Move memutils from core to logic (bug 4406, r=ds).

--HG--
rename : core/MemoryUtils.cpp => core/logic/MemoryUtils.cpp
rename : core/MemoryUtils.h => core/logic/MemoryUtils.h
rename : core/sm_symtable.h => core/logic/sm_symtable.h

core/logic/AMBuilder

@@ -32,6 +32,7 @@ files = [
 	'smn_functions.cpp',
 	'smn_timers.cpp',
 	'smn_players.cpp',
+	'MemoryUtils.cpp',
 	'sm_crc32.cpp'
 	]
 if AMBuild.target['platform'] == 'windows':

core/logic/Makefile

@@ -28,6 +28,7 @@ OBJECTS = \
 	smn_functions.cpp   \
 	sm_crc32.cpp		\
 	smn_timers.cpp		\
+	MemoryUtils.cpp		\
 	smn_players.cpp
 
 ##############################################

core/logic/MemoryUtils.cpp

@@ -0,0 +1,554 @@
+/**
+ * vim: set ts=4 sw=4 tw=99 noet :
+ * =============================================================================
+ * SourceMod
+ * Copyright (C) 2004-2010 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"
+#ifdef PLATFORM_LINUX
+#include <fcntl.h>
+#include <link.h>
+#include <sys/mman.h>
+#endif
+#ifdef PLATFORM_APPLE
+#include <mach-o/dyld_images.h>
+#include <mach-o/loader.h>
+#include <mach-o/nlist.h>
+#endif
+
+MemoryUtils g_MemUtils;
+
+MemoryUtils::MemoryUtils()
+{
+#ifdef PLATFORM_APPLE
+
+	/* Get pointer to struct that describes all loaded mach-o images in process */
+	struct nlist list[2];
+	memset(list, 0, sizeof(list));
+	list[0].n_un.n_name = (char *)"_dyld_all_image_infos";
+	nlist("/usr/lib/dyld", list);
+	m_ImageList = (struct dyld_all_image_infos *)list[0].n_value;
+
+#endif
+}
+
+MemoryUtils::~MemoryUtils()
+{
+#if defined PLATFORM_LINUX || defined PLATFORM_APPLE
+	for (size_t i = 0; i < m_SymTables.size(); i++)
+	{
+		delete m_SymTables[i];
+	}
+	m_SymTables.clear();
+#endif
+}
+
+void MemoryUtils::OnSourceModAllInitialized()
+{
+	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;
+
+#elif defined PLATFORM_APPLE
+	
+	uintptr_t dlbase;
+	uint32_t image_count;
+	struct mach_header *file_hdr;
+	struct load_command *loadcmds;
+	struct symtab_command *symtab_hdr;
+	struct nlist *symtab;
+	const char *strtab;
+	uint32_t loadcmd_count;
+	uint32_t symbol_count;
+	LibSymbolTable *libtable;
+	SymbolTable *table;
+	Symbol *symbol_entry;
+	
+	dlbase = 0;
+	image_count = m_ImageList->infoArrayCount;
+	symtab_hdr = NULL;
+	
+	/* Loop through mach-o images in process.
+	 * We can skip index 0 since that is just the executable.
+	 */
+	for (uint32_t i = 1; i < image_count; i++)
+	{
+		const struct dyld_image_info &info = m_ImageList->infoArray[i];
+		
+		/* "Load" each one until we get a matching handle */
+		void *h = dlopen(info.imageFilePath, RTLD_NOLOAD);
+		if (h == handle)
+		{
+			dlbase = (uintptr_t)info.imageLoadAddress;
+			dlclose(h);
+			break;
+		}
+		
+		dlclose(h);
+	}
+	
+	if (!dlbase)
+	{
+		/* Uh oh, we couldn't find a matching handle */
+		return 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 == dlbase)
+		{
+			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 = dlbase;
+		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 to locate it in memory */
+	
+	file_hdr = (struct mach_header *)dlbase;
+	loadcmds = (struct load_command *)(dlbase + sizeof(struct mach_header));
+	loadcmd_count = file_hdr->ncmds;
+	
+	/* Loop through load commands until we find the one for the symbol table */
+	for (uint32_t i = 0; i < loadcmd_count; i++)
+	{
+		if (loadcmds->cmd == LC_SYMTAB)
+		{
+			symtab_hdr = (struct symtab_command *)loadcmds;
+			break;
+		}
+		
+		/* Load commands are not of a fixed size which is why we add the size */
+		loadcmds = (struct load_command *)((uintptr_t)loadcmds + loadcmds->cmdsize);
+	}
+	
+	if (!symtab_hdr || !symtab_hdr->symoff || !symtab_hdr->stroff)
+	{
+		/* Uh oh, no symbol table */
+		return NULL;
+	}
+	
+	symtab = (struct nlist *)(dlbase + symtab_hdr->symoff);
+	strtab = (const char *)(dlbase + symtab_hdr->stroff);
+	symbol_count = symtab_hdr->nsyms;
+	
+	/* Iterate symbol table starting from the position we were at last time */
+	for (uint32_t i = libtable->last_pos; i < symbol_count; i++)
+	{
+		struct nlist &sym = symtab[i];
+		/* Ignore the prepended underscore on all symbols, so +1 here */
+		const char *sym_name = strtab + sym.n_un.n_strx + 1;
+		Symbol *cur_sym;
+		
+		/* Skip symbols that are undefined */
+		if (sym.n_sect == NO_SECT)
+		{
+			continue;
+		}
+		
+		/* Caching symbols as we go along */
+		cur_sym = table->InternSymbol(sym_name, strlen(sym_name), (void *)(dlbase + sym.n_value));
+		if (strcmp(symbol, sym_name) == 0)
+		{
+			symbol_entry = cur_sym;
+			libtable->last_pos = ++i;
+			break;
+		}
+	}
+	
+	return symbol_entry ? symbol_entry->address : NULL;
+
+#endif
+}
+
+bool MemoryUtils::GetLibraryInfo(const void *libPtr, DynLibInfo &lib)
+{
+	uintptr_t 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<uintptr_t>(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<uintptr_t>(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;
+		}
+	}
+	
+#elif defined PLATFORM_APPLE
+
+	Dl_info info;
+	struct mach_header *file;
+	struct segment_command *seg;
+	uint32_t cmd_count;
+
+	if (!dladdr(libPtr, &info))
+	{
+		return false;
+	}
+
+	if (!info.dli_fbase || !info.dli_fname)
+	{
+		return false;
+	}
+
+	/* This is for our insane sanity checks :o */
+	baseAddr = (uintptr_t)info.dli_fbase;
+	file = (struct mach_header *)baseAddr;
+
+	/* Check Mach-O magic */
+	if (file->magic != MH_MAGIC)
+	{
+		return false;
+	}
+
+	/* Check architecture (32-bit/x86) */
+	if (file->cputype != CPU_TYPE_I386 || file->cpusubtype != CPU_SUBTYPE_I386_ALL)
+	{
+		return false;
+	}
+
+	/* For our purposes, this must be a dynamic library */
+	if (file->filetype != MH_DYLIB)
+	{
+		return false;
+	}
+
+	cmd_count = file->ncmds;
+	seg = (struct segment_command *)(baseAddr + sizeof(struct mach_header));
+	
+	/* Add up memory sizes of mapped segments */
+	for (uint32_t i = 0; i < cmd_count; i++)
+	{		
+		if (seg->cmd == LC_SEGMENT)
+		{
+			lib.memorySize += seg->vmsize;
+		}
+		
+		seg = (struct segment_command *)((uintptr_t)seg + seg->cmdsize);
+	}
+
+#endif
+
+	lib.baseAddress = reinterpret_cast<void *>(baseAddr);
+
+	return true;
+}

