cpython/Lib/uuid.py at 3.15 · python/cpython · GitHub

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r"""UUID objects (universally unique identifiers) according to RFC 4122/9562.

This module provides immutable UUID objects (class UUID) and functions for

generating UUIDs corresponding to a specific UUID version as specified in

RFC 4122/9562, e.g., uuid1() for UUID version 1, uuid3() for UUID version 3,

and so on.

Note that UUID version 2 is deliberately omitted as it is outside the scope

of the RFC.

If all you want is a unique ID, you should probably call uuid1() or uuid4().

Note that uuid1() may compromise privacy since it creates a UUID containing

the computer's network address. uuid4() creates a random UUID.

Typical usage:

>>> import uuid

# make a UUID based on the host ID and current time

>>> uuid.uuid1() # doctest: +SKIP

UUID('a8098c1a-f86e-11da-bd1a-00112444be1e')

# make a UUID using an MD5 hash of a namespace UUID and a name

>>> uuid.uuid3(uuid.NAMESPACE_DNS, 'python.org')

UUID('6fa459ea-ee8a-3ca4-894e-db77e160355e')

# make a random UUID

>>> uuid.uuid4() # doctest: +SKIP

UUID('16fd2706-8baf-433b-82eb-8c7fada847da')

# make a UUID using a SHA-1 hash of a namespace UUID and a name

>>> uuid.uuid5(uuid.NAMESPACE_DNS, 'python.org')

UUID('886313e1-3b8a-5372-9b90-0c9aee199e5d')

# make a UUID from a string of hex digits (braces and hyphens ignored)

>>> x = uuid.UUID('{00010203-0405-0607-0809-0a0b0c0d0e0f}')

# convert a UUID to a string of hex digits in standard form

>>> str(x)

'00010203-0405-0607-0809-0a0b0c0d0e0f'

# get the raw 16 bytes of the UUID

>>> x.bytes

b'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f'

# make a UUID from a 16-byte bytes object

>>> uuid.UUID(bytes=x.bytes)

UUID('00010203-0405-0607-0809-0a0b0c0d0e0f')

# get the Nil UUID

>>> uuid.NIL

UUID('00000000-0000-0000-0000-000000000000')

# get the Max UUID

>>> uuid.MAX

UUID('ffffffff-ffff-ffff-ffff-ffffffffffff')

"""

import os

import sys

import time

from enum import Enum, _simple_enum

__author__ = 'Ka-Ping Yee <ping@zesty.ca>'

# The recognized platforms - known behaviors

if sys.platform in {'win32', 'darwin', 'emscripten', 'wasi'}:

_AIX = _LINUX = False

elif sys.platform == 'linux':

_LINUX = True

_AIX = False

else:

import platform

_platform_system = platform.system()

_AIX = _platform_system == 'AIX'

_LINUX = _platform_system in ('Linux', 'Android')

_MAC_DELIM = b':'

_MAC_OMITS_LEADING_ZEROES = False

if _AIX:

_MAC_DELIM = b'.'

_MAC_OMITS_LEADING_ZEROES = True

RESERVED_NCS, RFC_4122, RESERVED_MICROSOFT, RESERVED_FUTURE = [

'reserved for NCS compatibility', 'specified in RFC 4122',

'reserved for Microsoft compatibility', 'reserved for future definition']

int_ = int # The built-in int type

bytes_ = bytes # The built-in bytes type

@_simple_enum(Enum)

class SafeUUID:

safe = 0

unsafe = -1

unknown = None

_UINT_128_MAX = (1 << 128) - 1

# 128-bit mask to clear the variant and version bits of a UUID integral value

_RFC_4122_CLEARFLAGS_MASK = ~((0xf000 << 64) | (0xc000 << 48))

# RFC 4122 variant bits and version bits to activate on a UUID integral value.

_RFC_4122_VERSION_1_FLAGS = ((1 << 76) | (0x8000 << 48))

_RFC_4122_VERSION_3_FLAGS = ((3 << 76) | (0x8000 << 48))

_RFC_4122_VERSION_4_FLAGS = ((4 << 76) | (0x8000 << 48))

_RFC_4122_VERSION_5_FLAGS = ((5 << 76) | (0x8000 << 48))

_RFC_4122_VERSION_6_FLAGS = ((6 << 76) | (0x8000 << 48))

_RFC_4122_VERSION_7_FLAGS = ((7 << 76) | (0x8000 << 48))

_RFC_4122_VERSION_8_FLAGS = ((8 << 76) | (0x8000 << 48))

class UUID:

"""Instances of the UUID class represent UUIDs as specified in RFC 4122.

