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Subject[PATCH 06/12] time: Provide y2038 safe mktime() replacement
Date
From: "pang.xunlei" <pang.xunlei@linaro.org>

As part of addressing "y2038 problem" for in-kernel uses, this
patch adds safe mktime64() using time64_t.

After this patch, mktime() is deprecated and all its call sites
will be fixed using mktime64(), after that it can be removed.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnd Bergmann <arnd.bergmann@linaro.org>
Cc: pang.xunlei <pang.xunlei@linaro.org>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: pang.xunlei <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
include/linux/time.h | 17 ++++++++++++++---
kernel/time/time.c | 20 ++++++++------------
2 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/include/linux/time.h b/include/linux/time.h
index 8c42cf8..203c2ad 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -39,9 +39,20 @@ static inline int timeval_compare(const struct timeval *lhs, const struct timeva
return lhs->tv_usec - rhs->tv_usec;
}

-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);
+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);
+
+/**
+ * Deprecated. Use mktime64().
+ */
+static inline 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)
+{
+ return mktime64(year, mon, day, hour, min, 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 a9ae20f..65015ff 100644
--- a/kernel/time/time.c
+++ b/kernel/time/time.c
@@ -304,7 +304,9 @@ 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.
+/*
+ * mktime64 - Converts date to seconds.
+ * 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.
*
@@ -314,15 +316,10 @@ 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(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 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)
{
unsigned int mon = mon0, year = year0;

@@ -332,15 +329,14 @@ mktime(const unsigned int year0, const unsigned int mon0,
year -= 1;
}

- return ((((unsigned long)
+ return ((((time64_t)
(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 */
}
-
-EXPORT_SYMBOL(mktime);
+EXPORT_SYMBOL(mktime64);

/**
* set_normalized_timespec - set timespec sec and nsec parts and normalize
--
1.9.1


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