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authorJason Downs <downsj@cvs.openbsd.org>1996-08-19 10:13:38 +0000
committerJason Downs <downsj@cvs.openbsd.org>1996-08-19 10:13:38 +0000
commit14856225739aa48b6c9cf4c17925362b2d95cea3 (patch)
treedfd38f1b654fb5bbdfc38887c1a829b658e71530 /gnu/usr.bin/perl/lib/Time
parent77469082517e44fe6ca347d9e8dc7dffd1583637 (diff)
Import of Perl 5.003 into the tree. Makefile.bsd-wrapper and
config.sh.OpenBSD are the only local changes.
Diffstat (limited to 'gnu/usr.bin/perl/lib/Time')
-rw-r--r--gnu/usr.bin/perl/lib/Time/Local.pm112
1 files changed, 112 insertions, 0 deletions
diff --git a/gnu/usr.bin/perl/lib/Time/Local.pm b/gnu/usr.bin/perl/lib/Time/Local.pm
new file mode 100644
index 00000000000..451c7fa20c7
--- /dev/null
+++ b/gnu/usr.bin/perl/lib/Time/Local.pm
@@ -0,0 +1,112 @@
+package Time::Local;
+require 5.000;
+require Exporter;
+use Carp;
+
+@ISA = qw(Exporter);
+@EXPORT = qw(timegm timelocal);
+
+=head1 NAME
+
+Time::Local - efficiently compute tome from local and GMT time
+
+=head1 SYNOPSIS
+
+ $time = timelocal($sec,$min,$hours,$mday,$mon,$year);
+ $time = timegm($sec,$min,$hours,$mday,$mon,$year);
+
+=head1 DESCRIPTION
+
+These routines are quite efficient and yet are always guaranteed to agree
+with localtime() and gmtime(). We manage this by caching the start times
+of any months we've seen before. If we know the start time of the month,
+we can always calculate any time within the month. The start times
+themselves are guessed by successive approximation starting at the
+current time, since most dates seen in practice are close to the
+current date. Unlike algorithms that do a binary search (calling gmtime
+once for each bit of the time value, resulting in 32 calls), this algorithm
+calls it at most 6 times, and usually only once or twice. If you hit
+the month cache, of course, it doesn't call it at all.
+
+timelocal is implemented using the same cache. We just assume that we're
+translating a GMT time, and then fudge it when we're done for the timezone
+and daylight savings arguments. The timezone is determined by examining
+the result of localtime(0) when the package is initialized. The daylight
+savings offset is currently assumed to be one hour.
+
+Both routines return -1 if the integer limit is hit. I.e. for dates
+after the 1st of January, 2038 on most machines.
+
+=cut
+
+@epoch = localtime(0);
+$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 $epoch[5] == 70; # account for the date line
+}
+
+$SEC = 1;
+$MIN = 60 * $SEC;
+$HR = 60 * $MIN;
+$DAYS = 24 * $HR;
+$YearFix = ((gmtime(946684800))[5] == 100) ? 100 : 0;
+
+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;
+}
+
+sub timelocal {
+ $time = &timegm + $tzmin*$MIN;
+ return -1 if $cheat<0;
+ @test = localtime($time);
+ $time -= $HR if $test[2] != $_[2];
+ $time;
+}
+
+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 * $DAYS);
+ @g = gmtime($guess);
+ if (($thisguess = "@g") eq $lastguess){
+ return -1; #date beyond this machine's integer limit
+ }
+ $lastguess = $thisguess;
+ }
+ while ($diff = $month - $g[4]) {
+ $guess += $diff * (27 * $DAYS);
+ @g = gmtime($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] * $DAYS;
+ $cheat{$ym} = $guess;
+}
+
+1;