- tz - lists.iana.org

How to select zones for a TimeZone picker
by Guillermo Rodriguez Garcia Nov. 3, 2025

Nov. 3, 2025

Hi all, I'm building a TimeZone picker with the following constraints: 1. At least one distinct timezone per country (so that e.g. there is an entry for Atlantic/Reykjavik instead of mapping IS to Africa/Abidjan) 2. Within a country, do not show timezones that currently have identical rules to another timezone in the same country (i.e. historical differences don't matter). Because of (1) I started from zone.tab rather than zone1970.tab. However, I'm not sure how to handle (2). For example, Spain has three zones in zone.tab: Europe/Madrid, Africa/Ceuta, and Atlantic/Canary. But as far as most users are concerned, as of today there are only two timezones in Spain: Madrid and Canary Islands. Ceuta follows Madrid rules, so there should be no need to show this as an option to the user. Another example: the U.S. lists 29 zones, but only 8 are distinct today (ignoring historical changes). So, the question: Any suggestions on how to filter timezones within each country to drop those that as of today are not relevant except for historical differences? Thank you, Guillermo Rodriguez Garcia guille.rodriguez(a)gmail.com

8 17

[PROPOSED] tzfree now preserves errno
by Paul Eggert Nov. 3, 2025

Nov. 3, 2025

* Makefile, NEWS, newtzset.3: Mention this. * localtime.c (FREE_PRESERVES_ERRNO): Default to 1 if 'free' is known to preserve errno, 0 otherwise. (tzfree): Preserve errno if 'free' does not. --- Makefile | 2 ++ NEWS | 2 ++ localtime.c | 15 +++++++++++++++ newtzset.3 | 4 ++++ 4 files changed, 23 insertions(+) diff --git a/Makefile b/Makefile index 0fe8a9f8..0d33fa17 100644 --- a/Makefile +++ b/Makefile @@ -239,6 +239,8 @@ LDLIBS= # -DEPOCH_OFFSET=N if the 'time' function returns a value N greater # than what POSIX specifies, assuming local time is UT. # For example, N is 252460800 on AmigaOS. +# -DFREE_PRESERVES_ERRNO=[01] if the 'free' function munges or preserves errno +# (default is guessed) # -DHAVE_DECL_ASCTIME_R=0 if <time.h> does not declare asctime_r # on POSIX platforms predating POSIX.1-2024 # -DHAVE_DECL_ENVIRON if <unistd.h> declares 'environ' diff --git a/NEWS b/NEWS index 1ed9b2eb..a9b2d321 100644 --- a/NEWS +++ b/NEWS @@ -93,6 +93,8 @@ Unreleased, experimental changes option is incompatible with POSIX.1-2024 and earlier. It also costs CPU time and memory. + tzfree now preserves errno, consistently with POSIX.1-2024 'free'. + tzcode now uses mempcpy if available, guessing its availability. Compile with -DHAVE_MEMPCPY=1 or 0 to override the guess. diff --git a/localtime.c b/localtime.c index b85941f2..46acf3bd 100644 --- a/localtime.c +++ b/localtime.c @@ -2061,10 +2061,25 @@ tzalloc(char const *name) return sp; } +#ifndef FREE_PRESERVES_ERRNO +# if ((defined _POSIX_VERSION && 202405 <= _POSIX_VERSION) \ + || (defined __GLIBC__ && 2 < __GLIBC__ + (33 <= __GLIBC_MINOR__)) \ + || defined __OpenBSD__ || defined __sun) +# define FREE_PRESERVES_ERRNO 1 +# else +# define FREE_PRESERVES_ERRNO 0 +# endif +#endif + void tzfree(timezone_t sp) { + int err; + if (!FREE_PRESERVES_ERRNO) + err = errno; free(sp); + if (!FREE_PRESERVES_ERRNO) + errno = err; } /* diff --git a/newtzset.3 b/newtzset.3 index 3801ab1b..028cfd25 100644 --- a/newtzset.3 +++ b/newtzset.3 @@ -379,6 +379,10 @@ If successful, the function returns a nonnull pointer to the newly allocated object. Otherwise, it returns a null pointer and sets .IR errno . +The +.B tzfree +function does not modify +.IR errno . .SH ERRORS .TP .B EOVERFLOW -- 2.51.0

1 0

[PROPOSED] Improve TZ="/..." security and speed (NetBSD only)
by Paul Eggert Oct. 28, 2025

Oct. 28, 2025

* NEWS: Mention security. * localtime.c (O_REGULAR): Default to 0. (tzloadbody): Open TZif files with O_REGULAR. Suppress unnecessary call to 'stat' if O_REGULAR is present. --- NEWS | 3 +++ localtime.c | 7 +++++-- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/NEWS b/NEWS index 64d32bf3..1ed9b2eb 100644 --- a/NEWS +++ b/NEWS @@ -40,6 +40,9 @@ Unreleased, experimental changes and reject relative names containing ".." directory components; formerly, only privileged programs did those two things. These changes were inspired by similar behavior in FreeBSD. + On NetBSD, unprivileged programs now use O_REGULAR to check + whether a TZ setting starting with '/' names a regular file, + avoiding a minor security race still present elsewhere. TZ strings taken from tzalloc arguments are now treated with no less caution than TZ strings taken from the environment, as the old undocumented behavior would have been hard to explain. diff --git a/localtime.c b/localtime.c index 0d2d2a93..b85941f2 100644 --- a/localtime.c +++ b/localtime.c @@ -355,6 +355,9 @@ static int openat(int dd, char const *path, int oflag) { unreachable (); } #ifndef O_PATH # define O_PATH 0 #endif +#ifndef O_REGULAR +# define O_REGULAR 0 +#endif #ifndef O_RESOLVE_BENEATH # define O_RESOLVE_BENEATH 0 #endif @@ -900,7 +903,7 @@ tzloadbody(char const *name, struct state *sp, char tzloadflags, register int tzheadsize = sizeof(struct tzhead); int dd = AT_FDCWD; int oflags = (O_RDONLY | O_BINARY | O_CLOEXEC | O_CLOFORK - | O_IGNORE_CTTY | O_NOCTTY); + | O_IGNORE_CTTY | O_NOCTTY | O_REGULAR); int err; struct stat st; st.st_ctime = 0; @@ -927,7 +930,7 @@ tzloadbody(char const *name, struct state *sp, char tzloadflags, continue; else if (issetugid()) return ENOTCAPABLE; - else { + else if (!O_REGULAR) { /* Check for devices, as their mere opening could have unwanted side effects. Though racy, there is no portable way to fix the races. This check is needed -- 2.48.1

