amxmodx/dlls/hamsandwich/Trampolines.h

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/* Trampolines
*
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* In addition, as a special exception, the author gives permission to
* link the code of this program with the Half-Life Game Engine ("HL
* Engine") and Modified Game Libraries ("MODs") developed by Valve,
* L.L.C ("Valve"). You must obey the GNU General Public License in all
* respects for all of the code used other than the HL Engine and MODs
* from Valve. If you modify this file, you may extend this exception
* to your version of the file, but you are not obligated to do so. If
* you do not wish to do so, delete this exception statement from your
* version.
*/
#ifndef TRAMPOLINES_H
#define TRAMPOLINES_H
#ifndef NDEBUG
#define TPRINT(msg) printf msg
#else
#define TPRINT(msg) /* nothing */
#endif
#if defined _WIN32
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif // WIN32_LEAN_AND_MEAN
#if _MSC_VER >= 1400
#ifdef offsetof
#undef offsetof
#endif // offsetof
#endif // _MSC_VER >= 1400
#include <windows.h>
#elif defined(__linux__) || defined(__APPLE__)
#include <sys/mman.h>
#if defined (__linux__)
#include <malloc.h>
#endif
#endif
#include <stddef.h> // size_t
#include <string.h> // memcpy
#include <stdlib.h> // memalign
#include <stdio.h>
namespace Trampolines
{
/**
* List of x86 bytecodes for creating
* basic trampolines at runtime.
* -
* These are defined here so that, should
* the need ever arise, this can be ported
* to other architectures fairly painlessly
*/
namespace Bytecode
{
/**
* Prologue for a void function
* Clobbers EBX and EAX
*/
const unsigned char codeVoidPrologue[] = {
0x55, // push ebp
0x89, 0xE5, // mov ebp, esp
0x50, // push eax
};
/**
* Prologue for a function that returns
* Clobbers EBX, EAX too but not after call
*/
const unsigned char codeReturnPrologue[] = {
0x55, // push ebp
0x89, 0xE5, // mov ebp, esp
};
const unsigned char codeThisReturnPrologue[] = {
0x55, // push ebp
0x89, 0xE5, // mov ebp, esp
};
/**
* Takes a paramter from the trampoline's stack
* and pushes it onto the target's stack.
*/
const unsigned char codePushParam[] = {
0xFF, 0x75, 0xFF // pushl [ebp+0xFF]
};
/**
* Offset of codePushParam to modify at runtime
* that contains the stack offset
*/
const unsigned int codePushParamReplace = 2;
/**
* Takes the "this" pointer from the trampoline and
* pushes it onto the target's stack.
*/
const unsigned char codePushThis[] = {
#if defined(_WIN32)
0x51 // push ecx
#elif defined(__linux__) || defined(__APPLE__)
0xFF, 0x75, 0x04 // pushl [ebp+0x08h]
#endif
};
#if defined(__linux__) || defined(__APPLE__)
const int codePushThisReplace = 2;
#endif
/**
* Pushes a raw number onto the target's stack
*/
const unsigned char codePushID[] = {
0x68, 0xDE, 0xFA, 0xAD, 0xDE // push DEADFADEh
};
/**
* Offset of codePushID to modify at runtime
* to contain the number to push
*/
const unsigned int codePushIDReplace = 1;
/**
* Call our procedure
*/
const unsigned char codeCall[] = {
0xB8, 0xDE, 0xFA, 0xAD, 0xDE,// mov eax, DEADFADEh
0xFF, 0xD0 // call eax
};
/**
* Offset of codeCall to modify at runtime
* to contain the pointer to the function
*/
const unsigned int codeCallReplace = 1;
/**
* Adds to ESP, freeing up stack space
*/
const unsigned char codeFreeStack[] = {
0x81, 0xC4, 0xFF, 0xFF, 0xFF, 0xFF// add esp REPLACEME
};
/**
* Offset of codeFreeStack to modify at runtime
* to contain how much data to free
*/
const unsigned int codeFreeStackReplace = 2;
/**
* Epilogue of a simple return function
*/
const unsigned char codeReturnEpilogue[] = {
0x5D, // pop ebp
0xC3 // ret
};
const unsigned char codeReturnEpilogueN[] = {
0x5D, // pop ebp
0xC2, 0xCD, 0xAB // retn 0xABCD
};
const int codeReturnEpilogueNReplace = 2;
/**
* Epilogue of a void return function
*/
const unsigned char codeVoidEpilogue[] = {
0x58, // pop eax
0x5D, // pop ebp
0xC3 // ret
};
const unsigned char codeVoidEpilogueN[] = {
0x58, // pop eax
0x5D, // pop ebp
0xC2, 0xCD, 0xAB // retn 0xABCD
};
const int codeVoidEpilogueNReplace = 3;
const unsigned char codeBreakpoint[] = {
0xCC // int 3
};
}
/**
* Our actual maker of the trampolines!!@$
* I've no idea why I made this a class and not a namespace
* Oh well!
