In message: <[EMAIL PROTECTED]>
"Tom Van Baak" <[EMAIL PROTECTED]> writes:
: With the surge of leap second captures this time
: around, are there any concerns over the growing(?)
: use of double :59 second or double :00 second
: instead of :59:60 for a positive leap second?
:
: Although not technically correct, they do seem a
: practical, perhaps even clever, alternative -- in some
: cases -- to the upstream parsing trouble that the
: exceptional :59:60 causes.
:
: Given a choice I would vote for double :59 over
: double :00 since :59 is still in the previous day
: (where the leap second occurs). Also, :59 offers
: more symmetry between positive and negative
: leap seconds (58 and 00 are constant; 59 is
: double or nothing depending on leap type).
ntp implements the double 59, and that works well when one can't
represent the number as :60 (which is impossible to do in POSIX
time_t).
POSIX, interestingly enough, doesn't define what happens at the
leapsecond very well. On the one hand, they officially don't exist.
On the other, if you convert 23:59:60 to a time_t using mktime, you
get 0:00:00 due to normalization that happens in mktime (a more or
less accidental effect). This leads some to conclude that the proper
POSIX sequence is with two 0's in a row. While this is a conclusion
from reading POSIX, it isn't the only conclusion.
Warner
