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bpo-11063, bpo-20519: avoid ctypes and improve import time for uuid (#3796)

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bpo-11063, bpo-20519: avoid ctypes and improve import time for uuid.
This commit is contained in:
Antoine Pitrou 2017-09-28 23:03:06 +02:00 • committed by GitHub
parent 8d59aca4a9
commit a106aec2ed
5 changed files with 330 additions and 201 deletions
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168
Lib/uuid.py
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@ -45,6 +45,7 @@ Typical usage:
"""
import os
import sys
from enum import Enum
@ -475,73 +476,112 @@ def _netbios_getnode():
continue
return int.from_bytes(bytes, 'big')
# Thanks to Thomas Heller for ctypes and for his help with its use here.
# If ctypes is available, use it to find system routines for UUID generation.
# XXX This makes the module non-thread-safe!
_uuid_generate_time = _UuidCreate = None
_generate_time_safe = _UuidCreate = None
_has_uuid_generate_time_safe = None
# Import optional C extension at toplevel, to help disabling it when testing
try:
import ctypes, ctypes.util
import sys
import _uuid
except ImportError:
_uuid = None
# The uuid_generate_* routines are provided by libuuid on at least
# Linux and FreeBSD, and provided by libc on Mac OS X.
_libnames = ['uuid']
if not sys.platform.startswith('win'):
_libnames.append('c')
for libname in _libnames:
try:
lib = ctypes.CDLL(ctypes.util.find_library(libname))
except Exception: # pragma: nocover
continue
# Try to find the safe variety first.
if hasattr(lib, 'uuid_generate_time_safe'):
_uuid_generate_time = lib.uuid_generate_time_safe
# int uuid_generate_time_safe(uuid_t out);
break
elif hasattr(lib, 'uuid_generate_time'): # pragma: nocover
_uuid_generate_time = lib.uuid_generate_time
# void uuid_generate_time(uuid_t out);
_uuid_generate_time.restype = None
break
del _libnames
# The uuid_generate_* functions are broken on MacOS X 10.5, as noted
# in issue #8621 the function generates the same sequence of values
# in the parent process and all children created using fork (unless
# those children use exec as well).
#
# Assume that the uuid_generate functions are broken from 10.5 onward,
# the test can be adjusted when a later version is fixed.
if sys.platform == 'darwin':
if int(os.uname().release.split('.')[0]) >= 9:
_uuid_generate_time = None
def _load_system_functions():
"""
Try to load platform-specific functions for generating uuids.
"""
global _generate_time_safe, _UuidCreate, _has_uuid_generate_time_safe
if _has_uuid_generate_time_safe is not None:
return
_has_uuid_generate_time_safe = False
if sys.platform == "darwin" and int(os.uname().release.split('.')[0]) < 9:
# The uuid_generate_* functions are broken on MacOS X 10.5, as noted
# in issue #8621 the function generates the same sequence of values
# in the parent process and all children created using fork (unless
# those children use exec as well).
#
# Assume that the uuid_generate functions are broken from 10.5 onward,
# the test can be adjusted when a later version is fixed.
pass
elif _uuid is not None:
_generate_time_safe = _uuid.generate_time_safe
_has_uuid_generate_time_safe = True
return
# On Windows prior to 2000, UuidCreate gives a UUID containing the
# hardware address. On Windows 2000 and later, UuidCreate makes a
# random UUID and UuidCreateSequential gives a UUID containing the
# hardware address. These routines are provided by the RPC runtime.
# NOTE: at least on Tim's WinXP Pro SP2 desktop box, while the last
# 6 bytes returned by UuidCreateSequential are fixed, they don't appear
# to bear any relationship to the MAC address of any network device
# on the box.
try:
lib = ctypes.windll.rpcrt4
except:
lib = None
_UuidCreate = getattr(lib, 'UuidCreateSequential',
getattr(lib, 'UuidCreate', None))
except:
pass
# If we couldn't find an extension module, try ctypes to find
# system routines for UUID generation.
# Thanks to Thomas Heller for ctypes and for his help with its use here.
import ctypes
import ctypes.util
def _unixdll_getnode():
"""Get the hardware address on Unix using ctypes."""
