IANA 2025a

tz/Makefile

@@ -137,7 +137,7 @@ TIME_T_ALTERNATIVES_TAIL = int_least32_t.ck uint_least32_t.ck \
   uint_least64_t.ck
 
 # What kind of TZif data files to generate.  (TZif is the binary time
-# zone data format that zic generates; see Internet RFC 8536.)
+# zone data format that zic generates; see Internet RFC 9636.)
 # If you want only POSIX time, with time values interpreted as
 # seconds since the epoch (not counting leap seconds), use
 #	REDO=		posix_only
@@ -255,14 +255,15 @@ LDLIBS=
 #  -DHAVE_UNISTD_H=0 if <unistd.h> does not work*
 #  -DHAVE_UTMPX_H=0 if <utmpx.h> does not work*
 #  -Dlocale_t=XXX if your system uses XXX instead of locale_t
+#  -DMKTIME_MIGHT_OVERFLOW if mktime might fail due to time_t overflow
 #  -DPORT_TO_C89 if tzcode should also run on mostly-C89 platforms+
 #	Typically it is better to use a later standard.  For example,
 #	with GCC 4.9.4 (2016), prefer '-std=gnu11' to '-DPORT_TO_C89'.
 #	Even with -DPORT_TO_C89, the code needs at least one C99
 #	feature (integers at least 64 bits wide) and maybe more.
 #  -DRESERVE_STD_EXT_IDS if your platform reserves standard identifiers
 #	with external linkage, e.g., applications cannot define 'localtime'.
-#  -Dssize_t=long on hosts like MS-Windows that lack ssize_t
+#  -Dssize_t=int on hosts like MS-Windows that lack ssize_t
 #  -DSUPPORT_C89=0 if the tzcode library should not support C89 callers
 #	Although -DSUPPORT_C89=0 might work around latent bugs in callers,
 #	it does not conform to POSIX.
@@ -285,7 +286,7 @@ LDLIBS=
 #	This mishandles some past timestamps, as US DST rules have changed.
 #	It also mishandles settings like TZ='EET-2EEST' for eastern Europe,
 #	as Europe and US DST rules differ.
-#  -DTZNAME_MAXIMUM=N to limit time zone abbreviations to N bytes (default 255)
+#  -DTZNAME_MAXIMUM=N to limit time zone abbreviations to N bytes (default 254)
 #  -DUNINIT_TRAP if reading uninitialized storage can cause problems
 #	other than simply getting garbage data
 #  -DUSE_LTZ=0 to build zdump with the system time zone library
@@ -319,7 +320,8 @@ GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 \
   $(GCC_INSTRUMENT) \
   -Wall -Wextra \
   -Walloc-size-larger-than=100000 -Warray-bounds=2 \
-  -Wbad-function-cast -Wbidi-chars=any,ucn -Wcast-align=strict -Wdate-time \
+  -Wbad-function-cast -Wbidi-chars=any,ucn -Wcast-align=strict -Wcast-qual \
+  -Wdate-time \
   -Wdeclaration-after-statement -Wdouble-promotion \
   -Wduplicated-branches -Wduplicated-cond -Wflex-array-member-not-at-end \
   -Wformat=2 -Wformat-overflow=2 -Wformat-signedness -Wformat-truncation \
@@ -336,7 +338,7 @@ GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 \
   -Wsuggest-attribute=noreturn -Wsuggest-attribute=pure \
   -Wtrampolines -Wundef -Wunused-macros -Wuse-after-free=3 \
   -Wvariadic-macros -Wvla -Wwrite-strings \
-  -Wno-format-nonliteral -Wno-sign-compare
+  -Wno-format-nonliteral -Wno-sign-compare -Wno-type-limits
 #
 # If your system has a "GMT offset" field in its "struct tm"s
 # (or if you decide to add such a field in your system's "time.h" file),
@@ -614,8 +616,8 @@ TZS_YEAR=	2050
 TZS_CUTOFF_FLAG=	-c $(TZS_YEAR)
 TZS=		to$(TZS_YEAR).tzs
 TZS_NEW=	to$(TZS_YEAR)new.tzs
-TZS_DEPS=	$(YDATA) asctime.c localtime.c \
-			private.h tzfile.h zdump.c zic.c
+TZS_DEPS=	$(YDATA) localtime.c private.h \
+			strftime.c tzfile.h zdump.c zic.c
 TZDATA_DIST = $(COMMON) $(DATA) $(MISC)
 # EIGHT_YARDS is just a yard short of the whole ENCHILADA.
 EIGHT_YARDS = $(TZDATA_DIST) $(DOCS) $(SOURCES) tzdata.zi
@@ -855,10 +857,10 @@ tzselect:	tzselect.ksh version
 		chmod +x $@.out
 		mv $@.out $@
 