1 0

Iana build failures on Windows
by Manuela Friedrich Oct. 28, 2025

Oct. 28, 2025

Hello Paul, I have hit a compile error for zic.c on Windows. Git commit 9e0bf0b42d68b3d9ad0bc7ff70fc92d87f8b40d2 zic.c zic.c(152): error C2081: 'mode_t': name in formal parameter list illegal zic.c(2437): warning C4116: unnamed type definition in parentheses NMAKE : U1077: '"C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\VC\Tools\MSVC\14.12.25827\bin\HostX64\x64\cl.EXE"' : return code '0x2' Stop. Can you please advise? Please do not release a new version with this issue present. Thank you! Regards Manuela Friedrich

4 17

[PROPOSED] Be more like OpenBSD wrt ".."
by Paul Eggert Oct. 25, 2025

Oct. 25, 2025

* localtime.c (tzloadbody): Do not worry about settings like TZ=".." (i.e., trailing ".." component) as the later read will fail anyway. This simplifies the code slightly, and agrees with the security-conscious OpenBSD libc. --- localtime.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/localtime.c b/localtime.c index f1a82370..0d2d2a93 100644 --- a/localtime.c +++ b/localtime.c @@ -941,13 +941,13 @@ tzloadbody(char const *name, struct state *sp, char tzloadflags, if (relname[0] != '/') { if (!OPENAT_TZDIR || !O_RESOLVE_BENEATH) { - /* Fail if a relative name contains a ".." component, - as such a name could read a file outside TZDIR + /* Fail if a relative name contains a non-terminal ".." component, + as such a name could read a non-directory outside TZDIR when AT_FDCWD and O_RESOLVE_BENEATH are not available. */ char const *component; for (component = relname; component[0]; component++) if (component[0] == '.' && component[1] == '.' - && ((component[2] == '/') | !component[2]) + && component[2] == '/' && (component == relname || component[-1] == '/')) return ENOTCAPABLE; } -- 2.48.1

