view mercurial/utils/dateutil.py @ 40626:87a872555e90

revlog: detect incomplete revlog reads

_readsegment() is supposed to return N bytes of revlog revision
data starting at a file offset. Surprisingly, its behavior before
this patch never verified that it actually read and returned N
bytes! Instead, it would perform the read(), then return whatever
data was available. And even more surprisingly, nothing in the
call chain appears to have been validating that it received all
the data it was expecting.

This behavior could lead to partial or incomplete revision chunks
being operated on. This could result in e.g. cached deltas being
applied against incomplete base revisions. The delta application
process would happily perform this operation. Only hash
verification would detect the corruption and save us.

This commit changes the behavior of raw revlog reading to validate
that we actually read() the number of bytes that were requested.
We will raise a more specific error faster, rather than possibly
have it go undetected or manifest later in the call stack, at
delta application or hash verification.

Differential Revision: https://phab.mercurial-scm.org/D5266

# util.py - Mercurial utility functions relative to dates
#
#  Copyright 2018 Boris Feld <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import, print_function

import calendar
import datetime
import time

from ..i18n import _
from .. import (
    encoding,
    error,
    pycompat,
)

# used by parsedate
defaultdateformats = (
    '%Y-%m-%dT%H:%M:%S', # the 'real' ISO8601
    '%Y-%m-%dT%H:%M',    #   without seconds
    '%Y-%m-%dT%H%M%S',   # another awful but legal variant without :
    '%Y-%m-%dT%H%M',     #   without seconds
    '%Y-%m-%d %H:%M:%S', # our common legal variant
    '%Y-%m-%d %H:%M',    #   without seconds
    '%Y-%m-%d %H%M%S',   # without :
    '%Y-%m-%d %H%M',     #   without seconds
    '%Y-%m-%d %I:%M:%S%p',
    '%Y-%m-%d %H:%M',
    '%Y-%m-%d %I:%M%p',
    '%Y-%m-%d',
    '%m-%d',
    '%m/%d',
    '%m/%d/%y',
    '%m/%d/%Y',
    '%a %b %d %H:%M:%S %Y',
    '%a %b %d %I:%M:%S%p %Y',
    '%a, %d %b %Y %H:%M:%S',        #  GNU coreutils "/bin/date --rfc-2822"
    '%b %d %H:%M:%S %Y',
    '%b %d %I:%M:%S%p %Y',
    '%b %d %H:%M:%S',
    '%b %d %I:%M:%S%p',
    '%b %d %H:%M',
    '%b %d %I:%M%p',
    '%b %d %Y',
    '%b %d',
    '%H:%M:%S',
    '%I:%M:%S%p',
    '%H:%M',
    '%I:%M%p',
)

extendeddateformats = defaultdateformats + (
    "%Y",
    "%Y-%m",
    "%b",
    "%b %Y",
)

def makedate(timestamp=None):
    '''Return a unix timestamp (or the current time) as a (unixtime,
    offset) tuple based off the local timezone.'''
    if timestamp is None:
        timestamp = time.time()
    if timestamp < 0:
        hint = _("check your clock")
        raise error.Abort(_("negative timestamp: %d") % timestamp, hint=hint)
    delta = (datetime.datetime.utcfromtimestamp(timestamp) -
             datetime.datetime.fromtimestamp(timestamp))
    tz = delta.days * 86400 + delta.seconds
    return timestamp, tz

def datestr(date=None, format='%a %b %d %H:%M:%S %Y %1%2'):
    """represent a (unixtime, offset) tuple as a localized time.
    unixtime is seconds since the epoch, and offset is the time zone's
    number of seconds away from UTC.

