The following Usenet article describes a extension to Posix TZ strings that allows the strings to express the daylight savings time rules currently used in Britain. At the end of this message is a patch to the tz package that adds support for this extension. This patch also fixes a theoretical leap second problem with Posix TZ strings. But looking at the code, I suspect that leap seconds don't work at all with Posix TZ strings; perhaps this is intentional? Newsgroups: comp.unix.unixware From: jjf@dsbc.icl.co.uk (J J Farrell) Subject: Re: Daylight saving time in UW1.1 Message-ID: <CpCvnG.7Dy@dsbc.icl.co.uk> Organization: International Computers Limited References: <767043120.AA04204@cswamp.apana.org.au> <Cp9x6n.7uB@novell.co.uk> Date: Fri, 6 May 1994 00:50:03 GMT In article <Cp9x6n.7uB@novell.co.uk> msohnius@novell.co.uk (Martin Sohnius) writes: > UnixWare supports two different styles of timezone handling. > > One is what I may call "System V" style, with the TZ environment > variable as described in environ(5). It might be better described as "Standard" style - it's been specified by X/Open for many years, and I think Posix is the same. > Note also that the October rule for many parts of Australia > ("next-to-last Sunday in October") cannot be implemented with the > "System V" style TZ. (NB nor can the British rule, > "day after 4th Saturday in October"). I'm not sure about the Australian ones, but the British rule can be done in "System V" style TZ. The following works on SVR4 systems and has been issued by ICL for several years: GMT0BST,M3.5.0/1,M10.4.6/26 I've not looked up the wording in the SVR4 documentation, but this does break the wording in XPG3; they may have loosened the wording in XPG4, but I haven't checked. It is probably a bug that this works, but bugs can sometimes be useful! My opinions; I do not speak for my employer. =================================================================== RCS file: RCS/localtime.c,v retrieving revision 1994.6.1.2 retrieving revision 1994.6.1.3 diff -c -r1994.6.1.2 -r1994.6.1.3 *** localtime.c 1994/05/09 10:16:11 1994.6.1.2 --- localtime.c 1994/05/09 10:22:51 1994.6.1.3 *************** *** 414,423 **** { int num; ! strp = getnum(strp, &num, 0, HOURSPERDAY); if (strp == NULL) return NULL; ! *secsp = num * SECSPERHOUR; if (*strp == ':') { ++strp; strp = getnum(strp, &num, 0, MINSPERHOUR - 1); --- 414,429 ---- { int num; ! /* ! ** `HOURSPERDAY * DAYSPERWEEK - 1' allows quasi-Posix rules like ! ** "M10.4.6/26", which does not conform to Posix, ! ** but which specifies the equivalent of ! ** ``02:00 on the first Sunday on or after 23 Oct''. ! */ ! strp = getnum(strp, &num, 0, HOURSPERDAY * DAYSPERWEEK - 1); if (strp == NULL) return NULL; ! *secsp = num * (long) SECSPERHOUR; if (*strp == ':') { ++strp; strp = getnum(strp, &num, 0, MINSPERHOUR - 1); *************** *** 426,432 **** *secsp += num * SECSPERMIN; if (*strp == ':') { ++strp; ! strp = getnum(strp, &num, 0, SECSPERMIN - 1); if (strp == NULL) return NULL; *secsp += num; --- 432,439 ---- *secsp += num * SECSPERMIN; if (*strp == ':') { ++strp; ! /* `SECSPERMIN' allows for leap seconds. */ ! strp = getnum(strp, &num, 0, SECSPERMIN); if (strp == NULL) return NULL; *secsp += num;