/**

 * vim: set ts=4 :

 * ===============================================================

 * SourceMod (C)2004-2007 AlliedModders LLC.  All rights reserved.

 * ===============================================================

 *

 * This file is not open source and may not be copied without explicit

 * written permission of AlliedModders LLC.  This file may not be redistributed 

 * in whole or significant part.

 * For information, see LICENSE.txt or http://www.sourcemod.net/license.php

 *

 * Version: $Id$

 */

#include "MemoryUtils.h"

#include "sm_platform.h"

#ifdef PLATFORM_LINUX

#include <string.h>

#include <elf.h>

#endif

MemoryUtils g_MemUtils;

MemoryUtils::MemoryUtils()

{

#ifdef PLATFORM_WINDOWS

	/* This might be used in the future? */

	#if 0

	SYSTEM_INFO info;

	GetSystemInfo(&info);

	m_PageSize = info.dwPageSize;

	#endif

#elif defined PLATFORM_POSIX

	m_PageSize = sysconf(_SC_PAGE_SIZE);

#endif

}

void *MemoryUtils::FindPattern(void *libPtr, const char *pattern, size_t len)

{

	DynLibInfo lib;

	bool found;

	char *ptr, *end;

	memset(&lib, 0, sizeof(DynLibInfo));

	if (!GetLibraryInfo(libPtr, lib))

	{

		return NULL;

	}

	ptr = reinterpret_cast<char *>(lib.baseAddress);

	end = ptr + lib.memorySize;

	while (ptr < end)

	{

		found = true;

		for (register size_t i = 0; i < len; i++)

		{

			if (pattern[i] != '\x2A' && pattern[i] != ptr[i])

			{

				found = false;

				break;

			}

		}

		if (found)

			return ptr;

		ptr++;

	}

	return NULL;

}

bool MemoryUtils::GetLibraryInfo(void *libPtr, DynLibInfo &lib)

{

	unsigned long baseAddr;

	if (libPtr == NULL)

	{

		return false;

	}

#ifdef PLATFORM_WINDOWS

	MEMORY_BASIC_INFORMATION info;

	IMAGE_DOS_HEADER *dos;

	IMAGE_NT_HEADERS *pe;

	IMAGE_FILE_HEADER *file;

	IMAGE_OPTIONAL_HEADER *opt;

	if (!VirtualQuery(libPtr, &info, sizeof(MEMORY_BASIC_INFORMATION)))

	{

		return false;

	}

	baseAddr = reinterpret_cast<unsigned long>(info.AllocationBase);

	/* All this is for our insane sanity checks :o */

	dos = reinterpret_cast<IMAGE_DOS_HEADER *>(baseAddr);

	pe = reinterpret_cast<IMAGE_NT_HEADERS *>(baseAddr + dos->e_lfanew);

	file = &pe->FileHeader;

	opt = &pe->OptionalHeader;

	/* Check PE magic and signature */

	if (dos->e_magic != IMAGE_DOS_SIGNATURE || pe->Signature != IMAGE_NT_SIGNATURE || opt->Magic != IMAGE_NT_OPTIONAL_HDR32_MAGIC)

	{

		return false;

	}

	/* Check architecture, which is 32-bit/x86 right now

	 * Should change this for 64-bit if Valve gets their act together

	 */

	if (file->Machine != IMAGE_FILE_MACHINE_I386)

	{

		return false;

	}

	/* For our purposes, this must be a dynamic library */

	if ((file->Characteristics & IMAGE_FILE_DLL) == 0)

	{

		return false;

	}

	/* Finally, we can do this */

	lib.memorySize = opt->SizeOfImage;

#elif defined PLATFORM_LINUX

	Dl_info info;

	Elf32_Ehdr *file;

	Elf32_Phdr *phdr;

	uint16_t phdrCount;

	if (!dladdr(libPtr, &info))

	{

		return false;

	}

	if (!info.dli_fbase || !info.dli_fname)

	{

		return false;

	}

	/* This is for our insane sanity checks :o */

	baseAddr = reinterpret_cast<unsigned long>(info.dli_fbase);

	file = reinterpret_cast<Elf32_Ehdr *>(baseAddr);

	/* Check ELF magic */

	if (memcmp(ELFMAG, file->e_ident, SELFMAG) != 0)

	{

		return false;

	}

	/* Check ELF version */

	if (file->e_ident[EI_VERSION] != EV_CURRENT)

	{

		return false;

	}

	/* Check ELF architecture, which is 32-bit/x86 right now

	 * Should change this for 64-bit if Valve gets their act together

	 */

	if (file->e_ident[EI_CLASS] != ELFCLASS32 || file->e_machine != EM_386 || file->e_ident[EI_DATA] != ELFDATA2LSB)

	{

		return false;

	}

	/* For our purposes, this must be a dynamic library/shared object */

	if (file->e_type != ET_DYN)

	{

		return false;

	}

	phdrCount = file->e_phnum;

	phdr = reinterpret_cast<Elf32_Phdr *>(baseAddr + file->e_phoff);

	/* Add up the memory sizes of segments marked as PT_LOAD as those are the only ones that should be in memory */

	for (uint16_t i = 0; i < phdrCount; i++)

	{

		Elf32_Phdr &hdr = phdr[i];

		if (hdr.p_type == PT_LOAD)

		{

			lib.memorySize += hdr.p_memsz;

		}

	}

#endif

	lib.baseAddress = reinterpret_cast<void *>(baseAddr);

	return true;

}