*/
class TrampolineMaker
{
private:
unsigned char *m_buffer; // the actual buffer containing the code
int m_size; // size of the buffer
int m_mystack; // stack for the trampoline itself
int m_calledstack; // stack for the target function
int m_paramstart;
int m_thiscall;
int m_maxsize;
/**
* Adds data to the buffer
* data must be pre-formatted before hand!
*/
void Append(const unsigned char *src, size_t size)
{
int orig=m_size;
m_size+=size;
if (m_buffer==NULL)
{
m_maxsize=512;
m_buffer=(unsigned char *)malloc(m_maxsize);
}
else if (m_size > m_maxsize)
{
m_maxsize = m_size + 512;
m_buffer=(unsigned char *)realloc(m_buffer,m_maxsize);
}
unsigned char *dat=m_buffer+orig; // point dat to the end of the prewritten
while (orig<m_size)
{
*dat++=*src++;
orig++;
};
};
public:
TrampolineMaker()
{
m_buffer=NULL;
m_size=0;
m_mystack=0;
m_calledstack=0;
m_paramstart=0;
m_thiscall=0;
m_maxsize=0;
};
/**
* Inserts a breakpoint (int 3) into the trampoline.
*/
void Breakpoint()
{
Append(&::Trampolines::Bytecode::codeBreakpoint[0],sizeof(::Trampolines::Bytecode::codeBreakpoint));
};
/**
* Adds the "return prologue", pushes registers and prepares stack
*/
void ReturnPrologue()
{
Append(&::Trampolines::Bytecode::codeReturnPrologue[0],sizeof(::Trampolines::Bytecode::codeReturnPrologue));
m_paramstart=0;
m_thiscall=0;
};
void ThisReturnPrologue()
{
this->ReturnPrologue();
m_thiscall=1;
};
/**
* Adds the void prologue pushes registers, prepares the stack
*/
void VoidPrologue()
{
Append(&::Trampolines::Bytecode::codeVoidPrologue[0],sizeof(::Trampolines::Bytecode::codeVoidPrologue));
m_paramstart=0;
m_thiscall=0;
};
/**
* Flags this trampoline as a thiscall trampoline, and prepares the void prologue.
*/
void ThisVoidPrologue()
{
this->VoidPrologue();
m_thiscall=1;
};
/**
* Epilogue for a returning function pops registers but does not free any more of the stack!
*/
void ReturnEpilogue()
{
Append(&::Trampolines::Bytecode::codeReturnEpilogue[0],sizeof(::Trampolines::Bytecode::codeReturnEpilogue));
};
/**
* Epilogue that also frees it's estimated stack usage. Useful for stdcall/thiscall/fastcall.
*/
void ReturnEpilogueAndFree()
{
this->ReturnEpilogue(m_mystack);
};
/**
* Return epilogue. Pops registers, and frees given amount of data from the stack.
*
* @param howmuch How many bytes to free from the stack.
*/
void ReturnEpilogue(int howmuch)
{
unsigned char code[sizeof(::Trampolines::Bytecode::codeReturnEpilogueN)];
memcpy(&code[0],&::Trampolines::Bytecode::codeReturnEpilogueN[0],sizeof(::Trampolines::Bytecode::codeReturnEpilogueN));
unsigned char *c=&code[0];
union
{
int i;
unsigned char b[4];
} bi;
bi.i=howmuch;
c+=::Trampolines::Bytecode::codeReturnEpilogueNReplace;
*c++=bi.b[0];
*c++=bi.b[1];
Append(&code[0],sizeof(::Trampolines::Bytecode::codeReturnEpilogueN));
//Append(&::Trampolines::Bytecode::codeReturnEpilogueN[0],sizeof(::Trampolines::Bytecode::codeReturnEpilogueN));
};
/**
* Void epilogue, pops registers and frees the estimated stack usage of the trampoline.
