/***********************************************************************
This file contains functions that implement the delay loader on Windows.

This is a customized version of delay loader with limited functionalities.
It does not support:

* (manual) unloading
* multiple delay loaded DLLs
* multiple loading of the same DLL

This delay loader is used only by the InnoDB plugin. Other components (DLLs)
can still use the default delay loader, provided by MSVC.

Several acronyms used by Microsoft:
 * IAT: import address table
 * INT: import name table
 * RVA: Relative Virtual Address

See http://msdn.microsoft.com/en-us/magazine/bb985992.aspx for details of
PE format.

(c) 2008 Innobase Oy
***********************************************************************/
#if defined (__WIN__) && defined (MYSQL_DYNAMIC_PLUGIN)
# define WIN32_LEAN_AND_MEAN
# include <windows.h>
# include <delayimp.h>
# include <mysql_priv.h>

extern "C" {
# include "univ.i"
# include "hash0hash.h"
}

/***********************************************************************
This following contains a list of externals that can not be resolved by
delay loading. They have to be resolved indirectly via their addresses
in the .map file. All of them are external variables. */
CHARSET_INFO*		wdl_my_charset_bin;
CHARSET_INFO*		wdl_my_charset_latin1;
CHARSET_INFO*		wdl_my_charset_filename;
CHARSET_INFO**		wdl_system_charset_info;
CHARSET_INFO**		wdl_default_charset_info;
CHARSET_INFO**		wdl_all_charsets;
system_variables*	wdl_global_system_variables;
char*			wdl_mysql_real_data_home;
char**			wdl_mysql_data_home;
char**			wdl_tx_isolation_names;
char**			wdl_binlog_format_names;
char*			wdl_reg_ext;
pthread_mutex_t*	wdl_LOCK_thread_count;
key_map*		wdl_key_map_full;
MY_TMPDIR*		wdl_mysql_tmpdir_list;
bool*			wdl_mysqld_embedded;
uint*			wdl_lower_case_table_names;
ulong*			wdl_specialflag;
int*			wdl_my_umask;

/***********************************************************************
The following is defined in ha_innodb.cc. It is used for copying the
system variables from the builtin innodb plugin to the dynamic plugin.
*/
extern struct st_mysql_plugin*	builtin_innobase_plugin_ptr;

/***********************************************************************
The preffered load-address defined in PE (portable executable format).*/
#if defined(_M_IA64)
#pragma section(".base", long, read)
extern "C"
__declspec(allocate(".base"))
const IMAGE_DOS_HEADER __ImageBase;
#else
extern "C"
const IMAGE_DOS_HEADER __ImageBase;
#endif

/***********************************************************************
A template function for converting a relative address (RVA) to an
absolute address (VA). This is due to the pointers in the delay
descriptor (ImgDelayDescr in delayimp.h) have been changed from
VAs to RVAs to work on both 32- and 64-bit platforms. */
template <class X>
X PFromRva(RVA rva) {
	return X(PBYTE(&__ImageBase) + rva);
}

/***********************************************************************
Convert to the old format for convenience. The structure as well as its
element names follow the definition of ImgDelayDescr in delayimp.h. */
struct InternalImgDelayDescr {
	DWORD		grAttrs;	/* attributes */
	LPCSTR		szName;		/* pointer to dll name */
	HMODULE*	phmod;		/* address of module handle */
	PImgThunkData	pIAT;		/* address of the IAT */
	PCImgThunkData	pINT;		/* address of the INT */
	PCImgThunkData	pBoundIAT;	/* address of the optional bound IAT */
	PCImgThunkData	pUnloadIAT;	/* address of optional copy of
					   original IAT */
	DWORD		dwTimeStamp;	/* 0 if not bound,
					   otherwise date/time stamp of DLL
					   bound to (Old BIND) */
};

typedef struct map_hash_chain_struct	map_hash_chain_t;

struct map_hash_chain_struct {
	char*			symbol;	/* pointer to a symbol */
	ulint			value;	/* address of the symbol */
	map_hash_chain_t*	next;	/* pointer to the next cell
					in the same folder. */
	map_hash_chain_t*	chain;	/* a linear chain used for
					cleanup. */
};

static HMODULE				my_hmod = 0;
static struct hash_table_struct*	m_htbl = NULL ;
static map_hash_chain_t*		chain_header = NULL;
static ibool				wdl_init = FALSE;
const ulint				MAP_HASH_CELLS_NUM = 10000;

/*****************************************************************
Creates a hash table with >= n array cells. The actual number of cells is
chosen to be a prime number slightly bigger than n.

