| 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 | |