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[PATCH 1/2] Be more consistent about macro true/false vs 1/0
by Paul Eggert Nov. 29, 2024

Nov. 29, 2024

* private.h (HAVE_GETTEXT, HAVE_SYS_STAT_H, HAVE_UNISTD_H) (HAVE_STDINT_H, HAVE_STRTOLL, HAVE_STDCKDINT_H) (HAVE_DECL_TIMEGM): * strftime.c (MKTIME_MIGHT_OVERFLOW, DEPRECATE_TWO_DIGIT_YEARS): Default to 1 or 0, not to true or false, since these can be set via the command line as per the Makefile. * private.h (TZ_TIME_T): Set to true or false, not to 1 or 0, since this is boolean and is not set via the command line. --- private.h | 26 +++++++++++++------------- strftime.c | 6 +++--- 2 files changed, 16 insertions(+), 16 deletions(-) diff --git a/private.h b/private.h index 6088d885..1e4e69a4 100644 --- a/private.h +++ b/private.h @@ -88,11 +88,11 @@ #if !defined HAVE_GETTEXT && defined __has_include # if __has_include(<libintl.h>) -# define HAVE_GETTEXT true +# define HAVE_GETTEXT 1 # endif #endif #ifndef HAVE_GETTEXT -# define HAVE_GETTEXT false +# define HAVE_GETTEXT 0 #endif #ifndef HAVE_INCOMPATIBLE_CTIME_R @@ -125,20 +125,20 @@ #if !defined HAVE_SYS_STAT_H && defined __has_include # if !__has_include(<sys/stat.h>) -# define HAVE_SYS_STAT_H false +# define HAVE_SYS_STAT_H 0 # endif #endif #ifndef HAVE_SYS_STAT_H -# define HAVE_SYS_STAT_H true +# define HAVE_SYS_STAT_H 1 #endif #if !defined HAVE_UNISTD_H && defined __has_include # if !__has_include(<unistd.h>) -# define HAVE_UNISTD_H false +# define HAVE_UNISTD_H 0 # endif #endif #ifndef HAVE_UNISTD_H -# define HAVE_UNISTD_H true +# define HAVE_UNISTD_H 1 #endif #ifndef NETBSD_INSPIRED @@ -312,7 +312,7 @@ ** stdint.h, even with pre-C99 compilers. */ #if !defined HAVE_STDINT_H && defined __has_include -# define HAVE_STDINT_H true /* C23 __has_include implies C99 stdint.h. */ +# define HAVE_STDINT_H 1 /* C23 __has_include implies C99 stdint.h. */ #endif #ifndef HAVE_STDINT_H # define HAVE_STDINT_H \ @@ -386,7 +386,7 @@ typedef int int_fast32_t; # ifdef LLONG_MAX typedef long long intmax_t; # ifndef HAVE_STRTOLL -# define HAVE_STRTOLL true +# define HAVE_STRTOLL 1 # endif # if HAVE_STRTOLL # define strtoimax strtoll @@ -466,7 +466,7 @@ typedef unsigned long uintmax_t; hosts, unless compiled with -DHAVE_STDCKDINT_H=0 or with pre-C23 EDG. */ #if !defined HAVE_STDCKDINT_H && defined __has_include # if __has_include(<stdckdint.h>) -# define HAVE_STDCKDINT_H true +# define HAVE_STDCKDINT_H 1 # endif #endif #ifdef HAVE_STDCKDINT_H @@ -634,9 +634,9 @@ typedef unsigned long uintmax_t; ** typical platforms. */ #if defined time_tz || EPOCH_LOCAL || EPOCH_OFFSET != 0 -# define TZ_TIME_T 1 +# define TZ_TIME_T true #else -# define TZ_TIME_T 0 +# define TZ_TIME_T false #endif #if defined LOCALTIME_IMPLEMENTATION && TZ_TIME_T @@ -753,9 +753,9 @@ void tzset(void); || defined __GLIBC__ || defined __tm_zone /* musl */ \ || defined __FreeBSD__ || defined __NetBSD__ || defined __OpenBSD__ \ || (defined __APPLE__ && defined __MACH__)) -# define HAVE_DECL_TIMEGM true +# define HAVE_DECL_TIMEGM 1 # else -# define HAVE_DECL_TIMEGM false +# define HAVE_DECL_TIMEGM 0 # endif #endif #if !HAVE_DECL_TIMEGM && !defined timegm diff --git a/strftime.c b/strftime.c index fc0c87d2..487a5234 100644 --- a/strftime.c +++ b/strftime.c @@ -79,9 +79,9 @@ !defined __NetBSD_Version__ || __NetBSD_Version__ < 600000000) \ && (/* OpenBSD 5.5 (2014-05-01) and later has 64-bit time_t. */ \ !defined OpenBSD || OpenBSD < 201405))) -# define MKTIME_MIGHT_OVERFLOW true +# define MKTIME_MIGHT_OVERFLOW 1 # else -# define MKTIME_MIGHT_OVERFLOW false +# define MKTIME_MIGHT_OVERFLOW 0 # endif #endif /* Check that MKTIME_MIGHT_OVERFLOW is consistent with time_t's range. */ @@ -95,7 +95,7 @@ static_assert(MKTIME_MIGHT_OVERFLOW #endif #ifndef DEPRECATE_TWO_DIGIT_YEARS -# define DEPRECATE_TWO_DIGIT_YEARS false +# define DEPRECATE_TWO_DIGIT_YEARS 0 #endif struct lc_time_T { -- 2.43.0