core/logic/MemoryUtils.h

@@ -0,0 +1,84 @@
+/**
+ * vim: set ts=4 sw=4 tw=99 noet :
+ * =============================================================================
+ * SourceMod
+ * Copyright (C) 2004-2010 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>.
+ */
+
+#ifndef _INCLUDE_SOURCEMOD_MEMORYUTILS_H_
+#define _INCLUDE_SOURCEMOD_MEMORYUTILS_H_
+
+#include "common_logic.h"
+#include <IMemoryUtils.h>
+#if defined PLATFORM_LINUX || defined PLATFORM_APPLE
+#include <sh_vector.h>
+#include "sm_symtable.h"
+
+using namespace SourceHook;
+#endif
+
+using namespace SourceMod;
+
+struct DynLibInfo
+{
+	void *baseAddress;
+	size_t memorySize;
+};
+
+#if defined PLATFORM_LINUX || defined PLATFORM_APPLE
+struct LibSymbolTable
+{
+	SymbolTable table;
+	uintptr_t lib_base;
+	uint32_t last_pos;
+};
+#endif
+
+class MemoryUtils : 
+	public IMemoryUtils,
+	public SMGlobalClass
+{
+public:
+	MemoryUtils();
+	~MemoryUtils();
+public: // SMGlobalClass
+	void OnSourceModAllInitialized();
+public: // IMemoryUtils
+	void *FindPattern(const void *libPtr, const char *pattern, size_t len);
+	void *ResolveSymbol(void *handle, const char *symbol);
+public:
+	bool GetLibraryInfo(const void *libPtr, DynLibInfo &lib);
+#if defined PLATFORM_LINUX || defined PLATFORM_APPLE
+private:
+	CVector<LibSymbolTable *> m_SymTables;
+#ifdef PLATFORM_APPLE
+	struct dyld_all_image_infos *m_ImageList;
+#endif
+#endif
+};
+
+extern MemoryUtils g_MemUtils;
+
+#endif // _INCLUDE_SOURCEMOD_MEMORYUTILS_H_

