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1 | package Time::Local; |
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2 | |
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3 | require Exporter; |
4 | use Carp; |
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5 | use Config; |
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6 | use strict; |
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7 | use integer; |
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8 | |
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9 | use vars qw( $VERSION @ISA @EXPORT @EXPORT_OK ); |
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10 | $VERSION = '1.12'; |
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11 | $VERSION = eval $VERSION; |
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12 | @ISA = qw( Exporter ); |
13 | @EXPORT = qw( timegm timelocal ); |
14 | @EXPORT_OK = qw( timegm_nocheck timelocal_nocheck ); |
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15 | |
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16 | my @MonthDays = (31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31); |
17 | |
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18 | # Determine breakpoint for rolling century |
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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; |
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24 | my $SecOff = 0; |
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25 | |
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26 | my (%Options, %Cheat, %Min, %Max); |
27 | my ($MinInt, $MaxInt); |
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28 | |
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29 | use constant ONE_HOUR => 3600; |
30 | use constant ONE_DAY => 86400; |
31 | |
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32 | if ($^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; |
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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]); |
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44 | } |
45 | |
46 | $Max{Day} = ($MaxInt >> 1) / 43200; |
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47 | $Min{Day} = $MinInt ? -($Max{Day} + 1) : 0; |
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48 | |
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49 | $Max{Sec} = $MaxInt - ONE_DAY * $Max{Day}; |
50 | $Min{Sec} = $MinInt - ONE_DAY * $Min{Day}; |
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51 | |
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52 | # Determine the EPOC day for this machine |
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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 | $Epoc = _daygm((0, 0, 0, 1, 0, 70, 4, 0)); |
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58 | } |
59 | elsif ($^O eq 'MacOS') { |
60 | no integer; |
61 | |
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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 { |
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69 | $Epoc = _daygm(gmtime(0)); |
70 | } |
71 | |
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72 | %Cheat=(); # clear the cache as epoc has changed |
73 | |
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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 { |
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84 | my $sec = $SecOff + $_[0] + 60 * $_[1] + ONE_HOUR * $_[2]; |
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85 | |
86 | no integer; |
87 | |
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88 | $sec + ONE_DAY * &_daygm; |
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89 | } |
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90 | |
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91 | |
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92 | sub _zoneadjust { |
93 | my ($day, $sec, $time) = @_; |
94 | |
95 | $sec = $sec + _timegm(localtime($time)) - $time; |
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96 | if ($sec >= ONE_DAY) { $day++; $sec -= ONE_DAY; } |
97 | if ($sec < 0) { $day--; $sec += ONE_DAY; } |
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98 | |
99 | ($day, $sec); |
100 | } |
101 | |
102 | |
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103 | sub timegm { |
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104 | my ($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 | $year += 1900; |
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116 | croak "Cannot handle date ($sec, $min, $hour, $mday, $month, *$year*)"; |
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117 | } |
118 | |
119 | croak "Month '$month' out of range 0..11" if $month > 11 or $month < 0; |
120 | |
121 | my $md = $MonthDays[$month]; |
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122 | # ++$md if $month == 1 and $year % 4 == 0 and |
123 | # ($year % 100 != 0 or ($year + 1900) % 400 == 0); |
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124 | ++$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; |
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130 | } |
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131 | |
132 | my $days = _daygm(undef, undef, undef, $mday, $month, $year); |
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133 | my $xsec = $sec + $SecOff + 60*$min + ONE_HOUR*$hour; |
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134 | |
135 | unless ($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}; |
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143 | $year += 1900; |
144 | croak "Cannot handle date ($sec, $min, $hour, $mday, $month, $year)"; |
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145 | } |
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146 | |
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147 | no integer; |
148 | |
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149 | $xsec + ONE_DAY * $days; |
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150 | } |
151 | |
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152 | |
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153 | sub timegm_nocheck { |
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154 | local $Options{no_range_check} = 1; |
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155 | &timegm; |
156 | } |
157 | |
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158 | |
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159 | sub timelocal { |
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160 | # Adjust Max/Min allowed times to fit local time zone and call timegm |
161 | local ($Max{Day}, $Max{Sec}) = _zoneadjust($Max{Day}, $Max{Sec}, $MaxInt); |
162 | local ($Min{Day}, $Min{Sec}) = _zoneadjust($Min{Day}, $Min{Sec}, $MinInt); |
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163 | my $ref_t = &timegm; |
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164 | |
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165 | my $loc_t = _timegm(localtime($ref_t)); |
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166 | |
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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; |
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170 | |
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171 | # This hack is needed to always pick the first matching time |
172 | # during a DST change when time would otherwise be ambiguous |
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173 | $zone_off -= ONE_HOUR if $ref_t >= ONE_HOUR; |
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174 | |
