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Re: Ballot 4 - results (really POSIX / X3J11 relationship)
by seismo!cbpavo.MIS.OH.ATT.COM!mark May 3, 1987

May 3, 1987

I thought the idea behind POSIX requiring X3J11 was that it eliminated duplication (and possible conflict) between X3J11 and POSIX. If POSIX isn't going to require X3J11, what will they overlay upon? K&R is the only other well known standard, and it's not only incredibly old, but the C library it documents is very incomplete even by 1978 standards. (I have a table I can send out if people are interested.) A lot of stuff was taken out of the /usr/group document because it was already in X3J11; does P.1003 really want to put all that stuff back in? Mark

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Re: Ballot 4 - results (really POSIX / X3J11 relationship)
by seismo!hadron!jsdy May 3, 1987

May 3, 1987

To prevent runaway definitional anarchy, if POSIX includes some C language interface definitions, then oneof(X3J11,POSIX) should defer to the other. I think that POSIX deferring to X3J11 is natural, and should be done unless X3J11 gets really out of hand. Which I don't really think has happened yet. Joe

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Re: Ballot 4 - results
by seismo!hadron!jsdy May 3, 1987

May 3, 1987

> I was just rereading ANSI C X3J11 and noticed that strftime and mktime > are in there. Since POSIX is a superset (by definition) of ANSI C, I should mention that even though X3J11 isn't final, and POSIX is co-operating strongly with (but not subservient to) X3J11, I wish to alter my ballot to support whatever is in X3J11, since it is or will be (it seems) the standard issued first (of the two). Joe Yao jsdy(a)hadron.COM (not yet domainised) hadron!jsdy(a){seismo.CSS.GOV,dtix.ARPA,decuac.DEC.COM} {arinc,att,avatar,cos,decuac,dtix,ecogong,kcwc}!hadron!jsdy {netex,netxcom,rlgvax,seismo,smsdpg,sundc}!hadron!jsdy

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Re: Ballot 4 - results
by seismo!hadron!jsdy May 3, 1987

May 3, 1987

> POSIX will have strftime and mktime, it isn't an option. X3J11 is still a draft standard: it will go through (I hear tell) at least one more edit-RFC cycle. > Personally, I think strftime botches timezones - "hours" doesn't say > which time zone. Why, nor does ctime() at all, nor System V date. But there is, in the X3J11 strftime(), a %Z for the time zone. [ 10 Oct 1986 ] Joe Yao jsdy(a)hadron.COM (not yet domainised) hadron!jsdy(a){seismo.CSS.GOV,dtix.ARPA,decuac.DEC.COM} {arinc,att,avatar,cos,decuac,dtix,ecogong,kcwc}!hadron!jsdy {netex,netxcom,rlgvax,seismo,smsdpg,sundc}!hadron!jsdy

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Re: Ballot 4 - results
by seismo!meccts.mecc.mn.org!ahby May 2, 1987

May 2, 1987

> I was just rereading ANSI C X3J11 and noticed that strftime and mktime > are in there. Since POSIX is a superset (by definition) of ANSI C, > POSIX will have strftime and mktime, it isn't an option. Actually, at the working group meeting last week, we changed the definition of POSIX a little bit. X/OPEN had some reservations about POSIX requiring X3J11, because it would increase the time before there could be conforming systems. Also, a number of people from different implementors felt that when their companies had signed onto the POSIX concept, they had not necessarily bought into X3. These same people also said that they were planning on providing an X3 conforming environment, but not in the same timeframe as POSIX. As a result of these discussions, we redefined the terms CONFORMING APPLICATION and CONFORMING PORTABLE APPLICATION. The new names are PORTABLE APPLICATION USING EXTENSIONS and POSIX CONFORMING <language> APPLICATION. The text of these definitions is: Portable Application Using Extensions A Portable Application Using Extensions shall meet the following requirements: All extensions beyond those permitted to a Posix Conforming Language Application and the corresponding language shall be clearly documented. The application developer documents all application requirements for the operating environment that are implementation dependent including <limits.h> S2.9 characteristics and other related configuration requirements (linear address space, file store requirements, etc.) POSIX Conforming Applications POSIX Conforming Standard C Language Application A POSIX Conforming Standard C Language Application is a strictly conforming program, as defined in the ANSI/X3.159-198x standard, which utilizes only those extensions as described by the service bindings in this standard. In addition, a POSIX Conforming Standard C Language Application shall not depend on any unspecified, undefined, or implementation defined behavior, nor shall it require that any symbolic constant in <limits.h> S2.9 be outside its most restrictive value. As a result of these changes, it is possible to have a Conforming Implementation of POSIX that does not supply an X3 conforming environment. What environment it does provide is unspecified at this time, but the P1003.1 Working Group expects to see something from X/OPEN about a K&R C Language binding, which uses the X/OPEN Portability Guide as the basis for the C Language and its libraries. The unfortunate implication of all this is that strftime and friends are not really required by the POSIX standard. And since the POSIX Working Group decided at the December meeteing to defer to X3 in all things relating to time, the issue is a bit confused. -- Shane P. McCarron UUCP ihnp4!meccts!ahby, ahby(a)MECC.MN.ORG MECC Technical Services ATT (612) 481-3589 Secretary, IEEE P1003.1

