From fa1203489cee0009f1526c2717caea157da41f07 Mon Sep 17 00:00:00 2001
From: Ghabry <gabriel+github@mastergk.de>
Date: Sat, 21 Dec 2024 13:38:04 +0100
Subject: [PATCH] ExeReader: Support 64 Bit executables

Maniac Patch is now detected when the new exe is used.
---
 src/exe_reader.cpp | 28 ++++++++++++++++++++--------
 src/exe_reader.h   | 14 +++++++++++++-
 2 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/src/exe_reader.cpp b/src/exe_reader.cpp
index efb2ab6e23..5d0b28d4fc 100644
--- a/src/exe_reader.cpp
+++ b/src/exe_reader.cpp
@@ -34,19 +34,31 @@ namespace {
 EXEReader::EXEReader(Filesystem_Stream::InputStream core) : corefile(std::move(core)) {
 	// The Incredibly Dumb PE parser (tm)
 	// Extracts data from the resource section for engine detection and can read ExFont.
-	uint32_t ofs = GetU32(0x3C);
+	uint32_t ofs = GetU32(0x3C); // PE header offset
 	uint16_t machine = GetU16(ofs + 4);
-	if (machine != 0x14c) {
+	if (machine != 0x14c && machine != 0x8664) {
 		// FIXME: Newer versions of Maniac Patch can be 64 Bit
-		Output::Debug("EXEReader: Machine type is not i386 ({:#x})", machine);
-		file_info.is_i386 = false;
+		Output::Debug("EXEReader: Machine type is not i386 or amd64 ({:#x})", machine);
+		file_info.machine_type = MachineType::Unknown;
 		return;
 	}
 
+	if (machine == 0x14c) {
+		file_info.machine_type = MachineType::i386;
+	} else {
+		file_info.machine_type = MachineType::amd64;
+	}
+
 	// The largest known exe has 11 segments, guard against bogus section data here
 	uint16_t sections = std::min<uint16_t>(GetU16(ofs + 6), 11);
-	uint32_t sectionsOfs = ofs + 0x18 + GetU16(ofs + 0x14);
-	resource_rva = GetU32(ofs + 0x88);
+	uint32_t optional_header = ofs + 0x18;
+	uint32_t oh_magic = GetU16(optional_header);
+
+	bool format_pe32 = (oh_magic == 0x10b); // 0x20b is PE32+ (64 bit)
+
+	uint32_t sectionsOfs = optional_header + GetU16(ofs + 0x14); // skip opt header
+	uint32_t data_directory_ofs = (format_pe32 ? 0x60 : 0x70);
+	resource_rva = GetU32(optional_header + data_directory_ofs + 16);
 	if (!resource_rva) {
 		// Is some kind of encrypted EXE -> Give up
 		return;
@@ -379,13 +391,13 @@ bool EXEReader::ResNameCheck(uint32_t i, const char* p) {
 }
 
 void EXEReader::FileInfo::Print() const {
-	Output::Debug("RPG_RT information: version={} logos={} code={:#x} cherry={:#x} geep={:#x} i386={} easyrpg={}", version_str, logos, code_size, cherry_size, geep_size, is_i386, is_easyrpg_player);
+	Output::Debug("RPG_RT information: version={} logos={} code={:#x} cherry={:#x} geep={:#x} arch={} easyrpg={}", version_str, logos, code_size, cherry_size, geep_size, kMachineTypes[machine_type], is_easyrpg_player);
 }
 
 int EXEReader::FileInfo::GetEngineType(bool& is_maniac_patch) const {
 	is_maniac_patch = false;
 
-	if (is_easyrpg_player || !is_i386) {
+	if (is_easyrpg_player || machine_type == MachineType::Unknown) {
 		return Player::EngineNone;
 	}
 
diff --git a/src/exe_reader.h b/src/exe_reader.h
index 41f1c8625f..80899cfc7e 100644
--- a/src/exe_reader.h
+++ b/src/exe_reader.h
@@ -43,6 +43,18 @@ class EXEReader {
 	std::vector<uint8_t> GetExFont();
 	std::vector<std::vector<uint8_t>> GetLogos();
 
+	enum class MachineType {
+		Unknown,
+		i386,
+		amd64
+	};
+
+	static constexpr auto kMachineTypes = lcf::makeEnumTags<MachineType>(
+		"Unknown",
+		"i386",
+		"amd64"
+	);
+
 	struct FileInfo {
 		uint64_t version = 0;
 		int logos = 0;
@@ -50,7 +62,7 @@ class EXEReader {
 		uint32_t code_size = 0;
 		uint32_t cherry_size = 0;
 		uint32_t geep_size = 0;
-		bool is_i386 = true;
+		MachineType machine_type = MachineType::Unknown;
 		bool is_easyrpg_player = false;
 
 		int GetEngineType(bool& is_maniac_patch) const;