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[PROPOSED 1/2] Remove dependency of asctime on strftime
by Paul Eggert Nov. 28, 2024

Nov. 28, 2024

Also, remove calls to strlen and strcpy. * asctime.c (ASCTIME_FMT, ASCTIME_FMT_B): Remove; the strings are now merely literals in asctime_r. (SNPRINTF, SNPRINTFBUF): New macros. (asctime_r): Do not call strftime %Y, as this is dicey when tm_year is not a value that could be yielded by localtime. Instead, use snprintf, or sprintf on ancient hosts lacking snprintf. Also, rely on snprintf/sprintf's return value instead of calling strlen, as it's safe to assume C89 b6 now. If snprintf is available, output to the result buffer directly instead of to the stack and then copying. This saves one call to strftime, two calls to strlen, and one call to strcpy. * private.h (HAVE_SNPRINTF): Move here ... * zdump.c: ... from here. --- asctime.c | 96 +++++++++++++++++++++++++++++++------------------------ private.h | 4 +++ zdump.c | 4 --- 3 files changed, 58 insertions(+), 46 deletions(-) diff --git a/asctime.c b/asctime.c index f75ec868..7bc19fd1 100644 --- a/asctime.c +++ b/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 @@ -84,8 +64,20 @@ 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; + size_t bufsize = ((buf == buf_ctime + || (!SUPPORT_C89 && buf == buf_asctime)) + ? sizeof buf_asctime : STD_ASCTIME_BUF_SIZE); +#if HAVE_SNPRINTF + char *result = buf; +# define SNPRINTF snprintf +# define SNPRINTFBUF(buf, bufsize) buf, bufsize +#else + char stackbuf[sizeof buf_asctime]; + char *result = stackbuf; +# define SNPRINTF sprintf +# define SNPRINTFBUF(buf, bufsize) buf +#endif if (timeptr == NULL) { errno = EINVAL; @@ -97,26 +89,46 @@ asctime_r(struct tm const *restrict timeptr, char *restrict buf) 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) + + 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 <= INT_MAX - TM_YEAR_BASE + ? SNPRINTF (SNPRINTFBUF(result, bufsize), + ((-999 - TM_YEAR_BASE <= year + && year <= 9999 - TM_YEAR_BASE) + ? "%s %s%3d %.2d:%.2d:%.2d %04d\n" + : "%s %s%3d %.2d:%.2d:%.2d %d\n"), + wn, mn, mday, hour, min, sec, + year + TM_YEAR_BASE) + : SNPRINTF (SNPRINTFBUF(result, 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) { +#if HAVE_SNPRINTF + return buf; +#else return strcpy(buf, result); - else { +#endif + } else { errno = EOVERFLOW; return NULL; } diff --git a/private.h b/private.h index da6dc790..6088d885 100644 --- a/private.h +++ b/private.h @@ -263,6 +263,10 @@ # endif #endif +#ifndef HAVE_SNPRINTF +# define HAVE_SNPRINTF (!PORT_TO_C89 || 199901 <= __STDC_VERSION__) +#endif + #ifndef HAVE_STRFTIME_L # if _POSIX_VERSION < 200809 # define HAVE_STRFTIME_L 0 diff --git a/zdump.c b/zdump.c index 2c6725e5..c988f6b3 100644 --- a/zdump.c +++ b/zdump.c @@ -14,10 +14,6 @@ #include "private.h" #include <stdio.h> -#ifndef HAVE_SNPRINTF -# define HAVE_SNPRINTF (!PORT_TO_C89 || 199901 <= __STDC_VERSION__) -#endif - #ifndef HAVE_LOCALTIME_R # define HAVE_LOCALTIME_R 1 #endif -- 2.43.0