This is the same function as hash_create in hash0hash.c, except the
memory allocation. This function is invoked before the engine is
initialized, and buffer pools are not ready yet. */
static
hash_table_t*
wdl_hash_create(
/*============*/
			/* out, own: created hash table */
	ulint	n)	/* in: number of array cells */
{
	hash_cell_t*	array;
	ulint		prime;
	hash_table_t*	table;

	prime = ut_find_prime(n);

	table = (hash_table_t*) malloc(sizeof(hash_table_t));
	if (table == NULL) {
		return(NULL);
	}

	array = (hash_cell_t*) malloc(sizeof(hash_cell_t) * prime);
	if (array == NULL) {
		free(table);
		return(NULL);
	}

	table->array = array;
	table->n_cells = prime;
	table->n_mutexes = 0;
	table->mutexes = NULL;
	table->heaps = NULL;
	table->heap = NULL;
	table->magic_n = HASH_TABLE_MAGIC_N;

	/* Initialize the cell array */
	hash_table_clear(table);

	return(table);
}

/*****************************************************************
Frees a hash table. */
static
void
wdl_hash_table_free(
/*================*/
	hash_table_t*	table)	/* in, own: hash table */
{
	ut_a(table != NULL);
	ut_a(table->mutexes == NULL);

	free(table->array);
	free(table);
}

/***********************************************************************
Function for calculating the count of imports given the base of the IAT. */
static
ulint
wdl_import_count(
/*=============*/
					/* out: number of imports */
	PCImgThunkData	pitd_base)	/* in: base of the IAT */
{
	ulint		ret = 0;
	PCImgThunkData	pitd = pitd_base;

	while (pitd->u1.Function) {
		pitd++;
		ret++;
	}

	return(ret);
}

/***********************************************************************
Read Mapfile to a hashtable for faster access */
static
ibool
wdl_load_mapfile(
/*=============*/
					/* out: TRUE if the mapfile is
					loaded successfully. */
	const char*	filename)	/* in: name of the mapfile. */
{
	FILE*		fp;
	const size_t	nSize = 256;
	char		tmp_buf[nSize];
	char*		func_name;
	char*		func_addr;
	ulint		load_addr = 0;
	ibool		valid_load_addr = FALSE;

	fp = fopen(filename, "r");
	if (fp == NULL) {

		return(FALSE);
	}

	/* Check whether to create the hashtable */
	if (m_htbl == NULL) {

		m_htbl = wdl_hash_create(MAP_HASH_CELLS_NUM);

		if (m_htbl == NULL) {

			fclose(fp);
			return(FALSE);
		}
	}

	/* Search start of symbol list and get the preferred load address */
	while (fgets(tmp_buf, sizeof(tmp_buf), fp)) {

		if (sscanf(tmp_buf, " Preferred load address is %16X",
			   &load_addr) == 1) {

			valid_load_addr = TRUE;
		}

		if (strstr(tmp_buf, "Rva+Base") != NULL) {

			break;
		}
	}

	if (valid_load_addr == FALSE) {

		/* No "Preferred load address", the map file is wrong. */
		fclose(fp);
		return(FALSE);
	}

	/* Read symbol list */
	while (fgets(tmp_buf, sizeof(tmp_buf), fp))
	{
		map_hash_chain_t*	map_cell;
		ulint			map_fold;

		if (*tmp_buf == 0) {

			continue;
		}

		func_name = strtok(tmp_buf, " ");
		func_name = strtok(NULL, " ");
		func_addr = strtok(NULL, " ");

		if (func_name && func_addr) {

			ut_snprintf(tmp_buf, nSize, "0x%s", func_addr);
			if (*func_name == '_') {

				func_name++;
			}

			map_cell = (map_hash_chain_t*)
				   malloc(sizeof(map_hash_chain_t));
			if (map_cell == NULL) {
				return(FALSE);
			}