1 0

[PATCH 1/5] Clarify <sys/auxv.h> vs getauxval
by Paul Eggert Oct. 25, 2025

Oct. 25, 2025

FreeBSD has <sys/auxv.h> but not getauxval, so clarify ifdeffery to reflect this. This doesn’t fix any bugs (since FreeBSD also has issetugid) but makes things clearer. * Makefile, NEWS: Update to match new behavior and fix a few old typos. * localtime.c: Move the <sys/auv.h> code to be closer together. (HAVE_SYS_AUXV_H) [!HAVE_ISSETUGID]: New macro. * private.h (HAVE_GETAUXVAL): Remove. All uses replaced by HAVE_SYS_AUXV_H. --- Makefile | 12 ++++++------ NEWS | 9 +++++---- localtime.c | 25 +++++++++++++++++++------ private.h | 13 ------------- 4 files changed, 30 insertions(+), 29 deletions(-) diff --git a/Makefile b/Makefile index 3b259c80..0fe8a9f8 100644 --- a/Makefile +++ b/Makefile @@ -246,7 +246,6 @@ LDLIBS= # -DHAVE_DIRECT_H if mkdir needs <direct.h> (MS-Windows) # -DHAVE_FCHMOD=0 if your system lacks the fchmod function # -DHAVE__GENERIC=0 if _Generic does not work* -# -DHAVE_GETAUXVAL=1 if getauxval works, 0 otherwise (default is guessed) # -DHAVE_GETEUID=0 if gete?[ug]id do not work # -DHAVE_GETRANDOM if getrandom works (e.g., GNU/Linux), # -DHAVE_GETRANDOM=0 to avoid using getrandom @@ -258,7 +257,9 @@ LDLIBS= # ctime_r and asctime_r incompatibly with POSIX.1-2017 and earlier # (Solaris when _POSIX_PTHREAD_SEMANTICS is not defined). # -DHAVE_INTTYPES_H=0 if <inttypes.h> does not work*+ -# -DHAVE_ISSETUID=1 if issetugid works, 0 otherwise (default is guessed) +# -DHAVE_ISSETUGID=1 if issetugid works, 0 otherwise (default is guessed) +# If 0, you may also use -DHAVE_SYS_AUXV_H=1 if <sys/auxv.h> works, +# 0 otherwise (default is guessed). # -DHAVE_LINK=0 if your system lacks a link function # -DHAVE_LOCALTIME_R=0 if your system lacks a localtime_r function # -DHAVE_LOCALTIME_RZ=0 if you do not want zdump to use localtime_rz @@ -268,8 +269,8 @@ LDLIBS= # -DHAVE_POSIX_DECLS=0 if your system's include files do not declare # variables like 'tzname' required by POSIX # -DHAVE_PWD_H=0 if your system lacks pwd.h, grp.h and corresponding functions -# The following additional options may be needed: -# -Dgid_t=T, -Duid_t=T to define gid_t, uid_t to be type T +# If 0, you may also need -Dgid_t=G -Duid_t=U +# to define gid_t and uid_t to be types G and U. # -DHAVE_SETENV=0 if your system lacks the setenv function # -DHAVE_SETMODE=[01] if your system lacks or has the setmode and getmode # functions (default is guessed) @@ -285,8 +286,7 @@ LDLIBS= # -DHAVE_STRUCT_TIMESPEC=0 if your system lacks struct timespec+ # -DHAVE_SYMLINK=0 if your system lacks the symlink function # -DHAVE_SYS_STAT_H=0 if <sys/stat.h> does not work* -# The following additional option may be needed: -# -Dmode_t=T to define mode_t to be type T +# If 0, you may also need -Dmode_t=M to define mode_t to be type M. # -DHAVE_TZSET=0 if your system lacks a tzset function # -DHAVE_UNISTD_H=0 if <unistd.h> does not work* # -DHAVE_UTMPX_H=0 if <utmpx.h> does not work* diff --git a/NEWS b/NEWS index 37ac9fba..64d32bf3 100644 --- a/NEWS +++ b/NEWS @@ -44,12 +44,13 @@ Unreleased, experimental changes no less caution than TZ strings taken from the environment, as the old undocumented behavior would have been hard to explain. tzset etc. no longer use the 'access' system call to check access; - instead they now use the system calls issetuid, getauxval, + instead they now use the system calls issetugid, getauxval, getresuid/getresgid, and geteuid/getegid/getuid/getgid (whichever first works) to test whether a program is privileged. - Compile with -DHAVE_ISSETUID=[01], -DHAVE_GETAUXVAL=[01], - -DHAVE_GETRESUID=[01], and -DHAVE_GETEUID=[01] to enable or - disable these system calls' use. + Compile with -DHAVE_SYS_AUXV_H=[01] to enable or disable + <sys/auxv.h> which (if it defines AT_SECURE) enables getauxval, + and compile with -DHAVE_ISSETUGID=[01], -DHAVE_GETRESUID=[01], and + -DHAVE_GETEUID=[01] to enable or disable the other calls' use. The new CFLAGS option -DTZ_CHANGE_INTERVAL=N makes tzset etc. check for TZif file changes if the in-memory data are N seconds diff --git a/localtime.c b/localtime.c index a8c442dd..f2d35813 100644 --- a/localtime.c +++ b/localtime.c @@ -19,10 +19,6 @@ #include "tzfile.h" #include <fcntl.h> -#if HAVE_GETAUXVAL && !HAVE_ISSETUGID -# include <sys/auxv.h> -#endif - #if HAVE_SYS_STAT_H # include <sys/stat.h> # ifndef S_ISREG @@ -366,12 +362,29 @@ static int openat(int dd, char const *path, int oflag) { unreachable (); } # define O_SEARCH 0 #endif -/* Return 1 if the process is privileged, 0 otherwise. */ #if !HAVE_ISSETUGID + +# if !defined HAVE_SYS_AUXV_H && defined __has_include +# if __has_include(<sys/auxv.h>) +# define HAVE_SYS_AUXV_H 1 +# endif +# endif +# ifndef HAVE_SYS_AUXV_H +# if defined __GLIBC__ && 2 < __GLIBC__ + (19 <= __GLIBC_MINOR__) +# define HAVE_SYS_AUXV_H 1 +# else +# define HAVE_SYS_AUXV_H 0 +# endif +# endif +# if HAVE_SYS_AUXV_H +# include <sys/auxv.h> +# endif + +/* Return 1 if the process is privileged, 0 otherwise. */ static int issetugid(void) { -# if HAVE_GETAUXVAL && defined AT_SECURE +# if HAVE_SYS_AUXV_H && defined AT_SECURE unsigned long val; errno = 0; val = getauxval(AT_SECURE); diff --git a/private.h b/private.h index 8d3d6404..4daa4864 100644 --- a/private.h +++ b/private.h @@ -294,19 +294,6 @@ extern int optind; # endif #endif -#if !defined HAVE_GETAUXVAL && defined __has_include -# if __has_include(<sys/auxv.h>) -# define HAVE_GETAUXVAL 1 -# endif -#endif -#ifndef HAVE_GETAUXVAL -# if defined __GLIBC__ && 2 < __GLIBC__ + (19 <= __GLIBC_MINOR__) -# define HAVE_GETAUXVAL 1 -# else -# define HAVE_GETAUXVAL 0 -# endif -#endif - #ifndef HAVE_ISSETUGID # if (defined __FreeBSD__ || defined __NetBSD__ || defined __OpenBSD__ \ || (defined __linux__ && !defined __GLIBC__) /* Android, musl, etc. */ \ -- 2.51.0

1 4

[PROPOSED] Shorten GCC_INSTRUMENT à la GCC 14
by Paul Eggert Oct. 25, 2025

Oct. 25, 2025

* Makefile (GCC_INSTRUMENT): Switch from -fsanitize-undefined-trap-on-error to its shorter alias -fsanitize-trap=all, introduced in GCC 14. --- Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Makefile b/Makefile index f57042df..3b259c80 100644 --- a/Makefile +++ b/Makefile @@ -380,7 +380,7 @@ LDLIBS= # Select instrumentation via "make GCC_INSTRUMENT='whatever'". GCC_INSTRUMENT = \ -fsanitize=undefined -fsanitize-address-use-after-scope \ - -fsanitize-undefined-trap-on-error -fstack-protector + -fsanitize-trap=all -fstack-protector # Omit -fanalyzer from GCC_DEBUG_FLAGS, as it makes GCC too slow. GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 \ $(GCC_INSTRUMENT) \ -- 2.51.0

1 0

[PROPOSED 0/3] zic options -D, -m, and -u from FreeBSD
by Paul Eggert Oct. 24, 2025