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175 | # Adjust for timezone |
176 | $loc_t = $ref_t + $zone_off; |
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177 | |
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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 |
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183 | $loc_t += $dst_off; |
184 | |
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185 | return $loc_t if $dst_off >= 0; |
186 | |
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187 | # for a negative offset from GMT, and if the original date |
188 | # was a non-extent gap in a forward DST jump, we should |
189 | # now have the wrong answer - undo the DST adjust; |
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190 | my ($s,$m,$h) = localtime($loc_t); |
191 | $loc_t -= $dst_off if $s != $_[0] || $m != $_[1] || $h != $_[2]; |
192 | |
193 | $loc_t; |
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194 | } |
195 | |
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196 | |
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197 | sub timelocal_nocheck { |
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198 | local $Options{no_range_check} = 1; |
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199 | &timelocal; |
200 | } |
201 | |
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202 | 1; |
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203 | |
204 | __END__ |
205 | |
206 | =head1 NAME |
207 | |
208 | Time::Local - efficiently compute time from local and GMT time |
209 | |
210 | =head1 SYNOPSIS |
211 | |
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212 | $time = timelocal($sec,$min,$hour,$mday,$mon,$year); |
213 | $time = timegm($sec,$min,$hour,$mday,$mon,$year); |
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214 | |
215 | =head1 DESCRIPTION |
216 | |
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217 | These routines are the inverse of built-in perl functions localtime() |
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218 | and gmtime(). They accept a date as a six-element array, and return |
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219 | the corresponding time(2) value in seconds since the system epoch |
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220 | (Midnight, January 1, 1970 GMT on Unix, for example). This value can |
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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. |
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224 | |
225 | It is worth drawing particular attention to the expected ranges for |
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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). |
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228 | This is consistent with the values returned from localtime() and gmtime(). |
229 | |
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230 | The timelocal() and timegm() functions perform range checking on the |
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231 | input $sec, $min, $hour, $mday, and $mon values by default. If you'd |
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232 | rather they didn't, you can explicitly import the timelocal_nocheck() |
233 | and timegm_nocheck() functions. |
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234 | |
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235 | use Time::Local 'timelocal_nocheck'; |
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236 | |
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237 | { |
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238 | # The 365th day of 1999 |
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239 | print scalar localtime timelocal_nocheck 0,0,0,365,0,99; |
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240 | |
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241 | # The twenty thousandth day since 1970 |
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242 | print scalar localtime timelocal_nocheck 0,0,0,20000,0,70; |
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243 | |
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244 | # And even the 10,000,000th second since 1999! |
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245 | print scalar localtime timelocal_nocheck 10000000,0,0,1,0,99; |
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246 | } |
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247 | |
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248 | Your mileage may vary when trying these with minutes and hours, |
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249 | and it doesn't work at all for months. |
250 | |
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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, |
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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. |
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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. |
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284 | |
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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 | |
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293 | =head2 Ambiguous Local Times (DST) |
294 | |
295 | Because of DST changes, there are many time zones where the same local |
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296 | time occurs for two different GMT times on the same day. For example, |
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297 | in the "Europe/Paris" time zone, the local time of 2001-10-28 02:30:00 |
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298 | can represent either 2001-10-28 00:30:00 GMT, B<or> 2001-10-28 |
299 | 01:30:00 GMT. |
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300 | |
301 | When given an ambiguous local time, the timelocal() function should |
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302 | always return the epoch for the I<earlier> of the two possible GMT |
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303 | times. |
304 | |
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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 | |
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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 | |
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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 |
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332 | are calculated using a mathematical formula. Unlike other algorithms |
333 | that do multiple calls to gmtime(). |
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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 |
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340 | also be correct. |
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341 | |
342 | =head1 BUGS |
343 | |
344 | The whole scheme for interpreting two-digit years can be considered a bug. |
345 | |
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346 | =head1 SUPPORT |
347 | |
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348 | Support for this module is provided via the datetime@perl.org |
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349 | email list. See http://lists.perl.org/ for more details. |
350 | |
4ab0373f |
351 | Please submit bugs using the RT system at rt.cpan.org, or as a last |
352 | resort, to the datetime@perl.org list. |
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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 | |
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365 | =cut |
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366 | |