path: root/src/time
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2016-10-06fix strftime %y for negative tm_yearSzabolcs Nagy-0/+1
2016-07-07fix asctime day/month names not to vary by localeRich Felker-5/+4
the FIXME comment here was overlooked at the time locale support was added.
2016-01-27improve clock_gettime and adapt it to support slightly-broken vdsoRich Felker-22/+39
these changes are motivated by a functionally similar patch by Hauke Mehrtens to address the needs of the new mips vdso clock_gettime, which wrongly fails with ENOSYS rather than falling back to making a syscall for clock ids it cannot handle from userspace. in the process of preparing to handle that case, it was noticed that the old clock_gettime use of the vdso was actually wrong with respect to error handling -- the tail call to the vdso function failed to set errno and instead returned an error code. since tail calls to vdso are no longer possible and since the plain syscall code is now needed as a fallback path anyway, it does not make sense to use a function pointer to call the plain syscall code path. instead, it's inlined at the end of the main clock_gettime function. the new code also avoids the need to test for initialization of the vdso function pointer by statically initializing it to a self-init function, and eliminates redundant loads from the volatile pointer object. finally, the use of a_cas_p on an object of type other than void *, which is not permitted aliasing, is replaced by using an object with the correct type and casting the value.
2015-10-14fix strftime handling of out-of-range struct tm fieldsRich Felker-8/+12
strftime results are unspecified in this case, but should not invoke undefined behaviour. tm_wday, tm_yday, tm_mon and tm_year fields were used in signed int arithmetic that could overflow. based on patch by Szabolcs Nagy.
2015-10-08fix integer overflows in time_t/struct tm conversion codeRich Felker-3/+3
as found and reported by Brian Mastenbrook, the expressions 400*qc_cycles and years+100 in __secs_to_tm were both subject to integer overflow for extreme values of the input t. this patch by Szabolcs Nagy fixes the code by switching to larger types, and matches the original intent I had in mind when writing this code.
2015-09-24avoid reading uninitialized memory in __map_fileSzabolcs Nagy-2/+3
The value of *size is not relevant in case of failure, but it's better not to copy garbage from the stack into it. (The compiler cannot see through the syscall, so optimization was not affected by the unspecified value).
2015-08-14match historical behavior for tm_gmtoff member of struct tmNatanael Copa-12/+12
tm_gmtoff is a nonstandard field, but on historical systems which have this field, it stores the offset of the local time zone from GMT or UTC. this is the opposite of the POSIX extern long timezone object and the offsets used in POSIX-form TZ strings, which represent the offset from local time to UTC. previously we were storing these negated offsets in tm_gmtoff too. programs which only used this field indirectly via strftime were not affected since strftime performed the negation for presentation. however, some programs and libraries accesse tm_gmtoff directly and were obtaining negated time zone offsets.
2015-07-06treat empty TZ environment variable as GMT rather than defaultRich Felker-1/+2
this improves compatibility with the behavior of other systems and with some applications which set an empty TZ var to disable use of local time by mktime, etc.
2015-03-03make all objects used with atomic operations volatileRich Felker-2/+2
the memory model we use internally for atomics permits plain loads of values which may be subject to concurrent modification without requiring that a special load function be used. since a compiler is free to make transformations that alter the number of loads or the way in which loads are performed, the compiler is theoretically free to break this usage. the most obvious concern is with atomic cas constructs: something of the form tmp=*p;a_cas(p,tmp,f(tmp)); could be transformed to a_cas(p,*p,f(*p)); where the latter is intended to show multiple loads of *p whose resulting values might fail to be equal; this would break the atomicity of the whole operation. but even more fundamental breakage is possible. with the changes being made now, objects that may be modified by atomics are modeled as volatile, and the atomic operations performed on them by other threads are modeled as asynchronous stores by hardware which happens to be acting on the request of another thread. such modeling of course does not itself address memory synchronization between cores/cpus, but that aspect was already handled. this all seems less than ideal, but it's the best we can do without mandating a C11 compiler and using the C11 model for atomics. in the case of pthread_once_t, the ABI type of the underlying object is not volatile-qualified. so we are assuming that accessing the object through a volatile-qualified lvalue via casts yields volatile access semantics. the language of the C standard is somewhat unclear on this matter, but this is an assumption the linux kernel also makes, and seems to be the correct interpretation of the standard.
