Python winreg 模块，KEY_WOW64_64KEY 实例源码

def CoCreateInstanceC2R (self, store, reg, clsid, iid) :
        # Ugly code to find DLL in C2R version of COM object and get a COM
        # object despite the fact that COM doesn't handle C2R
        try:
            # Get DLL to load from 2R register 
            aReg = winreg.ConnectRegistry(None, store)
            aKey = winreg.OpenKey(aReg, reg, 0, winreg.KEY_READ | winreg.KEY_WOW64_64KEY)
            dummy_n, IconvDLL, dummy_t = winreg.EnumValue(aKey, 0)
            winreg.CloseKey(aKey)
            winreg.CloseKey(aReg)

            # Create OLE object from DLL
            IconvOLE = ctypes.OleDLL(IconvDLL)

            # Get COM Instance from OLE 
            clsid_class = uuid.UUID(str(clsid)).bytes_le
            iclassfactory = uuid.UUID(str(pythoncom.IID_IClassFactory)).bytes_le
            com_classfactory = ctypes.c_long(0)
            IconvOLE.DllGetClassObject(clsid_class, iclassfactory, ctypes.byref(com_classfactory))
            MyFactory = pythoncom.ObjectFromAddress(com_classfactory.value, pythoncom.IID_IClassFactory)
            return MyFactory.CreateInstance (None, str(iid))
        except:
            return None

def EnableCrashDumpCollection():
  """Tell Windows Error Reporting to record crash dumps so that we can diagnose
  linker crashes and other toolchain failures. Documented at:
  https://msdn.microsoft.com/en-us/library/windows/desktop/bb787181.aspx
  """
  if sys.platform == 'win32' and os.environ.get('CHROME_HEADLESS') == '1':
    key_name = r'SOFTWARE\Microsoft\Windows\Windows Error Reporting'
    try:
      key = winreg.CreateKeyEx(winreg.HKEY_LOCAL_MACHINE, key_name, 0,
                               winreg.KEY_WOW64_64KEY | winreg.KEY_ALL_ACCESS)
      # Merely creating LocalDumps is sufficient to enable the defaults.
      winreg.CreateKey(key, "LocalDumps")
      # Disable the WER UI, as documented here:
      # https://msdn.microsoft.com/en-us/library/windows/desktop/bb513638.aspx
      winreg.SetValueEx(key, "DontShowUI", 0, winreg.REG_DWORD, 1)
    # Trap OSError instead of WindowsError so pylint will succeed on Linux.
    # Catching errors is important because some build machines are not elevated
    # and writing to HKLM requires elevation.
    except OSError:
      pass

def _get_uid(self):
        hKey = regedit.OpenKey(regedit.HKEY_LOCAL_MACHINE,
            r"SOFTWARE\\Microsoft\\Cryptography", 0,
            regedit.KEY_READ | regedit.KEY_WOW64_64KEY)
        value, _ = regedit.QueryValueEx(hKey, "MachineGuid")
        return value

def set_up_windows_7_oem_background_reg():
    mid_key_str = 'SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Authentication\\LogonUI\\Background'
    target_key_name = 'OEMBackground'
    top_key = winreg.CreateKeyEx(winreg.HKEY_LOCAL_MACHINE, mid_key_str,
                                 access=winreg.KEY_ALL_ACCESS | winreg.KEY_WOW64_64KEY)
    winreg.SetValueEx(top_key, target_key_name, 0, winreg.REG_DWORD, 1)

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        from subprocess import Popen, PIPE
        try:
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except OSError:
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        from subprocess import Popen, PIPE
        try:
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except OSError:
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        from subprocess import Popen, PIPE
        try:
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except OSError:
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        from subprocess import Popen, PIPE
        try:
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except OSError:
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv

def get_machine_id():
    global _machine_id
    rv = _machine_id
    if rv is not None:
        return rv

    def _generate():
        # Potential sources of secret information on linux.  The machine-id
        # is stable across boots, the boot id is not
        for filename in '/etc/machine-id', '/proc/sys/kernel/random/boot_id':
            try:
                with open(filename, 'rb') as f:
                    return f.readline().strip()
            except IOError:
                continue

        # On OS X we can use the computer's serial number assuming that
        # ioreg exists and can spit out that information.
        try:
            # Also catch import errors: subprocess may not be available, e.g.
            # Google App Engine
            # See https://github.com/pallets/werkzeug/issues/925
            from subprocess import Popen, PIPE
            dump = Popen(['ioreg', '-c', 'IOPlatformExpertDevice', '-d', '2'],
                         stdout=PIPE).communicate()[0]
            match = re.search(b'"serial-number" = <([^>]+)', dump)
            if match is not None:
                return match.group(1)
        except (OSError, ImportError):
            pass

        # On Windows we can use winreg to get the machine guid
        wr = None
        try:
            import winreg as wr
        except ImportError:
            try:
                import _winreg as wr
            except ImportError:
                pass
        if wr is not None:
            try:
                with wr.OpenKey(wr.HKEY_LOCAL_MACHINE,
                                'SOFTWARE\\Microsoft\\Cryptography', 0,
                                wr.KEY_READ | wr.KEY_WOW64_64KEY) as rk:
                    return wr.QueryValueEx(rk, 'MachineGuid')[0]
            except WindowsError:
                pass

    _machine_id = rv = _generate()
    return rv