package Time::Local;
-require 5.000;
+use 5.006;
require Exporter;
use Carp;
+use Config;
+use strict;
+use integer;
+
+our $VERSION = '1.04';
+our @ISA = qw( Exporter );
+our @EXPORT = qw( timegm timelocal );
+our @EXPORT_OK = qw( timegm_nocheck timelocal_nocheck );
+
+my @MonthDays = (31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
+
+# Determine breakpoint for rolling century
+my $ThisYear = (localtime())[5];
+my $Breakpoint = ($ThisYear + 50) % 100;
+my $NextCentury = $ThisYear - $ThisYear % 100;
+ $NextCentury += 100 if $Breakpoint < 50;
+my $Century = $NextCentury - 100;
+
+my (%Options, %Cheat);
+
+# Determine the EPOC day for this machine
+my $Epoc = 0;
+if ($^O eq 'vos') {
+# work around posix-977 -- VOS doesn't handle dates in
+# the range 1970-1980.
+ $Epoc = _daygm((0, 0, 0, 1, 0, 70, 4, 0));
+} else {
+ $Epoc = _daygm(gmtime(0));
+}
-@ISA = qw(Exporter);
-@EXPORT = qw(timegm timelocal);
+%Cheat=(); # clear the cache as epoc has changed
-=head1 NAME
+my $MaxInt = ((1<<(8 * $Config{intsize} - 2))-1)*2 + 1;
+my $MaxDay = int(($MaxInt-43200)/86400)-1;
-Time::Local - efficiently compute time from local and GMT time
-=head1 SYNOPSIS
+sub _daygm {
+ $_[3] + ($Cheat{pack("ss",@_[4,5])} ||= do {
+ my $month = ($_[4] + 10) % 12;
+ my $year = $_[5] + 1900 - $month/10;
+ 365*$year + $year/4 - $year/100 + $year/400 + ($month*306 + 5)/10 - $Epoc
+ });
+}
- $time = timelocal($sec,$min,$hours,$mday,$mon,$year);
- $time = timegm($sec,$min,$hours,$mday,$mon,$year);
-=head1 DESCRIPTION
+sub _timegm {
+ $_[0] + 60 * $_[1] + 3600 * $_[2] + 86400 * &_daygm;
+}
-These routines are quite efficient and yet are always guaranteed to
-agree with localtime() and gmtime(), the most notable points being
-that year is year-1900 and month is 0..11. We manage this by caching
-the start times of any months we've seen before. If we know the start
-time of the month, we can always calculate any time within the month.
-The start times themselves are guessed by successive approximation
-starting at the current time, since most dates seen in practice are
-close to the current date. Unlike algorithms that do a binary search
-(calling gmtime once for each bit of the time value, resulting in 32
-calls), this algorithm calls it at most 6 times, and usually only once
-or twice. If you hit the month cache, of course, it doesn't call it
-at all.
-
-timelocal is implemented using the same cache. We just assume that we're
-translating a GMT time, and then fudge it when we're done for the timezone
-and daylight savings arguments. The timezone is determined by examining
-the result of localtime(0) when the package is initialized. The daylight
-savings offset is currently assumed to be one hour.
-Both routines return -1 if the integer limit is hit. I.e. for dates
-after the 1st of January, 2038 on most machines.
+sub timegm {
+ my ($sec,$min,$hour,$mday,$month,$year) = @_;
-=cut
+ if ($year >= 1000) {
+ $year -= 1900;
+ }
+ elsif ($year < 100 and $year >= 0) {
+ $year += ($year > $Breakpoint) ? $Century : $NextCentury;
+ }
+
+ unless ($Options{no_range_check}) {
+ if (abs($year) >= 0x7fff) {
+ $year += 1900;
+ croak "Cannot handle date ($sec, $min, $hour, $mday, $month, $year)";
+ }
+
+ croak "Month '$month' out of range 0..11" if $month > 11 or $month < 0;
-BEGIN {
- $SEC = 1;
- $MIN = 60 * $SEC;
- $HR = 60 * $MIN;
- $DAY = 24 * $HR;
- $epoch = (localtime(2*$DAY))[5]; # Allow for bugs near localtime == 0.