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[PROPOSED 1/2] Move MKTIME_MIGHT_OVERFLOW definition
by Paul Eggert Nov. 27, 2024

Nov. 27, 2024

* private.h (MKTIME_FITS_IN, MKTIME_MIGHT_OVERFLOW): Move definitions from here ... * strftime.c: ... to here, as it’s the only file needing them. --- private.h | 49 ------------------------------------------------- strftime.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 49 insertions(+), 49 deletions(-) diff --git a/private.h b/private.h index fc0b8755..95ab2e1d 100644 --- a/private.h +++ b/private.h @@ -914,55 +914,6 @@ enum { SIGNED_PADDING_CHECK_NEEDED = true }; static_assert(! TYPE_SIGNED(time_t) || ! SIGNED_PADDING_CHECK_NEEDED || TIME_T_MAX >> (TYPE_BIT(time_t) - 2) == 1); -/* If true, the value returned by an idealized unlimited-range mktime - always fits into an integer type with bounds MIN and MAX. - If false, the value might not fit. - This macro is usable in #if if its arguments are. - Add or subtract 2**31 - 1 for the maximum UT offset allowed in a TZif file, - divide by the maximum number of non-leap seconds in a year, - divide again by two just to be safe, - and account for the tm_year origin (1900) and time_t origin (1970). */ -#define MKTIME_FITS_IN(min, max) \ - ((min) < 0 \ - && ((min) + 0x7fffffff) / 366 / 24 / 60 / 60 / 2 + 1970 - 1900 < INT_MIN \ - && INT_MAX < ((max) - 0x7fffffff) / 366 / 24 / 60 / 60 / 2 + 1970 - 1900) - -/* MKTIME_MIGHT_OVERFLOW is true if mktime can fail due to time_t overflow - or if it is not known whether mktime can fail, - and is false if mktime definitely cannot fail. - This macro is usable in #if, and so does not use TIME_T_MAX or sizeof. - If the builder has not configured this macro, guess based on what - known platforms do. When in doubt, guess true. */ -#ifndef MKTIME_MIGHT_OVERFLOW -# if defined __FreeBSD__ || defined __NetBSD__ || defined __OpenBSD__ -# include <sys/param.h> -# endif -# if ((/* The following heuristics assume native time_t. */ \ - defined_time_tz) \ - || ((/* Traditional time_t is 'long', so if 'long' is not wide enough \ - assume overflow unless we're on a known-safe host. */ \ - !MKTIME_FITS_IN(LONG_MIN, LONG_MAX)) \ - && (/* GNU C Library 2.29 (2019-02-01) and later has 64-bit time_t \ - if __TIMESIZE is 64. */ \ - !defined __TIMESIZE || __TIMESIZE < 64) \ - && (/* FreeBSD 12 r320347 (__FreeBSD_version 1200036; 2017-06-26), \ - and later has 64-bit time_t on all platforms but i386 which \ - is currently scheduled for end-of-life on 2028-11-30. */ \ - !defined __FreeBSD_version || __FreeBSD_version < 1200036 \ - || defined __i386) \ - && (/* NetBSD 6.0 (2012-10-17) and later has 64-bit time_t. */ \ - !defined __NetBSD_Version__ || __NetBSD_Version__ < 600000000) \ - && (/* OpenBSD 5.5 (2014-05-01) and later has 64-bit time_t. */ \ - !defined OpenBSD || OpenBSD < 201405))) -# define MKTIME_MIGHT_OVERFLOW true -# else -# define MKTIME_MIGHT_OVERFLOW false -# endif -#endif -/* Check that MKTIME_MIGHT_OVERFLOW is consistent with