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1 | package Time::Local; |
2 | ||
3 | require Exporter; | |
4 | use Carp; | |
5 | use Config; | |
6 | use strict; | |
7 | use integer; | |
8 | ||
9 | use vars qw( $VERSION @ISA @EXPORT @EXPORT_OK ); | |
10 | $VERSION = '1.11'; | |
11 | $VERSION = eval $VERSION; | |
12 | @ISA = qw( Exporter ); | |
13 | @EXPORT = qw( timegm timelocal ); | |
14 | @EXPORT_OK = qw( timegm_nocheck timelocal_nocheck ); | |
15 | ||
16 | my @MonthDays = (31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31); | |
17 | ||
18 | # Determine breakpoint for rolling century | |
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; | |
24 | my $SecOff = 0; | |
25 | ||
26 | my (%Options, %Cheat, %Min, %Max); | |
27 | my ($MinInt, $MaxInt); | |
28 | ||
29 | if ($^O eq 'MacOS') { | |
30 | # time_t is unsigned... | |
31 | $MaxInt = (1 << (8 * $Config{intsize})) - 1; | |
32 | $MinInt = 0; | |
33 | } else { | |
34 | $MaxInt = ((1 << (8 * $Config{intsize} - 2))-1)*2 + 1; | |
35 | $MinInt = -$MaxInt - 1; | |
36 | ||
37 | # On Win32 (and others?) time_t appears to be signed, but negative | |
38 | # epochs still don't work. - XXX - this is experimental | |
39 | $MinInt = 0 | |
40 | unless defined ((localtime(-1))[0]); | |
41 | } | |
42 | ||
43 | $Max{Day} = ($MaxInt >> 1) / 43200; | |
44 | $Min{Day} = $MinInt ? -($Max{Day} + 1) : 0; | |
45 | ||
46 | $Max{Sec} = $MaxInt - 86400 * $Max{Day}; | |
47 | $Min{Sec} = $MinInt - 86400 * $Min{Day}; | |
48 | ||
49 | # Determine the EPOC day for this machine | |
50 | my $Epoc = 0; | |
51 | if ($^O eq 'vos') { | |
52 | # work around posix-977 -- VOS doesn't handle dates in | |
53 | # the range 1970-1980. | |
54 | $Epoc = _daygm((0, 0, 0, 1, 0, 70, 4, 0)); | |
55 | } | |
56 | elsif ($^O eq 'MacOS') { | |
57 | no integer; | |
58 | ||
59 | # MacOS time() is seconds since 1 Jan 1904, localtime | |
60 | # so we need to calculate an offset to apply later | |
61 | $Epoc = 693901; | |
62 | $SecOff = timelocal(localtime(0)) - timelocal(gmtime(0)); | |
63 | $Epoc += _daygm(gmtime(0)); | |
64 | } | |
65 | else { | |
66 | $Epoc = _daygm(gmtime(0)); | |
67 | } | |
68 | ||
69 | %Cheat=(); # clear the cache as epoc has changed | |
70 | ||
71 | sub _daygm { | |
72 | $_[3] + ($Cheat{pack("ss",@_[4,5])} ||= do { | |
73 | my $month = ($_[4] + 10) % 12; | |
74 | my $year = $_[5] + 1900 - $month/10; | |
75 | 365*$year + $year/4 - $year/100 + $year/400 + ($month*306 + 5)/10 - $Epoc | |
76 | }); | |
77 | } | |
78 | ||
79 | ||
80 | sub _timegm { | |
81 | my $sec = $SecOff + $_[0] + 60 * $_[1] + 3600 * $_[2]; | |
82 | ||
83 | no integer; | |
84 | ||
85 | $sec + 86400 * &_daygm; | |
86 | } | |
87 | ||
88 | ||
89 | sub _zoneadjust { | |
90 | my ($day, $sec, $time) = @_; | |
91 | ||
92 | $sec = $sec + _timegm(localtime($time)) - $time; | |
93 | if ($sec >= 86400) { $day++; $sec -= 86400; } | |
94 | if ($sec < 0) { $day--; $sec += 86400; } | |
95 | ||
96 | ($day, $sec); | |
97 | } | |
98 | ||
99 | ||
100 | sub timegm { | |
101 | my ($sec,$min,$hour,$mday,$month,$year) = @_; | |
102 | ||
103 | if ($year >= 1000) { | |
104 | $year -= 1900; | |
105 | } | |
106 | elsif ($year < 100 and $year >= 0) { | |
107 | $year += ($year > $Breakpoint) ? $Century : $NextCentury; | |
108 | } | |
109 | ||
110 | unless ($Options{no_range_check}) { | |
111 | if (abs($year) >= 0x7fff) { | |
112 | $year += 1900; | |
113 | croak "Cannot handle date ($sec, $min, $hour, $mday, $month, *$year*)"; | |
114 | } | |
115 | ||
