9fb22a3ec4
This is quite a large patch because we haven't updated for some time,
but the good news is that upstream is now thread-safe so a lot of our
changes go away in this update and the remaining diff is a lot smaller.
(Note that our whitespace still doesn't match upstream. I use diff -wub
to compare. Upstream doesn't even really have a consistent style. New
code seems to be two spaces, old code tabs.)
From the intervening changelogs (eliding the changes that only affected
the tools, which we don't use):
2014a:
An uninitialized-storage bug in 'localtime' has been fixed.
(Thanks to Logan Chien.)
2014b:
'zic' and 'localtime' no longer reject locations needing four
transitions per year for the forseeable future. (Thanks to Andrew
Main (Zefram).)
2014c:
<None>
2014d:
<None>
2014e:
<None>
2014f:
'localtime', 'mktime', etc. now use much less stack space if
ALL_STATE is defined. (Thanks to Elliott Hughes for reporting the
problem.)
Some lint has been removed when using GCC_DEBUG_FLAGS with GCC
4.9.0.
2014g:
Unless NETBSD_INSPIRED is defined to 0, the tz library now
supplies functions for creating and using objects that represent
time zones. The new functions are tzalloc, tzfree, localtime_rz,
mktime_z, and (if STD_INSPIRED is also defined) posix2time_z and
time2posix_z. They are intended for performance: for example,
localtime_rz (unlike localtime_r) is trivially thread-safe without
locking. (Thanks to Christos Zoulas for proposing NetBSD-inspired
functions, and to Alan Barrett and Jonathan Lennox for helping to
debug the change.)
If THREAD_SAFE is defined to 1, the tz library is now thread-safe.
Although not needed for tz's own applications, which are single-threaded,
this supports POSIX better if the tz library is used in multithreaded apps.
Some crashes have been fixed when zdump or the tz library is given
invalid or outlandish input.
The tz library no longer mishandles leap seconds on platforms with
unsigned time_t in time zones that lack ordinary transitions after 1970.
The tz code now attempts to infer TM_GMTOFF and TM_ZONE if not
already defined, to make it easier to configure on common platforms.
Define NO_TM_GMTOFF and NO_TM_ZONE to suppress this.
Unless the new macro UNINIT_TRAP is defined to 1, the tz code now
assumes that reading uninitialized memory yields garbage values
but does not cause other problems such as traps.
If TM_GMTOFF is defined and UNINIT_TRAP is 0, mktime is now
more likely to guess right for ambiguous time stamps near
transitions where tm_isdst does not change.
If HAVE_STRFTIME_L is defined to 1, the tz library now defines
strftime_l for compatibility with recent versions of POSIX.
Only the C locale is supported, though. HAVE_STRFTIME_L defaults
to 1 on recent POSIX versions, and to 0 otherwise.
tzselect -c now uses a hybrid distance measure that works better
in Africa. (Thanks to Alan Barrett for noting the problem.)
The C source code now ports to NetBSD when GCC_DEBUG_FLAGS is used,
or when time_tz is defined.
When HAVE_UTMPX_H is set the 'date' command now builds on systems
whose <utmpx.h> file does not define WTMPX_FILE, and when setting
the date it updates the wtmpx file if _PATH_WTMPX is defined.
This affects GNU/Linux and similar systems.
For easier maintenance later, some C code has been simplified,
some lint has been removed, and the code has been tweaked so that
plain 'make' is more likely to work.
The C type 'bool' is now used for boolean values, instead of 'int'.
The long-obsolete LOCALE_HOME code has been removed.
The long-obsolete 'gtime' function has been removed.
2014h:
The tz library's localtime and mktime functions now set tzname to a value
appropriate for the requested time stamp, and zdump now uses this
on platforms not defining TM_ZONE, fixing a 2014g regression.
(Thanks to Tim Parenti for reporting the problem.)
The tz library no longer sets tzname if localtime or mktime fails.
An access to uninitalized data has been fixed.
(Thanks to Jörg Richter for reporting the problem.)
When THREAD_SAFE is defined, the code ports to the C11 memory model.
A memory leak has been fixed if ALL_STATE and THREAD_SAFE are defined
and two threads race to initialize data used by gmtime-like functions.