time_t's range. */ -static_assert(MKTIME_MIGHT_OVERFLOW - || MKTIME_FITS_IN(TIME_T_MIN, TIME_T_MAX)); - /* ** 302 / 1000 is log10(2.0) rounded up. ** Subtract one for the sign bit if the type is signed; diff --git a/strftime.c b/strftime.c index 7be94de3..fc0c87d2 100644 --- a/strftime.c +++ b/strftime.c @@ -39,6 +39,55 @@ #include <locale.h> #include <stdio.h> +/* If true, the value returned by an idealized unlimited-range mktime + always fits into an integer type with bounds MIN and MAX. + If false, the value might not fit. + This macro is usable in #if if its arguments are. + Add or subtract 2**31 - 1 for the maximum UT offset allowed in a TZif file, + divide by the maximum number of non-leap seconds in a year, + divide again by two just to be safe, + and account for the tm_year origin (1900) and time_t origin (1970). */ +#define MKTIME_FITS_IN(min, max) \ + ((min) < 0 \ + && ((min) + 0x7fffffff) / 366 / 24 / 60 / 60 / 2 + 1970 - 1900 < INT_MIN \ + && INT_MAX < ((max) - 0x7fffffff) / 366 / 24 / 60 / 60 / 2 + 1970 - 1900) + +/* MKTIME_MIGHT_OVERFLOW is true if mktime can fail due to time_t overflow + or if it is not known whether mktime can fail, + and is false if mktime definitely cannot fail. + This macro is usable in #if, and so does not use TIME_T_MAX or sizeof. + If the builder has not configured this macro, guess based on what + known platforms do. When in doubt, guess true. */ +#ifndef MKTIME_MIGHT_OVERFLOW +# if defined __FreeBSD__ || defined __NetBSD__ || defined __OpenBSD__ +# include <sys/param.h> +# endif +# if ((/* The following heuristics assume native time_t. */ \ + defined_time_tz) \ + || ((/* Traditional time_t is 'long', so if 'long' is not wide enough \ + assume overflow unless we're on a known-safe host. */ \ + !MKTIME_FITS_IN(LONG_MIN, LONG_MAX)) \ + && (/* GNU C Library 2.29 (2019-02-01) and later has 64-bit time_t \ + if __TIMESIZE is 64. */ \ + !defined __TIMESIZE || __TIMESIZE < 64) \ + && (/* FreeBSD 12 r320347 (__FreeBSD_version 1200036; 2017-06-26), \ + and later has 64-bit time_t on all platforms but i386 which \ + is currently scheduled for end-of-life on 2028-11-30. */ \ + !defined __FreeBSD_version || __FreeBSD_version < 1200036 \ + || defined __i386) \ + && (/* NetBSD 6.0 (2012-10-17) and later has 64-bit time_t. */ \ + !defined __NetBSD_Version__ || __NetBSD_Version__ < 600000000) \ + && (/* OpenBSD 5.5 (2014-05-01) and later has 64-bit time_t. */ \ + !defined OpenBSD || OpenBSD < 201405))) +# define MKTIME_MIGHT_OVERFLOW true +# else +# define MKTIME_MIGHT_OVERFLOW false +# endif +#endif +/* Check that MKTIME_MIGHT_OVERFLOW is consistent with time_t's range. */ +static_assert(MKTIME_MIGHT_OVERFLOW + || MKTIME_FITS_IN(TIME_T_MIN, TIME_T_MAX)); + #if MKTIME_MIGHT_OVERFLOW /* Do this after system includes as it redefines time_t, mktime, timeoff. */ # define USE_TIMEX_T true -- 2.47.0

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[PROPOSED 1/2] Pacify GCC 15ish -Wleading-whitespace=blanks
by Paul Eggert Nov. 27, 2024

