X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FTime%2FLocal.pm;h=61805849f8ae99109da7dc5071deec0defaf0b23;hb=14fe70c2d1778829732c0549106909ab5b329425;hp=64e62405f723421327dd4190a29820ffb644c19a;hpb=a0d0e21ea6ea90a22318550944fe6cb09ae10cda;p=p5sagit%2Fp5-mst-13.2.git

diff --git a/lib/Time/Local.pm b/lib/Time/Local.pm
index 64e6240..6180584 100644
--- a/lib/Time/Local.pm
+++ b/lib/Time/Local.pm
@@ -1,105 +1,253 @@
 package Time::Local;
-require 5.000;
+require 5.6.0;
 require Exporter;
 use Carp;
+use strict;
 
-@ISA = qw(Exporter);
-@EXPORT = qw(timegm timelocal);
-
-# timelocal.pl
-#
-# Usage:
-#	$time = timelocal($sec,$min,$hours,$mday,$mon,$year);
-#	$time = timegm($sec,$min,$hours,$mday,$mon,$year);
-
-# These routines are quite efficient and yet are always guaranteed to agree
-# with localtime() and gmtime().  We manage this by caching the start times
-# of any months we've seen before.  If we know the start time of the month,
-# we can always calculate any time within the month.  The start times
-# themselves are guessed by successive approximation starting at the
-# current time, since most dates seen in practice are close to the
-# current date.  Unlike algorithms that do a binary search (calling gmtime
-# once for each bit of the time value, resulting in 32 calls), this algorithm
-# calls it at most 6 times, and usually only once or twice.  If you hit
-# the month cache, of course, it doesn't call it at all.
-
-# timelocal is implemented using the same cache.  We just assume that we're
-# translating a GMT time, and then fudge it when we're done for the timezone
-# and daylight savings arguments.  The timezone is determined by examining
-# the result of localtime(0) when the package is initialized.  The daylight
-# savings offset is currently assumed to be one hour.
-
-# Both routines return -1 if the integer limit is hit. I.e. for dates
-# after the 1st of January, 2038 on most machines.
-
-@epoch = localtime(0);
-$tzmin = $epoch[2] * 60 + $epoch[1];	# minutes east of GMT
-if ($tzmin > 0) {
-    $tzmin = 24 * 60 - $tzmin;		# minutes west of GMT
-    $tzmin -= 24 * 60 if $epoch[5] == 70;	# account for the date line
-}
+our $VERSION    = '1.02';
+our @ISA	= qw( Exporter );
+our @EXPORT	= qw( timegm timelocal );
+our @EXPORT_OK	= qw( timegm_nocheck timelocal_nocheck );
+
+# Set up constants
+our $SEC  = 1;
+our $MIN  = 60 * $SEC;
+our $HR   = 60 * $MIN;
+our $DAY  = 24 * $HR;
+# Determine breakpoint for rolling century
+    my $ThisYear = (localtime())[5];
+    my $NextCentury = int($ThisYear / 100) * 100;
+    my $Breakpoint = ($ThisYear + 50) % 100;
+       $NextCentury += 100 if $Breakpoint < 50;
 
-$SEC = 1;
-$MIN = 60 * $SEC;
-$HR = 60 * $MIN;
-$DAYS = 24 * $HR;
-$YearFix = ((gmtime(946684800))[5] == 100) ? 100 : 0;
+our(%Options, %Cheat);
 
 sub timegm {
-    $ym = pack(C2, @_[5,4]);
-    $cheat = $cheat{$ym} || &cheat;
-    return -1 if $cheat<0;
-    $cheat + $_[0] * $SEC + $_[1] * $MIN + $_[2] * $HR + ($_[3]-1) * $DAYS;
+    my (@date) = @_;
+    if ($date[5] > 999) {
+        $date[5] -= 1900;
+    }
+    elsif ($date[5] >= 0 && $date[5] < 100) {
+        $date[5] -= 100 if $date[5] > $Breakpoint;
+        $date[5] += $NextCentury;
+    }
+    my $ym = pack('C2', @date[5,4]);
+    my $cheat = $Cheat{$ym} || &cheat($ym, @date);
+    $cheat
+    + $date[0] * $SEC
+    + $date[1] * $MIN
+    + $date[2] * $HR
+    + ($date[3]-1) * $DAY;
+}
+
+sub timegm_nocheck {
+    local $Options{no_range_check} = 1;
+    &timegm;
 }
 
 sub timelocal {
-    $time = &timegm + $tzmin*$MIN;
-    return -1 if $cheat<0;
-    @test = localtime($time);
+    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 $tzsec = ($gt[1] - $lt[1]) * $MIN + ($gt[2] - $lt[2]) * $HR;
+
+    if($lt[5] > $gt[5]) {
+	$tzsec -= $DAY;
+    }
+    elsif($gt[5] > $lt[5]) {
+	$tzsec += $DAY;
+    }
+    else {
+	$tzsec += ($gt[7] - $lt[7]) * $DAY;
+    }
+
+    $tzsec += $HR if($lt[8]);
+    
+    my $time = $t + $tzsec;
+    my @test = localtime($time + ($tt - $t));
     $time -= $HR if $test[2] != $_[2];
     $time;
 }
 
