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Request to mailing list Lesstif rejected
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July 29, 2004

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RE: asctime.c
by Olson, Arthur David (NIH/NCI) July 28, 2004

July 28, 2004

snprintf's behavior is to return the number of characters that would have been generated had the output buffer not been limited. That being true, I think the asctime.c below does what Paul intended. Does anyone see problems with using this in the next bundle? --ado /* ** This file is in the public domain, so clarified as of ** 1996-06-05 by Arthur David Olson (arthur_david_olson(a)nih.gov) */ #ifndef lint #ifndef NOID static char elsieid[] = "@(#)asctime.c 7.13"; #endif /* !defined NOID */ #endif /* !defined lint */ /*LINTLIBRARY*/ #include "private.h" #include "tzfile.h" #define STANDARD_BUFFER_SIZE 26 /* ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. */ char * asctime_r(timeptr, buf) register const struct tm * timeptr; char * buf; { static const char wday_name[][3] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" }; static const char mon_name[][3] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" }; register const char * wn; register const char * mn; register int result; if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK) wn = "???"; else wn = wday_name[timeptr->tm_wday]; if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR) mn = "???"; else mn = mon_name[timeptr->tm_mon]; /* ** The format used in the (2004) standard is ** "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n" ** Use "%02d", as it is a bit more portable than "%.2d". */ result = snprintf(buf, STANDARD_BUFFER_SIZE, "%.3s %.3s%3d %02d:%02d:%02d %ld\n", wn, mn, timeptr->tm_mday, timeptr->tm_hour, timeptr->tm_min, timeptr->tm_sec, timeptr->tm_year + (long) TM_YEAR_BASE); if (result < 0 || result >= STANDARD_BUFFER_SIZE) { errno = EOVERFLOW; return NULL; } return buf; } /* ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition, ** with core dump avoidance. */ char * asctime(timeptr) register const struct tm * timeptr; { static char result[STANDARD_BUFFER_SIZE]; return asctime_r(timeptr, result); }

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FW: asctime.c
by Olson, Arthur David (NIH/NCI) July 28, 2004

July 28, 2004

-----Original Message----- From: Robert Elz [mailto:kre@munnari.OZ.AU] Sent: Tuesday, July 27, 2004 5:24 AM To: Paul Eggert Cc: Olson, Arthur David (NIH/NCI); Tz Subject: Re: asctime.c Date: Tue, 27 Jul 2004 00:37:12 -0700 From: Paul Eggert <eggert(a)CS.UCLA.EDU> Message-ID: <87zn5lew9j.fsf(a)penguin.cs.ucla.edu> None of my messages (these days) ever make it to the list - I suspect some absurd anti-spam "protection" killing all of my mail. But never mind that for now. | /* | ** The format used in the (2004) standard is | ** "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n" | ** Use "%02d", as it is a bit more portable than "%.2d". | */ The most postable format is %02.2d - that works on every printf I've ever seen that has any method to make a 2 column zero-filled numeric field. Nothing else works on everything (the %02d version is original Research unix/BSD variants, the %.2d version is original Sys III type stuff I think - for a 2 character field, it probably doesn't matter, except possibly for the value 0 (where a system that likes %.2d might produce just " 0" if given %02d - the "0" in the format (SysIII variant) requires a leading 0 in the result, or something like that, so for 1, you should get 01, but for 0 ...) | result = snprintf(buf, STANDARD_BUFFER_SIZE, | "%.3s %.3s%3d %02d:%02d:%02d %ld\n", Please make that %4ld - it never mattered before, because the year was always between 1900 and 21xx, so there were always 4 digits anyway. But now if you're going to allow for year 10, etc, that 4 digit field needs to be forced to be 4 characters wide. It really is supposed to be that, not just "the rest of the line". The \n should be in buf[25] and absolutely nowhere else (for correct historical compatibility). That is, doing buf[25] = '\0'; to the result of asctime() is the "time honoured" way of printing the result without the trailing \n (that or using "%.24s" which amounts to the same thing). kre

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RE: asctime.c
by Olson, Arthur David (NIH/NCI) July 28, 2004

July 28, 2004

> But the C standard says that sometimes fewer bytes of output must be generated (in particular, if the year is in the range -99 through 999)... What I find at http://www.opengroup.org/onlinepubs/009695399/functions/asctime.html (you may have to register via http://www.unix-systems.org/version3/iso_std.html to access the above, and your URLage may vary) is this text: The asctime() function shall convert the broken-down time in the structure pointed to by timeptr into a string in the form: Sun Sep 16 01:03:52 1973\n\0 using the equivalent of the following algorithm: char *asctime(const struct tm *timeptr) { static char wday_name[7][3] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" }; static char mon_name[12][3] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" }; static char result[26]; sprintf(result, "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n", wday_name[timeptr->tm_wday], mon_name[timeptr->tm_mon], timeptr->tm_mday, timeptr->tm_hour, timeptr->tm_min, timeptr->tm_sec, 1900 + timeptr->tm_year); return result; } That last "%d" in the sprintf would indeed produce less than four digits of year output in some cases. Of course we might also take the above as meaning that it's mandatory for asctime to overflow a buffer (and potentially dump core) for other cases (take tm_year >= 10000, please). Sidebar: I believe kre is proposing padding with spaces rather than zeroes. --ado