Nov. 27, 2024

Normalize indentation in a few source files to pacify gcc -Wleading-whitespace=blanks (in the forthcoming GCC 15). --- localtime.c | 2 +- private.h | 2 +- zdump.c | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/localtime.c b/localtime.c index ea2a6fb8..e6d79d05 100644 --- a/localtime.c +++ b/localtime.c @@ -1770,7 +1770,7 @@ timesub(const time_t *timep, int_fast32_t offset, dayoff = offset / SECSPERDAY - corr / SECSPERDAY + rem / SECSPERDAY - 3; rem %= SECSPERDAY; /* y = (EPOCH_YEAR - + floor((tdays + dayoff) / DAYSPERREPEAT) * YEARSPERREPEAT), + + floor((tdays + dayoff) / DAYSPERREPEAT) * YEARSPERREPEAT), sans overflow. But calculate against 1570 (EPOCH_YEAR - YEARSPERREPEAT) instead of against 1970 so that things work for localtime values before 1970 when time_t is unsigned. */ diff --git a/private.h b/private.h index bdd00013..fc0b8755 100644 --- a/private.h +++ b/private.h @@ -897,7 +897,7 @@ ATTRIBUTE_PURE time_t time2posix_z(timezone_t, time_t); default: TIME_T_MAX_NO_PADDING) \ : (time_t) -1) enum { SIGNED_PADDING_CHECK_NEEDED - = _Generic((time_t) 0, + = _Generic((time_t) 0, signed char: false, short: false, int: false, long: false, long long: false, default: true) }; diff --git a/zdump.c b/zdump.c index b668022d..2c6725e5 100644 --- a/zdump.c +++ b/zdump.c @@ -687,7 +687,7 @@ yeartot(intmax_t y) return absolute_max_time; seconds = diff400 * SECSPER400YEARS; years = diff400 * 400; - } else { + } else { seconds = isleap(myy) ? SECSPERLYEAR : SECSPERNYEAR; years = 1; } -- 2.43.0

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New timezone Antarctica/Concordia (UTC+8)
by Erik Geletti Nov. 26, 2024

Nov. 26, 2024

Goodmorning. I'm writing here to propose a new time zone for an all-year open Antarctic base. The base is a French–Italian research facility that was built 3,233 m (10,607 ft) above sea level at a location called Dome C on the Antarctic Plateau, Antarctica. https://en.wikipedia.org/wiki/Concordia_Station The timezone is UTC+8 without DST. Best regards, Erik Geletti -- Erik Geletti Servizi Tecnici ed Informatici Istituto Nazionale di Oceanografia e di Geofisica Sperimentale - OGS Borgo Grotta Gigante n. 42/c 34010 Sgonico (Trieste) - Italia Tel. 0402140286 www.ogs.it

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[PROPOSED 1/2] Move iinntt definition
by Paul Eggert Nov. 24, 2024

Nov. 24, 2024

It’s used only in localtime.c, so move its definition there. * localtime.c (IINNTT_MIN, IINNTT_MAX, iinntt): Move to here ... * private.h: ... from here. --- localtime.c | 18 ++++++++++++++++++ private.h | 17 ----------------- 2 files changed, 18 insertions(+), 17 deletions(-) diff --git a/localtime.c b/localtime.c index 14c356e1..1d42fc36 100644 --- a/localtime.c +++ b/localtime.c @@ -29,6 +29,24 @@ static int lock(void) { return 0; } static void unlock(void) { } #endif +/* A signed type wider than int, so that we can add 1900 + tm_mon/12 to tm_year + without overflow. The static_assert checks that it is indeed wider + than int; if this fails on your platform please let us know. */ +#if INT_MAX < LONG_MAX +typedef long iinntt; +# define IINNTT_MIN LONG_MIN +# define IINNTT_MAX LONG_MAX +#elif INT_MAX < LLONG_MAX +typedef long long iinntt; +# define IINNTT_MIN LLONG_MIN +# define IINNTT_MAX LLONG_MAX +#else +typedef intmax_t iinntt; +# define IINNTT_MIN INTMAX_MIN +# define IINNTT_MAX INTMAX_MAX +#endif +static_assert(IINNTT_MIN < INT_MIN && INT_MAX < IINNTT_MAX); + /* On platforms where offtime or mktime might overflow, strftime.c defines USE_TIMEX_T to be true and includes us. This tells us to #define time_t to an internal type timex_t that is diff --git a/private.h b/private.h index 3a699f0f..bdd00013 100644 --- a/private.h +++ b/private.h @@ -450,23 +450,6 @@ typedef unsigned long uintmax_t; #endif /* PORT_TO_C89 */ -/* A signed type wider than int, so that we can add 1900 to tm_year - without overflow. */ -#if INT_MAX < LONG_MAX -typedef long iinntt; -# define IINNTT_MIN LONG_MIN -# define IINNTT_MAX LONG_MAX -#elif INT_MAX < LLONG_MAX -typedef long long iinntt; -# define IINNTT_MIN LLONG_MIN -# define IINNTT_MAX LLONG_MAX -#else -typedef intmax_t iinntt; -# define IINNTT_MIN INTMAX_MIN -# define IINNTT_MAX INTMAX_MAX -#endif -static_assert(IINNTT_MIN < INT_MIN && INT_MAX < IINNTT_MAX); - /* The maximum size of any created object, as a signed integer. Although the C standard does not outright prohibit larger objects, behavior is undefined if the result of pointer subtraction does not -- 2.43.0

