From afa9d02e2ed9b600f4015252e48eab7cf4229541 Mon Sep 17 00:00:00 2001
From: Luke Usher <luke.usher@outlook.com>
Date: Fri, 19 Aug 2016 19:55:18 +0100
Subject: [PATCH] Implement fake kernel header to allow
 XapiRestrictCodeSelectorLimit to succeed

Cxbx now requires support for large address space on 32-bit applications, this may break some 32-bit operating systems.
---
 src/Cxbx/EmuExe.cpp       |  2 +-
 src/CxbxKrnl/CxbxKrnl.cpp | 30 +++++++++++++++++++++++++++++-
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/src/Cxbx/EmuExe.cpp b/src/Cxbx/EmuExe.cpp
index 04c570d01..3d0d5f292 100644
--- a/src/Cxbx/EmuExe.cpp
+++ b/src/Cxbx/EmuExe.cpp
@@ -61,7 +61,7 @@ EmuExe::EmuExe(Xbe *x_Xbe, DebugMode x_debug_mode, char *x_debug_filename, HWND
         m_Header.m_symbol_table_addr        = 0;                                        // unused
         m_Header.m_symbols                  = 0;                                        // unused
         m_Header.m_sizeof_optional_header   = sizeof(OptionalHeader);                   // size of optional header
-        m_Header.m_characteristics          = 0x010F;                                   // should be fine..
+        m_Header.m_characteristics          = 0x012F;                                   // should be fine..
 
         printf("OK\n");
     }
diff --git a/src/CxbxKrnl/CxbxKrnl.cpp b/src/CxbxKrnl/CxbxKrnl.cpp
index 6d77e200d..abf9b7366 100644
--- a/src/CxbxKrnl/CxbxKrnl.cpp
+++ b/src/CxbxKrnl/CxbxKrnl.cpp
@@ -297,6 +297,35 @@ extern "C" CXBXKRNL_API void CxbxKrnlInit
         #endif
     }
 
+	{
+		// Create a fake kernel header for XapiRestrictCodeSelectorLimit
+		// Thanks advancingdragon / DirtBox
+		typedef struct DUMMY_KERNEL
+		{
+			IMAGE_DOS_HEADER DosHeader;
+			DWORD Signature;
+			IMAGE_FILE_HEADER FileHeader;
+			IMAGE_SECTION_HEADER SectionHeader;
+		} *PDUMMY_KERNEL;
+
+		PDUMMY_KERNEL DummyKernel = (PDUMMY_KERNEL)VirtualAlloc(
+			(PVOID)0x80010000, sizeof(DUMMY_KERNEL),
+			MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE
+		);
+
+		if (DummyKernel == NULL)
+			CxbxKrnlCleanup("InitializeDummyKernel: Could not allocate dummy kernel.");
+		memset(DummyKernel, 0, sizeof(DUMMY_KERNEL));
+
+		// XapiRestrictCodeSelectorLimit only checks these fields.
+		DummyKernel->DosHeader.e_lfanew = sizeof(IMAGE_DOS_HEADER); // RVA of NtHeaders
+		DummyKernel->FileHeader.SizeOfOptionalHeader = 0;
+		DummyKernel->FileHeader.NumberOfSections = 1;
+		// as long as this doesn't start with "INIT"
+		strncpy_s((PSTR)DummyKernel->SectionHeader.Name, 8, "DONGS", 8);
+	}
+
+
     //
     // load the necessary pieces of XbeHeader
     //
@@ -320,7 +349,6 @@ extern "C" CXBXKRNL_API void CxbxKrnlInit
     }
 
 	// Initialize devices :
-
 	char szBuffer[260];
 	SHGetSpecialFolderPath(NULL, szBuffer, CSIDL_APPDATA, TRUE);
     strcat(szBuffer, "\\Cxbx\\");