| Message ID | 1414667745-7703-3-git-send-email-pang.xunlei@linaro.org |
|---|---|
| State | New |
| Headers | show |
On Thu, 30 Oct 2014, pang.xunlei wrote: Same problem with the $subject as in the previous patch. > As part of addressing 2038 saftey for in-kernel uses, this patch s/saftey/safety/ saftey is something completely different. > +/* > + * Converts Gregorian date to seconds since 1970-01-01 00:00:00. > + * Assumes input in normal date format, i.e. 1980-12-31 23:59:59 > + * => year=1980, mon=12, day=31, hour=23, min=59, sec=59. > + * > + * [For the Julian calendar (which was used in Russia before 1917, > + * Britain & colonies before 1752, anywhere else before 1582, > + * and is still in use by some communities) leave out the > + * -year/100+year/400 terms, and add 10.] > + * > + * This algorithm was first published by Gauss (I think). > + * So this blindly copies the comment from mktime but misses to add a proper docbook comment for the function. > + * Safe version 2038 safety on 32-bit systems. This sentence makes no sense at all. Aside of that you want to do the same as I suggested for do_settimeofday64 * mktime64 - Convert gregrorian date to seconds since 1970. y2038 safe > + */ > +time64_t > +mktime64(const unsigned int year0, const unsigned int mon0, > + const unsigned int day, const unsigned int hour, > + const unsigned int min, const unsigned int sec) Make this time64_t mktime64(const unsigned int year0, const unsigned int mon0, const unsigned int day, const unsigned int hour, const unsigned int min, const unsigned int sec) please. > +{ > + time64_t ret; > + unsigned int mon = mon0, year = year0; I pretty much prefer the following style: + unsigned int mon = mon0, year = year0; + time64_t ret; Way simpler to parse. > + /* 1..12 -> 11,12,1..10 */ > + if (0 >= (int) (mon -= 2)) { > + mon += 12; /* Puts Feb last since it has leap day */ Please get rid of the tail comments while you are at it: /* Put Feb last since it has a leap day */ mon += 12; Again simpler to parse. > + year -= 1; > + } > + > + ret = (year/4 - year/100 + year/400 + 367*mon/12 + day) + year*365 - 719499; For readability sake > + ret = ret*24 + hour; /* now have hours */ Please kill these pointless comments. The calculation above is the one which could do with a comment not the obvious days to hrs and hrs to min and min to sec conversions. We do not blindly copy code and leave the mess unchanged. > + ret = ret*60 + min; /* now have minutes */ > + ret = ret*60 + sec; /* finally seconds */ > + > + return ret; > +} > + > +EXPORT_SYMBOL(mktime64); EXPORT_SYMBOL_GPL please. > + > /* Converts Gregorian date to seconds since 1970-01-01 00:00:00. > * Assumes input in normal date format, i.e. 1980-12-31 23:59:59 > * => year=1980, mon=12, day=31, hour=23, min=59, sec=59. > @@ -318,6 +356,7 @@ EXPORT_SYMBOL(timespec_trunc); > * WARNING: this function will overflow on 2106-02-07 06:28:16 on > * machines where long is 32-bit! (However, as time_t is signed, we > * will already get problems at other places on 2038-01-19 03:14:08) > + * TODO: [2038 safety] should be replaced by mktime64(). > */ > unsigned long > mktime(const unsigned int year0, const unsigned int mon0, Why are you keeping this implementation instead of replacing the comment by a simple one liner /* * mktime - Convert gregrorian date to seconds since 1970. Deprecated. Use mktime64 */ No need to add a full docbook comment as this is going away anyway. and change the implementation to { return mktime64(....); } Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
diff --git a/include/linux/time.h b/include/linux/time.h index 8c42cf8..5c2c077 100644 --- a/include/linux/time.h +++ b/include/linux/time.h @@ -39,6 +39,10 @@ static inline int timeval_compare(const struct timeval *lhs, const struct timeva return lhs->tv_usec - rhs->tv_usec; } +extern time64_t mktime64(const unsigned int year, const unsigned int mon, + const unsigned int day, const unsigned int hour, + const unsigned int min, const unsigned int sec); + extern unsigned long mktime(const unsigned int year, const unsigned int mon, const unsigned int day, const unsigned int hour, const unsigned int min, const unsigned int sec); diff --git a/kernel/time/time.c b/kernel/time/time.c index a9ae20f..f44efdb 100644 --- a/kernel/time/time.c +++ b/kernel/time/time.c @@ -304,6 +304,44 @@ struct timespec timespec_trunc(struct timespec t, unsigned gran) } EXPORT_SYMBOL(timespec_trunc); +/* + * Converts Gregorian date to seconds since 1970-01-01 00:00:00. + * Assumes input in normal date format, i.e. 1980-12-31 23:59:59 + * => year=1980, mon=12, day=31, hour=23, min=59, sec=59. + * + * [For the Julian calendar (which was used in Russia before 1917, + * Britain & colonies before 1752, anywhere else before 1582, + * and is still in use by some communities) leave out the + * -year/100+year/400 terms, and add 10.] + * + * This algorithm was first published by Gauss (I think). + * + * Safe version 2038 safety on 32-bit systems. + */ +time64_t +mktime64(const unsigned int year0, const unsigned int mon0, + const unsigned int day, const unsigned int hour, + const unsigned int min, const unsigned int sec) +{ + time64_t ret; + unsigned int mon = mon0, year = year0; + + /* 1..12 -> 11,12,1..10 */ + if (0 >= (int) (mon -= 2)) { + mon += 12; /* Puts Feb last since it has leap day */ + year -= 1; + } + + ret = (year/4 - year/100 + year/400 + 367*mon/12 + day) + year*365 - 719499; + ret = ret*24 + hour; /* now have hours */ + ret = ret*60 + min; /* now have minutes */ + ret = ret*60 + sec; /* finally seconds */ + + return ret; +} + +EXPORT_SYMBOL(mktime64); + /* Converts Gregorian date to seconds since 1970-01-01 00:00:00. * Assumes input in normal date format, i.e. 1980-12-31 23:59:59 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59. @@ -318,6 +356,7 @@ EXPORT_SYMBOL(timespec_trunc); * WARNING: this function will overflow on 2106-02-07 06:28:16 on * machines where long is 32-bit! (However, as time_t is signed, we * will already get problems at other places on 2038-01-19 03:14:08) + * TODO: [2038 safety] should be replaced by mktime64(). */ unsigned long mktime(const unsigned int year0, const unsigned int mon0,
As part of addressing 2038 saftey for in-kernel uses, this patch adds safe mktime64() using time64_t. After this patch, mktime() should be replaced by mktime64() one by one. Eventually, mktime() will be removed from the kernel when it has no users. Signed-off-by: pang.xunlei <pang.xunlei@linaro.org> --- include/linux/time.h | 4 ++++ kernel/time/time.c | 39 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 43 insertions(+)