mirror of
https://github.com/alliedmodders/metamod-source.git
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328 lines
9.7 KiB
C++
328 lines
9.7 KiB
C++
/* ======== SourceHook ========
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* Copyright (C) 2004-2010 Metamod:Source Development Team
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* No warranties of any kind
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*
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* License: zlib/libpng
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*
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* Author(s): Pavol "PM OnoTo" Marko
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* ============================
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*/
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/**
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* @brief This file provides a way for getting information about a member function.
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* @file sh_memfuncinfo.h
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*/
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#ifndef __SHINT_MEMFUNC_INFO_H__
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#define __SHINT_MEMFUNC_INFO_H__
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namespace SourceHook
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{
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// Don Clugston:
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// implicit_cast< >
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// I believe this was originally going to be in the C++ standard but
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// was left out by accident. It's even milder than static_cast.
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// I use it instead of static_cast<> to emphasize that I'm not doing
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// anything nasty.
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// Usage is identical to static_cast<>
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template <class OutputClass, class InputClass>
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inline OutputClass implicit_cast(InputClass input){
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return input;
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}
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struct MemFuncInfo
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{
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bool isVirtual; // Is the function virtual?
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int thisptroffs; // The this pointer the function expects to be called with
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// If -1, you need to call the GetFuncInfo_GetThisPtr function
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int vtblindex; // The function's index in the vtable (0-based, 1=second entry, 2=third entry, ...)
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int vtbloffs; // The vtable pointer
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};
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// Ideas by Don Clugston.
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// Check out his excellent paper: http://www.codeproject.com/cpp/FastDelegate.asp
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template<int N> struct MFI_Impl
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{
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template<class MFP> static inline void GetFuncInfo(MFP *mfp, MemFuncInfo &out)
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{
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static char weird_memfunc_pointer_exclamation_mark_arrow_error[N-1000];
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}
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};
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# if SH_COMP == SH_COMP_GCC
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template<> struct MFI_Impl<2*SH_PTRSIZE> // All of these have size==8/16
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{
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struct GCC_MemFunPtr
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{
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union
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{
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void *funcadr; // always even
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intptr_t vtable_index_plus1; // = vindex+1, always odd
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};
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intptr_t delta;
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};
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template<class MFP> static inline void GetFuncInfo(MFP mfp, MemFuncInfo &out)
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{
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GCC_MemFunPtr *mfp_detail = (GCC_MemFunPtr*)&mfp;
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out.thisptroffs = mfp_detail->delta;
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if (mfp_detail->vtable_index_plus1 & 1)
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{
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out.vtblindex = (mfp_detail->vtable_index_plus1 - 1) / SH_PTRSIZE;
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out.vtbloffs = 0;
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out.isVirtual = true;
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}
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else
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out.isVirtual = false;
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}
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};
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# elif SH_COMP == SH_COMP_MSVC
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namespace
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{
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int MFI_GetVtblOffset(void *mfp)
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{
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unsigned char *addr = (unsigned char*)mfp;
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if (*addr == 0xE9) // Jmp
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{
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// May or may not be!
