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00daa520ce
I noticed these are available in Python 3.6+, which is what we support, and they're arguably nicer than using exponentiation. Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz> Reviewed-by: Andrew Bartlett <abartlet@samba.org>
121 lines
3.8 KiB
Python
121 lines
3.8 KiB
Python
#
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# NT Time utility functions.
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#
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# Copyright (C) Catalyst.Net Ltd 2023
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <https://www.gnu.org/licenses/>.
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#
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import datetime
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from typing import NewType
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import re
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NtTime = NewType("NtTime", int)
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NtTimeDelta = NewType("NtTimeDelta", int)
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NT_EPOCH = datetime.datetime(1601, 1, 1, 0, 0, 0, 0, tzinfo=datetime.timezone.utc)
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NT_TICKS_PER_μSEC = 10
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NT_TICKS_PER_SEC = NT_TICKS_PER_μSEC * 1_000_000
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def _validate_nt_time(nt_time: NtTime) -> None:
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if not isinstance(nt_time, int):
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raise ValueError(f"{nt_time} is not an integer")
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if not 0 <= nt_time < 2**64:
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raise ValueError(f"{nt_time} is out of range")
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def nt_time_from_datetime(tm: datetime.datetime) -> NtTime:
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time_since_epoch = tm - NT_EPOCH
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nt_time = NtTime(round(time_since_epoch.total_seconds() * NT_TICKS_PER_SEC))
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_validate_nt_time(nt_time)
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return nt_time
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def nt_now() -> NtTime:
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dt = datetime.datetime.now(datetime.timezone.utc)
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return nt_time_from_datetime(dt)
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def datetime_from_nt_time(nt_time: NtTime) -> datetime.datetime:
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_validate_nt_time(nt_time)
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time_since_epoch = datetime.timedelta(microseconds=nt_time / NT_TICKS_PER_μSEC)
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return NT_EPOCH + time_since_epoch
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def nt_time_delta_from_datetime(dt: datetime.timedelta) -> NtTimeDelta:
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return NtTimeDelta(round(dt.total_seconds() * NT_TICKS_PER_SEC))
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def timedelta_from_nt_time_delta(nt_time_delta: NtTimeDelta) -> datetime.timedelta:
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return datetime.timedelta(microseconds=nt_time_delta / NT_TICKS_PER_μSEC)
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def nt_time_from_string(s: str) -> NtTime:
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"""Convert a subset of ISO 8601 date/time strings, ldap timestamps,
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and the string 'now' into NT time.
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The ldap format is
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YYYYmmddHHMMSS.0Z
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which is 14 digits followed by the fixed string '.0Z'. This is
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used in LDIF and internally by ldb.
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The ISO format is
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YYYY-mm-dd[*HH[:MM[:SS[.fff[fff]]]][+HH:MM[:SS[.ffffff]]]]
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where the '*' can be any character, and the optional last
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'[+HH:MM[:SS[.ffffff]]]' is a timezone offset (use '+00:00' for
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UTC).
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"""
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try:
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if s == 'now':
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dt = datetime.datetime.now(datetime.timezone.utc)
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elif re.match(r'^\d{14}\.0Z$', s):
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# "20230127223641.0Z"
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dt = datetime.strptime(s, '%Y%m%d%H%M%S.0Z')
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else:
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dt = datetime.datetime.fromisoformat(s)
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except ValueError:
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raise ValueError("Expected a date in either "
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"ISO8601 'YYYY-MM-DD HH:MM:SS' format, "
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"LDAP timestamp 'YYYYmmddHHMMSS.0Z', "
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"or the literal string 'now'. "
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f" Got '{s}'.")
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if dt.tzinfo is None:
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# This is a cursed timestamp with no timezone info. We have to
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# guess or nt_time_from_datetime() will fail. The best guess
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# is the system timezone, which we can get this way:
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dt = dt.astimezone()
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return nt_time_from_datetime(dt)
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def string_from_nt_time(nttime: NtTime, format:str=None) -> str:
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"""Format an NtTime date as a string.
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If format is not provided, an ISO 8601 string is used.
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"""
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dt = datetime_from_nt_time(nttime)
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if format is not None:
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return dt.strftime(format)
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return dt.isoformat()
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