Commit | Line | Data |
---|---|---|
a0d0e21e | 1 | package Time::Local; |
1c41b6a4 | 2 | |
a0d0e21e LW |
3 | require Exporter; |
4 | use Carp; | |
e7ec2331 | 5 | use Config; |
b75c8c73 | 6 | use strict; |
326557bd | 7 | use integer; |
a0d0e21e | 8 | |
1c41b6a4 | 9 | use vars qw( $VERSION @ISA @EXPORT @EXPORT_OK ); |
8f230aaa | 10 | $VERSION = '1.12'; |
823a6996 | 11 | $VERSION = eval $VERSION; |
1c41b6a4 RGS |
12 | @ISA = qw( Exporter ); |
13 | @EXPORT = qw( timegm timelocal ); | |
14 | @EXPORT_OK = qw( timegm_nocheck timelocal_nocheck ); | |
a0d0e21e | 15 | |
326557bd GB |
16 | my @MonthDays = (31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31); |
17 | ||
06ef4121 | 18 | # Determine breakpoint for rolling century |
326557bd GB |
19 | my $ThisYear = (localtime())[5]; |
20 | my $Breakpoint = ($ThisYear + 50) % 100; | |
21 | my $NextCentury = $ThisYear - $ThisYear % 100; | |
22 | $NextCentury += 100 if $Breakpoint < 50; | |
23 | my $Century = $NextCentury - 100; | |
67627c52 | 24 | my $SecOff = 0; |
326557bd | 25 | |
823a6996 RGS |
26 | my (%Options, %Cheat, %Min, %Max); |
27 | my ($MinInt, $MaxInt); | |
326557bd | 28 | |
8f230aaa RGS |
29 | use constant ONE_HOUR => 3600; |
30 | use constant ONE_DAY => 86400; | |
31 | ||
823a6996 RGS |
32 | if ($^O eq 'MacOS') { |
33 | # time_t is unsigned... | |
34 | $MaxInt = (1 << (8 * $Config{intsize})) - 1; | |
35 | $MinInt = 0; | |
36 | } else { | |
37 | $MaxInt = ((1 << (8 * $Config{intsize} - 2))-1)*2 + 1; | |
38 | $MinInt = -$MaxInt - 1; | |
5847cf89 RGS |
39 | |
40 | # On Win32 (and others?) time_t appears to be signed, but negative | |
41 | # epochs still don't work. - XXX - this is experimental | |
42 | $MinInt = 0 | |
43 | unless defined ((localtime(-1))[0]); | |
823a6996 RGS |
44 | } |
45 | ||
46 | $Max{Day} = ($MaxInt >> 1) / 43200; | |
5847cf89 | 47 | $Min{Day} = $MinInt ? -($Max{Day} + 1) : 0; |
823a6996 | 48 | |
8f230aaa RGS |
49 | $Max{Sec} = $MaxInt - ONE_DAY * $Max{Day}; |
50 | $Min{Sec} = $MinInt - ONE_DAY * $Min{Day}; | |
67627c52 | 51 | |
326557bd | 52 | # Determine the EPOC day for this machine |
88db9e9a PG |
53 | my $Epoc = 0; |
54 | if ($^O eq 'vos') { | |
55 | # work around posix-977 -- VOS doesn't handle dates in | |
56 | # the range 1970-1980. | |
57 | $Epoc = _daygm((0, 0, 0, 1, 0, 70, 4, 0)); | |
67627c52 JH |
58 | } |
59 | elsif ($^O eq 'MacOS') { | |
60 | no integer; | |
61 | ||
67627c52 JH |
62 | # MacOS time() is seconds since 1 Jan 1904, localtime |
63 | # so we need to calculate an offset to apply later | |
64 | $Epoc = 693901; | |
65 | $SecOff = timelocal(localtime(0)) - timelocal(gmtime(0)); | |
66 | $Epoc += _daygm(gmtime(0)); | |
67 | } | |
68 | else { | |
88db9e9a PG |
69 | $Epoc = _daygm(gmtime(0)); |
70 | } | |
71 | ||
326557bd GB |
72 | %Cheat=(); # clear the cache as epoc has changed |
73 | ||
326557bd GB |
74 | sub _daygm { |
75 | $_[3] + ($Cheat{pack("ss",@_[4,5])} ||= do { | |
76 | my $month = ($_[4] + 10) % 12; | |
77 | my $year = $_[5] + 1900 - $month/10; | |
78 | 365*$year + $year/4 - $year/100 + $year/400 + ($month*306 + 5)/10 - $Epoc | |
79 | }); | |
80 | } | |
81 | ||
82 | ||
83 | sub _timegm { | |
8f230aaa | 84 | my $sec = $SecOff + $_[0] + 60 * $_[1] + ONE_HOUR * $_[2]; |