			/* Chain all cells together */
			map_cell->chain = chain_header;
			chain_header = map_cell;

			map_cell->symbol = strdup(func_name);
			map_cell->value = strtoul(tmp_buf, NULL, 0)
					  - load_addr;
			map_fold = ut_fold_string(map_cell->symbol);

			HASH_INSERT(map_hash_chain_t,
				    next,
				    m_htbl,
				    map_fold,
				    map_cell);
		}
	}

	fclose(fp);

	return(TRUE);
}

/*****************************************************************
Cleanup.during DLL unload */
static
void
wdl_cleanup(void)
/*=============*/
{
	while (chain_header != NULL) {
		map_hash_chain_t*	tmp;

		tmp = chain_header->chain;
		free(chain_header->symbol);
		free(chain_header);
		chain_header = tmp;
	}

	if (m_htbl != NULL) {

		wdl_hash_table_free(m_htbl);
	}
}

/***********************************************************************
Load the mapfile mysqld.map. */
static
HMODULE
wdl_get_mysqld_mapfile(void)
/*========================*/
			/* out: the module handle */
{
	char	file_name[MAX_PATH];
	char*	ext;
	ulint	err;

	if (my_hmod == 0) {

		size_t	nSize = MAX_PATH - strlen(".map") -1;

		/* First find out the name of current executable */
		my_hmod = GetModuleHandle(NULL);
		if (my_hmod == 0) {

			return(my_hmod);
		}

		err = GetModuleFileName(my_hmod, file_name, nSize);
		if (err == 0) {

			my_hmod = 0;
			return(my_hmod);
		}

		ext = strrchr(file_name, '.');
		if (ext != NULL) {

			*ext = 0;
			strcat(file_name, ".map");

			err = wdl_load_mapfile(file_name);
			if (err == 0) {

				my_hmod = 0;
			}
		} else {

			my_hmod = 0;
		}
	}

	return(my_hmod);
}

/***********************************************************************
Retrieves the address of an exported function. It follows the convention
of GetProcAddress(). */
static
FARPROC
wdl_get_procaddr_from_map(
/*======================*/
					/* out: address of exported
					function. */
	HANDLE		m_handle,	/* in: module handle */
	const char*	import_proc)	/* in: procedure name */
{
	map_hash_chain_t*	hash_chain;
	ulint			map_fold;

	map_fold = ut_fold_string(import_proc);
	HASH_SEARCH(
		next,
		m_htbl,
		map_fold,
		map_hash_chain_t*,
		hash_chain,
		(ut_strcmp(hash_chain->symbol, import_proc) == 0));

	if (hash_chain == NULL) {

#ifdef _WIN64
		/* On Win64, the leading '_' may not be taken out. In this
		case, search again without the leading '_'. */
		if (*import_proc == '_') {

			import_proc++;
		}

		map_fold = ut_fold_string(import_proc);
		HASH_SEARCH(
			next,
			m_htbl,
			map_fold,
			map_hash_chain_t*,
			hash_chain,
			(ut_strcmp(hash_chain->symbol, import_proc) == 0));

		if (hash_chain == NULL) {
#endif
			if (wdl_init == TRUE) {

				sql_print_error(
					"InnoDB: the procedure pointer of %s"
					" is not found.",
					import_proc);
			}

			return(0);
#ifdef _WIN64
		}
#endif
	}

	return((FARPROC) ((ulint) m_handle + hash_chain->value));
}

/***********************************************************************
Retrieves the address of an exported variable.
Note: It does not follow the Windows call convention FARPROC. */
static
void*
wdl_get_varaddr_from_map(
/*=====================*/
						/* out: address of exported
						variable. */
	HANDLE		m_handle,		/* in: module handle */
	const char*	import_variable)	/* in: variable name */
{
	map_hash_chain_t*	hash_chain;
	ulint			map_fold;

	map_fold = ut_fold_string(import_variable);
	HASH_SEARCH(
		next,
		m_htbl,
		map_fold,
		map_hash_chain_t*,
		hash_chain,
		(ut_strcmp(hash_chain->symbol, import_variable) == 0));

