amxmodx/dlls/hamsandwich/hook.h

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/* Ham Sandwich
* Copyright 2007
* By the AMX Mod X Development Team
*
* Ham Sandwich 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.
*
* Ham Sandwich 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 Ham Sandwich; 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 Ham Sandwich 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 HOOK_H
#define HOOK_H
#include "forward.h"
#include "Trampolines.h"
// This is just a simple container for data so I only have to add 1 extra
// parameter to calls that get trampolined
#define ALIGN(ar) ((intptr_t)ar & ~(sysconf(_SC_PAGESIZE)-1))
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, 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, 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