1 | package Time::Local;
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2 |
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3 | require Exporter;
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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 = '1.11';
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11 | $VERSION = eval $VERSION;
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12 | @ISA = qw( Exporter );
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13 | @EXPORT = qw( timegm timelocal );
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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);
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17 |
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18 | # Determine breakpoint for rolling century
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19 | my $ThisYear = (localtime())[5];
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20 | my $Breakpoint = ($ThisYear + 50) % 100;
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21 | my $NextCentury = $ThisYear - $ThisYear % 100;
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22 | $NextCentury += 100 if $Breakpoint < 50;
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23 | my $Century = $NextCentury - 100;
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24 | my $SecOff = 0;
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25 |
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26 | my (%Options, %Cheat, %Min, %Max);
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27 | my ($MinInt, $MaxInt);
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28 |
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29 | if ($^O eq 'MacOS') {
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30 | # time_t is unsigned...
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31 | $MaxInt = (1 << (8 * $Config{intsize})) - 1;
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32 | $MinInt = 0;
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33 | } else {
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34 | $MaxInt = ((1 << (8 * $Config{intsize} - 2))-1)*2 + 1;
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35 | $MinInt = -$MaxInt - 1;
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36 |
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37 | # On Win32 (and others?) time_t appears to be signed, but negative
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38 | # epochs still don't work. - XXX - this is experimental
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39 | $MinInt = 0
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40 | unless defined ((localtime(-1))[0]);
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41 | }
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42 |
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43 | $Max{Day} = ($MaxInt >> 1) / 43200;
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44 | $Min{Day} = $MinInt ? -($Max{Day} + 1) : 0;
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45 |
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46 | $Max{Sec} = $MaxInt - 86400 * $Max{Day};
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47 | $Min{Sec} = $MinInt - 86400 * $Min{Day};
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48 |
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49 | # Determine the EPOC day for this machine
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50 | my $Epoc = 0;
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51 | if ($^O eq 'vos') {
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52 | # work around posix-977 -- VOS doesn't handle dates in
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53 | # the range 1970-1980.
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54 | $Epoc = _daygm((0, 0, 0, 1, 0, 70, 4, 0));
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55 | }
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56 | elsif ($^O eq 'MacOS') {
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57 | no integer;
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58 |
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59 | # MacOS time() is seconds since 1 Jan 1904, localtime
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60 | # so we need to calculate an offset to apply later
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61 | $Epoc = 693901;
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62 | $SecOff = timelocal(localtime(0)) - timelocal(gmtime(0));
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63 | $Epoc += _daygm(gmtime(0));
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64 | }
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65 | else {
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66 | $Epoc = _daygm(gmtime(0));
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67 | }
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68 |
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69 | %Cheat=(); # clear the cache as epoc has changed
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70 |
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71 | sub _daygm {
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72 | $_[3] + ($Cheat{pack("ss",@_[4,5])} ||= do {
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73 | my $month = ($_[4] + 10) % 12;
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74 | my $year = $_[5] + 1900 - $month/10;
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75 | 365*$year + $year/4 - $year/100 + $year/400 + ($month*306 + 5)/10 - $Epoc
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76 | });
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77 | }
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78 |
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79 |
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80 | sub _timegm {
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81 | my $sec = $SecOff + $_[0] + 60 * $_[1] + 3600 * $_[2];
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82 |
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83 | no integer;
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84 |
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85 | $sec + 86400 * &_daygm;
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86 | }
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87 |
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88 |
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89 | sub _zoneadjust {
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90 | my ($day, $sec, $time) = @_;
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91 |
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92 | $sec = $sec + _timegm(localtime($time)) - $time;
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93 | if ($sec >= 86400) { $day++; $sec -= 86400; }
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94 | if ($sec < 0) { $day--; $sec += 86400; }
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95 |
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96 | ($day, $sec);
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97 | }
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98 |
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99 |
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100 | sub timegm {
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101 | my ($sec,$min,$hour,$mday,$month,$year) = @_;
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102 |
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103 | if ($year >= 1000) {
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104 | $year -= 1900;
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105 | }
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106 | elsif ($year < 100 and $year >= 0) {
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107 | $year += ($year > $Breakpoint) ? $Century : $NextCentury;
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108 | }
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109 |
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110 | unless ($Options{no_range_check}) {
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111 | if (abs($year) >= 0x7fff) {
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112 | $year += 1900;
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113 | croak "Cannot handle date ($sec, $min, $hour, $mday, $month, *$year*)";
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114 | }
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115 |