UUID objects are immutable, hashable, and usable as dictionary keys.

Converting a UUID to a string with str() yields something in the form

'12345678-1234-1234-1234-123456789abc'. The UUID constructor accepts

five possible forms: a similar string of hexadecimal digits, or a tuple

of six integer fields (with 32-bit, 16-bit, 16-bit, 8-bit, 8-bit, and

48-bit values respectively) as an argument named 'fields', or a 16-byte

bytes object (with all the integer fields in big-endian order) as an

argument named 'bytes', or a 16-byte bytes object (with the first three

fields in little-endian order) as an argument named 'bytes_le', or a single

128-bit integer as an argument named 'int'.

UUIDs have these read-only attributes:

bytes the UUID as a 16-byte bytes object (containing the six

integer fields in big-endian byte order)

bytes_le the UUID as a 16-byte bytes object (with time_low,

time_mid, and time_hi_version in little-endian byte order)

fields a tuple of the six integer fields of the UUID,

which are also available as six individual attributes

and two derived attributes. Those attributes are not

always relevant to all UUID versions:

The 'time_*' attributes are only relevant to version 1.

The 'clock_seq*' and 'node' attributes are only relevant

to versions 1 and 6.

The 'time' attribute is only relevant to versions 1, 6

and 7.

time_low the first 32 bits of the UUID

time_mid the next 16 bits of the UUID

time_hi_version the next 16 bits of the UUID

clock_seq_hi_variant the next 8 bits of the UUID

clock_seq_low the next 8 bits of the UUID

node the last 48 bits of the UUID

time the 60-bit timestamp for UUIDv1/v6,

or the 48-bit timestamp for UUIDv7

clock_seq the 14-bit sequence number

hex the UUID as a 32-character hexadecimal string

int the UUID as a 128-bit integer

urn the UUID as a URN as specified in RFC 4122/9562

variant the UUID variant (one of the constants RESERVED_NCS,

RFC_4122, RESERVED_MICROSOFT, or RESERVED_FUTURE)

version the UUID version number (1 through 8, meaningful only

when the variant is RFC_4122)

is_safe An enum indicating whether the UUID has been generated in

a way that is safe for multiprocessing applications, via

uuid_generate_time_safe(3).

"""

__slots__ = ('int', 'is_safe', '__weakref__')

def __init__(self, hex=None, bytes=None, bytes_le=None, fields=None,

int=None, version=None,

*, is_safe=SafeUUID.unknown):

r"""Create a UUID from either a string of 32 hexadecimal digits,

a 16-byte bytes object as the 'bytes' argument, a 16-byte bytes object

in little-endian order as the 'bytes_le' argument, a tuple of six

integers (32-bit time_low, 16-bit time_mid, 16-bit time_hi_version,

8-bit clock_seq_hi_variant, 8-bit clock_seq_low, 48-bit node) as

the 'fields' argument, or a single 128-bit integer as the 'int'

argument. When a string of hex digits is given, curly braces,

hyphens, and a URN prefix are all optional. For example, these

expressions all yield the same UUID:

UUID('{12345678-1234-5678-1234-567812345678}')

UUID('12345678123456781234567812345678')

UUID('urn:uuid:12345678-1234-5678-1234-567812345678')

UUID(bytes=b'\x12\x34\x56\x78'*4)

UUID(bytes_le=b'\x78\x56\x34\x12\x34\x12\x78\x56' +

b'\x12\x34\x56\x78\x12\x34\x56\x78')

UUID(fields=(0x12345678, 0x1234, 0x5678, 0x12, 0x34, 0x567812345678))

UUID(int=0x12345678123456781234567812345678)

Exactly one of 'hex', 'bytes', 'bytes_le', 'fields', or 'int' must

be given. The 'version' argument is optional; if given, the resulting

UUID will have its variant and version set according to RFC 4122,

overriding the given 'hex', 'bytes', 'bytes_le', 'fields', or 'int'.

is_safe is an enum exposed as an attribute on the instance. It

indicates whether the UUID has been generated in a way that is safe

for multiprocessing applications, via uuid_generate_time_safe(3).

