/* UFO Extender - Mod for X-COM
 * See <http://www.ufopaedia.org/index.php?title=User:Seb76> for more details.
 * Copyright (C) 2008 Seb76
 *
 * This file is part of UFO Extender.

 * UFO Extender 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 3 of the License, or
 * (at your option) any later version.

 * UFO Extender 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 UFO Extender.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "stdafx.h"
#include "patcher.h"

typedef struct patch_s
{
    unsigned int addr;
    int len;
    struct patch_s *next;
} patch_t;

static patch_t *head=NULL;

int CheckOverlap(unsigned int addr, unsigned int len)
{
    for(patch_t *patch=head;patch!=NULL;patch=patch->next)
    {
        if(addr+len>patch->addr&&addr<patch->addr+patch->len)
        {
            char buf[128];
            sprintf(buf,"Trying to patch the same place twice (0x%08x, 0x%08x).\nSend this error to the author to have it fixed.",addr, patch->addr);
            MessageBoxA(NULL,buf,"Patch overlap error",MB_ICONERROR);
            exit(0);
        }
    }

    return 1;
}

void AddPatch(unsigned int addr, unsigned int len)
{
//          char buf[128];
//          sprintf(buf,"Patching 0x%08x",addr);
//          MessageBoxA(NULL,buf,"Patch overlap error",MB_ICONERROR);




    CheckOverlap(addr,len);

    patch_t *patch=(patch_t *)malloc(sizeof patch_t);
    patch->next = head;
    head=patch;
    patch->addr=addr;
    patch->len=len;
}

void PatchInPlace(unsigned int dst, void *src, unsigned int len)
{
    AddPatch(dst, len);
    DWORD oldProtect;
    VirtualProtect((void *)dst,len,PAGE_EXECUTE_READWRITE,&oldProtect);
    memcpy((void *)dst,src,len);
    VirtualProtect((void *)dst,len,oldProtect,&oldProtect);
}

void InsertCall(unsigned int dst, void *func)
{
    AddPatch(dst, 5);
    DWORD oldProtect;
    DWORD *pOffset=(DWORD *)(((char *)dst)+1);

    VirtualProtect((void *)dst,5,PAGE_EXECUTE_READWRITE,&oldProtect);
    *(char *)dst=(char)0xE8;
    *pOffset=(int)func-(int)dst-5;
    VirtualProtect((void *)dst,5,oldProtect,&oldProtect);
}

void InsertJmp(unsigned int dst, void *func)
{
    AddPatch(dst, 5);
    DWORD oldProtect;
    DWORD *pOffset=(DWORD *)(((char *)dst)+1);

    VirtualProtect((void *)dst,5,PAGE_EXECUTE_READWRITE,&oldProtect);
    *(char *)dst=(char)0xE9;
    *pOffset=(int)func-(int)dst-5;
    VirtualProtect((void *)dst,5,oldProtect,&oldProtect);
}

void Nop(unsigned int dst, unsigned int len)
{
    AddPatch(dst, len);
    DWORD oldProtect;
    VirtualProtect((void *)dst,len,PAGE_EXECUTE_READWRITE,&oldProtect);
    memset((void *)dst,0x90,len);
    VirtualProtect((void *)dst,len,oldProtect,&oldProtect);
}

void InsertJnz(unsigned int dst, void *func)
{
    AddPatch(dst, 6);
    DWORD oldProtect;
    DWORD *pOffset=(DWORD *)(((char *)dst)+2);

    VirtualProtect((void *)dst,6,PAGE_EXECUTE_READWRITE,&oldProtect);
    *(char *)dst=(char)0x0F;
    *(char *)(dst+1)=(char)0x84;

    *pOffset=(int)func-(int)dst-6;
    VirtualProtect((void *)dst,6,oldProtect,&oldProtect);
}

void CheckForET()
{
    if(*(int *)0x45DEE0 == 0xFE28EBE9)
    {
        MessageBoxA(NULL,"ET is not supported, don't bother trying.","ET detected",MB_ICONEXCLAMATION);
        exit(666);
    }
}