Fix os.stat() to use 1970 epoch

Commit 95e70cd0ea6d 'time: Use 1970 epoch' changed epoch for the time
module, but not for other users. This patch does the same for the only
other core timeutils user: extmod/vfs_fat.c:fat_vfs_stat().
Other timeutils users: cc3200, esp8266 and stm32, are not changed.

Ports that don't use long ints, will still get wrong time values from
os.stat().

2 files changed, 19 insertions, 1 deletions

diff --git a/lib/timeutils/timeutils.c b/lib/timeutils/timeutils.c
index eb3dc80d4..b93a85dee 100644
--- a/lib/timeutils/timeutils.c
+++ b/lib/timeutils/timeutils.c
@@ -158,6 +158,17 @@ mp_uint_t timeutils_seconds_since_2000(mp_uint_t year, mp_uint_t month,
         + (year - 2000) * 31536000;
 }
 
+void timeutils_seconds_since_epoch_to_struct_time(mp_uint_t t, timeutils_struct_time_t *tm) {
+    t -= EPOCH1970_EPOCH2000_DIFF_SECS;
+    timeutils_seconds_since_2000_to_struct_time(t, tm);
+}
+
+mp_uint_t timeutils_seconds_since_epoch(mp_uint_t year, mp_uint_t month, mp_uint_t date,
+                                        mp_uint_t hour, mp_uint_t minute, mp_uint_t second) {
+    mp_uint_t t = timeutils_seconds_since_2000(year, month, date, hour, minute, second);
+    return t + EPOCH1970_EPOCH2000_DIFF_SECS;
+}
+
 mp_uint_t timeutils_mktime(mp_uint_t year, mp_int_t month, mp_int_t mday,
     mp_int_t hours, mp_int_t minutes, mp_int_t seconds) {
 
@@ -211,5 +222,5 @@ mp_uint_t timeutils_mktime(mp_uint_t year, mp_int_t month, mp_int_t mday,
             year++;
         }
     }
-    return timeutils_seconds_since_2000(year, month, mday, hours, minutes, seconds);
+    return timeutils_seconds_since_epoch(year, month, mday, hours, minutes, seconds);
 }
diff --git a/lib/timeutils/timeutils.h b/lib/timeutils/timeutils.h
index 9b1abeb8f..0ca6bb167 100644
--- a/lib/timeutils/timeutils.h
+++ b/lib/timeutils/timeutils.h
@@ -27,6 +27,8 @@
 #ifndef MICROPY_INCLUDED_LIB_TIMEUTILS_TIMEUTILS_H
 #define MICROPY_INCLUDED_LIB_TIMEUTILS_TIMEUTILS_H
 
+#define EPOCH1970_EPOCH2000_DIFF_SECS    946684800
+
 typedef struct _timeutils_struct_time_t {
     uint16_t    tm_year;    // i.e. 2014
     uint8_t     tm_mon;     // 1..12
@@ -48,6 +50,11 @@ void timeutils_seconds_since_2000_to_struct_time(mp_uint_t t,
 mp_uint_t timeutils_seconds_since_2000(mp_uint_t year, mp_uint_t month,
     mp_uint_t date, mp_uint_t hour, mp_uint_t minute, mp_uint_t second);
 
+void timeutils_seconds_since_epoch_to_struct_time(mp_uint_t t, timeutils_struct_time_t *tm);
+
+mp_uint_t timeutils_seconds_since_epoch(mp_uint_t year, mp_uint_t month, mp_uint_t date,
+                                       mp_uint_t hour, mp_uint_t minute, mp_uint_t second);
+
 mp_uint_t timeutils_mktime(mp_uint_t year, mp_int_t month, mp_int_t mday,
     mp_int_t hours, mp_int_t minutes, mp_int_t seconds);