summaryrefslogtreecommitdiff
path: root/src/time/strftime.c
AgeCommit message (Collapse)AuthorLines
2016-10-06fix strftime %y for negative tm_yearSzabolcs Nagy-0/+1
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.
2015-08-14match historical behavior for tm_gmtoff member of struct tmNatanael Copa-2/+2
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.
2014-07-02properly pass current locale to *_l functions when used internallyRich Felker-1/+2
this change is presently non-functional since the callees do not yet use their locale argument for anything.
2014-05-08fix strftime %s not to zero pad with default width=2Szabolcs Nagy-0/+1
2013-11-26fix off-by-one length failure in strftime/wcsftime and improve error behaviorRich Felker-6/+8
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.
2013-08-25add 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.
2013-08-24fix strftime handling of time zone dataRich Felker-3/+13
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 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-3/+32
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
2013-07-28fix semantically incorrect use of LC_GLOBAL_LOCALERich Felker-1/+1
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.
2013-07-27reorder strftime to eliminate the incorrect indention levelRich Felker-5/+5
this change is in preparation for possibly adding support for the field width and padding specifiers added in POSIX 2008.
2013-07-24rework langinfo code for ABI compat and for use by time codeRich Felker-4/+4
2013-07-24move strftime_l into strftime.c and add __-prefixed versionRich Felker-1/+10
the latter is both for ABI purposes, and to facilitate eventually adding LC_TIME support. it's also nice to eliminate an extra source file.
2013-07-17the big time handling overhaulRich Felker-6/+2
this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-06-28implement week-based-year year numbers in strftimeRich Felker-27/+34
in the process, I refactored the week-number code so it can be used by the week-based-year formats to determine year adjustments at the boundary values. this also improves indention/code readability.
2013-06-28fix breakage in last commit to strftime due to missing INT_MAXRich Felker-0/+1
that's what I get for changing a hard-coded threshold to a proper non-magic-number without testing.
2013-06-28implement week numbers and half of the week-based-year logic for strftimeRich Felker-3/+38
output for plain week numbers (%U and %W) has been sanity-checked, and output for the week-based-year week numbers (%V) has been checked extensively against known-good data for the full non-negative range of 32-bit time_t. year numbers for week-based years (%g and %G) are not yet implemented.
2012-09-06use restrict everywhere it's required by c99 and/or posix 2008Rich Felker-1/+1
to deal with the fact that the public headers may be used with pre-c99 compilers, __restrict is used in place of restrict, and defined appropriately for any supported compiler. we also avoid the form [restrict] since older versions of gcc rejected it due to a bug in the original c99 standard, and instead use the form *restrict.
2011-02-12initial check-in, version 0.5.0v0.5.0Rich Felker-0/+172