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// Check where it'd jump
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addr += 5 /*size of the instruction*/ + *(unsigned long*)(addr + 1);
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}
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// Check whether it's a virtual function call
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// They look like this:
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// 004125A0 8B 01 mov eax,dword ptr [ecx]
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// 004125A2 FF 60 04 jmp dword ptr [eax+4]
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// ==OR==
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// 00411B80 8B 01 mov eax,dword ptr [ecx]
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// 00411B82 FF A0 18 03 00 00 jmp dword ptr [eax+318h]
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// However, for vararg functions, they look like this:
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// 0048F0B0 8B 44 24 04 mov eax,dword ptr [esp+4]
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// 0048F0B4 8B 00 mov eax,dword ptr [eax]
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// 0048F0B6 FF 60 08 jmp dword ptr [eax+8]
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// ==OR==
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// 0048F0B0 8B 44 24 04 mov eax,dword ptr [esp+4]
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// 0048F0B4 8B 00 mov eax,dword ptr [eax]
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// 00411B82 FF A0 18 03 00 00 jmp dword ptr [eax+318h]
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// With varargs, the this pointer is passed as if it was the first argument
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bool ok = false;
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if (addr[0] == 0x8B && addr[1] == 0x44 && addr[2] == 0x24 && addr[3] == 0x04 &&
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addr[4] == 0x8B && addr[5] == 0x00)
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{
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addr += 6;
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ok = true;
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}
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else if (addr[0] == 0x8B && addr[1] == 0x01)
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{
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addr += 2;
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ok = true;
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}
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else if (addr[0] == 0x48 && addr[1] == 0x8B && addr[2] == 0x01)
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{
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addr += 3;
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ok = true;
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}
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if (!ok)
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return -1;
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if (*addr++ == 0xFF)
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{
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if (*addr == 0x60)
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{
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return *++addr / SH_PTRSIZE;
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}
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else if (*addr == 0xA0)
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{
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return *((unsigned int*)++addr) / SH_PTRSIZE;
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}
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else if (*addr == 0x20)
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return 0;
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else
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return -1;
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}
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return -1;
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}
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}
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template<> struct MFI_Impl<1*SH_PTRSIZE> // simple ones
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{
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template<class MFP> static inline void GetFuncInfo(MFP mfp, MemFuncInfo &out)
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{
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out.vtblindex = MFI_GetVtblOffset(*(void**)&mfp);
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out.isVirtual = out.vtblindex >= 0 ? true : false;
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out.thisptroffs = 0;
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out.vtbloffs = 0;
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}
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};
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template<> struct MFI_Impl<2*SH_PTRSIZE> // more complicated ones!
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{
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struct MSVC_MemFunPtr2
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{
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void *funcadr;
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int delta;
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};
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template<class MFP> static inline void GetFuncInfo(MFP mfp, MemFuncInfo &out)
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{
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out.vtblindex = MFI_GetVtblOffset(*(void**)&mfp);
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out.isVirtual = out.vtblindex >= 0 ? true : false;
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out.thisptroffs = reinterpret_cast<MSVC_MemFunPtr2*>(&mfp)->delta;
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out.vtbloffs = 0;
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}
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};
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// By Don Clugston, adapted
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template<> struct MFI_Impl<3*SH_PTRSIZE> // WOW IT"S GETTING BIGGER OMGOMOGMG
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{
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class __single_inheritance GenericClass;
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class GenericClass {};
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struct MicrosoftVirtualMFP {
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void (GenericClass::*codeptr)(); // points to the actual member function
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int delta; // #bytes to be added to the 'this' pointer
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int vtable_index; // or 0 if no virtual inheritance
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};
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struct GenericVirtualClass : virtual public GenericClass
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{
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typedef GenericVirtualClass * (GenericVirtualClass::*ProbePtrType)();
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GenericVirtualClass * GetThis() { return this; }
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};
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template<class MFP> static inline void GetFuncInfo(MFP mfp, MemFuncInfo &out)
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{
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out.vtblindex = MFI_GetVtblOffset(*(void**)&mfp);
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out.isVirtual = out.vtblindex >= 0 ? true : false;
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// This pointer
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/*
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union {
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MFP func;
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GenericClass* (T::*ProbeFunc)();
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MicrosoftVirtualMFP s;
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} u;
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u.func = mfp;
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union {
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GenericVirtualClass::ProbePtrType virtfunc;
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MicrosoftVirtualMFP s;
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} u2;
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// Check that the horrible_cast<>s will work
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typedef int ERROR_CantUsehorrible_cast[sizeof(mfp)==sizeof(u.s)
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&& sizeof(mfp)==sizeof(u.ProbeFunc)
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&& sizeof(u2.virtfunc)==sizeof(u2.s) ? 1 : -1];
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// Unfortunately, taking the address of a MF prevents it from being inlined, so
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// this next line can't be completely optimised away by the compiler.
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u2.virtfunc = &GenericVirtualClass::GetThis;
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u.s.codeptr = u2.s.codeptr;
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out.thisptroffs = (reinterpret_cast<T*>(NULL)->*u.ProbeFunc)();
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*/
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out.thisptroffs = -1;
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out.vtbloffs = 0;
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}
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};
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// Don: Nasty hack for Microsoft and Intel (IA32 and Itanium)
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// unknown_inheritance classes go here
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// This is probably the ugliest bit of code I've ever written. Look at the casts!