	if (hash_chain == NULL) {

#ifdef _WIN64
		/* On Win64, the leading '_' may not be taken out. In this
		case, search again without the leading '_'. */
		if (*import_variable == '_') {

			import_variable++;
		}

		map_fold = ut_fold_string(import_variable);
		HASH_SEARCH(
			next,
			m_htbl,
			map_fold,
			map_hash_chain_t*,
			hash_chain,
			(ut_strcmp(hash_chain->symbol, import_variable) == 0));

		if (hash_chain == NULL) {
#endif
			if (wdl_init == TRUE) {

				sql_print_error(
					"InnoDB: the variable address of %s"
					" is not found.",
					import_variable);
			}

			return(0);
#ifdef _WIN64
		}
#endif
	}

	return((void*) ((ulint) m_handle + hash_chain->value));
}

/***********************************************************************
Bind all unresolved external variables from the MySQL executable. */
static
bool
wdl_get_external_variables(void)
/*============================*/
			/* out: TRUE if successful */
{
	HMODULE	hmod = wdl_get_mysqld_mapfile();

	if (hmod == 0) {

		return(FALSE);
	}

#define GET_SYM(sym, var, type)					\
	var = (type*) wdl_get_varaddr_from_map(hmod, sym);	\
	if (var == NULL) return(FALSE)
#ifdef _WIN64
#define GET_SYM2(sym1, sym2, var, type)				\
	var = (type*) wdl_get_varaddr_from_map(hmod, sym1);	\
	if (var == NULL) return(FALSE)
#else
#define GET_SYM2(sym1, sym2, var, type)				\
	var = (type*) wdl_get_varaddr_from_map(hmod, sym2);	\
	if (var == NULL) return(FALSE)
#endif // (_WIN64)
#define GET_C_SYM(sym, type) GET_SYM(#sym, wdl_##sym, type)

	GET_C_SYM(my_charset_bin, CHARSET_INFO);
	GET_C_SYM(my_charset_latin1, CHARSET_INFO);
	GET_C_SYM(my_charset_filename, CHARSET_INFO);
	GET_C_SYM(default_charset_info, CHARSET_INFO*);
	GET_C_SYM(all_charsets, CHARSET_INFO*);
	GET_C_SYM(my_umask, int);

	GET_SYM("?global_system_variables@@3Usystem_variables@@A",
		wdl_global_system_variables, struct system_variables);
	GET_SYM("?mysql_real_data_home@@3PADA",
		wdl_mysql_real_data_home, char);
	GET_SYM("?reg_ext@@3PADA", wdl_reg_ext, char);
	GET_SYM("?LOCK_thread_count@@3U_RTL_CRITICAL_SECTION@@A",
		wdl_LOCK_thread_count, pthread_mutex_t);
	GET_SYM("?key_map_full@@3V?$Bitmap@$0EA@@@A",
		wdl_key_map_full, key_map);
	GET_SYM("?mysql_tmpdir_list@@3Ust_my_tmpdir@@A",
		wdl_mysql_tmpdir_list, MY_TMPDIR);
	GET_SYM("?mysqld_embedded@@3_NA",
		wdl_mysqld_embedded, bool);
	GET_SYM("?lower_case_table_names@@3IA",
		wdl_lower_case_table_names, uint);
	GET_SYM("?specialflag@@3KA", wdl_specialflag, ulong);
	GET_SYM("?builtin_innobase_plugin@@3PAUst_mysql_plugin@@A",
		builtin_innobase_plugin_ptr, struct st_mysql_plugin);

	GET_SYM2("?system_charset_info@@3PEAUcharset_info_st@@EA",
		 "?system_charset_info@@3PAUcharset_info_st@@A",
		 wdl_system_charset_info, CHARSET_INFO*);
	GET_SYM2("?mysql_data_home@@3PEADEA",
		 "?mysql_data_home@@3PADA",
		 wdl_mysql_data_home, char*);
	GET_SYM2("?tx_isolation_names@@3PAPEBDA",
		 "?tx_isolation_names@@3PAPBDA",
		 wdl_tx_isolation_names, char*);
	GET_SYM2("?binlog_format_names@@3PAPEBDA",
		 "?binlog_format_names@@3PAPBDA",
		 wdl_binlog_format_names, char*);

	wdl_init = TRUE;
	return(TRUE);

#undef GET_SYM
#undef GET_SYM2
#undef GET_C_SYM
}

/***********************************************************************
The DLL Delayed Loading Helper Function for resolving externals.

