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
139 sub timelocal_nocheck {
140 local $Options{no_range_check} = 1;
150 Time::Local - efficiently compute time from local and GMT time
154 $time = timelocal($sec,$min,$hour,$mday,$mon,$year);
155 $time = timegm($sec,$min,$hour,$mday,$mon,$year);
159 These routines are the inverse of built-in perl functions localtime()
160 and gmtime(). They accept a date as a six-element array, and return
161 the corresponding time(2) value in seconds since the Epoch (Midnight,
162 January 1, 1970). This value can be positive or negative.
164 It is worth drawing particular attention to the expected ranges for
165 the values provided. The value for the day of the month is the actual day
166 (ie 1..31), while the month is the number of months since January (0..11).
167 This is consistent with the values returned from localtime() and gmtime().
169 The timelocal() and timegm() functions perform range checking on the
170 input $sec, $min, $hour, $mday, and $mon values by default. If you'd
171 rather they didn't, you can explicitly import the timelocal_nocheck()
172 and timegm_nocheck() functions.
174 use Time::Local 'timelocal_nocheck';
177 # The 365th day of 1999
178 print scalar localtime timelocal_nocheck 0,0,0,365,0,99;
180 # The twenty thousandth day since 1970
181 print scalar localtime timelocal_nocheck 0,0,0,20000,0,70;
183 # And even the 10,000,000th second since 1999!
184 print scalar localtime timelocal_nocheck 10000000,0,0,1,0,99;
187 Your mileage may vary when trying these with minutes and hours,
188 and it doesn't work at all for months.
190 Strictly speaking, the year should also be specified in a form consistent
191 with localtime(), i.e. the offset from 1900.
192 In order to make the interpretation of the year easier for humans,
193 however, who are more accustomed to seeing years as two-digit or four-digit
194 values, the following conventions are followed:
200 Years greater than 999 are interpreted as being the actual year,
201 rather than the offset from 1900. Thus, 1963 would indicate the year
202 Martin Luther King won the Nobel prize, not the year 2863.
206 Years in the range 100..999 are interpreted as offset from 1900,
207 so that 112 indicates 2012. This rule also applies to years less than zero
208 (but see note below regarding date range).
212 Years in the range 0..99 are interpreted as shorthand for years in the
213 rolling "current century," defined as 50 years on either side of the current
214 year. Thus, today, in 1999, 0 would refer to 2000, and 45 to 2045,
215 but 55 would refer to 1955. Twenty years from now, 55 would instead refer
216 to 2055. This is messy, but matches the way people currently think about
217 two digit dates. Whenever possible, use an absolute four digit year instead.
221 The scheme above allows interpretation of a wide range of dates, particularly
222 if 4-digit years are used.
224 Please note, however, that the range of dates that can be actually be handled
225 depends on the size of an integer (time_t) on a given platform.
226 Currently, this is 32 bits for most systems, yielding an approximate range
227 from Dec 1901 to Jan 2038.
229 Both timelocal() and timegm() croak if given dates outside the supported
232 =head1 IMPLEMENTATION
234 These routines are quite efficient and yet are always guaranteed to agree
235 with localtime() and gmtime(). We manage this by caching the start times
236 of any months we've seen before. If we know the start time of the month,
237 we can always calculate any time within the month. The start times
238 are calculated using a mathematical formula. Unlike other algorithms
239 that do multiple calls to gmtime().
241 timelocal() is implemented using the same cache. We just assume that we're
242 translating a GMT time, and then fudge it when we're done for the timezone
243 and daylight savings arguments. Note that the timezone is evaluated for
244 each date because countries occasionally change their official timezones.
245 Assuming that localtime() corrects for these changes, this routine will
250 The whole scheme for interpreting two-digit years can be considered a bug.
252 The proclivity to croak() is probably a bug.