python ctypes win32 Get/SetTimeZoneInformation

ctypes_play.py

from contextlib import contextmanager

import ctypes
from ctypes.wintypes import WORD, DWORD, LONG, WCHAR, HANDLE

k32 = ctypes.windll.kernel32
a32 = ctypes.windll.advapi32

class SYSTEMTIME(ctypes.Structure):
    _fields_ = [
        ('wYear', WORD),
        ('wMonth', WORD),
        ('wDayOfWeek', WORD),
        ('wDay', WORD),
        ('wHour', WORD),
        ('wMinute', WORD),
        ('wSecond', WORD),
        ('wMilliseconds', WORD),
    ]
    
    def __str__(self):
        lines = ['    %s: %s'% (k, str(getattr(self, k)))
                 for k, t in self._fields_]
        return '\n'.join(lines)


class TIME_ZONE_INFORMATION(ctypes.Structure):
    _fields_ = [
        ('Bias', LONG),
        ('StandardName', WCHAR * 32),
        ('StandardDate', SYSTEMTIME),
        ('StandardBias', LONG),
        ('DaylightName', WCHAR * 32),
        ('DaylightDate', SYSTEMTIME),
        ('DaylightBias', LONG),
    ]
    
    def __str__(self):
        lines = ['%s: %s'% (k, str(getattr(self, k)))
                 for k, t in self._fields_]
        return '\n'.join(lines)

class LUID(ctypes.Structure):
    _fields_ = [
        ('LowPart', DWORD),
        ('HighPart', LONG)
    ]

class LUID_AND_ATTRIBUTES(ctypes.Structure):
    _fields_ = [
        ('Luid', LUID),
        ('Attributes', DWORD)
    ]

class TOKEN_PRIVILEGES(ctypes.Structure):
    _fields_ = [
        ('PrivilegeCount', DWORD),
        ('Privileges', LUID_AND_ATTRIBUTES * 1)
    ]

def getErrorText():
    buff = ctypes.create_string_buffer(1024)
    errCode = k32.GetLastError() & 0xFFFF
    k32.FormatMessageA(0x1000, 0, errCode, 0, buff, buff._length_, 0)
    return buff.value.strip()

def GetTimeZoneInformation():
    tzi = TIME_ZONE_INFORMATION()
    k32.GetTimeZoneInformation(ctypes.byref(tzi))
    return tzi

@contextmanager
def enableSetTimeZone():
    ''' see http://msdn.microsoft.com/en-us/library/windows/desktop/ms724944(v=vs.85).aspx
    '''
    
    TOKEN_ADJUST_PRIVILEGES = 0x0020
    TOKEN_QUERY             = 0x0008
    SE_PRIVILEGE_ENABLED    = 0x0002
    
    hToken = HANDLE()
    k32.OpenProcessToken(
        k32.GetCurrentProcess(),
        TOKEN_ADJUST_PRIVILEGES|TOKEN_QUERY,
        ctypes.byref(hToken))

    tkp = TOKEN_PRIVILEGES()
    a32.LookupPrivilegeValueA(
        0, "SeTimeZonePrivilege", ctypes.byref(tkp.Privileges[0].Luid))
    tkp.PrivilegeCount = 1
    tkp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED
    a32.AdjustTokenPrivileges(hToken, 0, ctypes.byref(tkp), 0, 0, 0)
    
    # Enabled; do what you want
    yield
    
    # Done; disable ..
    tkp.Privileges[0].Attributes = 0
    a32.AdjustTokenPrivileges(hToken, 0, ctypes.byref(tkp), 0, 0, 0)


def SetTimeZoneInformation(tzi):
    
    if not isinstance(tzi, TIME_ZONE_INFORMATION):
        raise ValueError("invalid 'tzi' argument")
    
    with enableSetTimeZone():
        rv = k32.SetTimeZoneInformation(ctypes.byref(tzi))
        if rv == 0:
            raise Exception(getErrorText())

tzi = GetTimeZoneInformation()
print tzi
SetTimeZoneInformation(tzi)