10 our @ISA = qw( Exporter );
11 our @EXPORT = qw( timegm timelocal );
12 our @EXPORT_OK = qw( timegm_nocheck timelocal_nocheck );
14 my @MonthDays = (31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
16 # Determine breakpoint for rolling century
17 my $ThisYear = (localtime())[5];
18 my $Breakpoint = ($ThisYear + 50) % 100;
19 my $NextCentury = $ThisYear - $ThisYear % 100;
20 $NextCentury += 100 if $Breakpoint < 50;
21 my $Century = $NextCentury - 100;
24 my (%Options, %Cheat);
26 my $MaxInt = ((1<<(8 * $Config{intsize} - 2))-1)*2 + 1;
27 my $MaxDay = int(($MaxInt-43200)/86400)-1;
29 # Determine the EPOC day for this machine
32 # work around posix-977 -- VOS doesn't handle dates in
33 # the range 1970-1980.
34 $Epoc = _daygm((0, 0, 0, 1, 0, 70, 4, 0));
36 elsif ($^O eq 'MacOS') {
39 $MaxDay *=2 if $^O eq 'MacOS'; # time_t unsigned ... quick hack?
40 # MacOS time() is seconds since 1 Jan 1904, localtime
41 # so we need to calculate an offset to apply later
43 $SecOff = timelocal(localtime(0)) - timelocal(gmtime(0));
44 $Epoc += _daygm(gmtime(0));
47 $Epoc = _daygm(gmtime(0));
50 %Cheat=(); # clear the cache as epoc has changed
53 $_[3] + ($Cheat{pack("ss",@_[4,5])} ||= do {
54 my $month = ($_[4] + 10) % 12;
55 my $year = $_[5] + 1900 - $month/10;
56 365*$year + $year/4 - $year/100 + $year/400 + ($month*306 + 5)/10 - $Epoc
62 my $sec = $SecOff + $_[0] + 60 * $_[1] + 3600 * $_[2];
66 $sec + 86400 * &_daygm;
71 my ($sec,$min,$hour,$mday,$month,$year) = @_;
76 elsif ($year < 100 and $year >= 0) {
77 $year += ($year > $Breakpoint) ? $Century : $NextCentury;
80 unless ($Options{no_range_check}) {
81 if (abs($year) >= 0x7fff) {
83 croak "Cannot handle date ($sec, $min, $hour, $mday, $month, $year)";
86 croak "Month '$month' out of range 0..11" if $month > 11 or $month < 0;
88 my $md = $MonthDays[$month];
89 ++$md unless $month != 1 or $year % 4 or !($year % 400);
91 croak "Day '$mday' out of range 1..$md" if $mday > $md or $mday < 1;
92 croak "Hour '$hour' out of range 0..23" if $hour > 23 or $hour < 0;
93 croak "Minute '$min' out of range 0..59" if $min > 59 or $min < 0;
94 croak "Second '$sec' out of range 0..59" if $sec > 59 or $sec < 0;
97 my $days = _daygm(undef, undef, undef, $mday, $month, $year);
99 unless ($Options{no_range_check} or abs($days) < $MaxDay) {
101 croak "Cannot handle date ($sec, $min, $hour, $mday, $month, $year)";
104 $sec += $SecOff + 60*$min + 3600*$hour;
113 local $Options{no_range_check} = 1;
121 my $loc_t = _timegm(localtime($ref_t));
123 # Is there a timezone offset from GMT or are we done
124 my $zone_off = $ref_t - $loc_t
127 # Adjust for timezone
128 $loc_t = $ref_t + $zone_off;
130 # Are we close to a DST change or are we done
131 my $dst_off = $ref_t - _timegm(localtime($loc_t))
134 # Adjust for DST change
137 # for a negative offset from GMT, and if the original date
138 # was a non-extent gap in a forward DST jump, we should
139 # now have the wrong answer - undo the DST adjust;
141 return $loc_t if $zone_off <= 0;
143 my ($s,$m,$h) = localtime($loc_t);
144 $loc_t -= $dst_off if $s != $_[0] || $m != $_[1] || $h != $_[2];
150 sub timelocal_nocheck {
151 local $Options{no_range_check} = 1;
161 Time::Local - efficiently compute time from local and GMT time
165 $time = timelocal($sec,$min,$hour,$mday,$mon,$year);
166 $time = timegm($sec,$min,$hour,$mday,$mon,$year);