+ my $md = $MonthDays[$month];
+ ++$md unless $month != 1 or $year % 4 or !($year % 400);
- $YearFix = ((gmtime(946684800))[5] == 100) ? 100 : 0;
+ croak "Day '$mday' out of range 1..$md" if $mday > $md or $mday < 1;
+ croak "Hour '$hour' out of range 0..23" if $hour > 23 or $hour < 0;
+ croak "Minute '$min' out of range 0..59" if $min > 59 or $min < 0;
+ croak "Second '$sec' out of range 0..59" if $sec > 59 or $sec < 0;
+ }
+
+ my $days = _daygm(undef, undef, undef, $mday, $month, $year);
+
+ unless ($Options{no_range_check} or abs($days) < $MaxDay) {
+ $year += 1900;
+ croak "Cannot handle date ($sec, $min, $hour, $mday, $month, $year)";
+ }
+ $sec + 60*$min + 3600*$hour + 86400*$days;
}
-sub timegm {
- $ym = pack(C2, @_[5,4]);
- $cheat = $cheat{$ym} || &cheat;
- return -1 if $cheat<0 and $^O ne 'VMS';
- $cheat + $_[0] * $SEC + $_[1] * $MIN + $_[2] * $HR + ($_[3]-1) * $DAY;
+
+sub timegm_nocheck {
+ local $Options{no_range_check} = 1;
+ &timegm;
}
+
sub timelocal {
- my $t = &timegm;
- my $tt = $t;
-
- my (@lt) = localtime($t);
- my (@gt) = gmtime($t);
- if ($t < $DAY and ($lt[5] >= 70 or $gt[5] >= 70 )) {
- # Wrap error, too early a date
- # Try a safer date
- $tt = $DAY;
- @lt = localtime($tt);
- @gt = gmtime($tt);
- }
+ my $ref_t = &timegm;
+ my $loc_t = _timegm(localtime($ref_t));
- my $tzsec = ($gt[1] - $lt[1]) * $MIN + ($gt[2] - $lt[2]) * $HR;
+ # Is there a timezone offset from GMT or are we done
+ my $zone_off = $ref_t - $loc_t
+ or return $loc_t;
- my($lday,$gday) = ($lt[7],$gt[7]);
- if($lt[5] > $gt[5]) {
- $tzsec -= $DAY;
- }
- elsif($gt[5] > $lt[5]) {
- $tzsec += $DAY;
- }
- else {
- $tzsec += ($gt[7] - $lt[7]) * $DAY;
- }
+ # Adjust for timezone
+ $loc_t = $ref_t + $zone_off;
- $tzsec += $HR if($lt[8]);
-
- $time = $t + $tzsec;
- return -1 if $cheat<0 and $^O ne 'VMS';
- @test = localtime($time + ($tt - $t));
- $time -= $HR if $test[2] != $_[2];
- $time;
+ # Are we close to a DST change or are we done
+ my $dst_off = $ref_t - _timegm(localtime($loc_t))
+ or return $loc_t;
+
+ # Adjust for DST change
+ $loc_t + $dst_off;
}
-sub cheat {
- $year = $_[5];
- $year -= 1900
- if $year > 1900;
- $month = $_[4];
- croak "Month '$month' out of range 0..11" if $month > 11 || $month < 0;
- croak "Day '$_[3]' out of range 1..31" if $_[3] > 31 || $_[3] < 1;
- croak "Hour '$_[2]' out of range 0..23" if $_[2] > 23 || $_[2] < 0;
- croak "Minute '$_[1]' out of range 0..59" if $_[1] > 59 || $_[1] < 0;
- croak "Second '$_[0]' out of range 0..59" if $_[0] > 59 || $_[0] < 0;
- $guess = $^T;
- @g = gmtime($guess);
- $year += $YearFix if $year < $epoch;
- $lastguess = "";
- $counter = 0;
- while ($diff = $year - $g[5]) {
- croak "Can't handle date (".join(", ",@_).")" if ++$counter > 255;
- $guess += $diff * (363 * $DAY);
- @g = gmtime($guess);
- if (($thisguess = "@g") eq $lastguess){
- return -1; #date beyond this machine's integer limit
- }
- $lastguess = $thisguess;
- }
- while ($diff = $month - $g[4]) {
- croak "Can't handle date (".join(", ",@_).")" if ++$counter > 255;
- $guess += $diff * (27 * $DAY);
- @g = gmtime($guess);
- if (($thisguess = "@g") eq $lastguess){
- return -1; #date beyond this machine's integer limit
- }
- $lastguess = $thisguess;
- }
- @gfake = gmtime($guess-1); #still being sceptic
- if ("@gfake" eq $lastguess){
- return -1; #date beyond this machine's integer limit
- }
- $g[3]--;
- $guess -= $g[0] * $SEC + $g[1] * $MIN + $g[2] * $HR + $g[3] * $DAY;
- $cheat{$ym} = $guess;
+
+sub timelocal_nocheck {
+ local $Options{no_range_check} = 1;
+ &timelocal;
}
1;
+
+__END__
+
+=head1 NAME
+
+Time::Local - efficiently compute time from local and GMT time
+
+=head1 SYNOPSIS
+
+ $time = timelocal($sec,$min,$hour,$mday,$mon,$year);
+ $time = timegm($sec,$min,$hour,$mday,$mon,$year);
+
+=head1 DESCRIPTION
+
+These routines are the inverse of built-in perl functions localtime()
+and gmtime(). They accept a date as a six-element array, and return
+the corresponding time(2) value in seconds since the Epoch (Midnight,
+January 1, 1970). This value can be positive or negative.