The function may fail due to one of the three reasons:

* Invalid parameter, which happens if the attributes in pidd aren't
  specified correctly.
* Failed to load the map file mysqld.map.
* Failed to find an external name in the map file mysqld.map.

Note: this function is called by run-time as well as __HrLoadAllImportsForDll.
So, it has to follow Windows call convention. */
extern "C"
FARPROC WINAPI
__delayLoadHelper2(
/*===============*/
					/* out: the address of the imported
					function*/
	PCImgDelayDescr	pidd,		/* in: a const pointer to a
					ImgDelayDescr, see delayimp.h. */
	FARPROC*	iat_entry)	/* in/out: A pointer to the slot in
					the delay load import address table
					to be updated with the address of the
					imported function. */
{
	ulint		iIAT, iINT;
	HMODULE		hmod;
	PCImgThunkData	pitd;
	FARPROC		fun = NULL;

	/* Set up data used for the hook procs  */
	InternalImgDelayDescr	idd = {
				pidd->grAttrs,
				PFromRva<LPCSTR>(pidd->rvaDLLName),
				PFromRva<HMODULE*>(pidd->rvaHmod),
				PFromRva<PImgThunkData>(pidd->rvaIAT),
				PFromRva<PCImgThunkData>(pidd->rvaINT),
				PFromRva<PCImgThunkData>(pidd->rvaBoundIAT),
				PFromRva<PCImgThunkData>(pidd->rvaUnloadIAT),
				pidd->dwTimeStamp
	};

	DelayLoadInfo		dli = {
				sizeof(DelayLoadInfo),
				pidd,
				iat_entry,
				idd.szName,
				{0},
				0,
				0,
				0
	};

	/* Check the Delay Load Attributes, log an error of invalid
	parameter, which happens if the attributes in pidd are not
	specified correctly. */
	if ((idd.grAttrs & dlattrRva) == 0) {

		sql_print_error("InnoDB: invalid parameter for delay loader.");
		return(0);
	}

	hmod = *idd.phmod;

	/* Calculate the index for the IAT entry in the import address table.
	The INT entries are ordered the same as the IAT entries so the
	calculation can be done on the IAT side. */
	iIAT = (PCImgThunkData) iat_entry - idd.pIAT;
	iINT = iIAT;

	pitd = &(idd.pINT[iINT]);

	dli.dlp.fImportByName = !IMAGE_SNAP_BY_ORDINAL(pitd->u1.Ordinal);

	if (dli.dlp.fImportByName) {

		dli.dlp.szProcName = (LPCSTR) (PFromRva<PIMAGE_IMPORT_BY_NAME>
			((RVA) ((UINT_PTR) pitd->u1.AddressOfData))->Name);
	} else {

		dli.dlp.dwOrdinal = (ulint) IMAGE_ORDINAL(pitd->u1.Ordinal);
	}

	/* Now, load the mapfile, if it has not been done yet */
	if (hmod == 0) {

		hmod = wdl_get_mysqld_mapfile();
	}

	if (hmod == 0) {
		/* LoadLibrary failed. */
		PDelayLoadInfo	rgpdli[1] = {&dli};

		dli.dwLastError = ::GetLastError();

		sql_print_error(
			"InnoDB: failed to load mysqld.map with error %d.",
			dli.dwLastError);

		return(0);
	}

	/* Store the library handle. */
	idd.phmod = &hmod;