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116 | croak "Month '$month' out of range 0..11" if $month > 11 or $month < 0;
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117 |
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118 | my $md = $MonthDays[$month];
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119 | # ++$md if $month == 1 and $year % 4 == 0 and
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120 | # ($year % 100 != 0 or ($year + 1900) % 400 == 0);
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121 | ++$md unless $month != 1 or $year % 4 or !($year % 400);
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122 |
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123 | croak "Day '$mday' out of range 1..$md" if $mday > $md or $mday < 1;
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124 | croak "Hour '$hour' out of range 0..23" if $hour > 23 or $hour < 0;
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125 | croak "Minute '$min' out of range 0..59" if $min > 59 or $min < 0;
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126 | croak "Second '$sec' out of range 0..59" if $sec > 59 or $sec < 0;
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127 | }
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128 |
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129 | my $days = _daygm(undef, undef, undef, $mday, $month, $year);
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130 | my $xsec = $sec + $SecOff + 60*$min + 3600*$hour;
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131 |
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132 | unless ($Options{no_range_check}
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133 | or ($days > $Min{Day} or $days == $Min{Day} and $xsec >= $Min{Sec})
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134 | and ($days < $Max{Day} or $days == $Max{Day} and $xsec <= $Max{Sec}))
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135 | {
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136 | warn "Day too small - $days > $Min{Day}\n" if $days < $Min{Day};
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137 | warn "Day too big - $days > $Max{Day}\n" if $days > $Max{Day};
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138 | warn "Sec too small - $days < $Min{Sec}\n" if $days < $Min{Sec};
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139 | warn "Sec too big - $days > $Max{Sec}\n" if $days > $Max{Sec};
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140 | $year += 1900;
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141 | croak "Cannot handle date ($sec, $min, $hour, $mday, $month, $year)";
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142 | }
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143 |
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144 | no integer;
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145 |
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146 | $xsec + 86400 * $days;
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147 | }
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148 |
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149 |
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150 | sub timegm_nocheck {
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151 | local $Options{no_range_check} = 1;
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152 | &timegm;
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153 | }
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154 |
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155 |
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156 | sub timelocal {
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157 | # Adjust Max/Min allowed times to fit local time zone and call timegm
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158 | local ($Max{Day}, $Max{Sec}) = _zoneadjust($Max{Day}, $Max{Sec}, $MaxInt);
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159 | local ($Min{Day}, $Min{Sec}) = _zoneadjust($Min{Day}, $Min{Sec}, $MinInt);
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160 | my $ref_t = &timegm;
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161 |
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162 | # Calculate first guess with a one-day delta to avoid localtime overflow
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163 | my $delta = ($_[5] < 100)? 86400 : -86400;
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164 | my $loc_t = _timegm(localtime( $ref_t + $delta )) - $delta;
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165 |
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166 | # Is there a timezone offset from GMT or are we done
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167 | my $zone_off = $ref_t - $loc_t
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168 | or return $loc_t;
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169 |
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170 | # This hack is needed to always pick the first matching time
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171 | # during a DST change when time would otherwise be ambiguous
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172 | $zone_off -= 3600 if ($delta > 0 && $ref_t >= 3600);
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173 |
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174 | # Adjust for timezone
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175 | $loc_t = $ref_t + $zone_off;
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176 |
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177 | # Are we close to a DST change or are we done
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178 | my $dst_off = $ref_t - _timegm(localtime($loc_t))
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179 | or return $loc_t;
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180 |
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181 | # Adjust for DST change
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182 | $loc_t += $dst_off;
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183 |
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184 | return $loc_t if $dst_off >= 0;
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185 |
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186 | # for a negative offset from GMT, and if the original date
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187 | # was a non-extent gap in a forward DST jump, we should
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188 | # now have the wrong answer - undo the DST adjust;
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189 |
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190 | my ($s,$m,$h) = localtime($loc_t);
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191 | $loc_t -= $dst_off if $s != $_[0] || $m != $_[1] || $h != $_[2];
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192 |
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193 | $loc_t;
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194 | }
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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;
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200 | }
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201 |
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202 | 1;
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203 |
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204 | __END__
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205 |
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206 | =head1 NAME
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207 |
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208 | Time::Local - efficiently compute time from local and GMT time
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209 |
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210 | =head1 SYNOPSIS
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211 |
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212 | $time = timelocal($sec,$min,$hour,$mday,$mon,$year);
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213 | $time = timegm($sec,$min,$hour,$mday,$mon,$year);
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214 |
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215 | =head1 DESCRIPTION
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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
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222 | positive values, so dates before the system's epoch may not work on
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223 | all operating systems.
