From roland@gnu.ai.mit.edu Sat May 15 18:14:48 1993 Return-Path: <roland@gnu.ai.mit.edu> Received: from churchy.gnu.ai.mit.edu by elsie.nci.nih.gov (4.1/SMI-4.1) id AA22472; Sat, 15 May 93 18:14:34 EDT Received: by churchy.gnu.ai.mit.edu (5.65/4.0) id <AA21556@churchy.gnu.ai.mit.edu>; Sat, 15 May 93 18:14:01 -0400 Date: Sat, 15 May 93 18:14:01 -0400 From: roland@gnu.ai.mit.edu (Roland McGrath) Message-Id: <9305152214.AA21556@churchy.gnu.ai.mit.edu> To: eggert@twinsun.com Cc: libc-alpha@gnu.ai.mit.edu, tz@elsie.nci.nih.gov Subject: Re: A brief history of (and agenda for) time zone libraries In-Reply-To: Paul Eggert's message of Sat, 15 May 93 00:08:44 PDT <9305150708.AA18312@bi.twinsun.com> X-Shopping-List: (1) Hot mutant holidays (2) Apologetic interruptions (3) Frenetic lesions

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Olson's 1989 code.

The original timezone code was written by Arthur David Olson. This public domain code has a good reputation. Even the Posix standard comes as close as a standard can to saying ``This is good stuff -- check it out!''; see Posix 1003.1-1990 section B.8.1.1, lines 4195-4201. The most famous publication of Olson's code was in comp.sources.unix 18, 111-117 (19 April 1989) -- see ftp.uu.net:/usenet/comp.sources.unix/volume18/localtime3/*.

I wish I had known that this code was being maintained, and where to get it from, before now.

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Proposal.

Olson's changes should be propagated into both Linux and the GNU C library.

Indeed. Linux is not my concern, but I plan to update glibc today.

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The GNU C library changes fall into two categories: (A) changes to Olson's localtime.c, and (B) everything else. Merging (B) is easy, almost as easy as merging the Linux timezone code, and I've already submitted patches to the GNU C library developers to do this. Merging (A) is harder, since the GNU C library has split up localtime.c into lots of little pieces. The GNU C library changes generally improve Olson's code -- they make the module interfaces cleaner, and the code is easier to follow.

These issues are very important to the GNU project, and to me.

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Unfortunately, it is now hard to tell how to propagate Olson's localtime.c changes and improvements into the GNU C library. The best person to do this propagation is the person who split up localtime.c in the first place.

I am that person, and I plan to do the work.

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Another possibility is for the GNU C library to switch to a version of localtime.c that is as close as possible to Olson's latest version; that might simplify future maintenance.

I really don't want to do this. It took me quite a while to untangle the spaghetti in the first place. This would certainly not simplify maintenance of the glibc code; it would return it to the obfuscated spaghetti I started with. Having the code be modular and clean simplifies maintenance for me. Using code close Olsen's code only simplifies future merging with Olsen's code.