"""

if [hex, bytes, bytes_le, fields, int].count(None) != 4:

raise TypeError('one of the hex, bytes, bytes_le, fields, '

'or int arguments must be given')

if int is not None:

pass

elif hex is not None:

hex = hex.replace('urn:', '').replace('uuid:', '')

hex = hex.strip('{}').replace('-', '')

if len(hex) != 32:

raise ValueError('badly formed hexadecimal UUID string')

int = int_(hex, 16)

elif bytes_le is not None:

if len(bytes_le) != 16:

raise ValueError('bytes_le is not a 16-char string')

assert isinstance(bytes_le, bytes_), repr(bytes_le)

bytes = (bytes_le[4-1::-1] + bytes_le[6-1:4-1:-1] +

bytes_le[8-1:6-1:-1] + bytes_le[8:])

int = int_.from_bytes(bytes) # big endian

elif bytes is not None:

if len(bytes) != 16:

raise ValueError('bytes is not a 16-char string')

assert isinstance(bytes, bytes_), repr(bytes)

int = int_.from_bytes(bytes) # big endian

elif fields is not None:

if len(fields) != 6:

raise ValueError('fields is not a 6-tuple')

(time_low, time_mid, time_hi_version,

clock_seq_hi_variant, clock_seq_low, node) = fields

if not 0 <= time_low < (1 << 32):

raise ValueError('field 1 out of range (need a 32-bit value)')

if not 0 <= time_mid < (1 << 16):

raise ValueError('field 2 out of range (need a 16-bit value)')

if not 0 <= time_hi_version < (1 << 16):

raise ValueError('field 3 out of range (need a 16-bit value)')

if not 0 <= clock_seq_hi_variant < (1 << 8):

raise ValueError('field 4 out of range (need an 8-bit value)')

if not 0 <= clock_seq_low < (1 << 8):

raise ValueError('field 5 out of range (need an 8-bit value)')

if not 0 <= node < (1 << 48):

raise ValueError('field 6 out of range (need a 48-bit value)')

clock_seq = (clock_seq_hi_variant << 8) | clock_seq_low

int = ((time_low << 96) | (time_mid << 80) |

(time_hi_version << 64) | (clock_seq << 48) | node)

if not 0 <= int <= _UINT_128_MAX:

raise ValueError('int is out of range (need a 128-bit value)')

if version is not None:

if not 1 <= version <= 8:

raise ValueError('illegal version number')

# clear the variant and the version number bits

int &= _RFC_4122_CLEARFLAGS_MASK

# Set the variant to RFC 4122/9562.

int |= 0x8000_0000_0000_0000 # (0x8000 << 48)

# Set the version number.

int |= version << 76

object.__setattr__(self, 'int', int)

object.__setattr__(self, 'is_safe', is_safe)

@classmethod

def _from_int(cls, value):

"""Create a UUID from an integer *value*. Internal use only."""

assert 0 <= value <= _UINT_128_MAX, repr(value)

self = object.__new__(cls)

object.__setattr__(self, 'int', value)

object.__setattr__(self, 'is_safe', SafeUUID.unknown)

return self

def __getstate__(self):

d = {'int': self.int}

if self.is_safe != SafeUUID.unknown:

# is_safe is a SafeUUID instance. Return just its value, so that

# it can be un-pickled in older Python versions without SafeUUID.

d['is_safe'] = self.is_safe.value

return d

def __setstate__(self, state):

object.__setattr__(self, 'int', state['int'])

# is_safe was added in 3.7; it is also omitted when it is "unknown"

object.__setattr__(self, 'is_safe',

SafeUUID(state['is_safe'])

if 'is_safe' in state else SafeUUID.unknown)

def __eq__(self, other):

if isinstance(other, UUID):

return self.int == other.int

return NotImplemented

# Q. What's the value of being able to sort UUIDs?

# A. Use them as keys in a B-Tree or similar mapping.

def __lt__(self, other):

if isinstance(other, UUID):

return self.int < other.int

return NotImplemented

def __gt__(self, other):

if isinstance(other, UUID):

return self.int > other.int

return NotImplemented

def __le__(self, other):

if isinstance(other, UUID):

return self.int <= other.int

return NotImplemented

def __ge__(self, other):

if isinstance(other, UUID):

return self.int >= other.int

return NotImplemented

def __hash__(self):

return hash(self.int)

def __int__(self):

return self.int

def __repr__(self):

return '%s(%r)' % (self.__class__.__name__, str(self))

def __setattr__(self, name, value):

raise TypeError('UUID objects are immutable')

def __str__(self):

x = self.hex

return f'{x[:8]}-{x[8:12]}-{x[12:16]}-{x[16:20]}-{x[20:]}'

@property

def bytes(self):

return self.int.to_bytes(16) # big endian

@property

def bytes_le(self):

bytes = self.bytes

return (bytes[4-1::-1] + bytes[6-1:4-1:-1] + bytes[8-1:6-1:-1] +

bytes[8:])

@property

def fields(self):

return (self.time_low, self.time_mid, self.time_hi_version,

self.clock_seq_hi_variant, self.clock_seq_low, self.node)