+
+It is worth drawing particular attention to the expected ranges for
+the values provided. The value for the day of the month is the actual day
+(ie 1..31), while the month is the number of months since January (0..11).
+This is consistent with the values returned from localtime() and gmtime().
+
+The timelocal() and timegm() functions perform range checking on the
+input $sec, $min, $hour, $mday, and $mon values by default. If you'd
+rather they didn't, you can explicitly import the timelocal_nocheck()
+and timegm_nocheck() functions.
+
+ use Time::Local 'timelocal_nocheck';
+
+ {
+ # The 365th day of 1999
+ print scalar localtime timelocal_nocheck 0,0,0,365,0,99;
+
+ # The twenty thousandth day since 1970
+ print scalar localtime timelocal_nocheck 0,0,0,20000,0,70;
+
+ # And even the 10,000,000th second since 1999!
+ print scalar localtime timelocal_nocheck 10000000,0,0,1,0,99;
+ }
+
+Your mileage may vary when trying these with minutes and hours,
+and it doesn't work at all for months.
+
+Strictly speaking, the year should also be specified in a form consistent
+with localtime(), i.e. the offset from 1900.
+In order to make the interpretation of the year easier for humans,
+however, who are more accustomed to seeing years as two-digit or four-digit
+values, the following conventions are followed:
+
+=over 4
+
+=item *
+
+Years greater than 999 are interpreted as being the actual year,
+rather than the offset from 1900. Thus, 1963 would indicate the year
+Martin Luther King won the Nobel prize, not the year 2863.
+
+=item *
+
+Years in the range 100..999 are interpreted as offset from 1900,
+so that 112 indicates 2012. This rule also applies to years less than zero
+(but see note below regarding date range).
+
+=item *
+
+Years in the range 0..99 are interpreted as shorthand for years in the
+rolling "current century," defined as 50 years on either side of the current
+year. Thus, today, in 1999, 0 would refer to 2000, and 45 to 2045,
+but 55 would refer to 1955. Twenty years from now, 55 would instead refer
+to 2055. This is messy, but matches the way people currently think about
+two digit dates. Whenever possible, use an absolute four digit year instead.
+
+=back
+
+The scheme above allows interpretation of a wide range of dates, particularly
+if 4-digit years are used.
+
+Please note, however, that the range of dates that can be actually be handled
+depends on the size of an integer (time_t) on a given platform.
+Currently, this is 32 bits for most systems, yielding an approximate range
+from Dec 1901 to Jan 2038.
+
+Both timelocal() and timegm() croak if given dates outside the supported
+range.
+
+=head1 IMPLEMENTATION
+
+These routines are quite efficient and yet are always guaranteed to agree
+with localtime() and gmtime(). We manage this by caching the start times
+of any months we've seen before. If we know the start time of the month,
+we can always calculate any time within the month. The start times
+are calculated using a mathematical formula. Unlike other algorithms
+that do multiple calls to gmtime().
+
+timelocal() is implemented using the same cache. We just assume that we're
+translating a GMT time, and then fudge it when we're done for the timezone
+and daylight savings arguments. Note that the timezone is evaluated for
+each date because countries occasionally change their official timezones.
+Assuming that localtime() corrects for these changes, this routine will
+also be correct.
+
+=head1 BUGS
+
+The whole scheme for interpreting two-digit years can be considered a bug.
+
+The proclivity to croak() is probably a bug.
+
+=cut
+
https://perl5.git.perl.org / perl5.git / blobdiff