October 2025 - tz - lists.iana.org

[PROPOSED] Support FreeBSD-style TZif polling
by Paul Eggert Oct. 7, 2025

Oct. 7, 2025

I installed the attached proposed patch, which adds a tzcode option to periodically poll the TZif file to see whether it changed. You can enable this option by compiling with -DTZ_CHANGE_INTERVAL=61 (or choose your own favorite polling interval instead of 61 seconds). The option affects localtime and other functions whose behavior depends on the TZ environment variable (or its absence); it does not affect tzalloc-related functions. This patch affects tzcode's behavior only if you compile with the new option. The remaining major difference between the functionalities of tzcode and FreeBSD is FreeBSD's support for calling localtime (not localtime_r) from multiple threads. I plan to take a look at that some time soon, with the idea of adding that as another tzcode option. While preparing this patch I noticed some issues in FreeBSD localtime.c, noted below. The attached patch addresses these issues. * A bug can occur in the first minute after reboot, where FreeBSD’s tzdata_is_fresh assumes that since the monotonic clock is less than 61, the cache must be fresh. * Prefer CLOCK_MONOTONIC_COARSE aka CLOCK_MONOTONIC_FAST if available, as its precision suffices here and it should be more efficient than CLOCK_MONOTONIC. * When checking the file timestamp, the code should not fail merely because fstat fails due to EOVERFLOW. Instead, it should assume the file has changed, as this results in better behavior for the user. * When checking the file timestamp the code should not use strlcpy to copy its name. The strlcpy could silently truncate the name in the unlikely case where a relative file name is shorter than PATH_MAX but the absolute file name is not. More importantly, the file contents are what matter here, and since the file name does not matter there is no need to copy it. * It’s a bit better to check st_ctim, not just st_ctime, as st_ctim has subsecond resolution and is more likely to avoid false matches on platforms with dicey st_dev or st_ino. * For efficiency do not bother checking st_mtim/st_mtime, as st_ctim is updated whenever st_mtim is. * For efficiency do not call fstat twice in the unlikely case where TZ is an absolute pathname. * tzdata_is_fresh is poorly named, as it returns 0 if the cache is fresh, 1 if not. And as a nit, in traditional English, “data” is a plural word. The attached patch uses a function fresh_tzdata instead, with the more common interpretation of true and false. * The attached patch ports to platforms with 32-bit time_t and without tm_gmtoff. On these platforms, strftime.c includes localtime.c and localtime.h uses ‘#define time_t timex_t’. For this reason, fresh_tzdata cannot use time_t (which might be timex_t); it needs to use the underlying system time_t. * The attached patch ports to platforms lacking <sys/stat.h>, struct timespec, clock_gettime, or CLOCK_MONOTONIC/CLOCK_MONOTONIC_COARSE.

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[PROPOSED] Port to -DHAVE_SYS_STAT_H=0 -DHAVE_POSIX_DECLS=0
by Paul Eggert Oct. 3, 2025

Oct. 3, 2025

This is mostly for testing that the code still might work on platforms lacking <sys/stat.h>. * zic.c [!HAVE_POSIX_DECLS && !mkdir]: Declare mkdir. [!HAVE_POSIX_DECLS && S_IWGRP]: Declare umask. --- zic.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/zic.c b/zic.c index e78dfd47..109dbef8 100644 --- a/zic.c +++ b/zic.c @@ -148,6 +148,12 @@ struct zone { extern int getopt(int argc, char * const argv[], const char * options); extern int link(const char * target, const char * linkname); +# ifndef mkdir +extern int mkdir(char const *, mode_t); +# endif +# ifdef S_IWGRP +extern mode_t umask(mode_t); +# endif extern char * optarg; extern int optind; #endif -- 2.48.1

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[PROPOSED 1/3] Pacify GCC 15 -Wunterminated-string-initialization
by Paul Eggert Oct. 3, 2025

Oct. 3, 2025

* private.h (ATTRIBUTE_NONSTRING): New macro. * localtime.c (tzdirslash) [!OPENAT_TZDIR]: Use it. --- localtime.c | 3 +++ private.h | 6 ++++++ 2 files changed, 9 insertions(+) diff --git a/localtime.c b/localtime.c index 186c7bf3..8ef529d5 100644 --- a/localtime.c +++ b/localtime.c @@ -571,6 +571,9 @@ union input_buffer { }; /* TZDIR with a trailing '/'. It is null-terminated if OPENAT_TZDIR. */ +#if !OPENAT_TZDIR +ATTRIBUTE_NONSTRING +#endif static char const tzdirslash[sizeof TZDIR + OPENAT_TZDIR] = TZDIR "/"; static size_t const tzdirslashlen = sizeof TZDIR; diff --git a/private.h b/private.h index 867340fa..23f1d9fb 100644 --- a/private.h +++ b/private.h @@ -555,6 +555,12 @@ typedef unsigned long uintmax_t; # define HAVE___HAS_C_ATTRIBUTE false #endif +#if 8 <= __GNUC__ +# define ATTRIBUTE_NONSTRING __attribute__((__nonstring__)) +#else +# define ATTRIBUTE_NONSTRING +#endif + #if HAVE___HAS_C_ATTRIBUTE # if __has_c_attribute(deprecated) # define ATTRIBUTE_DEPRECATED [[deprecated]] -- 2.51.0

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South African Daylight Saving Time for UTC+1 and UTC+2
by Saras Sing Oct. 2, 2025

Oct. 2, 2025

Here is a map for South Africa having UTC+1 and UTC+2 timezones so the timezone having UTC+1 have Daylight Saving Time to UTC+2 and the timezone having UTC+2 have Daylight Saving Time to UTC+3

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South African Daylight Saving Time
by Saras Sing Oct. 1, 2025

Oct. 1, 2025

https://www.timeanddate.com/time/change/south-africa?year=1942 https://www.timeanddate.com/time/change/south-africa?year=1944 https://www.timeanddate.com/time/change/south-africa Hello South Africa has Daylight Saving Time every year from September to April at every first Sunday of September at UTC/GMT+2 South Africa Standard Time from 00:00 to 01:00 South African Summer Time UTC/GMT+3 and it ends at every last Sunday of April at 01:00 to 0:00 back to South Africa Standard Time UTC/GMT+2

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British Summer Time end error
by Saras Sing Oct. 1, 2025

Oct. 1, 2025

Hello The United Kingdom British Summer Time ends at every last Sunday of November Thank you

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