Oct. 24, 2025

This thread contains proposed patches to add support for the zic options -D, -m, and -u, which have been in FreeBSD zic for many years. The implementation differs from that of FreeBSD, to fix some unlikely security races. I installed these patches in the development repository on GitHub. Paul Eggert (3): New zic option -D, inspired by FreeBSD New zic option -m, inspired by FreeBSD New zic option -u, inspired by FreeBSD Makefile | 8 ++ NEWS | 2 + zic.8 | 32 +++++++ zic.c | 259 +++++++++++++++++++++++++++++++++++++++++++++++++++++-- 4 files changed, 293 insertions(+), 8 deletions(-) -- 2.48.1

2 5

Possible timezone change in Argentina (starting in April?)
by Mariano Absatz - el Baby Oct. 24, 2025

Oct. 24, 2025

Hi, back here after 12+ years for a heads up... There is a Law proposal approved by the Cámara de Diputados (equivalent of the House) but yet to be approved in the Senate regarding Argentina's timezone. Argentina is currently in UTC-3 with no DST. The proposal establishes the Official Time for the whole country as UTC-4 (which is geographically more accurate), with a DST of UTC-3. The DST would start at 00:00 on the first April Sunday and would end at 00:00 on the first September Sunday. The Executive is authorized to modify these dates and to coordinate with other countries of MERCOSUR to apply changes on the same moment. This is just a heads up, since the Senate did not approve or modify the proposal. If this is approved and enacted before April 2026, we can assume the current status is DST and at 00:00 Sunday April 5th 2026 we would be moving the clock back to 23:00 Saturday April 4th. I'll keep you posted as this evolves, but don't hold your breath since on October 26th there are Legislative Elections (midterm), and half of the House and one third of the Senate will change. The new legislators will take office on December 10th. By the end of December the ordinary session of Congress ends; it may be extended by the Executive Branch, but there is no certainty about which bills can be discussed. References (all in Spanish): * Law proposal (official Cámara de Diputados site): https://www.hcdn.gob.ar/diputados/jcobos/proyecto.html?exp=1110-D-2024 (click on the "Ver documento original" button) * Status in the Senate: https://www.senado.gob.ar/parlamentario/comisiones/verExp/14.25/CD/PL (click on the "Texto Original" button for the signed proposal sent from the Cámara de Diputados; click on the "Trámite Legislativo" button for the process status in the Senate) * Brief article about the proposal on a reputed fact checking site: https://chequeado.com/el-explicador/cambio-de-huso-horario-en-la-argentina-… -- Mariano Absatz - el Baby www.clueless.ar

3 3

[PROPOSED 1/2] Refactor duplicate duplicate-option code
by Paul Eggert Oct. 24, 2025

Oct. 24, 2025

* zic.c (duplicate_options): New function. (main): Use it. --- zic.c | 73 +++++++++++++++++++---------------------------------------- 1 file changed, 23 insertions(+), 50 deletions(-) diff --git a/zic.c b/zic.c index 67bcaa43..34e7d91c 100644 --- a/zic.c +++ b/zic.c @@ -708,6 +708,13 @@ close_file(FILE *stream, char const *dir, char const *name, } } +ATTRIBUTE_NORETURN static void +duplicate_options(char const *opt) +{ + fprintf(stderr, _("%s: More than one %s option specified\n"), progname, opt); + exit(EXIT_FAILURE); +} + ATTRIBUTE_NORETURN static void usage(FILE *stream, int status) { @@ -1063,73 +1070,39 @@ main(int argc, char **argv) error(_("invalid option: -b '%s'"), optarg); break; case 'd': - if (directory == NULL) - directory = optarg; - else { - fprintf(stderr, - _("%s: More than one -d option" - " specified\n"), - progname); - return EXIT_FAILURE; - } + if (directory) + duplicate_options("-d"); + directory = optarg; break; case 'l': - if (lcltime == NULL) - lcltime = optarg; - else { - fprintf(stderr, - _("%s: More than one -l option" - " specified\n"), - progname); - return EXIT_FAILURE; - } + if (lcltime) + duplicate_options("-l"); + lcltime = optarg; break; case 'p': - if (psxrules == NULL) - psxrules = optarg; - else { - fprintf(stderr, - _("%s: More than one -p option" - " specified\n"), - progname); - return EXIT_FAILURE; - } + if (psxrules) + duplicate_options("-p"); + psxrules = optarg; break; case 't': - if (tzdefault != NULL) { - fprintf(stderr, - _("%s: More than one -t option" - " specified\n"), - progname); - return EXIT_FAILURE; - } + if (tzdefault) + duplicate_options("-t"); tzdefault = optarg; break; case 'y': warning(_("-y ignored")); break; case 'L': - if (leapsec == NULL) - leapsec = optarg; - else { - fprintf(stderr, - _("%s: More than one -L option" - " specified\n"), - progname); - return EXIT_FAILURE; - } + if (leapsec) + duplicate_options("-L"); + leapsec = optarg; break; case 'v': noise = true; break; case 'r': - if (timerange_given) { - fprintf(stderr, - _("%s: More than one -r option" - " specified\n"), - progname); - return EXIT_FAILURE; - } + if (timerange_given) + duplicate_options("-r"); if (! timerange_option(optarg)) { fprintf(stderr, _("%s: invalid time range: %s\n"), -- 2.48.1

1 1

South Africa Daylight Saving Time
by Saras Sing Oct. 21, 2025

Oct. 21, 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 March South African Daylight Saving Time starts at every first Sunday of September from GMT/UTC+02:00 00:00 to 01:00 to GMT/UTC+03:00 South African Daylight Saving Time ends at every last Sunday of March from GMT/UTC+03:00 01:00 to 00:00 back to South Africa Standard Time GMT/UTC+02:00 Thank you