_buffer = ctypes.create_string_buffer(16)
_uuid_generate_time(_buffer)
return UUID(bytes=bytes_(_buffer.raw)).node
# The uuid_generate_* routines are provided by libuuid on at least
# Linux and FreeBSD, and provided by libc on Mac OS X.
_libnames = ['uuid']
if not sys.platform.startswith('win'):
_libnames.append('c')
for libname in _libnames:
try:
lib = ctypes.CDLL(ctypes.util.find_library(libname))
except Exception: # pragma: nocover
continue
# Try to find the safe variety first.
if hasattr(lib, 'uuid_generate_time_safe'):
_uuid_generate_time_safe = lib.uuid_generate_time_safe
# int uuid_generate_time_safe(uuid_t out);
def _generate_time_safe():
_buffer = ctypes.create_string_buffer(16)
res = _uuid_generate_time_safe(_buffer)
return bytes(_buffer.raw), res
_has_uuid_generate_time_safe = True
break
elif hasattr(lib, 'uuid_generate_time'): # pragma: nocover
_uuid_generate_time = lib.uuid_generate_time
# void uuid_generate_time(uuid_t out);
_uuid_generate_time.restype = None
def _generate_time_safe():
_buffer = ctypes.create_string_buffer(16)
_uuid_generate_time(_buffer)
return bytes(_buffer.raw), None
break
# On Windows prior to 2000, UuidCreate gives a UUID containing the
# hardware address. On Windows 2000 and later, UuidCreate makes a
# random UUID and UuidCreateSequential gives a UUID containing the
# hardware address. These routines are provided by the RPC runtime.
# NOTE: at least on Tim's WinXP Pro SP2 desktop box, while the last
# 6 bytes returned by UuidCreateSequential are fixed, they don't appear
# to bear any relationship to the MAC address of any network device
# on the box.
try:
lib = ctypes.windll.rpcrt4
except:
lib = None
_UuidCreate = getattr(lib, 'UuidCreateSequential',
getattr(lib, 'UuidCreate', None))
except Exception as exc:
import warnings
warnings.warn(f"Could not find fallback ctypes uuid functions: {exc}",
ImportWarning)
def _unix_getnode():
"""Get the hardware address on Unix using the _uuid extension module
or ctypes."""
_load_system_functions()
uuid_time, _ = _generate_time_safe()
return UUID(bytes=uuid_time).node
def _windll_getnode():
"""Get the hardware address on Windows using ctypes."""
import ctypes
_load_system_functions()
_buffer = ctypes.create_string_buffer(16)
if _UuidCreate(_buffer) == 0:
return UUID(bytes=bytes_(_buffer.raw)).node
@ -551,6 +591,7 @@ def _random_getnode():
import random
return random.getrandbits(48) | 0x010000000000
_node = None
def getnode():
@ -561,16 +602,14 @@ def getnode():
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
import sys
if sys.platform == 'win32':
getters = [_windll_getnode, _netbios_getnode, _ipconfig_getnode]
else:
getters = [_unixdll_getnode, _ifconfig_getnode, _ip_getnode,
getters = [_unix_getnode, _ifconfig_getnode, _ip_getnode,
_arp_getnode, _lanscan_getnode, _netstat_getnode]
for getter in getters + [_random_getnode]:
@ -581,6 +620,7 @@ def getnode():
if _node is not None:
return _node
_last_timestamp = None
def uuid1(node=None, clock_seq=None):
@ -591,14 +631,14 @@ def uuid1(node=None, clock_seq=None):
# 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 _uuid_generate_time and node is clock_seq is None:
_buffer = ctypes.create_string_buffer(16)
safely_generated = _uuid_generate_time(_buffer)
_load_system_functions()
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
return UUID(bytes=bytes_(_buffer.raw), is_safe=is_safe)
return UUID(bytes=uuid_time, is_safe=is_safe)
global _last_timestamp
import time