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=-2.8 required=5.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 487262232F for ; Mon, 25 Mar 2024 14:45:15 +0100 (CET) Received: (qmail 27681 invoked by uid 550); 25 Mar 2024 13:40:30 -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 27649 invoked from network); 25 Mar 2024 13:40:29 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pm.me; s=protonmail3; t=1711374302; x=1711633502; bh=N5jGTjc02v6ApyVjJ/g4ZJPS4yTzbg59GQssKX36KSc=; h=Date:To:From:Cc:Subject:Message-ID:In-Reply-To:References: Feedback-ID:From:To:Cc:Date:Subject:Reply-To:Feedback-ID: Message-ID:BIMI-Selector; b=bz7sWr2F1IRHBNIRuVk0et0lOf9+UWgWU2jYvD2l66PuqHEhLEcKFI+8u6nNDx1Rx 57PHJvTBsbKiTWf3W9lPjpEu8jC+bwmn7UK0YuoW3mVdLlrDT8qP7u4AkW5ab7vuwq qBfu7VyN+ktB6SCdoxSZKrwclfI/LpGdHyohpUfax7bhjoTU7X7WBh/Gn4Uri6h3FU mm5237rFiwR6Fb68uJrJtL4nttE1880rnJOPOxddOpYhot3cqMoDjDj32dtQNlhIAn DCFX54TrfQ4mJ7LFYaPrddGuL7aIJ+/zM77VFewioXTgrK+S9pjEugLyag3QQvb5Pz wa414bY5bzvUQ== Date: Mon, 25 Mar 2024 13:44:57 +0000 To: Rich Felker From: Alexander Weps Cc: musl@lists.openwall.com Message-ID: <7RSpN12xzL2-U16pTCJqpy9JLwjl4wbnT-YbJ8jbFGQRp7FfUposZOQ4RIFQw2vTrWDKkYhTPbjdPCmZH-_uCLQUU2Nubvp5wkaGKqai_yo=@pm.me> In-Reply-To: References: <20240324192258.GY4163@brightrain.aerifal.cx> <-svm5EdX4OFN9hKzgS2FP6N1lgUGjT7edQONkAfCywgsRitwT6Vw22W3sUUGY_pnKGIXBKlujMZhPCDkJAMCYbBA5uF-IYgzhj8WB0wBE-A=@pm.me> <4YlR0YRqzZlDIOVv6SP8UDoop89n8u7BvQl_7eXNTvDZnogXMxG1z-TLGIBf-O4edUphddXGfADbk_d7Uzb37g5JoH7vOIvvNRMFDxPWZok=@pm.me> <20240325122113.GB4163@brightrain.aerifal.cx> <20240325131318.GD4163@brightrain.aerifal.cx> Feedback-ID: 20507743:user:proton MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [musl] Broken mktime calculations when crossing DST boundary > > What did you do that got glibc to output 2012-01-01? I guess you wrote > code to do some wacky arithmetic after the original code you already > had, rather than changing the code to start with 2011-12-31 as I > suggested to get a look at what's happening. > To address this. I would appreciate you not to lie or make some nonsense up= . There was only change related to calculations in the code and it was a chan= ge you requested: tm.tm_mday =3D 31; Complete code to run: #include #include #include void test10() { time_t t =3D 0; struct tm tm =3D {0}; char buf[64]; tm.tm_year =3D 2011 - 1900; tm.tm_mon =3D 12 - 1; tm.tm_mday =3D 31; // <-- here is the change tm.tm_hour =3D 0; tm.tm_min =3D 0; tm.tm_sec =3D 0; tm.tm_isdst =3D 0; strftime(buf, sizeof buf, "%F %T %Z", &tm); printf("before: %s %ld\n", buf, t); t =3D mktime(&tm); strftime(buf, sizeof buf, "%F %T %Z", &tm); printf("after1: %s %ld\n", buf, t); tm.tm_mday -=3D 1; t =3D mktime(&tm); strftime(buf, sizeof buf, "%F %T %Z", &tm); printf("after2: %s %ld\n", buf, t); tm.tm_mday +=3D 1; t =3D mktime(&tm); strftime(buf, sizeof buf, "%F %T %Z", &tm); printf("after3: %s %ld\n", buf, t); } int main(int argc, char *argv[]) { test10(); return 0; } $ musl-gcc foo.c -o foo && TZ=3DPacific/Apia ./foo before: 2011-12-31 00:00:00 0 <-- before first mktime call to verify after1: 2011-12-31 01:00:00 +14 1325242800 <-- mktime to normalize after2: 2011-12-29 01:00:00 -10 1325156400 <-- -day & mktime after3: 2011-12-29 01:00:00 -10 1325156400 <-- +day & mktime $ gcc foo.c -o foo && TZ=3DPacific/Apia ./foo before: 2011-12-31 00:00:00 +13 0 <-- before first mktime call to verify after1: 2012-01-01 01:00:00 +14 1325329200 <-- mktime to normalize after2: 2011-12-31 01:00:00 +14 1325242800 <-- -day & mktime after3: 2012-01-01 01:00:00 +14 1325329200 <-- +day & mktime So this is a bug in struct tm interpretation. AW On Monday, March 25th, 2024 at 14:24, Alexander Weps wrot= e: > 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=3D31, then do -=3D1 instead of +=3D1, you'll find that it g= ives > > > > 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 da= y that is interpreted by strftime. > > You said to set tm_mday =3D 31, which would be January 1st after normaliz= ation. > December 31s is 30th day of month represented as tm_mday =3D 30. > > > What did you do that got glibc to output 2012-01-01? I guess you wrote > > code to do some wacky arithmetic after the original code you already > > had, rather than changing the code to start with 2011-12-31 as I > > suggested to get a look at what's happening. > > > > > > In any case, the core issue you're hitting here is that time zones = are > > > > HARD to work with and that there is inherent complexity that libc > > > > cannot save you from. You only got lucky that what you were trying = to > > > > do "worked" with glibc because you were iterating days forward; if = you > > > > were doing reverse, it would break exactly the same way. > > > > > > I am not really commenting on this, until you sort out the above > > > inconsistencies. > > > > I already have but you refuse to look. > > > It was addressed, do didn't scroll at the end of the e-mail. > > > Rich