2014-10-09fix handling of negative offsets in timezone spec stringsRich Felker-10/+7
previously, the hours were considered as a signed quantity while minutes and seconds were always treated as positive offsets. however, semantically the '-' sign should negate the whole hh:mm:ss offset. this bug only affected timezones east of GMT with non-whole-hours offsets, such as those used in India and Nepal.
2014-09-06add C11 timespec_get function, with associated time.h changes for C11Rich Felker-0/+12
based on patch by Jens Gustedt for inclusion with C11 threads implementation, but committed separately since it's independent of threads.
2014-07-02properly pass current locale to *_l functions when used internallyRich Felker-2/+4
this change is presently non-functional since the callees do not yet use their locale argument for anything.
2014-06-06use default timezone from /etc/localtime if $TZ is unset/blankRich Felker-2/+3
the way this is implemented, it also allows explicit setting of TZ=/etc/localtime even for suid programs. this is not a problem because /etc/localtime is a trusted path, much like the trusted zoneinfo search path.
2014-06-06implement %y and %C specifiers in strptimeTimo Teräs-4/+10
2014-05-29support linux kernel apis (new archs) with old syscalls removedRich Felker-9/+6
such archs are expected to omit definitions of the SYS_* macros for syscalls their kernels lack from arch/$ARCH/bits/syscall.h. the preprocessor is then able to select the an appropriate implementation for affected functions. two basic strategies are used on a case-by-case basis: where the old syscalls correspond to deprecated library-level functions, the deprecated functions have been converted to wrappers for the modern function, and the modern function has fallback code (omitted at the preprocessor level on new archs) to make use of the old syscalls if the new syscall fails with ENOSYS. this also improves functionality on older kernels and eliminates the incentive to program with deprecated library-level functions for the sake of compatibility with older kernels. in other situations where the old syscalls correspond to library-level functions which are not deprecated but merely lack some new features, such as the *at functions, the old syscalls are still used on archs which support them. this may change at some point in the future if or when fallback code is added to the new functions to make them usable (possibly with reduced functionality) on old kernels.
2014-05-24support kernels with no SYS_open syscall, only SYS_openatRich Felker-2/+1
open is handled specially because it is used from so many places, in so many variants (2 or 3 arguments, setting errno or not, and cancellable or not). trying to do it as a function would not only increase bloat, but would also risk subtle breakage. this is the first step towards supporting "new" archs where linux lacks "old" syscalls.
2014-05-19fix unhandled cases in strptimeRich Felker-5/+16
%C, %U, %W, and %y handling were completely missing; %C wrongly fell-through to unrelated cases, and the rest returned failure. for now, they all parse numbers in the proper forms and range-check the values, but they do not store the value anywhere. it's not clear to me whether, as "derived" fields, %U and %W should produce any result. they certainly cannot produce a result unless the year and weekday are also converted, but in this case it might be desirable for them to do so. clarification is needed on the intended behavior of strptime in cases like this. %C and %y have well-defined behavior as long as they are used together (and %y is defined by itself but may change in the future). implementing them (including their correct interaction) is left as a later change to be made. finally, strptime now rejects unknown/invalid format characters instead of ignoring them.
2014-05-08fix strftime %s not to zero pad with default width=2Szabolcs Nagy-0/+1
2014-04-22perform minimal sanity checks on zoneinfo files loaded via TZ variableRich Felker-0/+5
previously, setting TZ to the pathname of a file which was not a valid zoneinfo file would usually cause programs using local time zone based operations to crash. the new code checks the file size and magic at the beginning of the file, which seems sufficient to prevent accidental misconfiguration from causing crashes. attempting to make fully-robust validation would be futile unless we wanted to drop use of mmap (shared zoneinfo) and instead read it into a local buffer, since such validation would be subject to race conditions with modification of the file.
2014-04-22do not try to interpret implementation specific strings as tz definitionTimo Teräs-0/+1
2014-04-21allow zoneinfo-path-relative filenames with no slashes in TZ variableRich Felker-12/+8
since the form TZ=name is reserved for POSIX-form time zone strings, TZ=:name needs to be used when the zoneinfo filename is in the top-level zoneinfo directory and therefore does not contain a slash. previously the leading colon was merely dropped, making it impossible to access such zones without a full absolute pathname. changes based on patch by Timo Teräs.
