cbor2: Add cbor2 library.

This aims to follow the API of the cbor2 library found at
https://github.com/agronholm/cbor2 (also on PyPI as cbor2).

The original source for this MicroPython version of cbor2 is from
https://github.com/kpn-iot/senml-micropython-library.

Author: iabdalkader

python-ecosys/cbor2/cbor2/__init__.py

@@ -0,0 +1,28 @@
+"""
+The MIT License (MIT)
+
+Copyright (c) 2023 Arduino SA
+Copyright (c) 2018 KPN (Jan Bogaerts)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+"""
+
+
+from . import decoder
+from . import encoder

python-ecosys/cbor2/cbor2/decoder.py

@@ -0,0 +1,262 @@
+"""
+The MIT License (MIT)
+
+Copyright (c) 2023 Arduino SA
+Copyright (c) 2018 KPN (Jan Bogaerts)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+"""
+
+
+import uio
+import ustruct as struct
+
+
+class CBORDecodeError(Exception):
+    """Raised when an error occurs deserializing a CBOR datastream."""
+
+
+break_marker = object()
+
+
+class CBORSimpleValue(object):
+    """
+    Represents a CBOR "simple value".
+    :param int value: the value (0-255)
+    """
+
+    def __init__(self, value):
+        if value < 0 or value > 255:
+            raise TypeError("simple value too big")
+        self.value = value
+
+    def __eq__(self, other):
+        if isinstance(other, CBORSimpleValue):
+            return self.value == other.value
+        elif isinstance(other, int):
+            return self.value == other
+        return NotImplemented
+
+    def __repr__(self):
+        return "CBORSimpleValue({self.value})".format(self=self)
+
+
+def decode_uint(decoder, subtype, allow_indefinite=False):
+    # Major tag 0
+    if subtype < 24:
+        return subtype
+    elif subtype == 24:
+        return struct.unpack(">B", decoder.read(1))[0]
+    elif subtype == 25:
+        return struct.unpack(">H", decoder.read(2))[0]
+    elif subtype == 26:
+        return struct.unpack(">L", decoder.read(4))[0]
+    elif subtype == 27:
+        return struct.unpack(">Q", decoder.read(8))[0]
+    elif subtype == 31 and allow_indefinite:
+        return None
+    else:
+        raise CBORDecodeError("unknown unsigned integer subtype 0x%x" % subtype)
+
+
+def decode_negint(decoder, subtype):
+    # Major tag 1
+    uint = decode_uint(decoder, subtype)
+    return -uint - 1
+
+
+def decode_bytestring(decoder, subtype):
+    # Major tag 2
+    length = decode_uint(decoder, subtype, allow_indefinite=True)
+    if length is None:
+        # Indefinite length
+        buf = bytearray()
+        while True:
+            initial_byte = decoder.read(1)[0]
+            if initial_byte == 255:
+                return buf
+            else:
+                length = decode_uint(decoder, initial_byte & 31)
+                value = decoder.read(length)
+                buf.extend(value)
+    else:
+        return decoder.read(length)
+
+
+def decode_string(decoder, subtype):
+    # Major tag 3
+    return decode_bytestring(decoder, subtype).decode("utf-8")
+
+
+def decode_array(decoder, subtype):
+    # Major tag 4
+    items = []
+    length = decode_uint(decoder, subtype, allow_indefinite=True)
+    if length is None:
+        # Indefinite length
+        while True:
+            value = decoder.decode()
+            if value is break_marker:
+                break
+            else:
+                items.append(value)
+    else:
+        for _ in range(length):
+            item = decoder.decode()
+            items.append(item)
+    return items
+
+
+def decode_map(decoder, subtype):
+    # Major tag 5
+    dictionary = {}
+    length = decode_uint(decoder, subtype, allow_indefinite=True)
+    if length is None:
+        # Indefinite length
+        while True:
+            key = decoder.decode()
+            if key is break_marker:
+                break
+            else:
+                value = decoder.decode()
+                dictionary[key] = value
+    else:
+        for _ in range(length):
+            key = decoder.decode()
+            value = decoder.decode()
+            dictionary[key] = value
+
+    return dictionary
+
+
+def decode_special(decoder, subtype):
+    # Simple value
+    if subtype < 20:
+        return CBORSimpleValue(subtype)
+
+    # Major tag 7
+    return special_decoders[subtype](decoder)
+
+
+def decode_simple_value(decoder):
+    return CBORSimpleValue(struct.unpack(">B", decoder.read(1))[0])
+
+
+def decode_float16(decoder):
+    payload = decoder.read(2)
+    return unpack_float16(payload)
+
+
+def decode_float32(decoder):
+    return struct.unpack(">f", decoder.read(4))[0]
+
+
+def decode_float64(decoder):
+    return struct.unpack(">d", decoder.read(8))[0]
+
+
+major_decoders = {
+    0: decode_uint,
+    1: decode_negint,
+    2: decode_bytestring,
+    3: decode_string,
+    4: decode_array,
+    5: decode_map,
+    7: decode_special,
+}
+
+special_decoders = {
+    20: lambda self: False,
+    21: lambda self: True,
+    22: lambda self: None,
+    23: lambda self: undefined,
+    24: decode_simple_value,
+    25: decode_float16,
+    26: decode_float32,
+    27: decode_float64,
+    31: lambda self: break_marker,
+}
+
+
+class CBORDecoder(object):
+    """
+    Deserializes a CBOR encoded byte stream.
+    """
+
+    def __init__(self, fp):
+        self.fp = fp
+
+    def read(self, amount):
+        """
+        Read bytes from the data stream.
+        :param int amount: the number of bytes to read
+        """
+        data = self.fp.read(amount)
+        if len(data) < amount:
+            raise CBORDecodeError(
+                "premature end of stream (expected to read {} bytes, got {} "
+                "instead)".format(amount, len(data))
+            )
+
+        return data
+
+    def decode(self):
+        """
+        Decode the next value from the stream.
+        :raises CBORDecodeError: if there is any problem decoding the stream
+        """
+        try:
+            initial_byte = self.fp.read(1)[0]
+            major_type = initial_byte >> 5
+            subtype = initial_byte & 31
+        except Exception as e:
+            raise CBORDecodeError(
+                "error reading major type at index {}: {}".format(self.fp.tell(), e)
+            )
+
+        decoder = major_decoders[major_type]
+        try:
+            return decoder(self, subtype)
+        except CBORDecodeError:
+            raise
+        except Exception as e:
+            raise CBORDecodeError(
+                "error decoding value {}".format(e)
+            )  # tell doesn't work on micropython at the moment
+
+
+def loads(payload, **kwargs):
+    """
+    Deserialize an object from a bytestring.
+    :param bytes payload: the bytestring to serialize
+    :param kwargs: keyword arguments passed to :class:`~.CBORDecoder`
+    :return: the deserialized object
+    """
+    fp = uio.BytesIO(payload)
+    return CBORDecoder(fp, **kwargs).decode()
+
+
+def load(fp, **kwargs):
+    """
+    Deserialize an object from an open file.
+    :param fp: the input file (any file-like object)
+    :param kwargs: keyword arguments passed to :class:`~.CBORDecoder`
+    :return: the deserialized object
+    """
+    return CBORDecoder(fp, **kwargs).decode()