-check: check_mild back.ck
+check: check_mild back.ck now.ck
 check_mild: check_web check_zishrink \
   character-set.ck white-space.ck links.ck mainguard.ck \
-  name-lengths.ck now.ck slashed-abbrs.ck sorted.ck \
+  name-lengths.ck slashed-abbrs.ck sorted.ck \
   tables.ck ziguard.ck tzs.ck
 
 # True if UTF8_LOCALE does not work;
@@ -1103,7 +1105,7 @@ set-timestamps.out: $(EIGHT_YARDS)
 		   touch -md @1 test.out; then \
 		  rm -f test.out && \
 		  for file in $$files; do \
-		    if git diff --quiet $$file; then \
+		    if git diff --quiet HEAD $$file; then \
 		      time=$$(TZ=UTC0 git log -1 \
 			--format='tformat:%cd' \
 			--date='format:%Y-%m-%dT%H:%M:%SZ' \
@@ -1354,13 +1356,13 @@ long-long.ck unsigned.ck: $(VERSION_DEPS)
 zonenames:	tzdata.zi
 		@$(AWK) '/^Z/ { print $$2 } /^L/ { print $$3 }' tzdata.zi
 
-asctime.o:	private.h tzfile.h
+asctime.o:	private.h
 date.o:		private.h
 difftime.o:	private.h
-localtime.o:	private.h tzfile.h tzdir.h
-strftime.o:	private.h tzfile.h
-zdump.o:	version.h
-zic.o:		private.h tzfile.h tzdir.h version.h
+localtime.o:	private.h tzdir.h tzfile.h
+strftime.o:	localtime.c private.h tzdir.h tzfile.h
+zdump.o:	private.h version.h
+zic.o:		private.h tzdir.h tzfile.h version.h
 
 .PHONY: ALL INSTALL all
 .PHONY: check check_mild check_time_t_alternatives

tz/NEWS

@@ -1,5 +1,83 @@
 News for the tz database
 
+Release 2025a - 2025-01-15 10:47:24 -0800
+
+  Briefly:
+    Paraguay adopts permanent -03 starting spring 2024.
+    Improve pre-1991 data for the Philippines.
+    Etc/Unknown is now reserved.
+
+  Changes to future timestamps
+
+    Paraguay will stop changing its clocks after the spring-forward
+    transition on 2024-10-06, so it is now permanently at -03.
+    (Thanks to Heitor David Pinto and Even Scharning.)
+    This affects timestamps starting 2025-03-22, as well as the
+    obsolescent tm_isdst flags starting 2024-10-15.
+
+  Changes to past timestamps
+
+    Correct timestamps for the Philippines before 1900, and from 1937
+    through 1990.  (Thanks to P Chan for the heads-up and citations.)
+    This includes adjusting local mean time before 1899; fixing
+    transitions in September 1899, January 1937, and June 1954; adding
+    transitions in December 1941, November 1945, March and September
+    1977, and May and July 1990; and removing incorrect transitions in
+    March and September 1978.
+
+  Changes to data
+
+    Add zone1970.tab lines for the Concordia and Eyre Bird Observatory
+    research stations.  (Thanks to Derick Rethans and Jule Dabars.)
+
+  Changes to code
+
+    strftime %s now generates the correct numeric string even when the
+    represented number does not fit into time_t.  This is better than
+    generating the numeric equivalent of (time_t) -1, as strftime did
+    in TZDB releases 96a (when %s was introduced) through 2020a and in
+    releases 2022b through 2024b.  It is also better than failing and
+    returning 0, as strftime did in releases 2020b through 2022a.
+
+    strftime now outputs an invalid conversion specifier as-is,
+    instead of eliding the leading '%', which confused debugging.
+
+    An invalid TZ now generates the time zone abbreviation "-00", not
+    "UTC", to help the user see that an error has occurred.  (Thanks
+    to Arthur David Olson for suggesting a "wrong result".)
+
+    mktime and timeoff no longer incorrectly fail merely because a
+    struct tm component near INT_MIN or INT_MAX overflows when a
+    lower-order component carries into it.
+
+    TZNAME_MAXIMUM, the maximum number of bytes in a proleptic TZ
+    string's time zone abbreviation, now defaults to 254 not 255.
+    This helps reduce the size of internal state from 25480 to 21384
+    on common platforms.  This change should not be a problem, as
+    nobody uses such long "abbreviations" and the longstanding tzcode
+    maximum was 16 until release 2023a.  For those who prefer no
+    arbitrary limits, you can now specify TZNAME_MAXIMUM values up to
+    PTRDIFF_MAX, a limit forced by C anyway; formerly tzcode silently
+    misbehaved unless TZNAME_MAXIMUM was less than INT_MAX.
+
+    tzset and related functions no longer leak a file descriptor if
+    another thread forks or execs at about the same time and if the
+    platform has O_CLOFORK and O_CLOEXEC respectively.  Also, the
+    functions no longer let a TZif file become a controlling terminal.
+
+    'zdump -' now reads TZif data from /dev/stdin.
+    (From a question by Arthur David Olson.)
+
+  Changes to documentation
+
+    The name Etc/Unknown is now reserved: it will not be used by TZDB.
+    This is for compatibility with CLDR, which uses the string
+    "Etc/Unknown" for an unknown or invalid timezone.  (Thanks to
+    Justin Grant, Mark Davis, and Guy Harris.)
+
+    Cite Internet RFC 9636, which obsoletes RFC 8536 for TZif format.
+
+
 Release 2024b - 2024-09-04 12:27:47 -0700
 