2014-04-16add working vdso clock_gettime support, including static linkingRich Felker-5/+13
the vdso symbol lookup code is based on the original 2011 patch by Nicholas J. Kain, with some streamlining, pointer arithmetic fixes, and one symbol version matching fix. on the consumer side (clock_gettime), per-arch macros for the particular symbol name and version to lookup are added in syscall_arch.h, and no vdso code is pulled in on archs which do not define these macros. at this time, vdso is enabled only on x86_64. the vdso support at the dynamic linker level is no longer useful to libc, but is left in place for the sake of debuggers (which may need the vdso in the link map to find its functions) and possibly use with dlsym.
2014-04-14fix fallback code for old kernels in clock_gettimeRich Felker-1/+1
2014-01-06eliminate explicit (long) casts when making syscallsRich Felker-4/+4
this practice came from very early, before internal/syscall.h defined macros that could accept pointer arguments directly and handle them correctly. aside from being ugly and unnecessary, it looks like it will be problematic when we add support for 32-bit ABIs on archs where registers (and syscall arguments) are 64-bit, e.g. x32 and mips n32.
2013-12-19fix hangs in localtime for near-overflowing time_t values on 64-bit archsRich Felker-0/+6
2013-12-12include cleanups: remove unused headers and add feature test macrosSzabolcs Nagy-6/+0
2013-11-26fix off-by-one length failure in strftime/wcsftime and improve error behaviorRich Felker-12/+16
these functions were spuriously failing in the case where the buffer size was exactly the number of bytes/characters to be written, including null termination. since these functions do not have defined error conditions other than buffer size, a reasonable application may fail to check the return value when the format string and buffer size are known to be valid; such an application could then attempt to use a non-terminated buffer. in addition to fixing the bug, I have changed the error handling behavior so that these functions always null-terminate the output except in the case where the buffer size is zero, and so that they always write as many characters as possible before failing, rather than dropping whole fields that do not fit. this actually simplifies the logic somewhat anyway.
2013-11-08remove O_NOFOLLOW from __map_file used for time zone file loadingRich Felker-1/+1
it's not clear why I originally wrote O_NOFOLLOW into this; I suspect the reason was with an aim of making the function more general for mapping partially or fully untrusted files provided by the user. however, the timezone code already precludes use of absolute or relative pathnames in suid/sgid programs, and disallows .. in pathnames which are relative to one of the system timezone locations, so there is no threat of opening a symlink which is not trusted by appropriate user. since some users may wish to put symbolic links in the zoneinfo directories to alias timezones, it seems preferable to allow this.
2013-11-08fix handling of overly-long TZ environment variable valuesRich Felker-1/+1
the rest of the code is not prepared to handle an empty TZ string, so falling back to __gmt ("GMT"), just as if TZ had been blank or unset, is the preferable action.
2013-11-04timezone parser: fix iteration over search dir pathsrofl0r-1/+1
try+l points to \0, so only one iteration was ever tried.
2013-11-04timezone parser: fix offset to transition table in 64bit code pathrofl0r-1/+1
we need to skip to the second TZif header, which starts at skip+44, and then skip another header (20 bytes) plus the following 6 32bit values.
2013-11-04fix timezone parser code crashing on 64bit sysrofl0r-1/+1
if sizeof(time_t) == 8, this code path was missing the correct offset into the zoneinfo file, using the header magic to do offset calculations. the 6 32bit fields to be read start at offset 20.
2013-10-25add legacy ftime function and sys/timeb.hRich Felker-0/+12
despite being marked legacy, this was specified by SUSv3 as part of the XSI option; only the most recent version of the standard dropped it. reportedly there's actual code using it.
2013-08-25add the %s (seconds since the epoch) format to strftimeRich Felker-0/+4
this is a nonstandard extension but will be required in the next version of POSIX, and it's widely used/useful in shell scripts utilizing the date utility.
2013-08-24fix strftime regression in %e formatRich Felker-2/+2
%e pads with spaces instead of zeros.
2013-08-24properly fill in tzname[] for old (pre-64-bit-format) zoneinfo filesRich Felker-1/+22
in this case, the first standard-time and first daylight-time rules should be taken as the "default" ones to expose.
2013-08-24minor fix to tz name checkingRich Felker-2/+2
if a zoneinfo file is not (or is no longer) in use, don't check the abbrevs pointers, which may be invalid.