(Thanks to Andy Heninger for reporting the problems.)
2014i:
The time-related library functions now set errno on failure,
and some crashes in the new tzalloc-related library functions
have been fixed. (Thanks to Christos Zoulas for reporting
most of these problems and for suggesting fixes.)
If USG_COMPAT is defined and the requested time stamp is
standard time, the tz library's localtime and mktime functions
now set the extern variable timezone to a value appropriate
for that time stamp; and similarly for ALTZONE, daylight
saving time, and the altzone variable. This change is a
companion to the tzname change in 2014h, and is designed to
make timezone and altzone more compatible with tzname.
The tz library's functions now set errno to EOVERFLOW if they
fail because the result cannot be represented. ctime and
ctime_r now return NULL and set errno when a time stamp is out
of range, rather than having undefined behavior.
Some bugs associated with the new 2014g functions have been
fixed. This includes a bug that largely incapacitated the new
functions time2posix_z and posix2time_z. (Thanks to Christos
Zoulas.) It also includes some uses of uninitialized
variables after tzalloc. The new code uses the standard type
'ssize_t', which the Makefile now gives porting advice about.
2014j:
<None>
2015a:
tzalloc now scrubs time zone abbreviations compatibly with the way
that tzset always has, by replacing invalid bytes with '_' and by
shortening too-long abbreviations.
2015b:
Fix integer overflow bug in reference 'mktime' implementation.
(Problem reported by Jörg Richter.)
Allow -Dtime_tz=time_t compilations, and allow -Dtime_tz=... libraries
to be used in the same executable as standard-library time_t functions.
(Problems reported by Bradley White.)
2015c:
<None>
2015d:
<None>
2015e:
<None>
2015f:
<None>
2015g:
localtime no longer mishandles America/Anchorage after 2037.
(Thanks to Bradley White for reporting the bug.)
On hosts with signed 32-bit time_t, localtime no longer mishandles
Pacific/Fiji after 2038-01-16 14:00 UTC.
The localtime module allows the variables 'timezone', 'daylight',
and 'altzone' to be in common storage shared with other modules,
and declares them in case the system <time.h> does not.
(Problems reported by Kees Dekker.)
On platforms with tm_zone, strftime.c now assumes it is not NULL.
This simplifies the code and is consistent with zdump.c.
(Problem reported by Christos Zoulas.)
Change-Id: I9eb0a8323cb8bd9968fcfe612dc14f45aa3b59d2
59 lines
1.4 KiB
C
59 lines
1.4 KiB
C
/*
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** This file is in the public domain, so clarified as of
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** 1996-06-05 by Arthur David Olson.
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*/
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/*LINTLIBRARY*/
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#include "private.h" /* for time_t and TYPE_SIGNED */
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/* Return -X as a double. Using this avoids casting to 'double'. */
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static double
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dminus(double x)
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{
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return -x;
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}
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double ATTRIBUTE_CONST
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difftime(time_t time1, time_t time0)
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{
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/*
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** If double is large enough, simply convert and subtract
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** (assuming that the larger type has more precision).
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*/
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if (sizeof (time_t) < sizeof (double)) {
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double t1 = time1, t0 = time0;
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return t1 - t0;
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}
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/*
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** The difference of two unsigned values can't overflow
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** if the minuend is greater than or equal to the subtrahend.
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*/
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if (!TYPE_SIGNED(time_t))
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return time0 <= time1 ? time1 - time0 : dminus(time0 - time1);
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/* Use uintmax_t if wide enough. */
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if (sizeof (time_t) <= sizeof (uintmax_t)) {
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uintmax_t t1 = time1, t0 = time0;
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return time0 <= time1 ? t1 - t0 : dminus(t0 - t1);
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}
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/*
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** Handle cases where both time1 and time0 have the same sign
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** (meaning that their difference cannot overflow).
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*/
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if ((time1 < 0) == (time0 < 0))
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return time1 - time0;
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/*
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** The values have opposite signs and uintmax_t is too narrow.
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** This suffers from double rounding; attempt to lessen that
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** by using long double temporaries.
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*/
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{
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long double t1 = time1, t0 = time0;
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return t1 - t0;
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}
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}
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