Fix os.stat() to use 1970 epoch

Commit 95e70cd0ea '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().

extmod/vfs_fat.c

@@ -320,7 +320,7 @@ STATIC mp_obj_t fat_vfs_stat(mp_obj_t vfs_in, mp_obj_t path_in) {
     } else {
         mode |= MP_S_IFREG;
     }
-    mp_int_t seconds = timeutils_seconds_since_2000(
+    mp_uint_t seconds = timeutils_seconds_since_epoch(
         1980 + ((fno.fdate >> 9) & 0x7f),
         (fno.fdate >> 5) & 0x0f,
         fno.fdate & 0x1f,
@@ -335,9 +335,9 @@ STATIC mp_obj_t fat_vfs_stat(mp_obj_t vfs_in, mp_obj_t path_in) {
     t->items[4] = MP_OBJ_NEW_SMALL_INT(0); // st_uid
     t->items[5] = MP_OBJ_NEW_SMALL_INT(0); // st_gid
     t->items[6] = mp_obj_new_int_from_uint(fno.fsize); // st_size
-    t->items[7] = MP_OBJ_NEW_SMALL_INT(seconds); // st_atime
+    t->items[7] = mp_obj_new_int_from_uint(seconds); // st_atime
-    t->items[8] = MP_OBJ_NEW_SMALL_INT(seconds); // st_mtime
+    t->items[8] = mp_obj_new_int_from_uint(seconds); // st_mtime
-    t->items[9] = MP_OBJ_NEW_SMALL_INT(seconds); // st_ctime
+    t->items[9] = mp_obj_new_int_from_uint(seconds); // st_ctime
 
     return MP_OBJ_FROM_PTR(t);
 }

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);
 }

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);
 

shared-bindings/time/__init__.c

@@ -36,8 +36,6 @@
 #include "shared-bindings/time/__init__.h"
 #include "supervisor/shared/translate.h"
 
-#define EPOCH1970_EPOCH2000_DIFF_SECS    946684800
-
 //| :mod:`time` --- time and timing related functions
 //| ========================================================
 //|
@@ -142,9 +140,9 @@ const mp_obj_namedtuple_type_t struct_time_type_obj = {
 
 mp_obj_t struct_time_from_tm(timeutils_struct_time_t *tm) {
     timeutils_struct_time_t tmp;
-    mp_uint_t secs = timeutils_seconds_since_2000(tm->tm_year, tm->tm_mon, tm->tm_mday,
+    mp_uint_t secs = timeutils_seconds_since_epoch(tm->tm_year, tm->tm_mon, tm->tm_mday,
                                                   tm->tm_hour, tm->tm_min, tm->tm_sec);
-    timeutils_seconds_since_2000_to_struct_time(secs, &tmp);
+    timeutils_seconds_since_epoch_to_struct_time(secs, &tmp);
     tm->tm_wday = tmp.tm_wday;
     tm->tm_yday = tmp.tm_yday;
 
@@ -202,9 +200,9 @@ mp_obj_t MP_WEAK rtc_get_time_source_time(void) {
 STATIC mp_obj_t time_time(void) {
     timeutils_struct_time_t tm;
     struct_time_to_tm(rtc_get_time_source_time(), &tm);
-    mp_uint_t secs = timeutils_seconds_since_2000(tm.tm_year, tm.tm_mon, tm.tm_mday,
+    mp_uint_t secs = timeutils_seconds_since_epoch(tm.tm_year, tm.tm_mon, tm.tm_mday,
                                                   tm.tm_hour, tm.tm_min, tm.tm_sec);
-    return mp_obj_new_int_from_uint(secs + EPOCH1970_EPOCH2000_DIFF_SECS);
+    return mp_obj_new_int_from_uint(secs);
 }
 MP_DEFINE_CONST_FUN_OBJ_0(time_time_obj, time_time);
 
@@ -228,7 +226,7 @@ STATIC mp_obj_t time_localtime(size_t n_args, const mp_obj_t *args) {
         mp_raise_msg(&mp_type_OverflowError, translate("timestamp out of range for platform time_t"));
 
     timeutils_struct_time_t tm;
-    timeutils_seconds_since_2000_to_struct_time(secs - EPOCH1970_EPOCH2000_DIFF_SECS, &tm);
+    timeutils_seconds_since_epoch_to_struct_time(secs, &tm);
 
     return struct_time_from_tm(&tm);
 }
@@ -262,7 +260,7 @@ STATIC mp_obj_t time_mktime(mp_obj_t t) {
 
     mp_uint_t secs = timeutils_mktime(mp_obj_get_int(elem[0]), mp_obj_get_int(elem[1]), mp_obj_get_int(elem[2]),
                                       mp_obj_get_int(elem[3]), mp_obj_get_int(elem[4]), mp_obj_get_int(elem[5]));
-    return mp_obj_new_int_from_uint(secs + EPOCH1970_EPOCH2000_DIFF_SECS);
+    return mp_obj_new_int_from_uint(secs);
 }
 MP_DEFINE_CONST_FUN_OBJ_1(time_mktime_obj, time_mktime);
 #endif // MICROPY_LONGINT_IMPL

tests/extmod/vfs_fat_ramdisk.py.exp

@@ -5,7 +5,7 @@ statvfs: (512, 512, 16, 16, 16, 0, 0, 0, 0, 255)
 getcwd: /
 True
 [('foo_file.txt', 32768, 0, 6)]
-stat root: (16384, 0, 0, 0, 0, 0, 0, 0, 0, 0)
+stat root: (16384, 0, 0, 0, 0, 0, 0, 946684800, 946684800, 946684800)
 stat file: (32768, 0, 0, 0, 0, 0, 6)
 True
 True