From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL autolearn=ham autolearn_force=no version=3.4.4 Received: from second.openwall.net (second.openwall.net [193.110.157.125]) by inbox.vuxu.org (Postfix) with SMTP id 685442279D for ; Mon, 25 Mar 2024 20:47:31 +0100 (CET) Received: (qmail 17743 invoked by uid 550); 25 Mar 2024 19:42:45 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 17587 invoked from network); 25 Mar 2024 19:42:36 -0000 Date: Mon, 25 Mar 2024 15:47:25 -0400 From: Rich Felker To: Alexander Weps Cc: musl@lists.openwall.com Message-ID: <20240325194725.GI4163@brightrain.aerifal.cx> References: <20240325122113.GB4163@brightrain.aerifal.cx> <20240325131318.GD4163@brightrain.aerifal.cx> <20240325134252.GE4163@brightrain.aerifal.cx> <20240325180208.GF4163@brightrain.aerifal.cx> <20240325185339.GG4163@brightrain.aerifal.cx> <4-8Ne4x6ZXfJmyaJ2YBFpLfCYySv9--JLQJl9OcSwaKyCashDhJXsqAPuh7G8QYwQpn2JnjUJxfZX8t9Fo101Mg_6rwb_MpmbRhFRUpYoz8=@pm.me> <20240325193813.GH4163@brightrain.aerifal.cx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240325193813.GH4163@brightrain.aerifal.cx> User-Agent: Mutt/1.5.21 (2010-09-15) Subject: Re: [musl] Broken mktime calculations when crossing DST boundary On Mon, Mar 25, 2024 at 03:38:13PM -0400, Rich Felker wrote: > On Mon, Mar 25, 2024 at 06:57:49PM +0000, Alexander Weps wrote: > > I am not sure which one you mean, all latest codes even includes > > headers and main... > > https://www.openwall.com/lists/musl/2024/03/25/3 > > > I have no idea what to tell you. > > The first version I found that's actually compilable is: > > https://www.openwall.com/lists/musl/2024/03/25/11 > > It roughly behaves as expected on musl, except possibly not applying > the tm_isdst=0, which is what was making the output confusing on > glibc -- that threw the input back across the rule change cutoff. No, it's deeper than this. glibc is offsetting the input by an entire day when tm_isdst=0, and I don't know why. It looks like a bug in glibc. > With tm_isdst=1 and tm_mday=31, on glibc, I get: > > before: 2011-12-31 00:00:00 WSDT 0 > after1: 2011-12-31 00:00:00 WSDT 1325239200 > after2: 2011-12-30 00:00:00 WSDT -1 > after3: 2011-12-31 00:00:00 WSDT 1325239200 > > The -1 in the after2 line indicates that mktime failed with an error > (and should not have modified tm; that's arguably a bug in glibc). The > partial modification that it made reflects the initial normalization > (type 1 in my notation) but not the rule change normalization (type 2 > in my notation) since glibc has failed the operation for an input date > that does not exist on the calendar (it does not do type 2 > normalization at all; it just rejects it). > > Running this same change on musl, I get: > > before: 2011-12-31 00:00:00 0 > after1: 2011-12-31 00:00:00 +14 1325239200 > after2: 2011-12-29 00:00:00 -10 1325152800 > after3: 2011-12-29 00:00:00 -10 1325152800 > > which again is what I expect. From one side, the move-by-1-day changes > the time to the next calendar day in that direction. From the other > side, it's unable to change it. > > I'll look into why the tm_isdst=0 application was not happening. Hmm, I must have misread the output. It seems to be correct with tm_isdst=0 too: before: 2011-12-31 00:00:00 0 after1: 2011-12-31 01:00:00 +14 1325242800 after2: 2011-12-29 01:00:00 -10 1325156400 after3: 2011-12-29 01:00:00 -10 1325156400 (If it's 00:00:00 in standard time, it's 01:00:00 in DST, so the initial time seems to have been interpreted correctly.) I also went back and tested both with tm_isdst=-1, and both glibc and musl do the same thing as they do with tm_isdst=1 (which is correct). Rich