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RE: asctime.c
by Olson, Arthur David (NIH/NCI) July 27, 2004

July 27, 2004

From: Robert Elz [mailto:kre@munnari.OZ.AU] Sent: Tuesday, July 27, 2004 11:49 AM To: Olson, Arthur David (NIH/NCI) Cc: Tz Subject: Re: asctime.c ... | /* | ** Big enough for something such as | ** ??? ???-2147483648 -2147483648:-2147483648:-2147483648 | -2147483648\n | ** (two three-character abbreviations, five strings denoting | integers, | ** three explicit spaces, two explicit colons, a newline, | ** and a trailing ASCII nul). | */ | char result[2 * 3 + 5 * INT_STRLEN_MAXIMUM(int) + | 3 + 2 + 1 + 1]; > That buffer is big enough for that string, but are we sure that string > is the longest that can ever happen? The year is after all printed > using %ld - so there must at least be the potential for that one to be a long, which might be -9223372036854775808. > Beyond that, C doesn't actually promise that "int" is limited to 32 > bits does it? Given that, the 2147483648 numbers are just speculation. We're using "INT_STRLEN_MAXIMUM(int)" to figure out how long the output for an integer value might be. The macro figures out the length based on "sizeof int", so even if an int is more than 32 bits things will come out right. While we're using a %ld format to print out out the year, what we're printing is the sum of an int (tm_year) and 1900 (TM_YEAR_BASE), so we know the result is int sized. --ado

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Where to download the database
by Craig Orput July 26, 2004

July 26, 2004

Your site is very confusing to me. Where do I download the actual time zone database, in text version? Regards Craig Orput Vice President - Logistics Engineering OIA SCM 17230 NE Sacramento Street Portland, OR 97230 Office 503.872.8470 craig.orput(a)oiascm.com http://www.oiascm.com/

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Re: another attempt to change the clocks in the UK
by Peter Ilieve July 26, 2004

July 26, 2004

Back on 9 June when I mentioned Nigel Beard's Lighter Evenings Bill I wrote: > I haven't found the text of the Bill itself yet. It will probably > turn up on the Parliament website next week. It was finally published on Wednesday. PDF and HTML versions can be found at <http://www.publications.parliament.uk/pa/cm200304/cmbills/115/2004115.htm>. It is a short Bill of only four sections. It changes the time for general purposes to one hour in advance of GMT. It amends the Scotland Act 1998 to make time zones and summer time arrangements a devolved rather than a reserved matter, which will allow the Scottish parliament to keep Scotland on GMT if they so wish. It makes some amendments to the Summer Time Act 1972 which I presume are to allow Northern Ireland, the Channel Islands and the Isle of Man to do their own thing as well (I don't have a copy of the 1972 Act handy to check this). By pure coincidence a relative of mine works as a researcher for Nigel Beard and has spent the last couple of months working on this. What seems to have happened is that Nigel became convinced by the safety arguments for change and decided to do something about it. At this stage he didn't know about John Butterfill's `Extra Daylight' Bill or Lord Archer's similar measure that he introduced during his doomed campaign for London mayoral candidate. Finding all this out was left to his researcher. She produced a briefing which Nigel's ten minute rule speech was based on. In turn, she then passed the specification for the proposed change on to the parliamentary draughtsmen, who add the legalese so it will pass muster as a Bill. The next stage is the Bill's second reading, which is set for 15 October. This is where the first vote on the Bill will take place. If the vote is lost that's it. If it passes the Bill goes to the next, committee, stage. If you look at the Public Bill List on the Parliament website (<http://www.publications.parliament.uk/pa/cm/cmpblist/cmpblist.htm>) you will see that there are literally dozens of Bills down for second reading on 15 October. The second reading is supposed to be the first detailed consideration of a Bill. You can judge for yourselves what sort of scrutiny each of these dozens of Bills will get. My view remains that this Bill has almost no chance of becoming law. Ten minute rule Bills come even further down the pecking order than private members' Bills like John Butterfill's one, and his failed. Bills like this only really stand a chance if they have government support, as the government can give them parliamentary time. I have spoken to someone at the DTI (the department now dealing with time related stuff) and they told me that the government is not in favour of this change, as it would be disruptive to business, transport and tourism, particularly if the UK no longer used a single time zone. Peter Ilieve peter(a)aldie.co.uk