core/logic/common_logic.cpp

@@ -37,6 +37,7 @@
 #include "TextParsers.h"
 #include "Profiler.h"
 #include "sm_crc32.h"
+#include "MemoryUtils.h"
 
 sm_core_t smcore;
 IHandleSys *handlesys;
@@ -59,6 +60,7 @@ static sm_logic_t logic =
 	NULL,
 	g_pThreader,
 	sm_profiler,
+	&g_MemUtils,
 	UTIL_CRC32
 };
 

core/logic/intercom.h

@@ -42,7 +42,7 @@ using namespace SourceMod;
  * Add 1 to the RHS of this expression to bump the intercom file
  * This is to prevent mismatching core/logic binaries
  */
-#define SM_LOGIC_MAGIC		(0x0F47C0DE - 5)
+#define SM_LOGIC_MAGIC		(0x0F47C0DE - 6)
 
 #if defined SM_LOGIC
 class IVEngineServer
@@ -65,6 +65,7 @@ namespace SourceMod
 	class IForwardManager;
 	class ITimerSystem;
 	class IPlayerManager;
+	class IMemoryUtils;
 }
 
 class IVEngineServer;
@@ -110,6 +111,7 @@ struct sm_logic_t
 	SMGlobalClass	*head;
 	IThreader		*threader;
 	IProfiler		*profiler;
+	IMemoryUtils    *memutils;
 	unsigned int    (*CRC32)(const void *, size_t);
 };
 