5 4

[PROPOSED 1/3] zic now uses is_digit
by Paul Eggert Oct. 18, 2025

Oct. 18, 2025

Refactor zic.c to use is_digit like others use. * zic.c (is_digit): New static function, copied from localtime.c and from zdump.c. It’s too bad we can’t avoid duplication by putting this into private.h, because gcc -Wunused-function would then complain about it. Perhaps ‘inline’ would pacify gcc but then we’d have to port ‘inline’ to ancient compilers and anyway ‘inline’ is supposed to be just a performance hint which is not needed here. --- zic.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/zic.c b/zic.c index 39e1e2bc..30426621 100644 --- a/zic.c +++ b/zic.c @@ -229,6 +229,13 @@ static bool rulesub(struct rule * rp, const char * dayp, const char * timep); static zic_t tadd(zic_t t1, zic_t t2); +/* Is C an ASCII digit? */ +static bool +is_digit(char c) +{ + return '0' <= c && c <= '9'; +} + /* Bound on length of what %z can expand to. */ enum { PERCENT_Z_LEN_BOUND = sizeof "+995959" - 1 }; @@ -1852,7 +1859,7 @@ gethms(char const *string, char const *errstring) &hh, &hhx, &mm, &mmx, &ss, &ssx, &tenths, &xr, &xs)) { default: ok = false; break; case 8: - ok = '0' <= xr && xr <= '9'; + ok = is_digit(xr); ATTRIBUTE_FALLTHROUGH; case 7: ok &= ssx == '.'; @@ -3952,7 +3959,7 @@ newabbr(const char *string) cp = string; mp = NULL; - while (is_alpha(*cp) || ('0' <= *cp && *cp <= '9') + while (is_alpha(*cp) || is_digit(*cp) || *cp == '-' || *cp == '+') ++cp; if (noise && cp - string < 3) -- 2.51.0

1 2

[PROPOSED] New compile-time option THREAD_TM_MULTI
by Paul Eggert Oct. 14, 2025

Oct. 14, 2025

* Makefile, NEWS: Mention it. * localtime.c (THREAD_TM_MULTI): Default to 0. The remaining changes affect only the THREAD_TM_MULTI case. (enum tm_multi): New enum. (N_TM_MULTI): New constant. (tm_multi_key, tm_multi_key_err): New static vars. (tm_multi): New static function. (localtime, gmtime, offtime): Use it. --- Makefile | 8 ++++++++ NEWS | 9 +++++++++ localtime.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++--- 3 files changed, 70 insertions(+), 3 deletions(-) diff --git a/Makefile b/Makefile index 8939869a..b172542a 100644 --- a/Makefile +++ b/Makefile @@ -316,6 +316,14 @@ LDLIBS= # This can improve paralellism and thus save real time # if many threads call tzcode functions simultaneously. # It also costs CPU time and thus energy. +# -DTHREAD_TM_MULTI to have gmtime, localtime, and offtime +# return different struct tm * addresses in different threads. +# This supports unportable programs that call +# gmtime/localtime/offtime when they should call +# gmtime_r/localtime_r/offtime_r to avoid races. +# Because the corresponding storage is freed on thread exit, +# this option is incompatible with POSIX.1-2024 and earlier. +# It also costs CPU time and memory. # -Dtime_tz=\"T\" to use T as the time_t type, rather than the system time_t # This is intended for internal use only; it mangles external names. # -DTZ_CHANGE_INTERVAL=N if functions depending on TZ should check diff --git a/NEWS b/NEWS index 5bfb7bb4..46bf48ed 100644 --- a/NEWS +++ b/NEWS @@ -80,6 +80,15 @@ Unreleased, experimental changes rarely changing and many threads call tzcode simultaneously. It costs more CPU time and energy. + The new CFLAGS option -TTHREAD_TM_MULTI causes localtime to return + a pointer to thread-specific memory, as FreeBSD does, instead of + to the same memory in all threads. This supports unportable + programs that incorrectly use localtime instead of localtime_r. + This option affects gmtime and offtime similarly to localtime. + Because the corresponding storage is freed on thread exit, this + option is incompatible with POSIX.1-2024 and earlier. It also + costs CPU time and memory. + tzcode now uses mempcpy if available, guessing its availability. Compile with -DHAVE_MEMPCPY=1 or 0 to override the guess. diff --git a/localtime.c b/localtime.c index 1191f810..709b954c 100644 --- a/localtime.c +++ b/localtime.c @@ -52,6 +52,10 @@ struct stat { char st_ctime, st_dev, st_ino; } # define THREAD_RWLOCK 0 #endif +#ifndef THREAD_TM_MULTI +# define THREAD_TM_MULTI 0 +#endif + #if THREAD_SAFE # include <pthread.h> @@ -171,6 +175,52 @@ once(once_t *once_control, void (*init_routine)(void)) #endif } +enum tm_multi { LOCALTIME_TM_MULTI, GMTIME_TM_MULTI, OFFTIME_TM_MULTI }; + +#if THREAD_SAFE && THREAD_TM_MULTI + +enum { N_TM_MULTI = OFFTIME_TM_MULTI + 1 }; +static pthread_key_t tm_multi_key; +static int tm_multi_key_err; + +static void +tm_multi_key_init(void) +{ + tm_multi_key_err = pthread_key_create(&tm_multi_key, free); +} + +#endif + +/* Return TMP, or a thread-specific struct tm * selected by WHICH. */ +static struct tm * +tm_multi(struct tm *tmp, ATTRIBUTE_MAYBE_UNUSED enum tm_multi which) +{ +#if THREAD_SAFE && THREAD_TM_MULTI + /* It is OK to check is_threaded() separately here; even if it + returns a different value in other places in the caller, + this function's behavior is still valid. */ + if (is_threaded()) { + /* Try to get a thread-specific struct tm *. + Fall back on TMP if this fails. */ + static pthread_once_t tm_multi_once = PTHREAD_ONCE_INIT; + pthread_once(&tm_multi_once, tm_multi_key_init); + if (!tm_multi_key_err) { + struct tm *p = pthread_getspecific(tm_multi_key); + if (!p) { + p = malloc(N_TM_MULTI * sizeof *p); + if (p && pthread_setspecific(tm_multi_key, p) != 0) { + free(p); + p = NULL; + } + } + if (p) + return &p[which]; + } + } +#endif + return tmp; +} + /* Unless intptr_t is missing, pacify gcc -Wcast-qual on char const * exprs. Use this carefully, as the casts disable type checking. This is a macro so that it can be used in static initializers. */ @@ -2156,7 +2206,7 @@ localtime(const time_t *timep) # if !SUPPORT_C89 static struct tm tm; # endif - return localtime_tzset(timep, &tm, true); + return localtime_tzset(timep, tm_multi(&tm, LOCALTIME_TM_MULTI), true); } struct tm * @@ -2208,7 +2258,7 @@ gmtime(const time_t *timep) # if !SUPPORT_C89 static struct tm tm; # endif - return gmtime_r(timep, &tm); + return gmtime_r(timep, tm_multi(&tm, GMTIME_TM_MULTI)); } # if STD_INSPIRED @@ -2229,7 +2279,7 @@ offtime(time_t const *timep, long offset) # if !SUPPORT_C89 static struct tm tm; # endif - return offtime_r(timep, offset, &tm); + return offtime_r(timep, offset, tm_multi(&tm, OFFTIME_TM_MULTI)); } # endif -- 2.48.1

