# Based on http://code.activestate.com/recipes/576362-list-system-process-and-process-information-on-win/
# License: MIT
from ctypes import c_long, c_int, c_uint, c_char, c_void_p
from ctypes import windll
from ctypes import Structure
from ctypes import sizeof, POINTER, pointer

# Constants
TH32CS_SNAPPROCESS = 2

# Struct for PROCESSENTRY32
class PROCESSENTRY32(Structure):
	_fields_ = [ ( 'dwSize' , c_uint ) , 
		( 'cntUsage' , c_uint) ,
		( 'th32ProcessID' , c_uint) ,
		( 'th32DefaultHeapID' , c_uint) ,
		( 'th32ModuleID' , c_uint) ,
		( 'cntThreads' , c_uint) ,
		( 'th32ParentProcessID' , c_uint) ,
		( 'pcPriClassBase' , c_long) ,
		( 'dwFlags' , c_uint) ,
		( 'szExeFile' , c_char * 260 ) , 
		( 'th32MemoryBase' , c_long) ,
		( 'th32AccessKey' , c_long ) ]

# Foreign functions
## CreateToolhelp32Snapshot
CreateToolhelp32Snapshot= windll.kernel32.CreateToolhelp32Snapshot
CreateToolhelp32Snapshot.reltype = c_long
CreateToolhelp32Snapshot.argtypes = [ c_int , c_int ]
## Process32First
Process32First = windll.kernel32.Process32First
Process32First.argtypes = [ c_void_p , POINTER( PROCESSENTRY32 ) ]
Process32First.rettype = c_int
## Process32Next
Process32Next = windll.kernel32.Process32Next
Process32Next.argtypes = [ c_void_p , POINTER(PROCESSENTRY32) ]
Process32Next.rettype = c_int
## CloseHandle
CloseHandle = windll.kernel32.CloseHandle
CloseHandle.argtypes = [ c_void_p ]
CloseHandle.rettype = c_int

def wingetppid(pid):
	''' Get get parent process pid for process `pid`
	'''
	ppid = None
	hProcessSnap = c_void_p(0)
	hProcessSnap = CreateToolhelp32Snapshot( TH32CS_SNAPPROCESS , 0 )

	pe32 = PROCESSENTRY32()
	pe32.dwSize = sizeof( PROCESSENTRY32 )
	ret = Process32First( hProcessSnap , pointer( pe32 ) )

	while ret:
		if pe32.th32ProcessID == pid:
			ppid = pe32.th32ParentProcessID
		ret = Process32Next( hProcessSnap, pointer(pe32) )
	CloseHandle(hProcessSnap)
	return ppid
	

if __name__ == '__main__':
	import os
	print ' pid:', os.getpid()
	print 'ppid:', wingetppid(os.getpid())