67627c52 JH |
85 | |
86 | no integer; | |
87 | ||
8f230aaa | 88 | $sec + ONE_DAY * &_daygm; |
326557bd | 89 | } |
9bb8015a | 90 | |
e36f48eb | 91 | |
823a6996 RGS |
92 | sub _zoneadjust { |
93 | my ($day, $sec, $time) = @_; | |
94 | ||
95 | $sec = $sec + _timegm(localtime($time)) - $time; | |
8f230aaa RGS |
96 | if ($sec >= ONE_DAY) { $day++; $sec -= ONE_DAY; } |
97 | if ($sec < 0) { $day--; $sec += ONE_DAY; } | |
823a6996 RGS |
98 | |
99 | ($day, $sec); | |
100 | } | |
101 | ||
102 | ||
9bb8015a | 103 | sub timegm { |
326557bd GB |
104 | my ($sec,$min,$hour,$mday,$month,$year) = @_; |
105 | ||
106 | if ($year >= 1000) { | |
107 | $year -= 1900; | |
108 | } | |
109 | elsif ($year < 100 and $year >= 0) { | |
110 | $year += ($year > $Breakpoint) ? $Century : $NextCentury; | |
111 | } | |
112 | ||
113 | unless ($Options{no_range_check}) { | |
114 | if (abs($year) >= 0x7fff) { | |
115 | $year += 1900; | |
823a6996 | 116 | croak "Cannot handle date ($sec, $min, $hour, $mday, $month, *$year*)"; |
326557bd GB |
117 | } |
118 | ||
119 | croak "Month '$month' out of range 0..11" if $month > 11 or $month < 0; | |
120 | ||
121 | my $md = $MonthDays[$month]; | |
5847cf89 RGS |
122 | # ++$md if $month == 1 and $year % 4 == 0 and |
123 | # ($year % 100 != 0 or ($year + 1900) % 400 == 0); | |
326557bd GB |
124 | ++$md unless $month != 1 or $year % 4 or !($year % 400); |
125 | ||
126 | croak "Day '$mday' out of range 1..$md" if $mday > $md or $mday < 1; | |
127 | croak "Hour '$hour' out of range 0..23" if $hour > 23 or $hour < 0; | |
128 | croak "Minute '$min' out of range 0..59" if $min > 59 or $min < 0; | |
129 | croak "Second '$sec' out of range 0..59" if $sec > 59 or $sec < 0; | |
06ef4121 | 130 | } |
326557bd GB |
131 | |
132 | my $days = _daygm(undef, undef, undef, $mday, $month, $year); | |
8f230aaa | 133 | my $xsec = $sec + $SecOff + 60*$min + ONE_HOUR*$hour; |
823a6996 RGS |
134 | |
135 | unless ($Options{no_range_check} | |
136 | or ($days > $Min{Day} or $days == $Min{Day} and $xsec >= $Min{Sec}) | |
137 | and ($days < $Max{Day} or $days == $Max{Day} and $xsec <= $Max{Sec})) | |
138 | { | |
139 | warn "Day too small - $days > $Min{Day}\n" if $days < $Min{Day}; | |
140 | warn "Day too big - $days > $Max{Day}\n" if $days > $Max{Day}; | |
141 | warn "Sec too small - $days < $Min{Sec}\n" if $days < $Min{Sec}; | |
142 | warn "Sec too big - $days > $Max{Sec}\n" if $days > $Max{Sec}; | |
326557bd GB |
143 | $year += 1900; |
144 | croak "Cannot handle date ($sec, $min, $hour, $mday, $month, $year)"; | |
06ef4121 | 145 | } |
326557bd | 146 | |
67627c52 JH |
147 | no integer; |
148 | ||
8f230aaa | 149 | $xsec + ONE_DAY * $days; |
9bb8015a MK |
150 | } |
151 | ||
326557bd | 152 | |
e36f48eb | 153 | sub timegm_nocheck { |
b75c8c73 | 154 | local $Options{no_range_check} = 1; |
e36f48eb GS |
155 | &timegm; |
156 | } | |
157 | ||
326557bd | 158 | |
9bb8015a | 159 | sub timelocal { |
823a6996 RGS |
160 | # Adjust Max/Min allowed times to fit local time zone and call timegm |
161 | local ($Max{Day}, $Max{Sec}) = _zoneadjust($Max{Day}, $Max{Sec}, $MaxInt); | |
162 | local ($Min{Day}, $Min{Sec}) = _zoneadjust($Min{Day}, $Min{Sec}, $MinInt); | |
326557bd | 163 | my $ref_t = &timegm; |