+sub timelocal_nocheck {
+    local $Options{no_range_check} = 1;
+    &timelocal;
+}
+
 sub cheat {
-    $year = $_[5];
-    $month = $_[4];
-    croak "Month out of range 0..11 in timelocal.pl" 
-	if $month > 11 || $month < 0;
-    croak "Day out of range 1..31 in timelocal.pl" 
-	if $_[3] > 31 || $_[3] < 1;
-    croak "Hour out of range 0..23 in timelocal.pl"
-	if $_[2] > 23 || $_[2] < 0;
-    croak "Minute out of range 0..59 in timelocal.pl"
-	if $_[1] > 59 || $_[1] < 0;
-    croak "Second out of range 0..59 in timelocal.pl"
-	if $_[0] > 59 || $_[0] < 0;
-    $guess = $^T;
-    @g = gmtime($guess);
-    $year += $YearFix if $year < $epoch[5];
-    $lastguess = "";
-    while ($diff = $year - $g[5]) {
-	$guess += $diff * (363 * $DAYS);
+    my($ym, @date) = @_;
+    my($sec, $min, $hour, $day, $month, $year) = @date;
+    unless ($Options{no_range_check}) {
+ croak "Month '$month' out of range 0..11" if $month > 11   || $month < 0;
+        my $md = (31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31)[$month];
+	$md++ if $month == 1 &&
+	    $year % 4 == 0 && ($year % 100 > 0 || $year % 400 == 100);	# leap
+ croak "Day '$day' out of range 1..$md"    if $day   > $md  || $day   < 1;
+ croak "Hour '$hour' out of range 0..23"   if $hour  > 23   || $hour  < 0;
+ croak "Minute '$min' out of range 0..59"  if $min   > 59   || $min   < 0;
+ croak "Second '$sec' out of range 0..59"  if $sec   > 59   || $sec   < 0;
+    }
+    my $guess = $^T;
+    my @g = gmtime($guess);
+    my $lastguess = "";
+    my $counter = 0;
+    while (my $diff = $year - $g[5]) {
+        my $thisguess;
+	croak "Can't handle date (".join(", ",@date).")" if ++$counter > 255;
+	$guess += $diff * (363 * $DAY);
 	@g = gmtime($guess);
 	if (($thisguess = "@g") eq $lastguess){
-	    return -1; #date beyond this machine's integer limit
+	    croak "Can't handle date (".join(", ",@date).")";
+	    #date beyond this machine's integer limit
 	}
 	$lastguess = $thisguess;
     }
-    while ($diff = $month - $g[4]) {
-	$guess += $diff * (27 * $DAYS);
+    while (my $diff = $month - $g[4]) {
+        my $thisguess;
+	croak "Can't handle date (".join(", ",@date).")" if ++$counter > 255;
+	$guess += $diff * (27 * $DAY);
 	@g = gmtime($guess);
 	if (($thisguess = "@g") eq $lastguess){
-	    return -1; #date beyond this machine's integer limit
+	    croak "Can't handle date (".join(", ",@date).")";
+	    #date beyond this machine's integer limit
 	}
 	$lastguess = $thisguess;
     }
-    @gfake = gmtime($guess-1); #still being sceptic
+    my @gfake = gmtime($guess-1); #still being sceptic
     if ("@gfake" eq $lastguess){
-	return -1; #date beyond this machine's integer limit
+        croak "Can't handle date (".join(", ",@date).")";
+        #date beyond this machine's integer limit
     }
     $g[3]--;
-    $guess -= $g[0] * $SEC + $g[1] * $MIN + $g[2] * $HR + $g[3] * $DAYS;
-    $cheat{$ym} = $guess;
+    $guess -= $g[0] * $SEC + $g[1] * $MIN + $g[2] * $HR + $g[3] * $DAY;
+    $Cheat{$ym} = $guess;
 }
 
 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
+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.  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.  The daylight savings offset is currently assumed 
+to be one hour.
+
+=head1 BUGS
+
+The whole scheme for interpreting two-digit years can be considered a bug.
+
+Note that the cache currently handles only years from 1900 through 2155.
+
+The proclivity to croak() is probably a bug.
+
+=cut