170 These routines are the inverse of built-in perl functions localtime()
171 and gmtime(). They accept a date as a six-element array, and return
172 the corresponding time(2) value in seconds since the Epoch (Midnight,
173 January 1, 1970). This value can be positive or negative.
175 It is worth drawing particular attention to the expected ranges for
176 the values provided. The value for the day of the month is the actual day
177 (ie 1..31), while the month is the number of months since January (0..11).
178 This is consistent with the values returned from localtime() and gmtime().
180 The timelocal() and timegm() functions perform range checking on the
181 input $sec, $min, $hour, $mday, and $mon values by default. If you'd
182 rather they didn't, you can explicitly import the timelocal_nocheck()
183 and timegm_nocheck() functions.
185 use Time::Local 'timelocal_nocheck';
188 # The 365th day of 1999
189 print scalar localtime timelocal_nocheck 0,0,0,365,0,99;
191 # The twenty thousandth day since 1970
192 print scalar localtime timelocal_nocheck 0,0,0,20000,0,70;
194 # And even the 10,000,000th second since 1999!
195 print scalar localtime timelocal_nocheck 10000000,0,0,1,0,99;
198 Your mileage may vary when trying these with minutes and hours,
199 and it doesn't work at all for months.
201 Strictly speaking, the year should also be specified in a form consistent
202 with localtime(), i.e. the offset from 1900.
203 In order to make the interpretation of the year easier for humans,
204 however, who are more accustomed to seeing years as two-digit or four-digit
205 values, the following conventions are followed:
211 Years greater than 999 are interpreted as being the actual year,
212 rather than the offset from 1900. Thus, 1963 would indicate the year
213 Martin Luther King won the Nobel prize, not the year 2863.
217 Years in the range 100..999 are interpreted as offset from 1900,
218 so that 112 indicates 2012. This rule also applies to years less than zero
219 (but see note below regarding date range).
223 Years in the range 0..99 are interpreted as shorthand for years in the
224 rolling "current century," defined as 50 years on either side of the current
225 year. Thus, today, in 1999, 0 would refer to 2000, and 45 to 2045,
226 but 55 would refer to 1955. Twenty years from now, 55 would instead refer
227 to 2055. This is messy, but matches the way people currently think about
228 two digit dates. Whenever possible, use an absolute four digit year instead.
232 The scheme above allows interpretation of a wide range of dates, particularly
233 if 4-digit years are used.
235 Please note, however, that the range of dates that can be actually be handled
236 depends on the size of an integer (time_t) on a given platform.
237 Currently, this is 32 bits for most systems, yielding an approximate range
238 from Dec 1901 to Jan 2038.
240 Both timelocal() and timegm() croak if given dates outside the supported
243 =head1 IMPLEMENTATION
245 These routines are quite efficient and yet are always guaranteed to agree
246 with localtime() and gmtime(). We manage this by caching the start times
247 of any months we've seen before. If we know the start time of the month,
248 we can always calculate any time within the month. The start times
249 are calculated using a mathematical formula. Unlike other algorithms
250 that do multiple calls to gmtime().
252 timelocal() is implemented using the same cache. We just assume that we're
253 translating a GMT time, and then fudge it when we're done for the timezone
254 and daylight savings arguments. Note that the timezone is evaluated for
255 each date because countries occasionally change their official timezones.
256 Assuming that localtime() corrects for these changes, this routine will
261 The whole scheme for interpreting two-digit years can be considered a bug.
263 The proclivity to croak() is probably a bug.