/*
 * Localize Bug Fix
 * Copyright (c) 2013 - 2014 AGHL.RU Dev Team
 * 
 * http://aghl.ru/forum/ - Russian Half-Life and Adrenaline Gamer Community
 *
 *
 *    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.
 *
 */

#include "memory.h"

#ifdef _WIN32
int lib_load_info(void *addr,lib_t *lib)
{
	MEMORY_BASIC_INFORMATION mem;
	VirtualQuery(addr,&mem,sizeof(mem));

	IMAGE_DOS_HEADER *dos = (IMAGE_DOS_HEADER*)mem.AllocationBase;
	IMAGE_NT_HEADERS *pe = (IMAGE_NT_HEADERS*)((dword)dos + (dword)dos->e_lfanew);

	if(pe->Signature != IMAGE_NT_SIGNATURE)
		return 0;

	lib->base = (char *)mem.AllocationBase;
	lib->size = (size_t)pe->OptionalHeader.SizeOfImage;

	return 1;
}
#else
char *lib_find_symbol(lib_t *lib,const char *symbol)
{
	return (char *)dlsym(lib->handle,symbol);
}
static ElfW(Addr) dlsize(void *base)
{
	int i;
	ElfW(Ehdr) *ehdr;
	ElfW(Phdr) *phdr;
	ElfW(Addr) end;

	ehdr = (ElfW(Ehdr)*)base;
	phdr = (ElfW(Phdr)*)((ElfW(Addr))ehdr + ehdr->e_phoff);

	for(i = 0; i < ehdr->e_phnum; ++i)
	{
		if(phdr[i].p_type == PT_LOAD)
			end = phdr[i].p_vaddr + phdr[i].p_memsz;
	}
	return end;
}
int lib_load_info(void *addr,lib_t *lib)
{
	Dl_info info;
	if(!dladdr(addr,&info) || !info.dli_fbase || !info.dli_fname)
		return 0;

	lib->base = (char *)info.dli_fbase;
	lib->size = dlsize(info.dli_fbase);
	lib->handle = dlopen(info.dli_fname,RTLD_NOW);

	return 1;
}
#endif
static inline int mem_compare_c(const char *addr,const char *pattern,const char *pattern_end)
{
	const char *c;
	for(c = pattern; c < pattern_end; ++c, ++addr)
	{
		if(*c == *addr || *c == '\x2A')
			continue;

		return 0;
	}
	return 1;
}
static char *mem_find_ref_c(char *pos,char *end,int opcode,dword ref,int relative)
{
	for(; pos < end; ++pos)
	{
		if(*pos == opcode)
		{
			if(relative)
			{
				if((dword)pos + 5 + *(dword *)(pos + 1) == ref)
					return pos;
			}
			else
			{
				if(*(dword *)(pos + 1) == ref)
					return pos;
			}
		}
	}
	return NULL;
}
char *mem_find_pattern(char *pos,int range,const char *pattern,int len)
{
	char *end;
	const char *pattern_end;
	
	pattern_end = pattern + len;

	for(end = pos + range - len; pos < end; ++pos)
	{
		if(mem_compare_c(pos,pattern,pattern_end))
			return pos;
	}
	return NULL;
}
static char *lib_find_string_push(lib_t *lib,const char *string)
{
	char *addr;
	addr = mem_find_pattern(lib->base,lib->size,string,strlen(string) + 1);
	return mem_find_ref_c(lib->base,lib->base + lib->size - 5,'\x68',(dword)addr,0);
}
char *mem_find_ref(char *start,int range,int opcode,dword ref,int relative)
{
	return mem_find_ref_c(start,start + range - 5,opcode,ref,relative);
}
char *lib_find_pattern(lib_t *lib,const char *pattern,int len)
{
	return mem_find_pattern(lib->base,lib->size,pattern,len);
}
char *lib_find_pattern_fstr(lib_t *lib,const char *string,int range,const char *pattern,int len)
{
	char *addr;
	addr = lib_find_string_push(lib,string);

	if(addr)
	{
		if(range < 0)
		{
			addr += range;
			range = -range;
		}
		return mem_find_pattern(addr,range,pattern,len);
	}
	return NULL;
}
int mem_change_protection(void *addr,const char *patch,int len)
{
#ifdef _WIN32
	static HANDLE process = 0;
	DWORD OldProtection,NewProtection = PAGE_EXECUTE_READWRITE;

	if(!process)
		process = GetCurrentProcess();

	FlushInstructionCache(process,addr,len);
	if(VirtualProtect(addr,len,NewProtection,&OldProtection))
	{
		memcpy(addr,patch,len);
		return VirtualProtect(addr,len,OldProtection,&NewProtection);
	}
#else
	size_t size = sysconf(_SC_PAGESIZE);
	void *alignedAddress = Align(addr);

	if(Align(addr + len - 1) != alignedAddress)
		size *= 2;

	if(!mprotect(alignedAddress,size,(PROT_READ|PROT_WRITE|PROT_EXEC)))
	{
		memcpy(addr,patch,len);
		return !mprotect(alignedAddress,size,(PROT_READ|PROT_EXEC));
	}
#endif
	return 0;
}