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Re: X3J11
by seismo!cbpavo.MIS.OH.ATT.COM!mark May 1, 1987

May 1, 1987

> Ignoring the coding and grammar errors in the Rationale, > the big problem here is that code like the Rationale's > > when = *localtime(now); > when.tm_hour += 1; > deadline = mktime(when); > > printf("Loop will finish: %s\n", asctime(when)); > while (difftime(time(0), deadline) > 0) whatever(); > > is *not* "a paradigm for continuing some loop for an hour." > The code may continue for two hours (or not at all) > if it is executed just before a daylight saving time transition. How? deadline is a time_t (GMT) and so is time(0). Mark

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Re: X3J11
by ado May 1, 1987

May 1, 1987

> > . . .the big problem here is that code like the Rationale's > > > > when = *localtime(now); > > when.tm_hour += 1; > > deadline = mktime(when); > > > > printf("Loop will finish: %s\n", asctime(when)); > > while (difftime(time(0), deadline) > 0) whatever(); > > > > is *not* "a paradigm for continuing some loop for an hour." > > The code may continue for two hours (or not at all) > > if it is executed just before a daylight saving time transition. > How? deadline is a time_t (GMT) and so is time(0). (I hope I don't end up with egg all over my face on this one!) First, assume that it's 1:30:00 a.m. on a "spring forward" day when we execute the when = *localtime(now); statement. We next do a when.tm_hour += 1; which sets when.tm_hour to 2. We then execute the deadline = mktime(when); statement to answer the question "At what elapsed time in seconds since 1970 will my wall clock read 2:30 a.m.?" Since mktime knows we're springing forward, it returns -1 as a way of saying "There is no such time today." This means that the test in the while (difftime(time(0), deadline) > 0) whatever(); line will *always* succeed--so "whatever" will never be called. (Side questions: does this say anything about whether time_t should be signed? Does it say anything about extra checking difftime should do?) Now assume that it's 1:30:00 a.m. (for the first time :-) on a "fall back" day when we execute the when = *localtime(now); statement. Again we when.tm_hour += 1; deadline = mktime(when); to learn when our local wall clock will read 2:30 a.m. But that won't be until two hours from "now", so the loop will run twice as long as we might expect. --ado

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Re: testing
by seismo!!dlm May 1, 1987

May 1, 1987

Yes, I am there I haven't seen or heard a word from the Time Mailing List in weeks! My mail address is {ihnp4,cbosgd,attunix,cbatt}!cuuxb!dlm. Maybe we're not polling cbosgd or cbatt but I thought so. -- =Dennis L. Mumaugh Lisle, IL ...!{ihnp4,cbosgd,lll-crg}!cuuxb!dlm

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mixed signed/unsigned systems; missing person; archives!?
by ado April 30, 1987

April 30, 1987

A while back I asked for ideas on how to set up time zone information files that could be shared (NFSwise, RFSwise, or otherwise) by machines that used signed time_t values (SVR2, BSD) and machines that used unsigned time_t values (those under Robert Elz's oversight, for example). Thanks to Chris Torek for pointing out the easy fix: limit the years that the file covers so that the only values filed are those for which it doesn't matter whether you interpret them to be signed or unsigned (values from 0 to 0x7fffffff on a VAX). I've added a few lines to the time zone compiler to do this; anyone interested in the lines should let me know. Missing persons department: Francisco Franco is still dead; Dennis Mumaugh is still missing. If you have a new address for either one, let me know. Astonishingly (to me, at least) I got a request for the mailing list "archives" today. So I bundled those letters that I had saved and sent them to the person making the request; I trust that there's not too much missing. And I've arranged for new items to be added to the archive automatically. All of which is a long way of saying that "time zone archives are available." (And of saying that "whenever you join a mailing list being handled by a novice mailing list handler, advise them to keep archives.") -- UUCP: ..seismo!elsie!ado ARPA: elsie!ado(a)seismo.CSS.GOV Elsie and Ado are trademarks of Borden, Inc. and Ampex.

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Re: Ballot 4 - results
by seismo!cbpavo.MIS.OH.ATT.COM!mark April 30, 1987

April 30, 1987

I was just rereading ANSI C X3J11 and noticed that strftime and mktime are in there. Since POSIX is a superset (by definition) of ANSI C, POSIX will have strftime and mktime, it isn't an option. Personally, I think strftime botches timezones - "hours" doesn't say which time zone. X3J11 says it's OK for gmtime to return NULL at run time if the operating system doesn't keep track of time zones! (Personally I'm a little tired of the timezone nonsense in MS DOS; some programs assume the clock/cal is GMT (those that use Microsoft C) and others local, so I have to set the TZ to EST0EDT to get all programs to work. Mark

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