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 2969A21F31 for ; Mon, 25 Mar 2024 20:38:07 +0100 (CET) Received: (qmail 1383 invoked by uid 550); 25 Mar 2024 19:33:21 -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 1342 invoked from network); 25 Mar 2024 19:33:21 -0000 Date: Mon, 25 Mar 2024 15:38:13 -0400 From: Rich Felker To: Alexander Weps Cc: musl@lists.openwall.com Message-ID: <20240325193813.GH4163@brightrain.aerifal.cx> References: <20240324192258.GY4163@brightrain.aerifal.cx> <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4-8Ne4x6ZXfJmyaJ2YBFpLfCYySv9--JLQJl9OcSwaKyCashDhJXsqAPuh7G8QYwQpn2JnjUJxfZX8t9Fo101Mg_6rwb_MpmbRhFRUpYoz8=@pm.me> 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 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. 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. Rich > On Monday, March 25th, 2024 at 19:53, Rich Felker wrote: > > > On Mon, Mar 25, 2024 at 06:28:14PM +0000, Alexander Weps wrote: > > > > > On Monday, March 25th, 2024 at 19:02, Rich Felker dalias@libc.org wrote: > > > > > > > On Mon, Mar 25, 2024 at 09:42:53AM -0400, Rich Felker wrote: > > > > > > > > > On Mon, Mar 25, 2024 at 01:24:57PM +0000, Alexander Weps wrote: > > > > > > > > > > > See below. > > > > > > > > > > > > AW > > > > > > > > > > > > On Monday, March 25th, 2024 at 14:13, Rich Felker dalias@libc.org wrote: > > > > > > > > > > > > > On Mon, Mar 25, 2024 at 12:55:28PM +0000, Alexander Weps wrote: > > > > > > > > > > > > > > > > If you take your test program and switch it to initialize with > > > > > > > > > tm_mday=31, then do -=1 instead of +=1, you'll find that it gives > > > > > > > > > 2011-12-29 01:00:00 -10 as well, only now it seems like the correct, > > > > > > > > > expected thing to happen. Any change to "fix" the case you're > > > > > > > > > complaining about would necessarily break this case. > > > > > > > > > > > > > > > > So (- day, +day): > > > > > > > > > > > > > > > > Musl: > > > > > > > > 2011-12-31 01:00:00 +14 > > > > > > > > 2011-12-29 01:00:00 -10 > > > > > > > > 2011-12-29 01:00:00 -10 > > > > > > > > > > > > > > > > Glibc: > > > > > > > > 2012-01-01 01:00:00 +14 > > > > > > > > 2011-12-31 01:00:00 +14 > > > > > > > > 2012-01-01 01:00:00 +14 > > > > > > > > > > > > > > > > Seems like musl doesn't even interpret the initial struct tm > > > > > > > > correctly in that case. It is off by day. > > > > > > > > > > > > > > > > Because December only had 30 days, 31s day after normalization is > > > > > > > > January 1st. > > > > > > > > > > > > > > This is nonsense. December has a day 31, which you can clearly see > > > > > > > from the glibc output. For this particular year in this zone, with the > > > > > > > zone rule change, there are "only 30 days" in December, but they are > > > > > > > numbered 1-29 and 31, not 1-30. > > > > > > > > > > > > You confuse day of month which is represented in tm_mday with > > > > > > calendar day that is interpreted by strftime. > > > > > > > > > > > > You said to set tm_mday = 31, which would be January 1st after normalization. > > > > > > December 31s is 30th day of month represented as tm_mday = 30. > > > > > > > > > > OK, I meant tm_mday=31-1. > > > > > > > > Um, no, where did you get that idea? I just assumed you were right > > > > because I always forget which tm_* are off-by-1, but tm_mday is > > > > one-based not zero-based: > > > > > > > > int tm_mday; // day of the month -- [1, 31] > > > > > > > > (per the standard). So how did you end up getting the wrong thing? Are > > > > you even running the code you say you are? > > > > > > I have to sincerely ask if you are feeling ok? > > > You seem not able to follow this conversation. > > > > > > What idea do you mean? > > > Also you have the codes. You can like "I don't know" run them yourself? > > > You question I run those codes without trying to run them yourself? Again?! > > > What is going on? > > > > > > The first few pieces of code you posted did not work because they > > depended on other code you did not include, so I stopped trying to run > > them. > > > > > Maybe I reiterate some basic facts for you and that will put you > > > back on track. > > > > > > This was an example from an article provided earlier in this thread (by somebody). > > > We are in TZ=Pacific/Apia. > > > The 30th December was skipped in 2011. There was no December 30th. > > > So, there were only 30 days in December. > > > 30th day of the month December was December 31st. > > > > > > And run those examples yourself. I have no idea why I am being > > > questioned if they generate the output when you can easily verify it > > > yourself. > > > > > > Which piece of self-contained, actually-runnable code would you like > > me to look at that demonstrates something wrong? (i.e. not something I > > have already said is behaving as expected)