@property

def time_low(self):

return self.int >> 96

@property

def time_mid(self):

return (self.int >> 80) & 0xffff

@property

def time_hi_version(self):

return (self.int >> 64) & 0xffff

@property

def clock_seq_hi_variant(self):

return (self.int >> 56) & 0xff

@property

def clock_seq_low(self):

return (self.int >> 48) & 0xff

@property

def time(self):

if self.version == 6:

# time_hi (32) | time_mid (16) | ver (4) | time_lo (12) | ... (64)

time_hi = self.int >> 96

time_lo = (self.int >> 64) & 0x0fff

return time_hi << 28 | (self.time_mid << 12) | time_lo

elif self.version == 7:

# unix_ts_ms (48) | ... (80)

return self.int >> 80

else:

# time_lo (32) | time_mid (16) | ver (4) | time_hi (12) | ... (64)

# For compatibility purposes, we do not warn or raise when the

# version is not 1 (timestamp is irrelevant to other versions).

time_hi = (self.int >> 64) & 0x0fff

time_lo = self.int >> 96

return time_hi << 48 | (self.time_mid << 32) | time_lo

@property

def clock_seq(self):

return (((self.clock_seq_hi_variant & 0x3f) << 8) |

self.clock_seq_low)

@property

def node(self):

return self.int & 0xffffffffffff

@property

def hex(self):

return self.bytes.hex()

@property

def urn(self):

return 'urn:uuid:' + str(self)

@property

def variant(self):

if not self.int & (0x8000 << 48):

return RESERVED_NCS

elif not self.int & (0x4000 << 48):

return RFC_4122

elif not self.int & (0x2000 << 48):

return RESERVED_MICROSOFT

else:

return RESERVED_FUTURE

@property

def version(self):

# The version bits are only meaningful for RFC 4122/9562 UUIDs.

if self.variant == RFC_4122:

return int((self.int >> 76) & 0xf)

def _get_command_stdout(command, *args):

import io, os, shutil, subprocess

try:

path_dirs = os.environ.get('PATH', os.defpath).split(os.pathsep)

path_dirs.extend(['/sbin', '/usr/sbin'])

executable = shutil.which(command, path=os.pathsep.join(path_dirs))

if executable is None:

return None

# LC_ALL=C to ensure English output, stderr=DEVNULL to prevent output

# on stderr (Note: we don't have an example where the words we search

# for are actually localized, but in theory some system could do so.)

env = dict(os.environ)

env['LC_ALL'] = 'C'

# Empty strings will be quoted by popen so we should just omit it

if args != ('',):

command = (executable, *args)

else:

command = (executable,)

proc = subprocess.Popen(command,

stdout=subprocess.PIPE,

stderr=subprocess.DEVNULL,

env=env)

if not proc:

return None

stdout, stderr = proc.communicate()

return io.BytesIO(stdout)

except (OSError, subprocess.SubprocessError):

return None

# For MAC (a.k.a. IEEE 802, or EUI-48) addresses, the second least significant

# bit of the first octet signifies whether the MAC address is universally (0)

# or locally (1) administered. Network cards from hardware manufacturers will

# always be universally administered to guarantee global uniqueness of the MAC

# address, but any particular machine may have other interfaces which are

# locally administered. An example of the latter is the bridge interface to

# the Touch Bar on MacBook Pros.

# This bit works out to be the 42nd bit counting from 1 being the least

# significant, or 1<<41. We'll prefer universally administered MAC addresses

# over locally administered ones since the former are globally unique, but

# we'll return the first of the latter found if that's all the machine has.

# See https://en.wikipedia.org/wiki/MAC_address#Universal_vs._local_(U/L_bit)

def _is_universal(mac):

return not (mac & (1 << 41))

def _find_mac_near_keyword(command, args, keywords, get_word_index):

"""Searches a command's output for a MAC address near a keyword.

Each line of words in the output is case-insensitively searched for

any of the given keywords. Upon a match, get_word_index is invoked

to pick a word from the line, given the index of the match. For

example, lambda i: 0 would get the first word on the line, while

lambda i: i - 1 would get the word preceding the keyword.