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Re: [PROPOSED 4/6] Fix bug near the year 2**31 - 1 - 1900
by Paul Eggert Nov. 23, 2024

Nov. 23, 2024

On 2024-11-22 22:08, Magnus Fromreide wrote: > The definition of iinntt does not guarantee that it is wider than an int, > does something break if INT_MAX == INTMAX_MAX and INT_MIN == INTMAX_MIN? That's checked statically by "static_assert(IINNTT_MIN < INT_MIN && INT_MAX < IINNTT_MAX);". I don't know of any tzcode platform where that static assertion would fail (and thus break the build) because no signed type is wider than 'int'. If you know of one, please let us know.

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(unofficial) Australian Central Western Time
by Stuart Bishop Nov. 22, 2024

Nov. 22, 2024

An article discussing the in-use but technically unofficial timezones in the Western Australian portion of the Nullarbor Plain. https://www.abc.net.au/news/2024-11-22/outback-wa-properties-strange-time-z… -- Stuart Bishop <stuart(a)stuartbishop.net> http://www.stuartbishop.net/

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[PROPOSED] Avoid time_t + int overflow
by Paul Eggert Nov. 22, 2024

Nov. 22, 2024

* localtime.c (increment_overflow_time_int): New function. (time2sub): Use it (instead of relying on possibly-undefined behavior) to check for time_t + int overflow. --- localtime.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/localtime.c b/localtime.c index 07ce41b8..14c356e1 100644 --- a/localtime.c +++ b/localtime.c @@ -1882,6 +1882,21 @@ increment_overflow_iinntt(iinntt *lp, int m) #endif } +static bool +increment_overflow_time_int(time_t *tp, int j) +{ +#ifdef ckd_add + return ckd_add(tp, *tp, j); +#else + if (j < 0 + ? (TYPE_SIGNED(time_t) ? *tp < TIME_T_MIN - j : *tp <= -1 - j) + : TIME_T_MAX - j < *tp) + return true; + *tp += j; + return false; +#endif +} + static bool increment_overflow_time(time_t *tp, int_fast32_t j) { @@ -2155,10 +2170,8 @@ time2sub(struct tm *const tmp, return WRONG; } label: - newt = t + saved_seconds; - if ((newt < t) != (saved_seconds < 0)) + if (increment_overflow_time_int(&t, saved_seconds)) return WRONG; - t = newt; if (funcp(sp, &t, offset, tmp)) *okayp = true; return t; -- 2.47.0

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Dead code in strftime()?
by Tom Lane Nov. 22, 2024

Nov. 22, 2024

strftime() in the 2024b tzcode distribution includes if (!p) { errno = EOVERFLOW; return 0; } AFAICS this is dead code, except maybe in the case that the call passes s = NULL, maxsize = 0, which doesn't seem like a case that the code intends to support (and EOVERFLOW would be a rather odd choice of error code if that's the idea). newstrftime.3.txt offers a clue about the intent: This function may fail if: [EOVERFLOW] The format includes an %s conversion and the number of seconds since the Epoch cannot be represented in a time_t. But the %s conversion code never returns zero. There's a suggestive comment there: /* If mktime fails, %s expands to the value of (time_t) -1 as a failure marker; this is better in practice than strftime failing. */ So it looks to me like somebody changed the error handling in the %s stanza but didn't bother to remove the now-dead path in the caller nor update the man page. Am I missing something? regards, tom lane

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