823a6996 | 164 | |
8f230aaa | 165 | my $loc_t = _timegm(localtime($ref_t)); |
a0d0e21e | 166 | |
326557bd GB |
167 | # Is there a timezone offset from GMT or are we done |
168 | my $zone_off = $ref_t - $loc_t | |
169 | or return $loc_t; | |
16bb4654 | 170 | |
823a6996 RGS |
171 | # This hack is needed to always pick the first matching time |
172 | # during a DST change when time would otherwise be ambiguous | |
8f230aaa | 173 | $zone_off -= ONE_HOUR if $ref_t >= ONE_HOUR; |
823a6996 | 174 | |
326557bd GB |
175 | # Adjust for timezone |
176 | $loc_t = $ref_t + $zone_off; | |
16bb4654 | 177 | |
326557bd GB |
178 | # Are we close to a DST change or are we done |
179 | my $dst_off = $ref_t - _timegm(localtime($loc_t)) | |
180 | or return $loc_t; | |
181 | ||
182 | # Adjust for DST change | |
13ef5feb DM |
183 | $loc_t += $dst_off; |
184 | ||
823a6996 RGS |
185 | return $loc_t if $dst_off >= 0; |
186 | ||
13ef5feb DM |
187 | # for a negative offset from GMT, and if the original date |
188 | # was a non-extent gap in a forward DST jump, we should | |
189 | # now have the wrong answer - undo the DST adjust; | |
13ef5feb DM |
190 | my ($s,$m,$h) = localtime($loc_t); |
191 | $loc_t -= $dst_off if $s != $_[0] || $m != $_[1] || $h != $_[2]; | |
192 | ||
193 | $loc_t; | |
a0d0e21e LW |
194 | } |
195 | ||
326557bd | 196 | |
e36f48eb | 197 | sub timelocal_nocheck { |
b75c8c73 | 198 | local $Options{no_range_check} = 1; |
e36f48eb GS |
199 | &timelocal; |
200 | } | |
201 | ||
a0d0e21e | 202 | 1; |
06ef4121 PC |
203 | |
204 | __END__ | |
205 | ||
206 | =head1 NAME | |
207 | ||
208 | Time::Local - efficiently compute time from local and GMT time | |
209 | ||
210 | =head1 SYNOPSIS | |
211 | ||
396e3838 DL |
212 | $time = timelocal($sec,$min,$hour,$mday,$mon,$year); |
213 | $time = timegm($sec,$min,$hour,$mday,$mon,$year); | |
06ef4121 PC |
214 | |
215 | =head1 DESCRIPTION | |
216 | ||
396e3838 | 217 | These routines are the inverse of built-in perl functions localtime() |
06ef4121 | 218 | and gmtime(). They accept a date as a six-element array, and return |
1c41b6a4 | 219 | the corresponding time(2) value in seconds since the system epoch |
4ab0373f | 220 | (Midnight, January 1, 1970 GMT on Unix, for example). This value can |
1c41b6a4 RGS |
221 | be positive or negative, though POSIX only requires support for |
222 | positive values, so dates before the system's epoch may not work on | |
223 | all operating systems. | |
06ef4121 PC |
224 | |
225 | It is worth drawing particular attention to the expected ranges for | |
eee32007 JH |
226 | the values provided. The value for the day of the month is the actual day |
227 | (ie 1..31), while the month is the number of months since January (0..11). | |
06ef4121 PC |
228 | This is consistent with the values returned from localtime() and gmtime(). |
229 | ||
e36f48eb | 230 | The timelocal() and timegm() functions perform range checking on the |
396e3838 | 231 | input $sec, $min, $hour, $mday, and $mon values by default. If you'd |
e36f48eb GS |
232 | rather they didn't, you can explicitly import the timelocal_nocheck() |
233 | and timegm_nocheck() functions. | |
ac54365a | 234 | |
e36f48eb | 235 | use Time::Local 'timelocal_nocheck'; |