"""

stdout = _get_command_stdout(command, args)

if stdout is None:

return None

first_local_mac = None

for line in stdout:

words = line.lower().rstrip().split()

for i in range(len(words)):

if words[i] in keywords:

try:

word = words[get_word_index(i)]

mac = int(word.replace(_MAC_DELIM, b''), 16)

except (ValueError, IndexError):

# Virtual interfaces, such as those provided by

# VPNs, do not have a colon-delimited MAC address

# as expected, but a 16-byte HWAddr separated by

# dashes. These should be ignored in favor of a

# real MAC address

pass

else:

if _is_universal(mac):

return mac

first_local_mac = first_local_mac or mac

return first_local_mac or None

def _parse_mac(word):

# Accept 'HH:HH:HH:HH:HH:HH' MAC address (ex: '52:54:00:9d:0e:67'),

# but reject IPv6 address (ex: 'fe80::5054:ff:fe9' or '123:2:3:4:5:6:7:8').

# Virtual interfaces, such as those provided by VPNs, do not have a

# colon-delimited MAC address as expected, but a 16-byte HWAddr separated

# by dashes. These should be ignored in favor of a real MAC address

parts = word.split(_MAC_DELIM)

if len(parts) != 6:

return

if _MAC_OMITS_LEADING_ZEROES:

# (Only) on AIX the macaddr value given is not prefixed by 0, e.g.

# en0 1500 link#2 fa.bc.de.f7.62.4 110854824 0 160133733 0 0

# not

# en0 1500 link#2 fa.bc.de.f7.62.04 110854824 0 160133733 0 0

if not all(1 <= len(part) <= 2 for part in parts):

return

hexstr = b''.join(part.rjust(2, b'0') for part in parts)

else:

if not all(len(part) == 2 for part in parts):

return

hexstr = b''.join(parts)

try:

return int(hexstr, 16)

except ValueError:

return

def _find_mac_under_heading(command, args, heading):

"""Looks for a MAC address under a heading in a command's output.

The first line of words in the output is searched for the given

heading. Words at the same word index as the heading in subsequent

lines are then examined to see if they look like MAC addresses.

"""

stdout = _get_command_stdout(command, args)

if stdout is None:

return None

keywords = stdout.readline().rstrip().split()

try:

column_index = keywords.index(heading)

except ValueError:

return None

first_local_mac = None

for line in stdout:

words = line.rstrip().split()

try:

word = words[column_index]

except IndexError:

continue

mac = _parse_mac(word)

if mac is None:

continue

if _is_universal(mac):

return mac

if first_local_mac is None:

first_local_mac = mac

return first_local_mac

# The following functions call external programs to 'get' a macaddr value to

# be used as basis for an uuid

def _ifconfig_getnode():

"""Get the hardware address on Unix by running ifconfig."""

# This works on Linux ('' or '-a'), Tru64 ('-av'), but not all Unixes.

keywords = (b'hwaddr', b'ether', b'address:', b'lladdr')

for args in ('', '-a', '-av'):

mac = _find_mac_near_keyword('ifconfig', args, keywords, lambda i: i+1)

if mac:

return mac

return None

def _ip_getnode():

"""Get the hardware address on Unix by running ip."""

# This works on Linux with iproute2.

mac = _find_mac_near_keyword('ip', 'link', [b'link/ether'], lambda i: i+1)

if mac:

return mac

return None

def _arp_getnode():

"""Get the hardware address on Unix by running arp."""

import os, socket

if not hasattr(socket, "gethostbyname"):

return None

try:

ip_addr = socket.gethostbyname(socket.gethostname())

except OSError:

return None

# Try getting the MAC addr from arp based on our IP address (Solaris).

mac = _find_mac_near_keyword('arp', '-an', [os.fsencode(ip_addr)], lambda i: -1)

if mac:

return mac

# This works on OpenBSD

mac = _find_mac_near_keyword('arp', '-an', [os.fsencode(ip_addr)], lambda i: i+1)

if mac:

return mac

# This works on Linux, FreeBSD and NetBSD

mac = _find_mac_near_keyword('arp', '-an', [os.fsencode('(%s)' % ip_addr)],

lambda i: i+2)

# Return None instead of 0.

if mac:

return mac

return None

def _lanscan_getnode():

"""Get the hardware address on Unix by running lanscan."""

# This might work on HP-UX.

return _find_mac_near_keyword('lanscan', '-ai', [b'lan0'], lambda i: 0)

def _netstat_getnode():

"""Get the hardware address on Unix by running netstat."""

# This works on AIX and might work on Tru64 UNIX.

return _find_mac_under_heading('netstat', '-ian', b'Address')

# Import optional C extension at toplevel, to help disabling it when testing

try:

import _uuid

_generate_time_safe = getattr(_uuid, "generate_time_safe", None)

_has_stable_extractable_node = _uuid.has_stable_extractable_node

_UuidCreate = getattr(_uuid, "UuidCreate", None)

except ImportError:

_uuid = None

_generate_time_safe = None

_has_stable_extractable_node = False

_UuidCreate = None

def _unix_getnode():

"""Get the hardware address on Unix using the _uuid extension module."""

if _generate_time_safe and _has_stable_extractable_node:

uuid_time, _ = _generate_time_safe()

return UUID(bytes=uuid_time).node

def _windll_getnode():

"""Get the hardware address on Windows using the _uuid extension module."""

if _UuidCreate and _has_stable_extractable_node:

uuid_bytes = _UuidCreate()

return UUID(bytes_le=uuid_bytes).node

def _random_getnode():

"""Get a random node ID."""