116 | croak "Month '$month' out of range 0..11" if $month > 11 or $month < 0; | |
117 | ||
118 | my $md = $MonthDays[$month]; | |
119 | # ++$md if $month == 1 and $year % 4 == 0 and | |
120 | # ($year % 100 != 0 or ($year + 1900) % 400 == 0); | |
121 | ++$md unless $month != 1 or $year % 4 or !($year % 400); | |
122 | ||
123 | croak "Day '$mday' out of range 1..$md" if $mday > $md or $mday < 1; | |
124 | croak "Hour '$hour' out of range 0..23" if $hour > 23 or $hour < 0; | |
125 | croak "Minute '$min' out of range 0..59" if $min > 59 or $min < 0; | |
126 | croak "Second '$sec' out of range 0..59" if $sec > 59 or $sec < 0; | |
127 | } | |
128 | ||
129 | my $days = _daygm(undef, undef, undef, $mday, $month, $year); | |
130 | my $xsec = $sec + $SecOff + 60*$min + 3600*$hour; | |
131 | ||
132 | unless ($Options{no_range_check} | |
133 | or ($days > $Min{Day} or $days == $Min{Day} and $xsec >= $Min{Sec}) | |
134 | and ($days < $Max{Day} or $days == $Max{Day} and $xsec <= $Max{Sec})) | |
135 | { | |
136 | warn "Day too small - $days > $Min{Day}\n" if $days < $Min{Day}; | |
137 | warn "Day too big - $days > $Max{Day}\n" if $days > $Max{Day}; | |
138 | warn "Sec too small - $days < $Min{Sec}\n" if $days < $Min{Sec}; | |
139 | warn "Sec too big - $days > $Max{Sec}\n" if $days > $Max{Sec}; | |
140 | $year += 1900; | |
141 | croak "Cannot handle date ($sec, $min, $hour, $mday, $month, $year)"; | |
142 | } | |
143 | ||
144 | no integer; | |
145 | ||
146 | $xsec + 86400 * $days; | |
147 | } | |
148 | ||
149 | ||
150 | sub timegm_nocheck { | |
151 | local $Options{no_range_check} = 1; | |
152 | &timegm; | |
153 | } | |
154 | ||
155 | ||
156 | sub timelocal { | |
157 | # Adjust Max/Min allowed times to fit local time zone and call timegm | |
158 | local ($Max{Day}, $Max{Sec}) = _zoneadjust($Max{Day}, $Max{Sec}, $MaxInt); | |
159 | local ($Min{Day}, $Min{Sec}) = _zoneadjust($Min{Day}, $Min{Sec}, $MinInt); | |
160 | my $ref_t = &timegm; | |
161 | ||
162 | # Calculate first guess with a one-day delta to avoid localtime overflow | |
163 | my $delta = ($_[5] < 100)? 86400 : -86400; | |
164 | my $loc_t = _timegm(localtime( $ref_t + $delta )) - $delta; | |
165 | ||
166 | # Is there a timezone offset from GMT or are we done | |
167 | my $zone_off = $ref_t - $loc_t | |
168 | or return $loc_t; | |
169 | ||
170 | # This hack is needed to always pick the first matching time | |
171 | # during a DST change when time would otherwise be ambiguous | |
172 | $zone_off -= 3600 if ($delta > 0 && $ref_t >= 3600); | |
173 | ||
174 | # Adjust for timezone | |
175 | $loc_t = $ref_t + $zone_off; | |
176 | ||
177 | # Are we close to a DST change or are we done | |
178 | my $dst_off = $ref_t - _timegm(localtime($loc_t)) | |
179 | or return $loc_t; | |
180 | ||
181 | # Adjust for DST change | |
182 | $loc_t += $dst_off; | |
183 | ||
184 | return $loc_t if $dst_off >= 0; | |
185 | ||
186 | # for a negative offset from GMT, and if the original date | |
187 | # was a non-extent gap in a forward DST jump, we should | |
188 | # now have the wrong answer - undo the DST adjust; | |
189 | ||
190 | my ($s,$m,$h) = localtime($loc_t); | |
191 | $loc_t -= $dst_off if $s != $_[0] || $m != $_[1] || $h != $_[2]; | |
192 | ||
193 | $loc_t; | |
194 | } | |
195 | ||
196 | ||
197 | sub timelocal_nocheck { | |
198 | local $Options{no_range_check} = 1; | |
199 | &timelocal; | |
200 | } | |
201 | ||
202 | 1; | |
203 | ||
204 | __END__ | |
205 | ||
206 | =head1 NAME | |
207 | ||