	/* Go for the procedure now. */
	dli.hmodCur = hmod;

	if (pidd->rvaBoundIAT && pidd->dwTimeStamp) {

		/* Bound imports exist, check the timestamp from the target
		image */
		PIMAGE_NT_HEADERS	pinh;

		pinh = (PIMAGE_NT_HEADERS) ((byte*) hmod
				+ ((PIMAGE_DOS_HEADER) hmod)->e_lfanew);

		if (pinh->Signature == IMAGE_NT_SIGNATURE
		    && pinh->FileHeader.TimeDateStamp == idd.dwTimeStamp
		    && (DWORD) hmod == pinh->OptionalHeader.ImageBase) {

			/* We have a decent address in the bound IAT. */
			fun = (FARPROC) (UINT_PTR)
					idd.pBoundIAT[iIAT].u1.Function;

			if (fun) {

				*iat_entry = fun;
				return(fun);
			}
		}
	}

	fun = wdl_get_procaddr_from_map(hmod, dli.dlp.szProcName);

	if (fun == 0) {

		return(0);
	}

	*iat_entry = fun;
	return(fun);
}

/***********************************************************************
Unload a DLL that was delay loaded. This function is called by run-time. */
extern "C"
BOOL WINAPI
__FUnloadDelayLoadedDLL2(
/*=====================*/
				/* out: TRUE is returned if the DLL is found
				and the IAT matches the original one. */
	LPCSTR	module_name)	/* in: DLL name */
{
	return(TRUE);
}

/******************************************************************
Load all imports from a DLL that was specified with the /delayload linker
option.
Note: this function is called by run-time. So, it has to follow Windows call
convention. */
extern "C"
HRESULT WINAPI
__HrLoadAllImportsForDll(
/*=====================*/
				/* out: S_OK if the DLL matches, otherwise
				ERROR_MOD_NOT_FOUND is returned. */
	LPCSTR	module_name)	/* in: DLL name */
{
	PIMAGE_NT_HEADERS	img;
	PCImgDelayDescr		pidd;
	IMAGE_DATA_DIRECTORY*	image_data;
	LPCSTR			current_module;
	HRESULT			ret = ERROR_MOD_NOT_FOUND;
	HMODULE			hmod = (HMODULE) &__ImageBase;

	img = (PIMAGE_NT_HEADERS) ((byte*) hmod
				   + ((PIMAGE_DOS_HEADER) hmod)->e_lfanew);
	image_data =
	 &img->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_DELAY_IMPORT];

	/* Scan the delay load IAT/INT for the DLL */
	if (image_data->Size) {

		pidd = PFromRva<PCImgDelayDescr>(image_data->VirtualAddress);

		/* Check all of the listed DLLs we want to load. */
		while (pidd->rvaDLLName) {

			current_module = PFromRva<LPCSTR>(pidd->rvaDLLName);

			if (stricmp(module_name, current_module) == 0) {

				/* Found it, break out with pidd and
				current_module set appropriately */
				break;
			}

			/* To the next delay import descriptor */
			pidd++;
		}

		if (pidd->rvaDLLName) {

			/* Found a matching DLL, now process it. */
			FARPROC*	iat_entry;
			size_t		count;

			iat_entry = PFromRva<FARPROC*>(pidd->rvaIAT);
			count = wdl_import_count((PCImgThunkData) iat_entry);

			/* now load all the imports from the DLL */
			while (count > 0) {

				/* No need to check the return value */
				__delayLoadHelper2(pidd, iat_entry);
				iat_entry++;
				count--;
			}

			ret = S_OK;
		}
	}

	return ret;
}

/******************************************************************
The main function of a DLL */
BOOL
WINAPI
DllMain(
/*====*/
					/* out: TRUE if the call succeeds */
	HINSTANCE	hinstDLL,	/* in: handle to the DLL module */
	DWORD		fdwReason,	/* Reason code that indicates why the
					DLL entry-point function is being
					called.*/
	LPVOID		lpvReserved)	/* in: additional parameter based on
					fdwReason */
{
	BOOL	success = TRUE;

	switch (fdwReason) {

	case DLL_PROCESS_ATTACH:
		success = wdl_get_external_variables();
		break;

	case DLL_PROCESS_DETACH:
		wdl_cleanup();
		break;
	}

	return(success);
}

#endif /* defined (__WIN__) && defined (MYSQL_DYNAMIC_PLUGIN) */