*/
void VoidEpilogueAndFree()
{
this->VoidEpilogue(m_mystack);
};
/**
* Void epilogue, pops registers, nothing else done with stack.
*/
void VoidEpilogue()
{
Append(&::Trampolines::Bytecode::codeVoidEpilogue[0],sizeof(::Trampolines::Bytecode::codeVoidEpilogue));
};
/**
* Void epilogue, pops registers, frees given amount of data off of the stack.
*
* @param howmuch How many bytes to free from the stack.
*/
void VoidEpilogue(int howmuch)
{
unsigned char code[sizeof(::Trampolines::Bytecode::codeVoidEpilogueN)];
memcpy(&code[0],&::Trampolines::Bytecode::codeVoidEpilogueN[0],sizeof(::Trampolines::Bytecode::codeVoidEpilogueN));
unsigned char *c=&code[0];
union
{
int i;
unsigned char b[4];
} bi;
bi.i=howmuch;
c+=::Trampolines::Bytecode::codeVoidEpilogueNReplace;
*c++=bi.b[0];
*c++=bi.b[1];
Append(&code[0],sizeof(::Trampolines::Bytecode::codeVoidEpilogueN));
Append(&::Trampolines::Bytecode::codeVoidEpilogueN[0],sizeof(::Trampolines::Bytecode::codeVoidEpilogueN));
};
/**
* Pushes the "this" pointer onto the callee stack. Pushes ECX for MSVC, and param0 on GCC.
*/
void PushThis()
{
if (!m_thiscall)
{
return;
}
unsigned char code[sizeof(::Trampolines::Bytecode::codePushThis)];
memcpy(&code[0],&::Trampolines::Bytecode::codePushThis[0],sizeof(::Trampolines::Bytecode::codePushThis));
#if defined(__linux__) || defined(__APPLE__)
unsigned char *c=&code[0];
union
{
int i;
unsigned char b[4];
} bi;
bi.i=m_paramstart+8;
c+=::Trampolines::Bytecode::codePushThisReplace;
*c++=bi.b[0];
#endif
Append(&code[0],sizeof(::Trampolines::Bytecode::codePushThis));
#if defined(__linux__) || defined(__APPLE__)
m_mystack+=4;
#endif
m_calledstack+=4;
};
/**
* Frees what is estimated as the stack usage of the trampoline.
*/
void FreeMyStack(void)
{
this->FreeStack(m_mystack);
};
/**
* Frees the estimated stack usage of the callee.
*/
void FreeTargetStack(void)
{
this->FreeStack(m_calledstack);
};
/**
* Frees the estimated stack usage of the callee and the trampoline.
*/
void FreeBothStacks(void)
{
this->FreeStack(m_calledstack + m_mystack);
};
/**
* Frees a given amount of bytes from the stack.
*
* @param howmuch How many bytes to free.
*/
void FreeStack(int howmuch)
{
unsigned char code[sizeof(::Trampolines::Bytecode::codeFreeStack)];
memcpy(&code[0],&::Trampolines::Bytecode::codeFreeStack[0],sizeof(::Trampolines::Bytecode::codeFreeStack));
unsigned char *c=&code[0];
union
{
int i;
unsigned char b[4];
} bi;
bi.i=howmuch;
c+=::Trampolines::Bytecode::codeFreeStackReplace;
*c++=bi.b[0];
*c++=bi.b[1];
*c++=bi.b[2];
*c++=bi.b[3];
Append(&code[0],sizeof(::Trampolines::Bytecode::codeFreeStack));
};
/**
* Pushes a raw number onto the callee stack.
*
* @param Number The number to push onto the callee stack.
*/
void PushNum(int Number)
{
unsigned char code[sizeof(::Trampolines::Bytecode::codePushID)];
memcpy(&code[0],&::Trampolines::Bytecode::codePushID[0],sizeof(::Trampolines::Bytecode::codePushID));
unsigned char *c=&code[0];
union
{
int i;
unsigned char b[4];
} bi;
bi.i=Number;
c+=::Trampolines::Bytecode::codePushIDReplace;
*c++=bi.b[0];
*c++=bi.b[1];
*c++=bi.b[2];
*c++=bi.b[3];
Append(&code[0],sizeof(::Trampolines::Bytecode::codePushID));
m_calledstack+=4; // increase auto detected stack size
};
/**
* Takes a parameter passed on the trampoline's stack and inserts it into the callee's stack.
