Re: Trying to use AUTHOR_DATE

From: Linus Torvalds <torvalds@osdl.org>
Date: Apr 30, 2005, 20:32 UTC
Message-ID: <Pine.LNX.4.58.0504301322130.2296@ppc970.osdl.org>
In-Reply-To: <87r7gs87a9.fsf@windlord.stanford.edu>

On Sat, 30 Apr 2005, Russ Allbery wrote:

> 
> You really cannot get portable behavior in this area without something
> akin to Autoconf probes, unfortunately.

Ok, since this only really matters for AUTHOR_DATE, which we pass in as a random string anyway, and which comes from various mail programs which may or may not follow all RFC's, I just rewrote it to give "almost correct results" for "pretty much any crap you throw at it".

As a test-bed, a "test-date" program that parses a date and then prints it out in git format _and_ in the local timezone format, here's a few examples:

	./test-date "$(date)" "April 4th, 1992 at 13:45" "13:04:09 +0100 2004 Yesterday, Friday 13th, December"

results in

	Sat Apr 30 13:26:52 PDT 2005 -> 1114892812 -0700 -> Sat Apr 30 13:26:52 2005

	April 4th, 1992 at 13:45 -> 702395100 +0000 -> Sat Apr  4 05:45:00 1992

	13:04:09 +0100 2004 Yesterday, Friday 13th, December -> 1102939449 +0100 -> Mon Dec 13 04:04:09 2004

which is just because it really doesn't check a hell of a lot.

For example, if you say

	"I caught 14 fishes in December 1998"

test-date will happily parse this as

	Sun Dec 13 16:00:00 1998

(That's "0:00:00 Dec 14th, 1998 UTC" shown in the local timezone ;). Or:

	./test-date  "12:15 4/17/2009"

	12:15 4/17/2009 -> 1239970500 +0000 -> Fri Apr 17 05:15:00 2009

ie it just greedily tries to make _some_ sense of the random strings you throw at it.

It doesn't even try getting timezones right - it doesn't know about summertime or anything. Besides, I probably used the wrong timezone info anyway.

I'll probably tweak it a bit more (make "no timezone means local timezone", for example, rather than UTC like it is now).

		Linus