3cb6de81 | 236 | |
a1f33342 | 237 | { |
a1f33342 | 238 | # The 365th day of 1999 |
e36f48eb | 239 | print scalar localtime timelocal_nocheck 0,0,0,365,0,99; |
ac54365a | 240 | |
a1f33342 | 241 | # The twenty thousandth day since 1970 |
e36f48eb | 242 | print scalar localtime timelocal_nocheck 0,0,0,20000,0,70; |
ac54365a | 243 | |
a1f33342 | 244 | # And even the 10,000,000th second since 1999! |
e36f48eb | 245 | print scalar localtime timelocal_nocheck 10000000,0,0,1,0,99; |
a1f33342 | 246 | } |
ac54365a | 247 | |
e36f48eb | 248 | Your mileage may vary when trying these with minutes and hours, |
ac54365a GS |
249 | and it doesn't work at all for months. |
250 | ||
06ef4121 PC |
251 | Strictly speaking, the year should also be specified in a form consistent |
252 | with localtime(), i.e. the offset from 1900. | |
253 | In order to make the interpretation of the year easier for humans, | |
254 | however, who are more accustomed to seeing years as two-digit or four-digit | |
255 | values, the following conventions are followed: | |
256 | ||
257 | =over 4 | |
258 | ||
259 | =item * | |
260 | ||
261 | Years greater than 999 are interpreted as being the actual year, | |
5847cf89 RGS |
262 | rather than the offset from 1900. Thus, 1964 would indicate the year |
263 | Martin Luther King won the Nobel prize, not the year 3864. | |
06ef4121 PC |
264 | |
265 | =item * | |
266 | ||
267 | Years in the range 100..999 are interpreted as offset from 1900, | |
268 | so that 112 indicates 2012. This rule also applies to years less than zero | |
269 | (but see note below regarding date range). | |
270 | ||
271 | =item * | |
272 | ||
273 | Years in the range 0..99 are interpreted as shorthand for years in the | |
274 | rolling "current century," defined as 50 years on either side of the current | |
275 | year. Thus, today, in 1999, 0 would refer to 2000, and 45 to 2045, | |
276 | but 55 would refer to 1955. Twenty years from now, 55 would instead refer | |
277 | to 2055. This is messy, but matches the way people currently think about | |
278 | two digit dates. Whenever possible, use an absolute four digit year instead. | |
279 | ||
280 | =back | |
281 | ||
282 | The scheme above allows interpretation of a wide range of dates, particularly | |
283 | if 4-digit years are used. | |
90ca0aaa | 284 | |
06ef4121 PC |
285 | Please note, however, that the range of dates that can be actually be handled |
286 | depends on the size of an integer (time_t) on a given platform. | |
287 | Currently, this is 32 bits for most systems, yielding an approximate range | |
288 | from Dec 1901 to Jan 2038. | |
289 | ||
290 | Both timelocal() and timegm() croak if given dates outside the supported | |
291 | range. | |
292 | ||
823a6996 RGS |
293 | =head2 Ambiguous Local Times (DST) |
294 | ||
295 | Because of DST changes, there are many time zones where the same local | |
4ab0373f | 296 | time occurs for two different GMT times on the same day. For example, |
823a6996 | 297 | in the "Europe/Paris" time zone, the local time of 2001-10-28 02:30:00 |
4ab0373f MB |
298 | can represent either 2001-10-28 00:30:00 GMT, B<or> 2001-10-28 |
299 | 01:30:00 GMT. | |
823a6996 RGS |
300 | |
