Re: os.time() and the last second of 1969

[Sean Conner <sean@...>]

It was thus said that the Great Dirk Jagdmann once stated:
> It seems as if all these implementations are not checking the values of 
> the struct tm member variables for a valid range, but simply take these 
> integer values and use them in their formula to calculate the timestamp 
> value.

  Here's what the standard says about mktime():

	The mktime function converts the broken-down time, expressed as
	local time, in the structure pointed to by timeptr into a calendar
	time value with the same encoding as that of the values returned by
	the time function. The original values of the tm_wday and tm_yday
	components of the structure are ignored, and the original values of
						 ^^^^^^^^^^^^^^^^^^^^^^^^^^
	the other components are not restricted to the ranges indicated
	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
	above.) On successful completion, the values of the tm_wday and
	^^^^^
	tm_yday components of the structure are set appropriately, and the
	other components are set to represent the specified calendar time,
	but with their values forced to the ranges indicated above; the
	final value of tm_mday is not set until tm_mon and tm_year are
	determined.

(Section 7.23.2.3 of the C99 standard)

  The standard does not say what to do when the original values exceed the
ranges specified:

	int tm_sec;	// seconds after the minute - [0, 60]
	int tm_min;	// minutes after the hour - [0, 59]
	int tm_hour;	// hours since midnight - [0, 23]
	int tm_mday;	// day of the month - [1, 31]
	int tm_mon;	// months since January - [0, 11]
	int tm_year;	// years since 1900
	int tm_wday;	// days since Sunday - [0, 6]
	int tm_yday;	// days since January 1 - [0, 365]
	int tm_isdst;	// Daylight Saving Time flag

(Section 7.23.1 of the C99 standard)

  -spc