME mkw_sc_serial_tests COMMAND mkw_sc_serial_tests)
+
 # The input expression engine is self-contained, so it can be exercised without
 # linking the runtime or SDL.
 add_executable(mkw_input_expr_tests

runtime/include/sc_serial_contract.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include <charconv>
+#include <cstddef>
+#include <cstdint>
+#include <string_view>
+#include <system_error>
+
+namespace RuntimeScSerial {
+
+// SCGetProductSN's output is a u32, not a character buffer. DWC loads
+// that word and formats it with the product code to construct csnum.
+template <typename RangeValidator, typename WordWriter>
+uint32_t Write(std::string_view serial, uint32_t address,
+               RangeValidator&& contains, WordWriter&& write32) {
+    if (serial.empty() || serial.size() > 9 ||
+        serial.find_first_not_of("0123456789") != std::string_view::npos) return 0;
+    uint32_t number = 0;
+    const auto parsed = std::from_chars(serial.data(), serial.data() + serial.size(), number);
+    if (parsed.ec != std::errc{} || parsed.ptr != serial.data() + serial.size() ||
+        !address || !contains(address, sizeof(uint32_t))) return 0;
+    write32(address, number);
+    return 1;
+}
+
+} // namespace RuntimeScSerial

runtime/src/hle/sc.cpp

@@ -1,6 +1,7 @@
 #include "hle_stubs.h"
 
 #include "console_identity.h"
+#include "sc_serial_contract.h"
 #include <cstdlib>
 #include <cstddef>
 #include <cstdint>
@@ -97,12 +98,9 @@ PPC_NATIVE_OVERRIDE(801B2424, SCGetProductCode_HLE, uint32_t, (), ());
 extern "C" uint32_t SCGetProductSN_HLE(uint32_t serialAddress)
 {
     const std::string& serial = RuntimeConsoleIdentity::Current().serial;
-    if (!serialAddress || !Memory::Contains(serialAddress, serial.size() + 1)) {
-        return 0;
-    }
-    std::memcpy(Memory::GetPointer(serialAddress, serial.size() + 1),
-                serial.c_str(), serial.size() + 1);
-    return 1;
+    return RuntimeScSerial::Write(serial, serialAddress,
+        [](uint32_t address, size_t size) { return Memory::Contains(address, size); },
+        [](uint32_t address, uint32_t value) { Memory::Write32(address, value); });
 }
 
 PPC_NATIVE_OVERRIDE(801B2460, SCGetProductSN_HLE, uint32_t, (uint32_t serialAddress), (serialAddress));

runtime/tests/sc_serial_tests.cpp

@@ -0,0 +1,81 @@
+#include "sc_serial_contract.h"
+#include "nand_settings.h"
+
+#include <algorithm>
+#include <array>
+#include <iostream>
+#include <iomanip>
+#include <stdexcept>
+#include <string>
+
+static void Require(bool condition, const char* message) {
+    if (!condition) throw std::runtime_error(message);
+}
+
+static uint32_t ReadWord(const unsigned char* bytes) {
+    return (uint32_t(bytes[0]) << 24) | (uint32_t(bytes[1]) << 16) |
+           (uint32_t(bytes[2]) << 8) | uint32_t(bytes[3]);
+}
+
+int main(int argc, char** argv) {
+    try {
+        // Feed real generator + SC ABI outputs to the upstream bot decoder.
+        // Usage: mkw_sc_serial_tests --timestamp-vectors <unix-seconds> ...
+        if (argc > 1 && std::string(argv[1]) == "--timestamp-vectors") {
+            for (int i = 2; i < argc; ++i) {
+                const auto timestamp = std::stoll(argv[i]);
+                const auto serial = RuntimeNandSettings::GenerateSerial(static_cast<std::time_t>(timestamp));
+                std::array<unsigned char, 4> output{};
+                Require(RuntimeScSerial::Write(serial, 4,
+                    [](uint32_t address, size_t size) { return address == 4 && size == 4; },
+                    [&](uint32_t, uint32_t value) {
+                        for (unsigned j = 0; j < 4; ++j)
+                            output[j] = static_cast<unsigned char>(value >> (24 - 8 * j));
+                    }) == 1, "Generated serial must pass SC ABI");
+                std::cout << timestamp << '\t' << serial << "\tLEH"
+                          << std::setfill('0') << std::setw(9) << ReadWord(output.data()) << '\n';
+            }
+            return 0;
+        }
+        // Reproduce the reported csnums from the old string-writing override.
+        const unsigned char old7886[] = {'7', '8', '8', '6'};
+        const unsigned char old7618[] = {'7', '6', '1', '8'};
+        Require(ReadWord(old7886) == 926431286, "Reproduce shared LEH926431286");
+        Require(ReadWord(old7618) == 926298424, "Reproduce shared LEH926298424");
+
+        std::array<unsigned char, 16> memory;
+        size_t available = 4;
+        unsigned writes = 0;
+        const auto contains = [&](uint32_t address, size_t size) {
+            return address == 4 && size <= available;
+        };
+        const auto write32 = [&](uint32_t address, uint32_t value) {
+            ++writes;
+            for (unsigned i = 0; i < 4; ++i)
+                memory[address + i] = static_cast<unsigned char>(value >> (24 - 8 * i));
+        };
+        for (const auto& pair : {std::pair{"788600001", 788600001u}, {"788699999", 788699999u},
+                 {"761800001", 761800001u}, {"761899999", 761899999u},
+                 {"012345678", 12345678u}, {"000000001", 1u}, {"999999999", 999999999u}}) {
+            memory.fill(0xa5);
+            writes = 0;
+            Require(RuntimeScSerial::Write(pair.first, 4, contains, write32) == 1, "Accept an exactly four-byte output buffer");
+            Require(writes == 1 && ReadWord(memory.data() + 4) == pair.second, "Return full numeric serial, including digits after common prefix");
+            for (size_t i = 0; i < memory.size(); ++i)
+                if (i < 4 || i >= 8) Require(memory[i] == 0xa5, "Do not overwrite adjacent guest stack data");
+        }
+        for (const char* serial : {"", "1234567890", "7886x1234", "-12345678", "+12345678"}) {
+            writes = 0;
+            Require(RuntimeScSerial::Write(serial, 4, contains, write32) == 0 && writes == 0, "Reject malformed serial without a write");
+        }
+        writes = 0;
+        Require(RuntimeScSerial::Write("788600001", 0, contains, write32) == 0 && writes == 0, "Reject null output");
+        available = 3;
+        Require(RuntimeScSerial::Write("788600001", 4, contains, write32) == 0 && writes == 0, "Reject undersized output");
+        std::cout << "SC serial collision reproduction, numeric output and memory-boundary tests passed\n";
+        return 0;
+    } catch (const std::exception& error) {
+        std::cerr << error.what() << '\n';
+        return 1;
+    }
+}