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224 |
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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
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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().
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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()
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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.
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250 |
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251 | Strictly speaking, the year should also be specified in a form consistent
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252 | with localtime(), i.e. the offset from 1900.
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253 | In order to make the interpretation of the year easier for humans,
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254 | however, who are more accustomed to seeing years as two-digit or four-digit
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255 | values, the following conventions are followed:
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256 |
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257 | =over 4
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258 |
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259 | =item *
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260 |
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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
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263 | Martin Luther King won the Nobel prize, not the year 3864.
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264 |
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265 | =item *
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266 |
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267 | Years in the range 100..999 are interpreted as offset from 1900,
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268 | so that 112 indicates 2012. This rule also applies to years less than zero
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269 | (but see note below regarding date range).
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270 |
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271 | =item *
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272 |
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273 | Years in the range 0..99 are interpreted as shorthand for years in the
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274 | rolling "current century," defined as 50 years on either side of the current
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275 | year. Thus, today, in 1999, 0 would refer to 2000, and 45 to 2045,
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276 | but 55 would refer to 1955. Twenty years from now, 55 would instead refer
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277 | to 2055. This is messy, but matches the way people currently think about
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278 | two digit dates. Whenever possible, use an absolute four digit year instead.
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279 |
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280 | =back
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281 |
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282 | The scheme above allows interpretation of a wide range of dates, particularly
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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
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286 | depends on the size of an integer (time_t) on a given platform.
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287 | Currently, this is 32 bits for most systems, yielding an approximate range
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288 | from Dec 1901 to Jan 2038.
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289 |
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290 | Both timelocal() and timegm() croak if given dates outside the supported
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291 | range.
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292 |
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293 | =head2 Ambiguous Local Times (DST)
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294 |
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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
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299 | 01:30:00 GMT.
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300 |
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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.
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304 |
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305 | =head2 Non-Existent Local Times (DST)
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306 |
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307 | When a DST change causes a locale clock to skip one hour forward,
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308 | there will be an hour's worth of local times that don't exist. Again,
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309 | for the "Europe/Paris" time zone, the local clock jumped from
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310 | 2001-03-25 01:59:59 to 2001-03-25 03:00:00.
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311 |
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312 | If the timelocal() function is given a non-existent local time, it
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313 | will simply return an epoch value for the time one hour later.
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314 |
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315 | =head2 Negative Epoch Values
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316 |
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317 | Negative epoch (time_t) values are not officially supported by the
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318 | POSIX standards, so this module's tests do not test them. On some
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319 | systems, they are known not to work. These include MacOS (pre-OSX)
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320 | and Win32.
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321 |
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322 | On systems which do support negative epoch values, this module should
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323 | be able to cope with dates before the start of the epoch, down the
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324 | minimum value of time_t for the system.
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325 |
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326 | =head1 IMPLEMENTATION
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327 |
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328 | These routines are quite efficient and yet are always guaranteed to agree
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329 | with localtime() and gmtime(). We manage this by caching the start times
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330 | of any months we've seen before. If we know the start time of the month,
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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
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333 | that do multiple calls to gmtime().
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334 |
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335 | timelocal() is implemented using the same cache. We just assume that we're
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336 | translating a GMT time, and then fudge it when we're done for the timezone
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337 | and daylight savings arguments. Note that the timezone is evaluated for
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338 | each date because countries occasionally change their official timezones.
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339 | Assuming that localtime() corrects for these changes, this routine will
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340 | also be correct.
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341 |
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342 | =head1 BUGS
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343 |
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344 | The whole scheme for interpreting two-digit years can be considered a bug.
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345 |
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346 | =head1 SUPPORT
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347 |
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348 | Support for this module is provided via the [email protected]
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349 | email list. See http://lists.perl.org/ for more details.
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350 |
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351 | Please submit bugs using the RT system at rt.cpan.org, or as a last
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352 | resort, to the [email protected] list.
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353 |
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354 | =head1 AUTHOR
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355 |
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356 | This module is based on a Perl 4 library, timelocal.pl, that was
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357 | included with Perl 4.036, and was most likely written by Tom
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358 | Christiansen.
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359 |
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360 | The current version was written by Graham Barr.
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361 |
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362 | It is now being maintained separately from the Perl core by Dave
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363 | Rolsky, <[email protected]>.
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364 |
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365 | =cut
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366 |
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