2013-08-24fix strftime handling of time zone dataRich Felker-8/+36
this may need further revision in the future, since POSIX is rather unclear on the requirements, and is designed around the assumption of POSIX TZ specifiers which are not sufficiently powerful to represent real-world timezones (this is why zoneinfo support was added). the basic issue is that strftime gets the string and numeric offset for the timezone from the extra fields in struct tm, which are initialized when calling localtime/gmtime/etc. however, a conforming application might have created its own struct tm without initializing these fields, in which case using __tm_zone (a pointer) could crash. other zoneinfo-based implementations simply check for a null pointer, but otherwise can still crash of the field contains junk. simply ignoring __tm_zone and using tzname[] would "work" but would give incorrect results in time zones with more complex rules. I feel like this would lower the quality of implementation. instead, simply validate __tm_zone: unless it points to one of the zone name strings managed by the timezone system, assume it's invalid. this commit also fixes several other minor bugs with formatting: tm_isdst being negative is required to suppress printing of the zone formats, and %z was using the wrong format specifiers since the type of val was changed, resulting in bogus output.
2013-08-23fix mishandling of empty or blank TZ environment variableRich Felker-1/+1
the empty TZ string was matching equal to the initial value of the cached TZ name, thus causing do_tzset never to run and never to initialize the time zone data.
2013-08-23fix missing string.h in strftime.c (needed by new strftime code)Rich Felker-0/+1
this bug was masked by local experimental CFLAGS in my config.mak.
2013-08-22add strftime and wcsftime field widthsRich Felker-24/+81
at present, since POSIX requires %F to behave as %+4Y-%m-%d and ISO C requires %F to behave as %Y-%m-%d, the default behavior for %Y has been changed to match %+4Y. this seems to be the only way to conform to the requirements of both standards, and it does not affect years prior to the year 10000. depending on the outcome of interpretations from the standards bodies, this may be adjusted at some point.
2013-08-22simplify strftime and fix integer overflowsRich Felker-28/+12
use a long long value so that even with offsets, values cannot overflow. instead of using different format strings for different numeric formats, simply use a per-format width and %0*lld for all of them. this width specifier is not for use with strftime field widths; that will be a separate step in the caller.
2013-08-22strftime cleanup: avoid recomputing strlen when it's knownRich Felker-10/+16
2013-08-22more strftime refactoringRich Felker-23/+25
make __strftime_fmt_1 return a string (possibly in the caller-provided temp buffer) rather than writing into the output buffer. this approach makes more sense when padding to a minimum field width might be required, and it's also closer to what wcsftime wants.
2013-08-22begin refactoring strftime to make adding field widths easierRich Felker-151/+161
2013-08-03have new timer threads unblock their own SIGTIMERRich Felker-2/+2
unblocking it in the pthread_once init function is not sufficient, since multiple threads, some of them with the signal blocked, could already exist before this is called; timers started from such threads would be non-functional.
2013-08-03add system for resetting TLS to initial valuesRich Felker-0/+3
this is needed for reused threads in the SIGEV_THREAD timer notification system, and could be reused elsewhere in the future if needed, though it should be refactored for such use. for static linking, __init_tls.c is simply modified to export the TLS info in a structure with external linkage, rather than using statics. this perhaps makes the code more clear, since the statics were poorly named for statics. the new __reset_tls.c is only linked if it is used. for dynamic linking, the code is in dynlink.c. sharing code with __copy_tls is not practical since __reset_tls must also re-zero thread-local bss.
2013-08-03fix multiple bugs in SIGEV_THREAD timersRich Felker-21/+35
1. the thread result field was reused for storing a kernel timer id, but would be overwritten if the application code exited or cancelled the thread. 2. low pointer values were used as the indicator that the timer id is a kernel timer id rather than a thread id. this is not portable, as mmap may return low pointers on some conditions. instead, use the fact that pointers must be aligned and kernel timer ids must be non-negative to map pointers into the negative integer space. 3. signals were not blocked until after the timer thread started, so a race condition could allow a signal handler to run in the timer thread when it's not supposed to exist. this is mainly problematic if the calling thread was the only thread where the signal was unblocked and the signal handler assumes it runs in that thread.
2013-08-02add wcsftime_t aliasRich Felker-0/+3
this is a nonstandard extension.
2013-07-28fix semantically incorrect use of LC_GLOBAL_LOCALERich Felker-2/+2
LC_GLOBAL_LOCALE refers to the global locale, controlled by setlocale, not the thread-local locale in effect which these functions should be using. neither LC_GLOBAL_LOCALE nor 0 has an argument to the *_l functions has behavior defined by the standard, but 0 is a more logical choice for requesting the callee to lookup the current locale. in the future I may move the current locale lookup the the caller (the non-_l-suffixed wrapper). at this point, all of the locale logic is dummied out, so no harm was done, but it should at least avoid misleading usage.