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Re: asctime.c
by Olson, Arthur David (NIH/NCI) July 23, 2004

July 23, 2004

Code in "asctime" such as... { long y; y = timeptr->tm_year + (long) TM_YEAR_BASE; if (y >= -999 && y <= 9999) (void) sprintf(buf, "%.3s %.3s%3d %02d:%02d:%02d %ld\n", wn, mn, timeptr->tm_mday, timeptr->tm_hour, timeptr->tm_min, timeptr->tm_sec, y); else (void) sprintf(buf, "%.3s %.3s%3d %ld\n", wn, mn, timeptr->tm_mday, y); } ...never returns NULL and never (when applied to a "struct tm" derived from a 64-bit time_t) overflows a 26-character buffer passed to asctime. It does lose time-of-day information in the distant past and distant future. --ado

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Asctime.c
by Olson, Arthur David (NIH/NCI) July 22, 2004

July 22, 2004

At the end of this message is a revised version of asctime.c. There are a couple of standard-related matters. 1. The POSIX standard calls for a struct tm that includes an "int tm_year" member. If time_t is 64 bits and int is 32 bits, tm_year won't be able to represent all the years associated with time_t values. Should the standard address this issue? 2. The standard reads... The asctime_r() function shall convert the broken-down time in the structure pointed to by tm into a string (of the same form as that returned by asctime()) that is placed in the user-supplied buffer pointed to by buf (which shall contain at least 26 bytes) and then return buf. ...but a 26-byte buffer won't be adequate if a five-digit (or more) year is involved. Should the standard address this issue? Should "asctime_r" assume that the fed-in buffer is at most 26 bytes and avoid overflowing it? --ado /* ** This file is in the public domain, so clarified as of ** 1996-06-05 by Arthur David Olson (arthur_david_olson(a)nih.gov) */ #ifndef lint #ifndef NOID static char elsieid[] = "@(#)asctime.c 7.11"; #endif /* !defined NOID */ #endif /* !defined lint */ /*LINTLIBRARY*/ #include "private.h" #include "tzfile.h" /* ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. */ char * asctime_r(timeptr, buf) register const struct tm * timeptr; char * buf; { static const char wday_name[][3] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" }; static const char mon_name[][3] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" }; register const char * wn; register const char * mn; if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK) wn = "???"; else wn = wday_name[timeptr->tm_wday]; if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR) mn = "???"; else mn = mon_name[timeptr->tm_mon]; /* ** The format used in the (2004) standard is ** "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n" ** Use "%02d", as it is a bit more portable than "%.2d". ** Drop each .3 since they're superfluous given how we set wn and mn. */ (void) sprintf(buf, "%s %s%3d %02d:%02d:%02d %ld\n", wn, mn, timeptr->tm_mday, timeptr->tm_hour, timeptr->tm_min, timeptr->tm_sec, timeptr->tm_year + (long) TM_YEAR_BASE); return buf; } /* ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition, ** with core dump avoidance. */ char * asctime(timeptr) register const struct tm * timeptr; { /* ** Big enough for something such as ** ??? ???-2147483648 -2147483648:-2147483648:-2147483648 -2147483648\n ** (two three-character abbreviations, five strings denoting integers, ** three explicit spaces, two explicit colons, a newline, ** and a trailing ASCII nul). */ static char result[3 * 2 + 5 * INT_STRLEN_MAXIMUM(int) + 3 + 2 + 1 + 1]; return asctime_r(timeptr, result); }

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FW: Definition of time_t changed from signed to unsigned...
by Olson, Arthur David (NIH/NCI) July 20, 2004

July 20, 2004

Chris Richards is not on the time zone mailing list; direct replies appropriately. --ado -----Original Message----- From: Chris Richards [mailto:cj_richards@hotmail.com] Sent: Friday, July 09, 2004 9:53 AM To: tz(a)lecserver.nci.nih.gov Subject: Definition of time_t changed from signed to unsigned... Hello, I am in the process of upgrading the kernel version on a platform that I work on. I noticed that the time_t definition has been changed in the newer version of the OS. It used to be a simple "long". But it is now an "unsigned long". Basically it changed from a signed to an unsigned definition. The problem is that the timezone subsystem seems to expect time_t to be signed. There are a number of functions that only work if time_t is signed. E.g. function localsub() in file localtime.c. My question is: am I just using an obsolete version of the timezone source or should I just change the time_t typedef in the OS? I quickly scanned the latest source of localtime.c and did not see any changes regarding to how time_t is declared. Thanks in advance, Chris. _________________________________________________________________ MSN Toolbar provides one-click access to Hotmail from any Web page - FREE download! http://toolbar.msn.click-url.com/go/onm00200413ave/direct/01/

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