amxmodx/dlls/hamsandwich/hook.h

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// vim: set ts=4 sw=4 tw=99 noet:
//
// AMX Mod X, based on AMX Mod by Aleksander Naszko ("OLO").
// Copyright (C) The AMX Mod X Development Team.
//
// This software is licensed under the GNU General Public License, version 3 or higher.
// Additional exceptions apply. For full license details, see LICENSE.txt or visit:
// https://alliedmods.net/amxmodx-license
//
// Ham Sandwich Module
//
#ifndef HOOK_H
#define HOOK_H
#include "forward.h"
#include "Trampolines.h"
#define ALIGN(ar) ((intptr_t)ar & ~(sysconf(_SC_PAGESIZE)-1))
// This is just a simple container for data so I only have to add 1 extra
// parameter to calls that get trampolined
class Hook
{
public:
CVector<Forward *> pre; // pre forwards
CVector<Forward *> post; // post forwards
void *func; // original function
void **vtable; // vtable of the original location
int entry; // vtable entry of the function
void *target; // target function being called (the hook)
int exec; // 1 when this hook is in execution
int del; // 1 if this hook should be destroyed after exec
void *tramp; // trampoline for this hook
char *ent; // ent name that's being hooked
Hook(void **vtable_, int entry_, void *target_, bool voidcall, bool retbuf, int paramcount, char *name) :
func(NULL), vtable(vtable_), entry(entry_), target(target_), exec(0), del(0), tramp(NULL)
{
// original function is vtable[entry]
// to not make the compiler whine, cast vtable to int **
int **ivtable=(int **)vtable;
func=(void *)ivtable[entry];
// now install a trampoline
// (int thiscall, int voidcall, int paramcount, void *extraptr)
tramp = CreateGenericTrampoline(true, voidcall, retbuf, paramcount, (void*)this, target);
// Insert into vtable
#if defined(_WIN32)
DWORD OldFlags;
VirtualProtect(&ivtable[entry],sizeof(int*),PAGE_READWRITE,&OldFlags);
#elif defined(__linux__) || defined(__APPLE__)
void *addr = (void *)ALIGN(&ivtable[entry]);
mprotect(addr,sysconf(_SC_PAGESIZE),PROT_READ|PROT_WRITE);
#endif
ivtable[entry]=(int*)tramp;
size_t len=strlen(name);
ent=new char[len+1];
snprintf(ent,len+1,"%s",name);
};
~Hook()
{
// Insert the original function back into the vtable
int **ivtable=(int **)vtable;
#if defined(_WIN32)
DWORD OldFlags;
VirtualProtect(&ivtable[entry],sizeof(int*),PAGE_READWRITE,&OldFlags);
#elif defined(__linux__) || defined(__APPLE__)
void *addr = (void *)ALIGN(&ivtable[entry]);
mprotect(addr,sysconf(_SC_PAGESIZE),PROT_READ|PROT_WRITE);
#endif
ivtable[entry]=(int *)func;
#if defined(_WIN32)
VirtualFree(tramp, 0, MEM_RELEASE);
#elif defined(__linux__) || defined(__APPLE__)
free(tramp);
#endif
delete[] ent;
CVector<Forward *>::iterator end=pre.end();
for (CVector<Forward *>::iterator i=pre.begin();
i!=end;
++i)
{
delete (*i);
}
end=post.end();
for (CVector<Forward *>::iterator i=post.begin();
i!=end;
++i)
{
delete (*i);
}
pre.clear();
post.clear();
}
};
#endif