core/logic/sm_symtable.h

@@ -0,0 +1,231 @@
+/**
+ * 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>.
+ */
+
+#ifndef _INCLUDE_SOURCEMOD_CORE_SYMBOLTABLE_H_
+#define _INCLUDE_SOURCEMOD_CORE_SYMBOLTABLE_H_
+
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+
+#define KESTRING_TABLE_START_SIZE 65536
+
+struct Symbol
+{
+	size_t length;
+	uint32_t hash;
+	void *address;
+	Symbol *tbl_next;
+
+	inline char *buffer()
+	{
+		return reinterpret_cast<char *>(this + 1);
+	}
+};
+
+class SymbolTable
+{
+public:
+	~SymbolTable()
+	{
+		for (uint32_t i = 0; i < nbuckets; i++)
+		{
+			Symbol *sym = buckets[i];
+			while (sym != NULL)
+			{
+				Symbol *next = sym->tbl_next;
+				free(sym);
+				sym = next;
+			}
+		}
+		free(buckets);
+	}
+
+	bool Initialize()
+	{
+		buckets = (Symbol **)malloc(sizeof(Symbol *) * KESTRING_TABLE_START_SIZE);
+		if (buckets == NULL)
+		{
+			return false;
+		}
+		memset(buckets, 0, sizeof(Symbol *) * KESTRING_TABLE_START_SIZE);
+
+		nbuckets = KESTRING_TABLE_START_SIZE;
+		nused = 0;
+		bucketmask = KESTRING_TABLE_START_SIZE - 1;
+		return true;
+	}
+
+	static inline uint32_t HashString(const char *data, size_t len)
+	{
+		#undef get16bits
+		#if (defined(__GNUC__) && defined(__i386__)) || defined(__WATCOMC__) \
+				|| defined(_MSC_VER) || defined (__BORLANDC__) || defined (__TURBOC__)
+			#define get16bits(d) (*((const uint16_t *) (d)))
+		#endif
+		#if !defined (get16bits)
+			#define get16bits(d) ((((uint32_t)(((const uint8_t *)(d))[1])) << 8)\
+											 +(uint32_t)(((const uint8_t *)(d))[0]) )
+		#endif
+		uint32_t hash = len, tmp;
+		int rem;
+
+		if (len <= 0 || data == NULL)
+		{
+			return 0;
+		}
+
+		rem = len & 3;
+		len >>= 2;
+
+		/* Main loop */
+		for (;len > 0; len--) {
+				hash	+= get16bits (data);
+				tmp		= (get16bits (data+2) << 11) ^ hash;
+				hash	 = (hash << 16) ^ tmp;
+				data	+= 2 * sizeof (uint16_t);
+				hash	+= hash >> 11;
+		}
+
+		/* Handle end cases */
+		switch (rem) {
+				case 3: hash += get16bits (data);
+								hash ^= hash << 16;
+								hash ^= data[sizeof (uint16_t)] << 18;
+								hash += hash >> 11;
+								break;
+				case 2: hash += get16bits (data);
+								hash ^= hash << 11;
+								hash += hash >> 17;
+								break;
+				case 1: hash += *data;
+								hash ^= hash << 10;
+								hash += hash >> 1;
+		}
+
+		/* Force "avalanching" of final 127 bits */
+		hash ^= hash << 3;
+		hash += hash >> 5;
+		hash ^= hash << 4;
+		hash += hash >> 17;
+		hash ^= hash << 25;
+		hash += hash >> 6;
+
+		return hash;
+
+		#undef get16bits
+	}
+
+	Symbol **FindSymbolBucket(const char *str, size_t len, uint32_t hash)
+	{
+		uint32_t bucket = hash & bucketmask;
+		Symbol **pkvs = &buckets[bucket];
+
+		Symbol *kvs = *pkvs;
+		while (kvs != NULL)
+		{
+			if (len == kvs->length && memcmp(str, kvs->buffer(), len * sizeof(char)) == 0)
+			{
+				return pkvs;
+			}
+			pkvs = &kvs->tbl_next;
+			kvs = *pkvs;
+		}
+
+		return pkvs;
+	}
+
+	void ResizeSymbolTable()
+	{
+		uint32_t xnbuckets = nbuckets * 2;
+		Symbol **xbuckets = (Symbol **)malloc(sizeof(Symbol *) * xnbuckets);
+		if (xbuckets == NULL)
+		{
+			return;
+		}
+		memset(xbuckets, 0, sizeof(Symbol *) * xnbuckets);
+		uint32_t xbucketmask = xnbuckets - 1;
+		for (uint32_t i = 0; i < nbuckets; i++)
+		{
+			Symbol *sym = buckets[i];
+			while (sym != NULL)
+			{
+				Symbol *next = sym->tbl_next;
+				uint32_t bucket = sym->hash & xbucketmask;
+				sym->tbl_next = xbuckets[bucket];
+				xbuckets[bucket] = sym;
+				sym = next;
+			}
+		}
+		free(buckets);
+		buckets = xbuckets;
+		nbuckets = xnbuckets;
+		bucketmask = xbucketmask;
+	}
+
+	Symbol *FindSymbol(const char *str, size_t len)
+	{
+		uint32_t hash = HashString(str, len);
+		Symbol **pkvs = FindSymbolBucket(str, len, hash);
+		return *pkvs;
+	}
+
+	Symbol *InternSymbol(const char* str, size_t len, void *address)
+	{
+		uint32_t hash = HashString(str, len);
+		Symbol **pkvs = FindSymbolBucket(str, len, hash);
+		if (*pkvs != NULL)
+		{
+			return *pkvs;
+		}
+
+		Symbol *kvs = (Symbol *)malloc(sizeof(Symbol) + sizeof(char) * (len + 1));
+		kvs->length = len;
+		kvs->hash = hash;
+		kvs->address = address;
+		kvs->tbl_next = NULL;
+		memcpy(kvs + 1, str, sizeof(char) * (len + 1));
+		*pkvs = kvs;
+		nused++;
+
+		if (nused > nbuckets && nbuckets <= INT_MAX / 2)
+		{
+			ResizeSymbolTable();
+		}
+
+		return kvs;
+	}
+private:
+	uint32_t nbuckets;
+	uint32_t nused;
+	uint32_t bucketmask;
+	Symbol **buckets;
+};
+
+#endif //_INCLUDE_SOURCEMOD_CORE_SYMBOLTABLE_H_