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// There is a compiler bug in MSVC6 which prevents it from using this code.
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template<> struct MFI_Impl<4*SH_PTRSIZE> // THE BIGGEST ONE!!!1GABEN
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{
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template<class MFP> static inline void GetFuncInfo(MFP mfp, MemFuncInfo &out)
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{
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out.vtblindex = MFI_GetVtblOffset(*(void**)&mfp);
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out.isVirtual = out.vtblindex >= 0 ? true : false;
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// The member function pointer is 16 bytes long. We can't use a normal cast, but
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// we can use a union to do the conversion.
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union {
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MFP func;
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// In VC++ and ICL, an unknown_inheritance member pointer
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// is internally defined as:
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struct {
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void *m_funcaddress; // points to the actual member function
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int delta; // #bytes to be added to the 'this' pointer
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int vtordisp; // #bytes to add to 'this' to find the vtable
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int vtable_index; // or 0 if no virtual inheritance
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} s;
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} u;
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// Check that the horrible_cast will work
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typedef int ERROR_CantUsehorrible_cast[sizeof(u.func)==sizeof(u.s)? 1 : -1];
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u.func = mfp;
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int virtual_delta = 0;
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if (u.s.vtable_index) { // Virtual inheritance is used
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/*
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// First, get to the vtable.
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// It is 'vtordisp' bytes from the start of the class.
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int * vtable = *reinterpret_cast<int **>(
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reinterpret_cast<char *>(thisptr) + u.s.vtordisp );
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// 'vtable_index' tells us where in the table we should be looking.
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virtual_delta = u.s.vtordisp + *reinterpret_cast<const int *>(
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reinterpret_cast<const char *>(vtable) + u.s.vtable_index);
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// The int at 'virtual_delta' gives us the amount to add to 'this'.
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// Finally we can add the three components together. Phew!
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out.thisptr = reinterpret_cast<void *>(
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reinterpret_cast<char *>(thisptr) + u.s.delta + virtual_delta);
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*/
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out.vtbloffs = u.s.vtordisp;
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out.thisptroffs = -1;
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}
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else
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{
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out.vtbloffs = out.vtblindex < 0 ? 0 : u.s.delta;
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out.thisptroffs = u.s.delta;
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}
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};
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};
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# else
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# error Unsupported compiler
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# endif
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// This version does not take a this pointer
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// Useful for hookdecls, as they ensure that mfp is correct through a static_cast
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template<class X> inline void GetFuncInfo(X mfp, MemFuncInfo &out)
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{
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MFI_Impl<sizeof(mfp)>::GetFuncInfo(mfp, out);
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}
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// Versions which do take a this
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//
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template<class X, class Y, class RetType, class ... Params>
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inline void GetFuncInfo(Y *ptr, RetType(X::*mfp)(Params...), MemFuncInfo &out)
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{
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RetType(Y::*mfp2)(Params...) = mfp;
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MFI_Impl<sizeof(mfp2)>::GetFuncInfo(mfp2, out);
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}
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template<class X, class Y, class RetType, class ... Params>
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inline void GetFuncInfo(Y *ptr, RetType(X::*mfp)(Params...) const, MemFuncInfo &out)
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{
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RetType(Y::*mfp2)(Params...) const = mfp;
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MFI_Impl<sizeof(mfp2)>::GetFuncInfo(mfp2, out);
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}
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template<class X, class Y, class RetType, class ... Params>
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inline void GetFuncInfo(Y *ptr, RetType(X::*mfp)(Params..., ...), MemFuncInfo &out)
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{
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RetType(Y::*mfp2)(Params..., ...) = mfp;
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MFI_Impl<sizeof(mfp2)>::GetFuncInfo(mfp2, out);
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}
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template<class X, class Y, class RetType, class ... Params>
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inline void GetFuncInfo(Y *ptr, RetType(X::*mfp)(Params..., ...) const, MemFuncInfo &out)
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{
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RetType(Y::*mfp2)(Params..., ...) const = mfp;
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MFI_Impl<sizeof(mfp2)>::GetFuncInfo(mfp2, out);
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}
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}
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#endif
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