301 | When given an ambiguous local time, the timelocal() function should | |
4ab0373f | 302 | always return the epoch for the I<earlier> of the two possible GMT |
823a6996 RGS |
303 | times. |
304 | ||
4ab0373f MB |
305 | =head2 Non-Existent Local Times (DST) |
306 | ||
307 | When a DST change causes a locale clock to skip one hour forward, | |
308 | there will be an hour's worth of local times that don't exist. Again, | |
309 | for the "Europe/Paris" time zone, the local clock jumped from | |
310 | 2001-03-25 01:59:59 to 2001-03-25 03:00:00. | |
311 | ||
312 | If the timelocal() function is given a non-existent local time, it | |
313 | will simply return an epoch value for the time one hour later. | |
314 | ||
823a6996 RGS |
315 | =head2 Negative Epoch Values |
316 | ||
317 | Negative epoch (time_t) values are not officially supported by the | |
318 | POSIX standards, so this module's tests do not test them. On some | |
319 | systems, they are known not to work. These include MacOS (pre-OSX) | |
320 | and Win32. | |
321 | ||
322 | On systems which do support negative epoch values, this module should | |
323 | be able to cope with dates before the start of the epoch, down the | |
324 | minimum value of time_t for the system. | |
325 | ||
06ef4121 PC |
326 | =head1 IMPLEMENTATION |
327 | ||
328 | These routines are quite efficient and yet are always guaranteed to agree | |
329 | with localtime() and gmtime(). We manage this by caching the start times | |
330 | of any months we've seen before. If we know the start time of the month, | |
331 | we can always calculate any time within the month. The start times | |
326557bd GB |
332 | are calculated using a mathematical formula. Unlike other algorithms |
333 | that do multiple calls to gmtime(). | |
06ef4121 PC |
334 | |
335 | timelocal() is implemented using the same cache. We just assume that we're | |
336 | translating a GMT time, and then fudge it when we're done for the timezone | |
337 | and daylight savings arguments. Note that the timezone is evaluated for | |
338 | each date because countries occasionally change their official timezones. | |
339 | Assuming that localtime() corrects for these changes, this routine will | |
326557bd | 340 | also be correct. |
06ef4121 PC |
341 | |
342 | =head1 BUGS | |
343 | ||
344 | The whole scheme for interpreting two-digit years can be considered a bug. | |
345 | ||
1c41b6a4 RGS |
346 | =head1 SUPPORT |
347 | ||
4ab0373f | 348 | Support for this module is provided via the datetime@perl.org |
1c41b6a4 RGS |
349 | email list. See http://lists.perl.org/ for more details. |
350 | ||
4ab0373f MB |
351 | Please submit bugs using the RT system at rt.cpan.org, or as a last |
352 | resort, to the datetime@perl.org list. | |
1c41b6a4 RGS |
353 | |
354 | =head1 AUTHOR | |
355 | ||
356 | This module is based on a Perl 4 library, timelocal.pl, that was | |
357 | included with Perl 4.036, and was most likely written by Tom | |
358 | Christiansen. | |
359 | ||
360 | The current version was written by Graham Barr. | |
361 | ||
362 | It is now being maintained separately from the Perl core by Dave | |
363 | Rolsky, <autarch@urth.org>. | |
364 | ||
06ef4121 | 365 | =cut |
326557bd | 366 |