/**

 * 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;

}