# RFC 9562, §6.10-3 says that

# Implementations MAY elect to obtain a 48-bit cryptographic-quality

# random number as per Section 6.9 to use as the Node ID. [...] [and]

# implementations MUST set the least significant bit of the first octet

# of the Node ID to 1. This bit is the unicast or multicast bit, which

# will never be set in IEEE 802 addresses obtained from network cards.

# The "multicast bit" of a MAC address is defined to be "the least

# significant bit of the first octet". This works out to be the 41st bit

# counting from 1 being the least significant bit, or 1<<40.

# See https://en.wikipedia.org/w/index.php?title=MAC_address&oldid=1128764812#Universal_vs._local_(U/L_bit)

return int.from_bytes(os.urandom(6)) | (1 << 40)

# _OS_GETTERS, when known, are targeted for a specific OS or platform.

# The order is by 'common practice' on the specified platform.

# Note: 'posix' and 'windows' _OS_GETTERS are prefixed by a dll/dlload() method

# which, when successful, means none of these "external" methods are called.

# _GETTERS is (also) used by test_uuid.py to SkipUnless(), e.g.,

# @unittest.skipUnless(_uuid._ifconfig_getnode in _uuid._GETTERS, ...)

if _LINUX:

_OS_GETTERS = [_ip_getnode, _ifconfig_getnode]

elif sys.platform == 'darwin':

_OS_GETTERS = [_ifconfig_getnode, _arp_getnode, _netstat_getnode]

elif sys.platform == 'win32':

# bpo-40201: _windll_getnode will always succeed, so these are not needed

_OS_GETTERS = []

elif _AIX:

_OS_GETTERS = [_netstat_getnode]

else:

_OS_GETTERS = [_ifconfig_getnode, _ip_getnode, _arp_getnode,

_netstat_getnode, _lanscan_getnode]

if os.name == 'posix':

_GETTERS = [_unix_getnode] + _OS_GETTERS

elif os.name == 'nt':

_GETTERS = [_windll_getnode] + _OS_GETTERS

else:

_GETTERS = _OS_GETTERS

_node = None

def getnode():

"""Get the hardware address as a 48-bit positive integer.

The first time this runs, it may launch a separate program, which could

be quite slow. If all attempts to obtain the hardware address fail, we

choose a random 48-bit number with its eighth bit set to 1 as recommended

in RFC 4122.

"""

global _node

if _node is not None:

return _node

for getter in _GETTERS + [_random_getnode]:

try:

_node = getter()

except:

continue

if (_node is not None) and (0 <= _node < (1 << 48)):

return _node

assert False, '_random_getnode() returned invalid value: {}'.format(_node)

_last_timestamp = None

def uuid1(node=None, clock_seq=None):

"""Generate a UUID from a host ID, sequence number, and the current time.

If 'node' is not given, getnode() is used to obtain the hardware

address. If 'clock_seq' is given, it is used as the sequence number;

otherwise a random 14-bit sequence number is chosen."""

# When the system provides a version-1 UUID generator, use it (but don't

# use UuidCreate here because its UUIDs don't conform to RFC 4122).

if _generate_time_safe is not None and node is clock_seq is None:

uuid_time, safely_generated = _generate_time_safe()

try:

is_safe = SafeUUID(safely_generated)

except ValueError:

is_safe = SafeUUID.unknown

# The version field is assumed to be handled by _generate_time_safe().

return UUID(bytes=uuid_time, is_safe=is_safe)

global _last_timestamp

nanoseconds = time.time_ns()

# 0x01b21dd213814000 is the number of 100-ns intervals between the

# UUID epoch 1582-10-15 00:00:00 and the Unix epoch 1970-01-01 00:00:00.

timestamp = nanoseconds // 100 + 0x01b21dd213814000

if _last_timestamp is not None and timestamp <= _last_timestamp:

timestamp = _last_timestamp + 1

_last_timestamp = timestamp

if clock_seq is None:

import random

clock_seq = random.getrandbits(14) # instead of stable storage

time_low = timestamp & 0xffffffff

time_mid = (timestamp >> 32) & 0xffff

time_hi_version = (timestamp >> 48) & 0x0fff

clock_seq_low = clock_seq & 0xff

clock_seq_hi_variant = (clock_seq >> 8) & 0x3f

if node is None:

node = getnode()

return UUID(fields=(time_low, time_mid, time_hi_version,

clock_seq_hi_variant, clock_seq_low, node), version=1)

def uuid3(namespace, name):