208 | Time::Local - efficiently compute time from local and GMT time | |
209 | ||
210 | =head1 SYNOPSIS | |
211 | ||
212 | $time = timelocal($sec,$min,$hour,$mday,$mon,$year); | |
213 | $time = timegm($sec,$min,$hour,$mday,$mon,$year); | |
214 | ||
215 | =head1 DESCRIPTION | |
216 | ||
217 | These routines are the inverse of built-in perl functions localtime() | |
218 | and gmtime(). They accept a date as a six-element array, and return | |
219 | the corresponding time(2) value in seconds since the system epoch | |
220 | (Midnight, January 1, 1970 GMT on Unix, for example). This value can | |
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. | |
224 | ||
225 | It is worth drawing particular attention to the expected ranges for | |
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). | |
228 | This is consistent with the values returned from localtime() and gmtime(). | |
229 | ||
230 | The timelocal() and timegm() functions perform range checking on the | |
231 | input $sec, $min, $hour, $mday, and $mon values by default. If you'd | |
232 | rather they didn't, you can explicitly import the timelocal_nocheck() | |
233 | and timegm_nocheck() functions. | |
234 | ||
235 | use Time::Local 'timelocal_nocheck'; | |
236 | ||
237 | { | |
238 | # The 365th day of 1999 | |
239 | print scalar localtime timelocal_nocheck 0,0,0,365,0,99; | |
240 | ||
241 | # The twenty thousandth day since 1970 | |
242 | print scalar localtime timelocal_nocheck 0,0,0,20000,0,70; | |
243 | ||
244 | # And even the 10,000,000th second since 1999! | |
245 | print scalar localtime timelocal_nocheck 10000000,0,0,1,0,99; | |
246 | } | |
247 | ||
248 | Your mileage may vary when trying these with minutes and hours, | |
249 | and it doesn't work at all for months. | |
250 | ||
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, | |
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. | |
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. | |
284 | ||
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 | ||
293 | =head2 Ambiguous Local Times (DST) | |
294 | ||
295 | Because of DST changes, there are many time zones where the same local | |
296 | time occurs for two different GMT times on the same day. For example, | |
297 | in the "Europe/Paris" time zone, the local time of 2001-10-28 02:30:00 | |
298 | can represent either 2001-10-28 00:30:00 GMT, B<or> 2001-10-28 | |
299 | 01:30:00 GMT. | |
300 | ||
301 | When given an ambiguous local time, the timelocal() function should | |
302 | always return the epoch for the I<earlier> of the two possible GMT | |
303 | times. | |
304 | ||
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 | ||
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 | ||
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 | |
332 | are calculated using a mathematical formula. Unlike other algorithms | |
333 | that do multiple calls to gmtime(). | |
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 | |
340 | also be correct. | |
341 | ||
342 | =head1 BUGS | |
343 | ||
344 | The whole scheme for interpreting two-digit years can be considered a bug. | |
345 | ||
346 | =head1 SUPPORT | |
347 | ||
348 | Support for this module is provided via the datetime@perl.org | |
349 | email list. See http://lists.perl.org/ for more details. | |
350 | ||
351 | Please submit bugs using the RT system at rt.cpan.org, or as a last | |
352 | resort, to the datetime@perl.org list. | |
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 | ||
365 | =cut | |
366 |