Implement 3DS region auto-detect

include/loader/ncch.hpp

@@ -5,6 +5,7 @@
 #include "io_file.hpp"
 #include "helpers.hpp"
 #include "crypto/aes_engine.hpp"
+#include "services/region_codes.hpp"
 
 struct NCCH {
     struct EncryptionInfo {
@@ -60,6 +61,8 @@ struct NCCH {
     std::vector<u8> codeFile;
     // Contains of the cart's save data
     std::vector<u8> saveData;
+    // The cart region. Only the CXI's region matters to us. Necessary to get past region locking
+	std::optional<Regions> region = std::nullopt;
 
     // Returns true on success, false on failure
     // Partition index/offset/size must have been set before this
@@ -71,6 +74,9 @@ struct NCCH {
     bool hasCode() { return codeFile.size() != 0; }
     bool hasSaveData() { return saveData.size() != 0; }
 
+    // Parse SMDH for region info and such. Returns false on failure, true on success
+    bool parseSMDH(const std::vector<u8>& smdh);
+
     std::pair<bool, Crypto::AESKey> getPrimaryKey(Crypto::AESEngine &aesEngine, const Crypto::AESKey &keyY);
     std::pair<bool, Crypto::AESKey> getSecondaryKey(Crypto::AESEngine &aesEngine, const Crypto::AESKey &keyY);
 

include/memory.hpp

@@ -9,6 +9,7 @@
 #include "helpers.hpp"
 #include "handles.hpp"
 #include "loader/ncsd.hpp"
+#include "services/region_codes.hpp"
 #include "services/shared_font.hpp"
 
 namespace PhysicalAddrs {
@@ -151,6 +152,8 @@ private:
 
 	// Values taken from 3DBrew and Citra
 	static constexpr FirmwareInfo firm{.unk = 0, .revision = 0, .minor = 0x34, .major = 2, .syscoreVer = 2, .sdkVer = 0x0000F297};
+	// Adjusted upon loading a ROM based on the ROM header. Used by CFG::SecureInfoGetArea to get past region locks
+	Regions region = Regions::USA;
 
 public:
 	u16 kernelVersion = 0;
@@ -261,4 +264,5 @@ public:
 
 	void setVRAM(u8* pointer) { vram = pointer; }
 	bool allocateMainThreadStack(u32 size);
+	Regions getConsoleRegion();
 };

src/core/loader/elf.cpp

@@ -63,5 +63,7 @@ std::optional<u32> Memory::loadELF(std::ifstream& file) {
         allocateMemory(vaddr, fcramAddr, memorySize, true, r, w, x);
     }
 
+    // ELF can't specify a region, make it default to USA
+    region = Regions::USA;
     return static_cast<u32>(reader.get_entry());
 }

src/core/loader/ncch.cpp

@@ -209,10 +209,25 @@ bool NCCH::loadFromHeader(Crypto::AESEngine &aesEngine, IOFile& file, const FSIn
 					codeFile.resize(fileSize);
 					readFromFile(file, exeFS, codeFile.data(), fileOffset + exeFSHeaderSize, fileSize);
 				}
+			} else if (std::strcmp(name, "icon") == 0) {
+				// Parse icon file to extract region info and more in the future (logo, etc)
+				std::vector<u8> tmp;
+				tmp.resize(fileSize);
+				readFromFile(file, exeFS, tmp.data(), fileOffset + exeFSHeaderSize, fileSize);
+
+				if (!parseSMDH(tmp)) {
+					printf("Failed to parse SMDH!\n");
+				}
 			}
 		}
 	}
 
+	// If no region has been detected for CXI, set the region to USA by default
+	if (!region.has_value() && partitionIndex == 0) {
+		printf("No region detected for CXI, defaulting to USA\n");
+		region = Regions::USA;
+	}
+
 	if (hasRomFS()) {
 		printf("RomFS offset: %08llX, size: %08llX\n", romFS.offset, romFS.size);
 	}
@@ -221,6 +236,51 @@ bool NCCH::loadFromHeader(Crypto::AESEngine &aesEngine, IOFile& file, const FSIn
 	return true;
 }
 
+bool NCCH::parseSMDH(const std::vector<u8>& smdh) {
+	if (smdh.size() < 0x36C0) {
+		printf("The cartridge .icon file is too small, considered invalid. Must be 0x36C0 bytes minimum\n");
+		return false;
+	}
+
+	if (char(smdh[0]) != 'S' || char(smdh[1]) != 'M' || char(smdh[2]) != 'D' || char(smdh[3]) != 'H') {
+		printf("Invalid SMDH magic!\n");
+		return false;
+	}
+
+	// Bitmask showing which regions are allowed.
+	// https://www.3dbrew.org/wiki/SMDH#Region_Lockout
+	const u32 regionMasks = *(u32*)&smdh[0x2018];
+	// Detect when games are region free (ie all regions are allowed) for future use
+	[[maybe_unused]] const bool isRegionFree = (regionMasks & 0x7f) == 0x7f;
+
+	// See which countries are allowed
+	const bool japan = (regionMasks & 0x1) != 0;
+	const bool northAmerica = (regionMasks & 0x2) != 0;
+	const bool europe = (regionMasks & 0x4) != 0;
+	const bool australia = (regionMasks & 0x8) != 0;
+	const bool china = (regionMasks & 0x10) != 0;
+	const bool korea = (regionMasks & 0x20) != 0;
+	const bool taiwan = (regionMasks & 0x40) != 0;
+
+	// Based on the allowed regions, set the autodetected 3DS region. We currently prefer English-speaking regions for practical purposes.
+	// But this should be configurable later.
+	if (northAmerica) {
+		region = Regions::USA;
+	} else if (europe) {
+		region = Regions::Europe;
+	} else if (australia) {
+		region = Regions::Australia;
+	} else if (japan) {
+		region = Regions::Japan;
+	} else if (korea) {
+		region = Regions::Korea;
+	} else if (china) {
+		region = Regions::China;
+	} else if (taiwan) {
+		region = Regions::Taiwan;
+	}
+}
+
 std::pair<bool, Crypto::AESKey> NCCH::getPrimaryKey(Crypto::AESEngine &aesEngine, const Crypto::AESKey &keyY) {
 	Crypto::AESKey result;
 

src/core/loader/ncsd.cpp

@@ -11,6 +11,9 @@ bool Memory::mapCXI(NCSD& ncsd, NCCH& cxi) {
 	printf("Data address = %08X, size = %08X\n", cxi.data.address, cxi.data.size);
 	printf("Stack size: %08X\n", cxi.stackSize);
 
+	// Set autodetected 3DS region to one of the values allowed by the CXI's SMDH
+	region = cxi.region.value();
+
 	if (!isAligned(cxi.stackSize)) {
 		Helpers::warn("CXI has a suspicious stack size of %08X which is not a multiple of 4KB", cxi.stackSize);
 	}

src/core/memory.cpp

@@ -59,6 +59,9 @@ void Memory::reset() {
 		readTable[i + initialPage] = pointer;
 		writeTable[i + initialPage] = pointer;
 	}
+
+	// Later adjusted based on ROM header when possible
+	region = Regions::USA;
 }
 
 bool Memory::allocateMainThreadStack(u32 size) {
@@ -472,3 +475,9 @@ u64 Memory::timeSince3DSEpoch() {
 	milliseconds ms = duration_cast<milliseconds>(seconds(rawTime + timezoneDifference + offset));
 	return ms.count();
 }
+
+Regions Memory::getConsoleRegion() {
+	// TODO: Let the user force the console region as they want
+	// For now we pick one based on the ROM header
+	return region;
+}