1 files changed, 61 insertions, 0 deletions

diff --git a/kernel/time.c b/kernel/time.c
index b94bfa8c03e0..fa569885e22b 100644
--- a/kernel/time.c
+++ b/kernel/time.c
@@ -583,6 +583,67 @@ void getnstimestamp(struct timespec *ts)
 }
 EXPORT_SYMBOL_GPL(getnstimestamp);
 
+/* 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).
+ *
+ * WARNING: this function will overflow on 2106-02-07 06:28:16 on
+ * machines were 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 (unsigned int year, unsigned int mon,
+        unsigned int day, unsigned int hour,
+        unsigned int min, unsigned int sec)
+{
+        if (0 >= (int) (mon -= 2)) {    /* 1..12 -> 11,12,1..10 */
+                mon += 12;              /* Puts Feb last since it has leap day */
+                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 */
+}
+
+/**
+ * set_normalized_timespec - set timespec sec and nsec parts and normalize
+ *
+ * @ts:         pointer to timespec variable to be set
+ * @sec:        seconds to set
+ * @nsec:       nanoseconds to set
+ *
+ * Set seconds and nanoseconds field of a timespec variable and
+ * normalize to the timespec storage format
+ *
+ * Note: The tv_nsec part is always in the range of
+ *      0 <= tv_nsec < NSEC_PER_SEC
+ * For negative values only the tv_sec field is negative !
+ */
+void set_normalized_timespec (struct timespec *ts, time_t sec, long nsec)
+{
+        while (nsec >= NSEC_PER_SEC) {
+                nsec -= NSEC_PER_SEC;
+                ++sec;
+        }
+        while (nsec < 0) {
+                nsec += NSEC_PER_SEC;
+                --sec;
+        }
+        ts->tv_sec = sec;
+        ts->tv_nsec = nsec;
+}
+
 #if (BITS_PER_LONG < 64)
 u64 get_jiffies_64(void)
 {