1 0

[PROPOSED 1/3] Define fullname only if needed
by Paul Eggert Oct. 14, 2025

Oct. 14, 2025

* localtime.c (union local_storage): Define fullname member only if needed. This saves space on unlikely platforms where sizeof (struct file_analysis) < PATH_MAX, and is closer to FreeBSD. (tzloadbody): Mention fullname only if declared. --- localtime.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/localtime.c b/localtime.c index a78962a6..c9836b2d 100644 --- a/localtime.c +++ b/localtime.c @@ -771,7 +771,7 @@ union local_storage { struct state st; } u; -#ifdef PATH_MAX +#if defined PATH_MAX && !OPENAT_TZDIR && !SUPPRESS_TZDIR /* The name of the file to be opened. */ char fullname[PATH_MAX]; #endif @@ -890,7 +890,7 @@ tzloadbody(char const *name, struct state *sp, char tzloadflags, cp = mempcpy(lsp, tzdirslash, tzdirslashlen); cp = mempcpy(cp, name, namelen); *cp = '\0'; -#ifdef PATH_MAX +#if defined PATH_MAX && !OPENAT_TZDIR && !SUPPRESS_TZDIR name = lsp->fullname; #else name = (char *) lsp; -- 2.48.1

1 2

[PROPOSED 1/2] Simplify function parameter decl style
by Paul Eggert Oct. 14, 2025

Oct. 14, 2025

* localtime.c (time2sub, time2, time1): Use simpler style for declaring function parameters. Although this style has worked since C89, I didn’t know about it until reading Jens Gustedt’s book Modern C. Switching to this style now can simplify future future changes that also use a functional programming style. --- localtime.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/localtime.c b/localtime.c index 63b8ea0a..24972b20 100644 --- a/localtime.c +++ b/localtime.c @@ -2442,8 +2442,8 @@ mktmcpy(struct tm *dest, struct tm const *src) static time_t time2sub(struct tm *const tmp, - struct tm *(*funcp)(struct state const *, time_t const *, - int_fast32_t, struct tm *), + struct tm *funcp(struct state const *, time_t const *, + int_fast32_t, struct tm *), struct state const *sp, const int_fast32_t offset, bool *okayp, @@ -2661,8 +2661,8 @@ label: static time_t time2(struct tm * const tmp, - struct tm *(*funcp)(struct state const *, time_t const *, - int_fast32_t, struct tm *), + struct tm *funcp(struct state const *, time_t const *, + int_fast32_t, struct tm *), struct state const *sp, const int_fast32_t offset, bool *okayp) @@ -2680,8 +2680,8 @@ time2(struct tm * const tmp, static time_t time1(struct tm *const tmp, - struct tm *(*funcp)(struct state const *, time_t const *, - int_fast32_t, struct tm *), + struct tm *funcp(struct state const *, time_t const *, + int_fast32_t, struct tm *), struct state const *sp, const int_fast32_t offset) { -- 2.48.1

1 1

[PROPOSED] Port recent PATH_MAX change to strict C23
by Paul Eggert Oct. 14, 2025

Oct. 14, 2025

* localtime.c (tzdirslashlen): Now an enum, not a const size_t, as strict C23 requires this for the static_assert that uses tzdirslashlen when PATH_MAX is defined. --- localtime.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/localtime.c b/localtime.c index 3f3bdce5..ec13ed71 100644 --- a/localtime.c +++ b/localtime.c @@ -676,7 +676,7 @@ union input_buffer { ATTRIBUTE_NONSTRING #endif static char const tzdirslash[sizeof TZDIR + OPENAT_TZDIR] = TZDIR "/"; -static size_t const tzdirslashlen = sizeof TZDIR; +enum { tzdirslashlen = sizeof TZDIR }; /* Local storage needed for 'tzloadbody'. */ union local_storage { -- 2.48.1

3 5

[PROPOSED 1/2] Optionally use read-write locks instead of mutexes
by Paul Eggert Oct. 13, 2025

