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opack: implement dates #2466

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opack: implement dates #2466

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15 changes: 11 additions & 4 deletions pyatv/support/opack.py
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Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
"""Support for the OPACK serialization format.

Notes:
* Absolute time (0x06) is not implemented (can unpack as integer, not pack)
* Pack implementation does not implement UID referencing
* Likely other cases missing
"""
Expand All @@ -15,6 +14,8 @@

_SIZED_INT_TYPES: Dict[int, Type] = {}

_OPACK_TIME_OFFSET: float = 978307200.0
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Can you add a comment (and possibly rename the constant) making it clear that this is a conversion from offset between unix time and mach absolute time? This is a very magic constant.



def _sized_int(value: int, size: int) -> int:
"""Return an int subclass with a size attribute.
Expand Down Expand Up @@ -44,7 +45,9 @@ def _pack(data, object_list):
elif isinstance(data, UUID):
packed_bytes = b"\x05" + data.bytes
elif isinstance(data, datetime):
raise NotImplementedError("absolute time")
packed_bytes = b"\x06" + struct.pack(
">d", data.timestamp() - _OPACK_TIME_OFFSET
)
elif isinstance(data, int):
size_hint = getattr(data, "size", None) # if created with _sized_int()
if data < 0x28 and not size_hint:
Expand Down Expand Up @@ -154,8 +157,12 @@ def _unpack(data, object_list):
value = UUID(bytes=data[1:17])
remaining = data[17:]
elif data[0] == 0x06:
# TODO: Dummy implementation: only parse as integer
value, remaining = int.from_bytes(data[1:9], byteorder="little"), data[9:]
value, remaining = (
datetime.fromtimestamp(
struct.unpack(">d", data[1:9])[0] + _OPACK_TIME_OFFSET
),
data[9:],
)
elif 0x08 <= data[0] <= 0x2F:
value, remaining = data[0] - 8, data[1:]
add_to_object_list = False
Expand Down
9 changes: 5 additions & 4 deletions tests/support/test_opack.py
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Expand Up @@ -36,8 +36,7 @@ def test_pack_uuid():


def test_pack_absolute_time():
with pytest.raises(NotImplementedError):
pack(datetime.now())
assert pack(datetime.fromtimestamp(978307200.0)) == b"\x06" + (b"\x00" * 8)
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Same with the tests, I don't really like magic constants. I have used mach time in MRP IIRC, so you could add some kind of helper method to convert datetime objects mach time (and possibly pack) if you like.



def test_pack_small_integers():
Expand Down Expand Up @@ -223,8 +222,10 @@ def test_unpack_uuid():


def test_unpack_absolute_time():
# TODO: This is not implemented, it only parses the time stamp as an integer
assert unpack(b"\x06\x01\x00\x00\x00\x00\x00\x00\x00") == (1, b"")
assert unpack(b"\x06\x00\x00\x00\x00\x00\x00\x00\x00") == (
datetime.fromtimestamp(978307200.0),
b"",
)


def test_unpack_small_integers():
Expand Down