The y2038 implementation for perl =========================================================================== This is an implementation of POSIX time.h which solves the year 2038 bug on systems where time_t is only 32 bits. It is implemented in bog-standard ANSI C. The latest version can be found at It makes use of the system's native 32 bit functions to perform time zone and daylight savings time calculations and thus does *not* need to ship its own time zone table. time64.h currently implements three public functions, localtime64_r(), gmtime64_r() and timegm64(). They are implementations of localtime_r(), gmtime_r() and timegm64(). To install, simply copy time64.c and time64.h into your project and make use of the functions. To test, run "make test". You must have Perl, prove (which comes with a recent version of the Test::Harness Perl module) and bzdiff installed to run the full test suite. It will do a number of unit tests, plus test against a large table of known good values in different time zones. Limitations, Issues, etc... --------------------------- localtime64_r() gets its time zone and daylight savings time information by mapping the future year back to a similar one between 2010 and 2037, safe for localtime_r(). The calculations are accurate according to current time zone and daylight savings information, but may become inaccurate if a change is made that takes place after 2010. Future versions will probe for a 64 bit safe system localtime_r() and gmtime_r() and use that. The maximum date is still limited by your tm struct. Most 32 bit systems use a signed integer tm_year which means the practical upper limit is the year 2147483647 which is somewhere around 2**54. You can use a 64 bit clean tm struct by setting USE_TM64 in time64.h Portability ----------- I would like to add some configuration detection stuff in the future, but for now all I can do is document the assumptions... This code assumes that long longs are 64 bit integers which is technically in violation of the C standard. This can be changed in time64.h by changing the Time64_T and Int64 typedefs. There are a number of configuration options in time64.h. Configure variables ------------------- Configure probes for the maximum and minimum values that gmtime () and localtime () accept on the local system. Configure however is only used on unix-like systems. For windows and VMS these values are hard-coded. You can use timecheck.c in the Porting directory to check those values yourself, using the same technique that is used in Configure based on bit-shifting: $ cd perl/Porting $ cc -O -o timecheck timecheck.c $ ./timecheck ====================== Sizeof time_t = 8 gmtime () boundaries: 8: 0x00f0c2ab7c54a97f: 2147485547-12-31 23:59:59 8: -0x0000000e79747c00: 0-01-01 00:00:00 localtime () boundaries: 8: 0x00f0c2ab7c549b6f: 2147485547-12-31 23:59:59 8: -0x0000000e79748094: 0-01-01 00:00:00 Configure variables: sGMTIME_max='67768036191676799' sGMTIME_min='-62167219200' sLOCALTIME_max='67768036191673199' sLOCALTIME_min='-62167220372' In the rare case that your system uses a double for time_t, you can use the alternate approach to test for these values: $ cd perl/Porting $ cc -O -o timecheck2{,.c} $ ./timecheck2 gmtime max 67768036191676800 localtime max 67768036191673200 gmtime min -67768040609740800 localtime min -67768040609741968