FreeBSD timezone(3) is V7 char *timezone(int zone, int dst), our documentation would imply it's impossible to service this type of system portably Indeed, glibc defines them both, and they make more sense for most use-cases than trying to use the globals glibc cited for __USE_MISC, tm_zone invalidation is Debian 2.33-7 POSIX cited for XSI marking is Issue 7 TC2 CSRG CD #2 contains 4.3BSD-Tahoe with both members We currently ship an outdated (and factually misleading) version of this description in ctime.3 Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@xxxxxxxxxxxxxxxxxx> --- man3/tm.3type | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) diff --git a/man3/tm.3type b/man3/tm.3type index 4117b36a0..4b98819f9 100644 --- a/man3/tm.3type +++ b/man3/tm.3type @@ -26,8 +26,26 @@ Standard C library .BR " int tm_yday;" \ " /* Day of the year [" 0 ", " 365 "] (Jan/01 = " 0 ") */" .BR " int tm_isdst;" " /* Daylight savings flag */" +.PP +.BR " long tm_gmtoff;" " /* Seconds East of UTC */" +.BR " const char *tm_zone;" " /* Timezone abbreviation */" .B }; .fi +.PP +.RS -4 +Feature Test Macro Requirements for glibc (see +.BR feature_test_macros (7)): +.RE +.PP +.IR tm_gmtoff , +.IR tm_zone : +.nf +.\" Guarded with __USE_MISC: + Since glibc 2.20: + _DEFAULT_SOURCE + Glibc 2.20 and earlier: + _BSD_SOURCE +.fi .SH DESCRIPTION Describes time, broken down into distinct components. .PP @@ -36,6 +54,17 @@ describes wether daylight saving time is in effect at the time described. The value is positive if daylight saving time is in effect, zero if it is not, and negative if the information is not available. +.PP +.I tm_gmtoff +is the difference, in seconds, +of the timezone represented by this broken-down time and UTC +(this is the additive inverse of +.BR timezone (3)). +.PP +.I tm_zone +is the equivalent of +.BR tzname (3) +for the timezone represented by this broken-down time. .SH VERSIONS In C90, .I tm_sec @@ -49,10 +78,32 @@ in C99. .SH CONFORMING TO C90 and later; POSIX.1-2001 and later. +.PP +.I tm_gmtoff +and +.I tm_zone +originate from 4.3BSD-Tahoe (where +.I tm_zone +is a +.IR "char *" ). .SH NOTES .I tm_sec can represent a leap second with the value .BR 60 . +.PP +.BR timezone (3), +as a variable, is an XSI extension: some systems provide the V7-compatible +.\" FreeBSD +.BR timezone (3) +function. +The +.I tm_gmtoff +field provides an alternative (with the opposite sign) for those systems. +.PP +.I tm_zone +points to static storage and may be overriden on subsequent calls to +.BR localtime (3) +and similar functions (however, this never happens under glibc). .SH SEE ALSO .BR ctime (3), .BR strftime (3), -- 2.30.2
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