Oct. 13, 2025

This avoids bottlenecks when many threads access local time but no thread is changing TZ. It costs CPU time and energy. * Makefile, NEWS: Mention this. * localtime.c (THREAD_RWLOCK): New macro, defaulting to 0. (locallock) [THREAD_RWLOCK]: Now of type pthread_rwlock_t, not pthread_mutex_t. All uses changed. (rd2wrlock): New function. (tzset_unlocked): If THREAD_RWLOCK, upgrade the read lock to a write lock if needed. (tzset_unlocked, gmtcheck): Upgrade the read to a write lock in the unlikely case where writing is needed. --- Makefile | 5 +++ NEWS | 5 +++ localtime.c | 100 +++++++++++++++++++++++++++++++++++++--------------- 3 files changed, 82 insertions(+), 28 deletions(-) diff --git a/Makefile b/Makefile index 85c2c50b..c2c82c3a 100644 --- a/Makefile +++ b/Makefile @@ -304,6 +304,11 @@ LDLIBS= # -DTHREAD_SAFE to make localtime.c thread-safe, as POSIX requires; # not needed by the main-program tz code, which is single-threaded. # Append other compiler flags as needed, e.g., -pthread on GNU/Linux. +# The following option can also be used: +# -DTHREAD_RWLOCK to use read-write locks intead of mutexes. +# This can improve paralellism and thus save real time +# if many threads call tzcode functions simultaneously. +# It also costs CPU time and thus energy. # -Dtime_tz=\"T\" to use T as the time_t type, rather than the system time_t # This is intended for internal use only; it mangles external names. # -DTZ_CHANGE_INTERVAL=N if functions depending on TZ should check diff --git a/NEWS b/NEWS index 64d9336d..8ba97ab4 100644 --- a/NEWS +++ b/NEWS @@ -68,6 +68,11 @@ Unreleased, experimental changes transition begun in release 96k, which removed spaces in tzdata because the spaces break time string parsers. + The new CFLAGS option -DTHREAD_RWLOCK uses read-write locks, as + macOS does, instead of mutexes. This saves real time when TZ is + rarely changing and many threads call tzcode simultaneously. + It costs more CPU time and energy. + tzcode now uses mempcpy if available, guessing its availability. Compile with -DHAVE_MEMPCPY=1 or 0 to override the guess. diff --git a/localtime.c b/localtime.c index ec13ed71..3a38ef04 100644 --- a/localtime.c +++ b/localtime.c @@ -44,16 +44,39 @@ struct stat { char st_ctime, st_dev, st_ino; } # define st_ctim st_ctimespec #endif +#ifndef THREAD_RWLOCK +# define THREAD_RWLOCK 0 +#endif + #if defined THREAD_SAFE && THREAD_SAFE # include <pthread.h> +# if THREAD_RWLOCK +static pthread_rwlock_t locallock = PTHREAD_RWLOCK_INITIALIZER; +static int lock(void) { return pthread_rwlock_rdlock(&locallock); } +static void unlock(void) { pthread_rwlock_unlock(&locallock); } +# else static pthread_mutex_t locallock = PTHREAD_MUTEX_INITIALIZER; static int lock(void) { return pthread_mutex_lock(&locallock); } static void unlock(void) { pthread_mutex_unlock(&locallock); } +# endif #else static int lock(void) { return 0; } static void unlock(void) { } #endif +/* Upgrade a read lock to a write lock. + Return 0 on success, an errno value otherwise. */ +static int +rd2wrlock(void) +{ +# if THREAD_RWLOCK + unlock(); + return pthread_rwlock_wrlock(&locallock); +# else + return 0; +# endif +} + /* Unless intptr_t is missing, pacify gcc -Wcast-qual on char const * exprs. Use this carefully, as the casts disable type checking. This is a macro so that it can be used in static initializers. */ @@ -1733,38 +1756,55 @@ zoneinit(struct state *sp, char const *name, char tzloadflags) } /* Like tzset(), but in a critical section. + If THREAD_RWLOCK the caller has a read lock, + and this function might ugrade it to a write lock. If tz_change_interval is positive the time is NOW; otherwise ignore NOW. */ static void tzset_unlocked(monotime_t now) { - char const *name = getenv("TZ"); - struct state *sp = lclptr; - char tzloadflags = TZLOAD_FROMENV | TZLOAD_TZSTRING; - size_t namelen = sizeof lcl_TZname + 1; /* placeholder for no name */ - - if (name) { - namelen = strnlen(name, sizeof lcl_TZname); - - /* Abbreviate a string like "/usr/share/zoneinfo/America/Los_Angeles" - to its shorter equivalent "America/Los_Angeles". */ - if (!SUPPRESS_TZDIR && tzdirslashlen < namelen - && memcmp(name, tzdirslash, tzdirslashlen) == 0) { - char const *p = name + tzdirslashlen; - while (*p == '/') - p++; - if (*p && *p != ':') { - name = p; - namelen = strnlen(name, sizeof lcl_TZname); - tzloadflags |= TZLOAD_TZDIR_SUB; + char const *name; + struct state *sp; + char tzloadflags; + size_t namelen; + bool writing = false; + + for (;;) { + name = getenv("TZ"); + sp = lclptr; + tzloadflags = TZLOAD_FROMENV | TZLOAD_TZSTRING; + namelen = sizeof lcl_TZname + 1; /* placeholder for no name */ + + if (name) { + namelen = strnlen(name, sizeof lcl_TZname); + + /* Abbreviate a string like "/usr/share/zoneinfo/America/Los_Angeles" + to its shorter equivalent "America/Los_Angeles". */ + if (!SUPPRESS_TZDIR && tzdirslashlen < namelen + && memcmp(name, tzdirslash, tzdirslashlen) == 0) { + char const *p = name + tzdirslashlen; + while (*p == '/') + p++; + if (*p && *p != ':') { + name = p; + namelen = strnlen(name, sizeof lcl_TZname); + tzloadflags |= TZLOAD_TZDIR_SUB; + } } } + + if ((tz_change_interval <= 0 ? tz_change_interval < 0 : fresh_tzdata(now)) + && (name + ? 0 < lcl_is_set && strcmp(lcl_TZname, name) == 0 + : lcl_is_set < 0)) + return; + + if (!THREAD_RWLOCK || writing) + break; + if (rd2wrlock() != 0) + return; + writing = true; } - if ((tz_change_interval <= 0 ? tz_change_interval < 0 : fresh_tzdata(now)) - && (name - ? 0 < lcl_is_set && strcmp(lcl_TZname, name) == 0 - : lcl_is_set < 0)) - return; # if ALL_STATE if (! sp) lclptr = sp = malloc(sizeof *lclptr); @@ -1829,12 +1869,16 @@ gmtcheck(void) if (lock() != 0) return; if (! gmt_is_set) { + if (rd2wrlock() != 0) + return; + if (!THREAD_RWLOCK || !gmt_is_set) { #if ALL_STATE - gmtptr = malloc(sizeof *gmtptr); + gmtptr = malloc(sizeof *gmtptr); #endif - if (gmtptr) - gmtload(gmtptr); - gmt_is_set = true; + if (gmtptr) + gmtload(gmtptr); + gmt_is_set = true; + } } unlock(); } -- 2.51.0

