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Diffstat (limited to 'contrib/ntp/scripts/monitoring/timelocal.pl')
-rw-r--r-- | contrib/ntp/scripts/monitoring/timelocal.pl | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/contrib/ntp/scripts/monitoring/timelocal.pl b/contrib/ntp/scripts/monitoring/timelocal.pl new file mode 100644 index 0000000..d0f73a2 --- /dev/null +++ b/contrib/ntp/scripts/monitoring/timelocal.pl @@ -0,0 +1,77 @@ +;# timelocal.pl +;# +;# Usage: +;# $time = timelocal($sec,$min,$hours,$mday,$mon,$year,$junk,$junk,$isdst); +;# $time = timegm($sec,$min,$hours,$mday,$mon,$year); + +;# These routines are quite efficient and yet are always guaranteed to agree +;# with localtime() and gmtime(). We manage this by caching the start times +;# of any months we've seen before. If we know the start time of the month, +;# we can always calculate any time within the month. The start times +;# themselves are guessed by successive approximation starting at the +;# current time, since most dates seen in practice are close to the +;# current date. Unlike algorithms that do a binary search (calling gmtime +;# once for each bit of the time value, resulting in 32 calls), this algorithm +;# calls it at most 6 times, and usually only once or twice. If you hit +;# the month cache, of course, it doesn't call it at all. + +;# timelocal is implemented using the same cache. We just assume that we're +;# translating a GMT time, and then fudge it when we're done for the timezone +;# and daylight savings arguments. The timezone is determined by examining +;# the result of localtime(0) when the package is initialized. The daylight +;# savings offset is currently assumed to be one hour. + +CONFIG: { + package timelocal; + + @epoch = localtime(0); + $tzmin = $epoch[2] * 60 + $epoch[1]; # minutes east of GMT + if ($tzmin > 0) { + $tzmin = 24 * 60 - $tzmin; # minutes west of GMT + $tzmin -= 24 * 60 if $epoch[5] == 70; # account for the date line + } + + $SEC = 1; + $MIN = 60 * $SEC; + $HR = 60 * $MIN; + $DAYS = 24 * $HR; + $YearFix = ((gmtime(946684800))[5] == 100) ? 100 : 0; +} + +sub timegm { + package timelocal; + + $ym = pack(C2, @_[5,4]); + $cheat = $cheat{$ym} || &cheat; + $cheat + $_[0] * $SEC + $_[1] * $MIN + $_[2] * $HR + ($_[3]-1) * $DAYS; +} + +sub timelocal { + package timelocal; + + $ym = pack(C2, @_[5,4]); + $cheat = $cheat{$ym} || &cheat; + $cheat + $_[0] * $SEC + $_[1] * $MIN + $_[2] * $HR + ($_[3]-1) * $DAYS + + $tzmin * $MIN - 60 * 60 * ($_[8] != 0); +} + +package timelocal; + +sub cheat { + $year = $_[5]; + $month = $_[4]; + $guess = $^T; + @g = gmtime($guess); + $year += $YearFix if $year < $epoch[5]; + while ($diff = $year - $g[5]) { + $guess += $diff * (364 * $DAYS); + @g = gmtime($guess); + } + while ($diff = $month - $g[4]) { + $guess += $diff * (28 * $DAYS); + @g = gmtime($guess); + } + $g[3]--; + $guess -= $g[0] * $SEC + $g[1] * $MIN + $g[2] * $HR + $g[3] * $DAYS; + $cheat{$ym} = $guess; +} |