   Briefly:
@@ -116,7 +194,7 @@ Release 2024b - 2024-09-04 12:27:47 -0700
   Changes to commentary
 
     Commentary about historical transitions in Portugal and her former
-    colonies has been expanded with links to many relevant legislation.
+    colonies has been expanded with links to relevant legislation.
     (Thanks to Tim Parenti.)
 
 
@@ -204,10 +282,10 @@ Release 2023d - 2023-12-21 20:02:24 -0800
     changing its time zone from -01/+00 to -02/-01 at the same moment
     as the spring-forward transition.  Its clocks will therefore not
     spring forward as previously scheduled.  The time zone change
-    reverts to its common practice before 1981.
+    reverts to its common practice before 1981.  (Thanks to Jule Dabars.)
 
     Fix predictions for DST transitions in Palestine in 2072-2075,
-    correcting a typo introduced in 2023a.
+    correcting a typo introduced in 2023a.  (Thanks to Jule Dabars.)
 
   Changes to past and future timestamps
 

tz/antarctica

@@ -174,6 +174,8 @@ Zone Antarctica/Mawson	0	-	-00	1954 Feb 13
 
 # France & Italy - year-round base
 # Concordia, -750600+1232000, since 2005
+# https://en.wikipedia.org/wiki/Concordia_Station
+# Can use Asia/Singapore, which it has agreed with since inception.
 
 # Germany - year-round base
 # Neumayer III, -704080-0081602, since 2009

tz/asctime.c

@@ -7,6 +7,7 @@
 
 /*
 ** Avoid the temptation to punt entirely to strftime;
+** strftime can behave badly when tm components are out of range, and
 ** the output of strftime is supposed to be locale specific
 ** whereas the output of asctime is supposed to be constant.
 */
@@ -16,27 +17,6 @@
 #include "private.h"
 #include <stdio.h>
 
-/*
-** All years associated with 32-bit time_t values are exactly four digits long;
-** some years associated with 64-bit time_t values are not.
-** Vintage programs are coded for years that are always four digits long
-** and may assume that the newline always lands in the same place.
-** For years that are less than four digits, we pad the output with
-** leading zeroes to get the newline in the traditional place.
-** The -4 ensures that we get four characters of output even if
-** we call a strftime variant that produces fewer characters for some years.
-** This conforms to recent ISO C and POSIX standards, which say behavior
-** is undefined when the year is less than 1000 or greater than 9999.
-*/
-static char const ASCTIME_FMT[] = "%s %s%3d %.2d:%.2d:%.2d %-4s\n";
-/*
-** For years that are more than four digits we put extra spaces before the year
-** so that code trying to overwrite the newline won't end up overwriting
-** a digit within a year and truncating the year (operating on the assumption
-** that no output is better than wrong output).
-*/
-static char const ASCTIME_FMT_B[] = "%s %s%3d %.2d:%.2d:%.2d     %s\n";
-
 enum { STD_ASCTIME_BUF_SIZE = 26 };
 /*
 ** Big enough for something such as
@@ -50,14 +30,24 @@ enum { STD_ASCTIME_BUF_SIZE = 26 };
 */
 static char buf_asctime[2*3 + 5*INT_STRLEN_MAXIMUM(int) + 7 + 2 + 1 + 1];
 