    >>> datestr((0, 0))
    'Thu Jan 01 00:00:00 1970 +0000'
    >>> datestr((42, 0))
    'Thu Jan 01 00:00:42 1970 +0000'
    >>> datestr((-42, 0))
    'Wed Dec 31 23:59:18 1969 +0000'
    >>> datestr((0x7fffffff, 0))
    'Tue Jan 19 03:14:07 2038 +0000'
    >>> datestr((-0x80000000, 0))
    'Fri Dec 13 20:45:52 1901 +0000'
    """
    t, tz = date or makedate()
    if "%1" in format or "%2" in format or "%z" in format:
        sign = (tz > 0) and "-" or "+"
        minutes = abs(tz) // 60
        q, r = divmod(minutes, 60)
        format = format.replace("%z", "%1%2")
        format = format.replace("%1", "%c%02d" % (sign, q))
        format = format.replace("%2", "%02d" % r)
    d = t - tz
    if d > 0x7fffffff:
        d = 0x7fffffff
    elif d < -0x80000000:
        d = -0x80000000
    # Never use time.gmtime() and datetime.datetime.fromtimestamp()
    # because they use the gmtime() system call which is buggy on Windows
    # for negative values.
    t = datetime.datetime(1970, 1, 1) + datetime.timedelta(seconds=d)
    s = encoding.strtolocal(t.strftime(encoding.strfromlocal(format)))
    return s

def shortdate(date=None):
    """turn (timestamp, tzoff) tuple into iso 8631 date."""
    return datestr(date, format='%Y-%m-%d')

def parsetimezone(s):
    """find a trailing timezone, if any, in string, and return a
       (offset, remainder) pair"""
    s = pycompat.bytestr(s)

    if s.endswith("GMT") or s.endswith("UTC"):
        return 0, s[:-3].rstrip()

    # Unix-style timezones [+-]hhmm
    if len(s) >= 5 and s[-5] in "+-" and s[-4:].isdigit():
        sign = (s[-5] == "+") and 1 or -1
        hours = int(s[-4:-2])
        minutes = int(s[-2:])
        return -sign * (hours * 60 + minutes) * 60, s[:-5].rstrip()

    # ISO8601 trailing Z
    if s.endswith("Z") and s[-2:-1].isdigit():
        return 0, s[:-1]

    # ISO8601-style [+-]hh:mm
    if (len(s) >= 6 and s[-6] in "+-" and s[-3] == ":" and
        s[-5:-3].isdigit() and s[-2:].isdigit()):
        sign = (s[-6] == "+") and 1 or -1
        hours = int(s[-5:-3])
        minutes = int(s[-2:])
        return -sign * (hours * 60 + minutes) * 60, s[:-6]

    return None, s

def strdate(string, format, defaults=None):
    """parse a localized time string and return a (unixtime, offset) tuple.
    if the string cannot be parsed, ValueError is raised."""
    if defaults is None:
        defaults = {}

    # NOTE: unixtime = localunixtime + offset
    offset, date = parsetimezone(string)

    # add missing elements from defaults
    usenow = False # default to using biased defaults
    for part in ("S", "M", "HI", "d", "mb", "yY"): # decreasing specificity
        part = pycompat.bytestr(part)
        found = [True for p in part if ("%"+p) in format]
        if not found:
            date += "@" + defaults[part][usenow]
            format += "@%" + part[0]
        else:
            # We've found a specific time element, less specific time
            # elements are relative to today
            usenow = True

    timetuple = time.strptime(encoding.strfromlocal(date),
                              encoding.strfromlocal(format))
    localunixtime = int(calendar.timegm(timetuple))
    if offset is None:
        # local timezone
        unixtime = int(time.mktime(timetuple))
        offset = unixtime - localunixtime
    else:
        unixtime = localunixtime + offset
    return unixtime, offset

def parsedate(date, formats=None, bias=None):
    """parse a localized date/time and return a (unixtime, offset) tuple.

    The date may be a "unixtime offset" string or in one of the specified
    formats. If the date already is a (unixtime, offset) tuple, it is returned.