"""Generate a UUID from the MD5 hash of a namespace UUID and a name."""

if isinstance(name, str):

name = bytes(name, "utf-8")

import hashlib

h = hashlib.md5(namespace.bytes + name, usedforsecurity=False)

int_uuid_3 = int.from_bytes(h.digest())

int_uuid_3 &= _RFC_4122_CLEARFLAGS_MASK

int_uuid_3 |= _RFC_4122_VERSION_3_FLAGS

return UUID._from_int(int_uuid_3)

def uuid4():

"""Generate a random UUID."""

int_uuid_4 = int.from_bytes(os.urandom(16))

int_uuid_4 &= _RFC_4122_CLEARFLAGS_MASK

int_uuid_4 |= _RFC_4122_VERSION_4_FLAGS

return UUID._from_int(int_uuid_4)

def uuid5(namespace, name):

"""Generate a UUID from the SHA-1 hash of a namespace UUID and a name."""

if isinstance(name, str):

name = bytes(name, "utf-8")

import hashlib

h = hashlib.sha1(namespace.bytes + name, usedforsecurity=False)

int_uuid_5 = int.from_bytes(h.digest()[:16])

int_uuid_5 &= _RFC_4122_CLEARFLAGS_MASK

int_uuid_5 |= _RFC_4122_VERSION_5_FLAGS

return UUID._from_int(int_uuid_5)

_last_timestamp_v6 = None

def uuid6(node=None, clock_seq=None):

"""Similar to :func:`uuid1` but where fields are ordered differently

for improved DB locality.

More precisely, given a 60-bit timestamp value as specified for UUIDv1,

for UUIDv6 the first 48 most significant bits are stored first, followed

by the 4-bit version (same position), followed by the remaining 12 bits

of the original 60-bit timestamp.

"""

global _last_timestamp_v6

import time

nanoseconds = time.time_ns()

# 0x01b21dd213814000 is the number of 100-ns intervals between the

# UUID epoch 1582-10-15 00:00:00 and the Unix epoch 1970-01-01 00:00:00.

timestamp = nanoseconds // 100 + 0x01b21dd213814000

if _last_timestamp_v6 is not None and timestamp <= _last_timestamp_v6:

timestamp = _last_timestamp_v6 + 1

_last_timestamp_v6 = timestamp

if clock_seq is None:

import random

clock_seq = random.getrandbits(14) # instead of stable storage

time_hi_and_mid = (timestamp >> 12) & 0xffff_ffff_ffff

time_lo = timestamp & 0x0fff # keep 12 bits and clear version bits

clock_s = clock_seq & 0x3fff # keep 14 bits and clear variant bits

if node is None:

node = getnode()

# --- 32 + 16 --- -- 4 -- -- 12 -- -- 2 -- -- 14 --- 48

int_uuid_6 = time_hi_and_mid << 80

int_uuid_6 |= time_lo << 64

int_uuid_6 |= clock_s << 48

int_uuid_6 |= node & 0xffff_ffff_ffff

# by construction, the variant and version bits are already cleared

int_uuid_6 |= _RFC_4122_VERSION_6_FLAGS

return UUID._from_int(int_uuid_6)

_last_timestamp_v7 = None

_last_counter_v7 = 0 # 42-bit counter

def _uuid7_get_counter_and_tail():

rand = int.from_bytes(os.urandom(10))

# 42-bit counter with MSB set to 0

counter = (rand >> 32) & 0x1ff_ffff_ffff

# 32-bit random data

tail = rand & 0xffff_ffff

return counter, tail

def uuid7():

"""Generate a UUID from a Unix timestamp in milliseconds and random bits.

UUIDv7 objects feature monotonicity within a millisecond.

"""

# --- 48 --- -- 4 -- --- 12 --- -- 2 -- --- 30 --- - 32 -

# 'counter = counter_hi | counter_lo' is a 42-bit counter constructed

# with Method 1 of RFC 9562, §6.2, and its MSB is set to 0.

# 'random' is a 32-bit random value regenerated for every new UUID.

# If multiple UUIDs are generated within the same millisecond, the LSB

# of 'counter' is incremented by 1. When overflowing, the timestamp is

# advanced and the counter is reset to a random 42-bit integer with MSB

# set to 0.

global _last_timestamp_v7

global _last_counter_v7

nanoseconds = time.time_ns()

timestamp_ms = nanoseconds // 1_000_000

if _last_timestamp_v7 is None or timestamp_ms > _last_timestamp_v7:

counter, tail = _uuid7_get_counter_and_tail()

else:

if timestamp_ms < _last_timestamp_v7:

timestamp_ms = _last_timestamp_v7 + 1

# advance the 42-bit counter

counter = _last_counter_v7 + 1

if counter > 0x3ff_ffff_ffff:

# advance the 48-bit timestamp

timestamp_ms += 1

counter, tail = _uuid7_get_counter_and_tail()

else:

# 32-bit random data

tail = int.from_bytes(os.urandom(4))

unix_ts_ms = timestamp_ms & 0xffff_ffff_ffff

counter_msbs = counter >> 30

# keep 12 counter's MSBs and clear variant bits

counter_hi = counter_msbs & 0x0fff

# keep 30 counter's LSBs and clear version bits

counter_lo = counter & 0x3fff_ffff

# ensure that the tail is always a 32-bit integer (by construction,

# it is already the case, but future interfaces may allow the user

# to specify the random tail)

tail &= 0xffff_ffff

int_uuid_7 = unix_ts_ms << 80

int_uuid_7 |= counter_hi << 64

int_uuid_7 |= counter_lo << 32

int_uuid_7 |= tail

# by construction, the variant and version bits are already cleared

int_uuid_7 |= _RFC_4122_VERSION_7_FLAGS

res = UUID._from_int(int_uuid_7)

# defer global update until all computations are done

_last_timestamp_v7 = timestamp_ms

_last_counter_v7 = counter

return res

def uuid8(a=None, b=None, c=None):

"""Generate a UUID from three custom blocks.

* 'a' is the first 48-bit chunk of the UUID (octets 0-5);

* 'b' is the mid 12-bit chunk (octets 6-7);

* 'c' is the last 62-bit chunk (octets 8-15).

When a value is not specified, a pseudo-random value is generated.

"""

if a is None:

import random

a = random.getrandbits(48)

if b is None:

import random

b = random.getrandbits(12)

if c is None:

import random

c = random.getrandbits(62)

int_uuid_8 = (a & 0xffff_ffff_ffff) << 80

int_uuid_8 |= (b & 0xfff) << 64

int_uuid_8 |= c & 0x3fff_ffff_ffff_ffff

# by construction, the variant and version bits are already cleared

int_uuid_8 |= _RFC_4122_VERSION_8_FLAGS

return UUID._from_int(int_uuid_8)

def main():

"""Run the uuid command line interface."""

uuid_funcs = {

"uuid1": uuid1,

"uuid3": uuid3,

"uuid4": uuid4,

"uuid5": uuid5,

"uuid6": uuid6,

"uuid7": uuid7,

"uuid8": uuid8,

}

uuid_namespace_funcs = ("uuid3", "uuid5")

namespaces = {

"@dns": NAMESPACE_DNS,

"@url": NAMESPACE_URL,

"@oid": NAMESPACE_OID,

"@x500": NAMESPACE_X500

}

import argparse

parser = argparse.ArgumentParser(

formatter_class=argparse.ArgumentDefaultsHelpFormatter,

description="Generate a UUID using the selected UUID function.",

)

parser.add_argument("-u", "--uuid",

choices=uuid_funcs.keys(),

default="uuid4",

help="function to generate the UUID")

parser.add_argument("-n", "--namespace",

metavar=f"{{any UUID,{','.join(namespaces)}}}",

help="`uuid3`/`uuid5` only: "

"a UUID, or a well-known predefined UUID addressed "

"by namespace name")

parser.add_argument("-N", "--name",

help="`uuid3`/`uuid5` only: "

"name used as part of generating the UUID")

parser.add_argument("-C", "--count", metavar="NUM", type=int, default=1,

help="generate `NUM` fresh UUIDs")

args = parser.parse_args()

uuid_func = uuid_funcs[args.uuid]

namespace = args.namespace

name = args.name

if args.uuid in uuid_namespace_funcs:

if not namespace or not name:

parser.error(

"Incorrect number of arguments. "

f"{args.uuid} requires a namespace and a name. "

"Run 'python -m uuid -h' for more information."

)

if namespace in namespaces:

namespace = namespaces[namespace]

else:

try:

namespace = UUID(namespace)

except ValueError as exc:

parser.error(f"{exc}: {args.namespace!r}")

for _ in range(args.count):

print(uuid_func(namespace, name))

else:

for _ in range(args.count):

print(uuid_func())

# The following standard UUIDs are for use with uuid3() or uuid5().

View remainder of file in raw view

cpython/Lib/uuid.py at 3.15 · python/cpython · GitHub

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