1 1

[PROPOSED] Port better to platforms lacking mempcpy
by Paul Eggert Oct. 13, 2025

Oct. 13, 2025

* private.h (mempcpy) [!HAVE_MEMPCPY]: Args are pointer to void, not pointer to char, for compatibility with glibc. --- private.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/private.h b/private.h index f6f12aa2..befa6db1 100644 --- a/private.h +++ b/private.h @@ -844,7 +844,7 @@ extern char **environ; #endif #if !HAVE_MEMPCPY static void * -mempcpy(char *restrict s1, char const *restrict s2, size_t n) +mempcpy(void *restrict s1, void const *restrict s2, size_t n) { char *p = memcpy(s1, s2, n); return p + n; -- 2.51.0

1 0

[PROPOSED 1/3] tzset sets errno if lock fails
by Paul Eggert Oct. 10, 2025

Oct. 10, 2025

* localtime.c (tzset): Set errno if the lock fails. This should never happen, but if it does the least we can do is set errno, as other functions do. --- localtime.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/localtime.c b/localtime.c index 54db0ab7..ef094560 100644 --- a/localtime.c +++ b/localtime.c @@ -1788,8 +1788,11 @@ void tzset(void) { monotime_t now = get_monotonic_time(); - if (lock() != 0) + int err = lock(); + if (err != 0) { + errno = err; return; + } tzset_unlocked(now); unlock(); } -- 2.51.0

1 3

[PROPOSED 1/2] Simplify port to NetBSD struct __state
by Paul Eggert Oct. 8, 2025

Oct. 8, 2025

NetBSD uses ‘struct __state’ where tzcode uses ‘struct state’. tzcode 2014g worked around this by a tricky #define and #undef of the relevant names. However, as I recall, this was motivated by an old compatibility issue as to whether the functions would take pointer-to-const or plain pointer. That issue has been resolved in favor of the latter (which is what NetBSD did all along, despite its attempt to do the former), so use a less-tricky workaround similar to what NetBSD libc is already using. * private.h (localtime_rz, mktime_z, posix2time_z, time2posix_z) (timezone_t, tzalloc, tzfree): Do not #define and #undef. (state) [NETBSD_INSPIRED && _NETBSD_SOURCE]: New macro. --- private.h | 28 +++++++--------------------- 1 file changed, 7 insertions(+), 21 deletions(-) diff --git a/private.h b/private.h index 23f1d9fb..4599d0b9 100644 --- a/private.h +++ b/private.h @@ -194,30 +194,15 @@ ** Nested includes */ -/* Avoid clashes with NetBSD by renaming NetBSD's declarations. - If defining the 'timezone' variable, avoid a clash with FreeBSD's +/* If defining the 'timezone' variable, avoid a clash with FreeBSD's 'timezone' function by renaming its declaration. */ -#define localtime_rz sys_localtime_rz -#define mktime_z sys_mktime_z -#define posix2time_z sys_posix2time_z -#define time2posix_z sys_time2posix_z #if defined USG_COMPAT && USG_COMPAT == 2 # define timezone sys_timezone #endif -#define timezone_t sys_timezone_t -#define tzalloc sys_tzalloc -#define tzfree sys_tzfree #include <time.h> -#undef localtime_rz -#undef mktime_z -#undef posix2time_z -#undef time2posix_z #if defined USG_COMPAT && USG_COMPAT == 2 # undef timezone #endif -#undef timezone_t -#undef tzalloc -#undef tzfree #include <stddef.h> @@ -920,15 +905,16 @@ time_t posix2time(time_t); #endif /* -** Define functions that are ABI compatible with NetBSD but have -** better prototypes. NetBSD 6.1.4 defines a pointer type timezone_t -** and labors under the misconception that 'const timezone_t' is a -** pointer to a constant. This use of 'const' is ineffective, so it -** is not done here. What we call 'struct state' NetBSD calls +** Define functions that are ABI compatible with NetBSD. +** What we call 'struct state' NetBSD calls ** 'struct __state', but this is a private name so it doesn't matter. */ #if NETBSD_INSPIRED +# ifdef _NETBSD_SOURCE +# define state __state +# else typedef struct state *timezone_t; +# endif struct tm *localtime_rz(timezone_t restrict, time_t const *restrict, struct tm *restrict); time_t mktime_z(timezone_t restrict, struct tm *restrict); -- 2.51.0

1 1

[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.

4 13

[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

1 0

[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

1 2

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

5 4

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

6 10