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About
=====

This library provides encoding and decoding for the Concise Binary Object Representation (CBOR)
(`RFC 8949`_) serialization format. The specification is fully compatible with the original RFC 7049.
`Read the docs <https://cbor2.readthedocs.io/>`_ to learn more.

It is implemented in pure python with an optional C backend.

On PyPy, cbor2 runs with almost identical performance to the C backend.

.. _RFC 8949: https://www.rfc-editor.org/rfc/rfc8949.html

Features
--------

* Simple api like ``json`` or ``pickle`` modules.
* Support many `CBOR tags`_ with `stdlib objects`_.
* Generic tag decoding.
* `Shared value`_ references including cyclic references.
* `String references`_ compact encoding with repeated strings replaced with indices.
* Optional C module backend tested on big- and little-endian architectures.
* Extensible `tagged value handling`_ using ``tag_hook`` and ``object_hook`` on decode and ``default`` on encode.
* Command-line diagnostic tool, converting CBOR file or stream to JSON ``python -m cbor2.tool``
  (This is a lossy conversion, for diagnostics only)
* Thorough test suite.

.. _CBOR tags: https://www.iana.org/assignments/cbor-tags/cbor-tags.xhtml
.. _stdlib objects: https://cbor2.readthedocs.io/en/latest/usage.html#tag-support
.. _Shared value: http://cbor.schmorp.de/value-sharing
.. _String references: http://cbor.schmorp.de/stringref
.. _tagged value handling: https://cbor2.readthedocs.io/en/latest/customizing.html#using-the-cbor-tags-for-custom-types

Installation
============

::

    pip install cbor2

Requirements
------------

* Python >= 3.9 (or `PyPy3`_ 3.9+)
* C-extension: Any C compiler that can build Python extensions.
  Any modern libc with the exception of Glibc<2.9

.. _PyPy3: https://www.pypy.org/

Building the C-Extension
------------------------

To force building of the optional C-extension, set OS env ``CBOR2_BUILD_C_EXTENSION=1``.
To disable building of the optional C-extension, set OS env ``CBOR2_BUILD_C_EXTENSION=0``.
If this environment variable is unset, setup.py will default to auto detecting a compatible C library and
attempt to compile the extension.


Usage
=====

`Basic Usage <https://cbor2.readthedocs.io/en/latest/usage.html#basic-usage>`_

Command-line Usage
==================

The provided command line tool (``cbor2``) converts CBOR data in raw binary or base64
encoding into a representation that allows printing as JSON. This is a lossy
transformation as each datatype is converted into something that can be represented as a
JSON value.

The tool can alternatively be invoked with ``python -m cbor2.tool``.

Usage::

    # Pass hexadecimal through xxd.
    $ echo a16568656c6c6f65776f726c64 | xxd -r -ps | cbor2 --pretty
    {
        "hello": "world"
    }
    # Decode Base64 directly
    $ echo ggEC | python -m cbor2.tool --decode
    [1, 2]
    # Read from a file encoded in Base64
    $ python -m cbor2.tool -d tests/examples.cbor.b64
    {...}

It can be used in a pipeline with json processing tools like `jq`_ to allow syntax
coloring, field extraction and more.

CBOR data items concatenated into a sequence can be decoded also::

    $ echo ggECggMEggUG | cbor2 -d --sequence
    [1, 2]
    [3, 4]
    [5, 6]

Multiple files can also be sent to a single output file::

    $ cbor2 -o all_files.json file1.cbor file2.cbor ... fileN.cbor

.. _jq: https://stedolan.github.io/jq/

Security
========

This library has not been tested against malicious input. In theory it should be
as safe as JSON, since unlike ``pickle`` the decoder does not execute any code.
