For time-based functions that work with absolute time there is the need for
an Epoch, to set the zero-point at which the absolute time starts counting.
Such functions include time.time() and filesystem stat return values. And
different ports may use a different Epoch.
To make it clearer what functions use the Epoch (whatever it may be), and
make the ports more consistent with their use of the Epoch, this commit
renames all Epoch related functions to include the word "epoch" in their
name (and remove references to "2000").
Along with this rename, the following things have changed:
- mp_hal_time_ns() is now specified to return the number of nanoseconds
since the Epoch, rather than since 1970 (but since this is an internal
function it doesn't change anything for the user).
- littlefs timestamps on the esp8266 have been fixed (they were previously
off by 30 years in nanoseconds).
Otherwise, there is no functional change made by this commit.
Signed-off-by: Damien George <damien@micropython.org>
This commit adds support for modification time of files on littlefs v2
filesystems, using file attributes. For some background see issue #6114.
Features/properties of this implementation:
- Only supported on littlefs2 (not littlefs1).
- Uses littlefs2's general file attributes to store the timestamp.
- The timestamp is 64-bits and stores nanoseconds since 1970/1/1 (if the
range to the year 2554 is not enough then additional bits can be added to
this timestamp by adding another file attribute).
- mtime is enabled by default but can be disabled in the constructor, eg:
uos.mount(uos.VfsLfs2(bdev, mtime=False), '/flash')
- It's fully backwards compatible, existing littlefs2 filesystems will work
without reformatting and timestamps will be added transparently to
existing files (once they are opened for writing).
- Files without timestamps will open correctly, and stat will just return 0
for their timestamp.
- mtime can be disabled or enabled each mount time and timestamps will only
be updated if mtime is enabled (otherwise they will be untouched).
Signed-off-by: Damien George <damien@micropython.org>
