Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751998AbaJ0FrL (ORCPT ); Mon, 27 Oct 2014 01:47:11 -0400 Received: from mail-pd0-f180.google.com ([209.85.192.180]:42789 "EHLO mail-pd0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751368AbaJ0FrJ (ORCPT ); Mon, 27 Oct 2014 01:47:09 -0400 From: "pang.xunlei" To: linux-kernel@vger.kernel.org, rtc-linux@googlegroups.com Cc: John Stultz , Thomas Gleixner , Alessandro Zummo , "pang.xunlei" Subject: [PATCH RFC 02/12] time: Add mktime() safe version(using time64_t) Date: Mon, 27 Oct 2014 13:46:32 +0800 Message-Id: <1414388802-5866-1-git-send-email-pang.xunlei@linaro.org> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The kernel uses 32-bit signed value(time_t) for seconds since 1970-01-01:00:00:00, thus it will overflow at 2038-01-19 03:14:08 on 32-bit systems. We call this "2038 safety" issue. As part of addressing 2038 saftey for in-kernel uses, this patch adds the safe mktime() using time64_t. After this patch, mktime_unsafe() should be replaced by mktime() one by one. Eventually, mktime_unsafe() will be removed from the kernel when it has no users. Signed-off-by: pang.xunlei --- include/linux/time.h | 8 ++++++-- kernel/time/time.c | 39 ++++++++++++++++++++++++++------------- 2 files changed, 32 insertions(+), 15 deletions(-) diff --git a/include/linux/time.h b/include/linux/time.h index e49d421..08f413c 100644 --- a/include/linux/time.h +++ b/include/linux/time.h @@ -39,9 +39,13 @@ static inline int timeval_compare(const struct timeval *lhs, const struct timeva return lhs->tv_usec - rhs->tv_usec; } +extern time64_t 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); + extern unsigned long mktime_unsafe(const unsigned int year, const unsigned int mon, - const unsigned int day, const unsigned int hour, - const unsigned int min, const unsigned int sec); + const unsigned int day, const unsigned int hour, + const unsigned int min, const unsigned int sec); extern void set_normalized_timespec(struct timespec *ts, time_t sec, s64 nsec); diff --git a/kernel/time/time.c b/kernel/time/time.c index d6a4464..f9521fa 100644 --- a/kernel/time/time.c +++ b/kernel/time/time.c @@ -304,7 +304,8 @@ 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. +/* + * 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. * @@ -314,16 +315,13 @@ EXPORT_SYMBOL(timespec_trunc); * -year/100+year/400 terms, and add 10.] * * This algorithm was first published by Gauss (I think). - * - * 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) */ -unsigned long -mktime_unsafe(const unsigned int year0, const unsigned int mon0, +time64_t +mktime(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 */ @@ -332,12 +330,27 @@ mktime_unsafe(const unsigned int year0, const unsigned int mon0, year -= 1; } - return ((((unsigned long) - (year/4 - year/100 + year/400 + 367*mon/12 + day) + - year*365 - 719499 - )*24 + hour /* now have hours */ - )*60 + min /* now have minutes */ - )*60 + sec; /* finally seconds */ + 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(mktime); + +/* + * TODO: [2038 safety] 2038 unsafe for legacy, replace it by mktime(). + * WARNING: mktime_unsafe() 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) + */ +unsigned long mktime_unsafe(const unsigned int year0, const unsigned int mon0, + const unsigned int day, const unsigned int hour, + const unsigned int min, const unsigned int sec) +{ + return (unsigned long) mktime(year0, mon0, day, hour, min, sec); } EXPORT_SYMBOL(mktime_unsafe); -- 1.7.9.5 -- 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/