    >>> parsedate(b' today ') == parsedate(
    ...     datetime.date.today().strftime('%b %d').encode('ascii'))
    True
    >>> parsedate(b'yesterday ') == parsedate(
    ...     (datetime.date.today() - datetime.timedelta(days=1)
    ...      ).strftime('%b %d').encode('ascii'))
    True
    >>> now, tz = makedate()
    >>> strnow, strtz = parsedate(b'now')
    >>> (strnow - now) < 1
    True
    >>> tz == strtz
    True
    """
    if bias is None:
        bias = {}
    if not date:
        return 0, 0
    if isinstance(date, tuple) and len(date) == 2:
        return date
    if not formats:
        formats = defaultdateformats
    date = date.strip()

    if date == 'now' or date == _('now'):
        return makedate()
    if date == 'today' or date == _('today'):
        date = datetime.date.today().strftime(r'%b %d')
        date = encoding.strtolocal(date)
    elif date == 'yesterday' or date == _('yesterday'):
        date = (datetime.date.today() -
                datetime.timedelta(days=1)).strftime(r'%b %d')
        date = encoding.strtolocal(date)

    try:
        when, offset = map(int, date.split(' '))
    except ValueError:
        # fill out defaults
        now = makedate()
        defaults = {}
        for part in ("d", "mb", "yY", "HI", "M", "S"):
            # this piece is for rounding the specific end of unknowns
            b = bias.get(part)
            if b is None:
                if part[0:1] in "HMS":
                    b = "00"
                else:
                    b = "0"

            # this piece is for matching the generic end to today's date
            n = datestr(now, "%" + part[0:1])

            defaults[part] = (b, n)

        for format in formats:
            try:
                when, offset = strdate(date, format, defaults)
            except (ValueError, OverflowError):
                pass
            else:
                break
        else:
            raise error.ParseError(
                _('invalid date: %r') % pycompat.bytestr(date))
    # validate explicit (probably user-specified) date and
    # time zone offset. values must fit in signed 32 bits for
    # current 32-bit linux runtimes. timezones go from UTC-12
    # to UTC+14
    if when < -0x80000000 or when > 0x7fffffff:
        raise error.ParseError(_('date exceeds 32 bits: %d') % when)
    if offset < -50400 or offset > 43200:
        raise error.ParseError(_('impossible time zone offset: %d') % offset)
    return when, offset

def matchdate(date):
    """Return a function that matches a given date match specifier

    Formats include:

    '{date}' match a given date to the accuracy provided

    '<{date}' on or before a given date

    '>{date}' on or after a given date

    >>> p1 = parsedate(b"10:29:59")
    >>> p2 = parsedate(b"10:30:00")
    >>> p3 = parsedate(b"10:30:59")
    >>> p4 = parsedate(b"10:31:00")
    >>> p5 = parsedate(b"Sep 15 10:30:00 1999")
    >>> f = matchdate(b"10:30")
    >>> f(p1[0])
    False
    >>> f(p2[0])
    True
    >>> f(p3[0])
    True
    >>> f(p4[0])
    False
    >>> f(p5[0])
    False
    """

    def lower(date):
        d = {'mb': "1", 'd': "1"}
        return parsedate(date, extendeddateformats, d)[0]

    def upper(date):
        d = {'mb': "12", 'HI': "23", 'M': "59", 'S': "59"}
        for days in ("31", "30", "29"):
            try:
                d["d"] = days
                return parsedate(date, extendeddateformats, d)[0]
            except error.ParseError:
                pass
        d["d"] = "28"
        return parsedate(date, extendeddateformats, d)[0]

    date = date.strip()

    if not date:
        raise error.Abort(_("dates cannot consist entirely of whitespace"))
    elif date[0:1] == b"<":
        if not date[1:]:
            raise error.Abort(_("invalid day spec, use '<DATE'"))
        when = upper(date[1:])
        return lambda x: x <= when
    elif date[0:1] == b">":
        if not date[1:]:
            raise error.Abort(_("invalid day spec, use '>DATE'"))
        when = lower(date[1:])
        return lambda x: x >= when
    elif date[0:1] == b"-":
        try:
            days = int(date[1:])
        except ValueError:
            raise error.Abort(_("invalid day spec: %s") % date[1:])
        if days < 0:
            raise error.Abort(_("%s must be nonnegative (see 'hg help dates')")
                % date[1:])
        when = makedate()[0] - days * 3600 * 24
        return lambda x: x >= when
    elif b" to " in date:
        a, b = date.split(b" to ")
        start, stop = lower(a), upper(b)
        return lambda x: x >= start and x <= stop
    else:
        start, stop = lower(date), upper(date)
        return lambda x: x >= start and x <= stop