/**

  * vim: set ts=4 sw=4 tw=99 noet :

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

  * SourceMod

  * Copyright (C) 2004-2009 AlliedModders LLC.  All rights reserved.

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

  *

  * This program is free software; you can redistribute it and/or modify it under

  * the terms of the GNU General Public License, version 3.0, as published by the

  * Free Software Foundation.

  * 

  * 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, see <http://www.gnu.org/licenses/>.

  *

  * As a special exception, AlliedModders LLC gives you permission to link the

  * code of this program (as well as its derivative works) to "Half-Life 2," the

  * "Source Engine," the "SourcePawn JIT," and any Game MODs that run on software

  * by the Valve Corporation.  You must obey the GNU General Public License in

  * all respects for all other code used.  Additionally, AlliedModders LLC grants

  * this exception to all derivative works.  AlliedModders LLC defines further

  * exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),

  * or <http://www.sourcemod.net/license.php>.

  */

 #include "MemoryUtils.h"

 #include "ShareSys.h"

 #ifdef PLATFORM_LINUX

 #include <fcntl.h>

 #include <link.h>

 #include <sys/mman.h>

 #endif

 MemoryUtils g_MemUtils;

 #if 0

 MemoryUtils::MemoryUtils()

 {

 #ifdef PLATFORM_WINDOWS

 	SYSTEM_INFO info;

 	GetSystemInfo(&info);

 	m_PageSize = info.dwPageSize;

 #elif defined PLATFORM_POSIX

 	m_PageSize = sysconf(_SC_PAGE_SIZE);

 #endif

 }

 #endif

 MemoryUtils::~MemoryUtils()

 {

 #ifdef PLATFORM_LINUX

 	for (size_t i = 0; i < m_SymTables.size(); i++)

 	{

 		delete m_SymTables[i];

 	}

 	m_SymTables.clear();

 #endif

 }

 void MemoryUtils::OnSourceModAllInitialized()

 {

 	g_ShareSys.AddInterface(NULL, this);

 }

 void *MemoryUtils::FindPattern(const 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;

 }

 void *MemoryUtils::ResolveSymbol(void *handle, const char *symbol)

 {

 #ifdef PLATFORM_WINDOWS

 	return GetProcAddress((HMODULE)handle, symbol);

 #elif defined PLATFORM_LINUX

 	struct link_map *dlmap;

 	struct stat dlstat;

 	int dlfile;

 	uintptr_t map_base;

 	Elf32_Ehdr *file_hdr;

 	Elf32_Shdr *sections, *shstrtab_hdr, *symtab_hdr, *strtab_hdr;

 	Elf32_Sym *symtab;

 	const char *shstrtab, *strtab;

 	uint16_t section_count;

 	uint32_t symbol_count;

 	LibSymbolTable *libtable;

 	SymbolTable *table;

 	Symbol *symbol_entry;

 	dlmap = (struct link_map *)handle;

 	symtab_hdr = NULL;

 	strtab_hdr = NULL;

 	table = NULL;

 	/* See if we already have a symbol table for this library */

 	for (size_t i = 0; i < m_SymTables.size(); i++)

 	{

 		libtable = m_SymTables[i];

 		if (libtable->lib_base == dlmap->l_addr)

 		{

 			table = &libtable->table;

 			break;

 		}

 	}

 	/* If we don't have a symbol table for this library, then create one */

 	if (table == NULL)

 	{

 		libtable = new LibSymbolTable();

 		libtable->table.Initialize();

 		libtable->lib_base = dlmap->l_addr;

 		libtable->last_pos = 0;

 		table = &libtable->table;

 		m_SymTables.push_back(libtable);

 	}

 	/* See if the symbol is already cached in our table */

 	symbol_entry = table->FindSymbol(symbol, strlen(symbol));

 	if (symbol_entry != NULL)

 	{

 		return symbol_entry->address;

 	}

 	/* If symbol isn't in our table, then we have open the actual library */

 	dlfile = open(dlmap->l_name, O_RDONLY);

 	if (dlfile == -1 || fstat(dlfile, &dlstat) == -1)

 	{

 		close(dlfile);

 		return NULL;

 	}

 	/* Map library file into memory */

 	file_hdr = (Elf32_Ehdr *)mmap(NULL, dlstat.st_size, PROT_READ, MAP_PRIVATE, dlfile, 0);

 	map_base = (uintptr_t)file_hdr;

 	if (file_hdr == MAP_FAILED)

 	{

 		close(dlfile);

 		return NULL;

 	}

 	close(dlfile);

 	if (file_hdr->e_shoff == 0 || file_hdr->e_shstrndx == SHN_UNDEF)

 	{

 		munmap(file_hdr, dlstat.st_size);

 		return NULL;

 	}

 	sections = (Elf32_Shdr *)(map_base + file_hdr->e_shoff);

 	section_count = file_hdr->e_shnum;

 	/* Get ELF section header string table */

 	shstrtab_hdr = &sections[file_hdr->e_shstrndx];

 	shstrtab = (const char *)(map_base + shstrtab_hdr->sh_offset);

 	/* Iterate sections while looking for ELF symbol table and string table */

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

 	{

 		Elf32_Shdr &hdr = sections[i];

 		const char *section_name = shstrtab + hdr.sh_name;

 		if (strcmp(section_name, ".symtab") == 0)

 		{

 			symtab_hdr = &hdr;

 		}

 		else if (strcmp(section_name, ".strtab") == 0)

 		{

 			strtab_hdr = &hdr;

 		}

 	}

 	/* Uh oh, we don't have a symbol table or a string table */

 	if (symtab_hdr == NULL || strtab_hdr == NULL)

 	{

 		munmap(file_hdr, dlstat.st_size);

 		return NULL;

 	}

 	symtab = (Elf32_Sym *)(map_base + symtab_hdr->sh_offset);

 	strtab = (const char *)(map_base + strtab_hdr->sh_offset);

 	symbol_count = symtab_hdr->sh_size / symtab_hdr->sh_entsize;

 	/* Iterate symbol table starting from the position we were at last time */

 	for (uint32_t i = libtable->last_pos; i < symbol_count; i++)

 	{

 		Elf32_Sym &sym = symtab[i];

 		unsigned char sym_type = ELF32_ST_TYPE(sym.st_info);

 		const char *sym_name = strtab + sym.st_name;

 		Symbol *cur_sym;

 		/* Skip symbols that are undefined or do not refer to functions or objects */

 		if (sym.st_shndx == SHN_UNDEF || (sym_type != STT_FUNC && sym_type != STT_OBJECT))

 		{

 			continue;

 		}

 		/* Caching symbols as we go along */

 		cur_sym = table->InternSymbol(sym_name, strlen(sym_name), (void *)(dlmap->l_addr + sym.st_value));

 		if (strcmp(symbol, sym_name) == 0)

 		{

 			symbol_entry = cur_sym;

 			libtable->last_pos = ++i;

 			break;

 		}

 	}

 	munmap(file_hdr, dlstat.st_size);

 	return symbol_entry ? symbol_entry->address : NULL;

 #endif

 }

 bool MemoryUtils::GetLibraryInfo(const 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;

 }