148 lines
		
	
	
		
			4.6 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			148 lines
		
	
	
		
			4.6 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
/**
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 * vim: set ts=4 :
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 * =============================================================================
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 * SourceMod
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 * Copyright (C) 2004-2010 AlliedModders LLC.  All rights reserved.
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 * =============================================================================
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 *
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 * This program is free software; you can redistribute it and/or modify it under
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 * the terms of the GNU General Public License, version 3.0, as published by the
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 * Free Software Foundation.
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 * 
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 * This program is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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 * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
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 * details.
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 *
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 * You should have received a copy of the GNU General Public License along with
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 * this program.  If not, see <http://www.gnu.org/licenses/>.
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 *
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 * As a special exception, AlliedModders LLC gives you permission to link the
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 * code of this program (as well as its derivative works) to "Half-Life 2," the
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 * "Source Engine," the "SourcePawn JIT," and any Game MODs that run on software
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 * by the Valve Corporation.  You must obey the GNU General Public License in
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 * all respects for all other code used.  Additionally, AlliedModders LLC grants
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 * this exception to all derivative works.  AlliedModders LLC defines further
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 * exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),
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 * or <http://www.sourcemod.net/license.php>.
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 *
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 * Version: $Id: detourhelpers.h 248 2008-08-27 00:56:22Z pred $
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 */
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#ifndef _INCLUDE_SOURCEMOD_DETOURHELPERS_H_
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#define _INCLUDE_SOURCEMOD_DETOURHELPERS_H_
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#if defined PLATFORM_POSIX
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#include <sys/mman.h>
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#define	PAGE_EXECUTE_READWRITE	PROT_READ|PROT_WRITE|PROT_EXEC
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#endif
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#include <amtl/am-bits.h>
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#include <jit/x86/x86_macros.h>
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#include <amtl/os/am-system-errors.h>
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#include <cstdio>
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struct patch_t
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{
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	patch_t()
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	{
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		patch[0] = 0;
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		bytes = 0;
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	}
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	unsigned char patch[20];
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	size_t bytes;
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};
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inline void ProtectMemory(void *addr, int length, int prot)
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{
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	char error[256];
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#if defined PLATFORM_POSIX
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	long pageSize = sysconf(_SC_PAGESIZE);
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	void *startPage = ke::AlignedBase(addr, pageSize);
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	void *endPage = ke::AlignedBase((void *)((intptr_t)addr + length), pageSize);
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	if (mprotect(startPage, ((intptr_t)endPage - (intptr_t)startPage) + pageSize, prot) == -1) {
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		ke::FormatSystemError(error, sizeof(error));
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		fprintf(stderr, "mprotect: %s\n", error);
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	}
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#elif defined PLATFORM_WINDOWS
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	DWORD old_prot;
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	if (!VirtualProtect(addr, length, prot, &old_prot)) {
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		ke::FormatSystemError(error, sizeof(error));
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		fprintf(stderr, "VirtualProtect: %s\n", error);
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	}
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#endif
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}
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inline void SetMemPatchable(void *address, size_t size)
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{
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	ProtectMemory(address, (int)size, PAGE_EXECUTE_READWRITE);
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}
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inline void PatchRelJump32(unsigned char *target, void *callback)
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{
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	SetMemPatchable(target, 5);
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	// jmp <32-bit displacement>
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	target[0] = IA32_JMP_IMM32;
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	*(int32_t *)(&target[1]) = int32_t((unsigned char *)callback - (target + 5));
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}
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inline void PatchAbsJump64(unsigned char *target, void *callback)
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{
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	int i = 0;
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	SetMemPatchable(target, 14);
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	// push <lower 32-bits>         ; allocates 64-bit stack space on x64
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	// mov [rsp+4], <upper 32-bits> ; unnecessary if upper bits are 0
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	// ret                          ; jump to address on stack
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	target[i++] = IA32_PUSH_IMM32;
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	*(int32_t *)(&target[i]) = int32_t(int64_t(callback));
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	i += 4;
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	if ((int64_t(callback) >> 32) != 0)
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	{
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		target[i++] = IA32_MOV_RM_IMM32;
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		target[i++] = ia32_modrm(MOD_DISP8, 0, kREG_SIB);
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		target[i++] = ia32_sib(NOSCALE, kREG_NOIDX, kREG_ESP);
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		target[i++] = 0x04;
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		*(int32_t *)(&target[i]) = (int64_t(callback) >> 32);
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		i += 4;
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	}
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	target[i] = IA32_RET;
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}
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inline void DoGatePatch(unsigned char *target, void *callback)
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{
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#if defined(_WIN64) || defined(__x86_64__)
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	int64_t diff = int64_t(callback) - (int64_t(target) + 5);
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	int32_t upperBits = (diff >> 32);
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	if (upperBits == 0 || upperBits == -1)
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		PatchRelJump32(target, callback);
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	else
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		PatchAbsJump64(target, callback);
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#else
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	PatchRelJump32(target, callback);
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#endif
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}
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inline void ApplyPatch(void *address, int offset, const patch_t *patch, patch_t *restore)
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{
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	unsigned char *addr = (unsigned char *)address + offset;
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	SetMemPatchable(addr, patch->bytes);
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	if (restore)
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	{
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		for (size_t i=0; i<patch->bytes; i++)
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		{
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			restore->patch[i] = addr[i];
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		}
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		restore->bytes = patch->bytes;
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	}
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	for (size_t i=0; i<patch->bytes; i++)
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	{
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		addr[i] = patch->patch[i];
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	}
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}
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#endif //_INCLUDE_SOURCEMOD_DETOURHELPERS_H_
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