-/* A similar buffer for ctime.
-   C89 requires that they be the same buffer.
-   This requirement was removed in C99, so support it only if requested,
-   as support is more likely to lead to bugs in badly written programs.  */
-#if SUPPORT_C89
-# define buf_ctime buf_asctime
-#else
-static char buf_ctime[sizeof buf_asctime];
+/* On pre-C99 platforms, a snprintf substitute good enough for us.  */
+#if !HAVE_SNPRINTF
+# include <stdarg.h>
+ATTRIBUTE_FORMAT((printf, 3, 4)) static int
+my_snprintf(char *s, size_t size, char const *format, ...)
+{
+  int n;
+  va_list args;
+  char stackbuf[sizeof buf_asctime];
+  va_start(args, format);
+  n = vsprintf(stackbuf, format, args);
+  va_end (args);
+  if (0 <= n && n < size)
+    memcpy (s, stackbuf, n + 1);
+  return n;
+}
+# undef snprintf
+# define snprintf my_snprintf
 #endif
 
 /* Publish asctime_r and ctime_r only when supporting older POSIX.  */
@@ -84,38 +74,59 @@ asctime_r(struct tm const *restrict timeptr, char *restrict buf)
 	};
 	register const char *	wn;
 	register const char *	mn;
-	char			year[INT_STRLEN_MAXIMUM(int) + 2];
-	char result[sizeof buf_asctime];
+	int year, mday, hour, min, sec;
+	long long_TM_YEAR_BASE = TM_YEAR_BASE;
+	size_t bufsize = (buf == buf_asctime
+			  ? sizeof buf_asctime : STD_ASCTIME_BUF_SIZE);
 
 	if (timeptr == NULL) {
+		strcpy(buf, "??? ??? ?? ??:??:?? ????\n");
+		/* Set errno now, since strcpy might change it in
+		   POSIX.1-2017 and earlier.  */
 		errno = EINVAL;
-		return strcpy(buf, "??? ??? ?? ??:??:?? ????\n");
+		return buf;
 	}
 	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];
-	/*
-	** Use strftime's %Y to generate the year, to avoid overflow problems
-	** when computing timeptr->tm_year + TM_YEAR_BASE.
-	** Assume that strftime is unaffected by other out-of-range members
-	** (e.g., timeptr->tm_mday) when processing "%Y".
-	*/
-	strftime(year, sizeof year, "%Y", timeptr);
-	/*
-	** We avoid using snprintf since it's not available on all systems.
-	*/
-	sprintf(result,
-		((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B),
-		wn, mn,
-		timeptr->tm_mday, timeptr->tm_hour,
-		timeptr->tm_min, timeptr->tm_sec,
-		year);
-	if (strlen(result) < STD_ASCTIME_BUF_SIZE
-	    || buf == buf_ctime || buf == buf_asctime)
-		return strcpy(buf, result);
+
+	year = timeptr->tm_year;
+	mday = timeptr->tm_mday;
+	hour = timeptr->tm_hour;
+	min = timeptr->tm_min;
+	sec = timeptr->tm_sec;
+
+	/* Vintage programs are coded for years that are always four bytes long
+	   and may assume that the newline always lands in the same place.
+	   For years that are less than four bytes, pad the output with
+	   leading zeroes to get the newline in the traditional place.
+	   For years longer than four bytes, put extra spaces before the year
+	   so that vintage code trying to overwrite the newline
+	   won't overwrite a digit within a year and truncate the year,
+	   using the principle that no output is better than wrong output.
+	   This conforms to ISO C and POSIX standards, which say behavior
+	   is undefined when the year is less than 1000 or greater than 9999.
+
+	   Also, avoid overflow when formatting tm_year + TM_YEAR_BASE.  */
+
+	if ((year <= LONG_MAX - TM_YEAR_BASE
+	     ? snprintf (buf, bufsize,
+			 ((-999 - TM_YEAR_BASE <= year
+			   && year <= 9999 - TM_YEAR_BASE)
+			  ? "%s %s%3d %.2d:%.2d:%.2d %04ld\n"
+			  : "%s %s%3d %.2d:%.2d:%.2d     %ld\n"),
+			 wn, mn, mday, hour, min, sec,
+			 year + long_TM_YEAR_BASE)
+	     : snprintf (buf, bufsize,
+			 "%s %s%3d %.2d:%.2d:%.2d     %d%d\n",
+			 wn, mn, mday, hour, min, sec,
+			 year / 10 + TM_YEAR_BASE / 10,
+			 year % 10))
+	    < bufsize)
+		return buf;
 	else {
 		errno = EOVERFLOW;
 		return NULL;
@@ -140,5 +151,8 @@ ctime_r(const time_t *timep, char *buf)
 char *
 ctime(const time_t *timep)
 {
-  return ctime_r(timep, buf_ctime);
+  /* Do not call localtime_r, as C23 requires ctime to initialize the
+     static storage that localtime updates.  */
+  struct tm *tmp = localtime(timep);
+  return tmp ? asctime(tmp) : NULL;
 }