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>
Damien George