*
* @param which The parameter number to push. 1-based. "thiscall" trampolines automatically compensate for the off-number on GCC.
*/
void PushParam(int which)
{
#if defined(__linux__) || defined(__APPLE__)
if (m_thiscall)
{
which++;
}
#endif
which=which*4;
which+=m_paramstart+4;
unsigned char value=which;
unsigned char code[sizeof(::Trampolines::Bytecode::codePushParam)];
memcpy(&code[0],&::Trampolines::Bytecode::codePushParam[0],sizeof(::Trampolines::Bytecode::codePushParam));
unsigned char *c=&code[0];
c+=::Trampolines::Bytecode::codePushParamReplace;
*c=value;
Append(&code[0],sizeof(::Trampolines::Bytecode::codePushParam));
m_calledstack+=4; // increase auto detected stack size
m_mystack+=4;
};
/**
* Insert a function to call into the trampoline.
*
* @param ptr The function to call, cast to void*.
*/
void Call(void *ptr)
{
unsigned char code[sizeof(::Trampolines::Bytecode::codeCall)];
memcpy(&code[0],&::Trampolines::Bytecode::codeCall[0],sizeof(::Trampolines::Bytecode::codeCall));
unsigned char *c=&code[0];
union
{
void *p;
unsigned char b[4];
} bp;
bp.p=ptr;
c+=::Trampolines::Bytecode::codeCallReplace;
*c++=bp.b[0];
*c++=bp.b[1];
*c++=bp.b[2];
*c++=bp.b[3];
Append(&code[0],sizeof(::Trampolines::Bytecode::codeCall));
};
/**
* Finalizes the trampoline. Do not try to modify it after this.
*
* @param size A pointer to retrieve the size of the trampoline. Ignored if set to NULL.
* @return The trampoline pointer, cast to void*.
*/
void *Finish(int *size)
{
//void *ret=(void *)m_buffer;
if (size)
{
*size=m_size;
}
// Reallocate with proper flags
#if defined(_WIN32)
void *ret=VirtualAlloc(NULL, m_size, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
#elif defined(__GNUC__)
# if defined(__APPLE__)
void *ret = valloc(m_size);
# else
void *ret=memalign(sysconf(_SC_PAGESIZE), m_size);
# endif
mprotect(ret,m_size,PROT_READ|PROT_WRITE|PROT_EXEC);
#endif
memcpy(ret, m_buffer, m_size);
m_size=0;
free(m_buffer);
m_buffer=NULL; // so we don't accidentally rewrite!
m_mystack=0;
m_calledstack=0;
m_maxsize=512;
return ret;
};
};
};
/**
* Utility to make a generic trampoline.
*/
inline void *CreateGenericTrampoline(bool thiscall, bool voidcall, bool retbuf, int paramcount, void *extraptr, void *callee)
{
Trampolines::TrampolineMaker tramp;
if (voidcall)
{
if (thiscall)
{
tramp.ThisVoidPrologue();
}
else
{
tramp.VoidPrologue();
}
}
else
{
if (thiscall)
{
tramp.ThisReturnPrologue();
}
else
{
tramp.ReturnPrologue();
}
}
while (paramcount)
{
tramp.PushParam(paramcount--);
}
if (thiscall)
{
tramp.PushThis();
}
tramp.PushNum(reinterpret_cast<int>(extraptr));
tramp.Call(callee);
tramp.FreeTargetStack();
if (voidcall)
{
#if defined(_WIN32)
tramp.VoidEpilogueAndFree();
#elif defined(__linux__) || defined(__APPLE__)
if (retbuf)
{
tramp.VoidEpilogue(4);
}
else
{
tramp.ThisVoidPrologue();
}
#endif
}
else
{
#if defined(_WIN32)
tramp.ReturnEpilogueAndFree();
#elif defined(__linux__) || defined(__APPLE__)
tramp.ReturnEpilogue();
#endif
}
return tramp.Finish(NULL);
};
#endif // TRAMPOLINEMANAGER_H