Exosphere.ATProto.CAR (Exosphere v0.2.0)

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CAR (Content Addressable aRchive) file parser.

CAR files are used in Exosphere.ATProto to bundle multiple CBOR blocks together, typically containing record data and MST (Merkle Search Tree) nodes.

Format

A CAR file consists of:

  1. Header: varint-length-prefixed CBOR with {version, roots}
  2. Blocks: repeated <varint-length><CID><data> entries

Usage

# Parse CAR blocks from firehose
{:ok, blocks} = Exosphere.ATProto.CAR.decode(car_binary)

# Get a specific record by CID
record = Exosphere.ATProto.CAR.get_block(blocks, cid)

Summary

Types

block_map()

Functions

decode(data)

Decode a CAR file into a map of CID → decoded data.

get_block(blocks, cid)

Get a block by CID from the parsed blocks map.

Types

block_map()

@type block_map() :: %{required(Exosphere.ATProto.CID.t()) => term()}

Functions

decode(data)

@spec decode(binary()) :: {:ok, block_map()} | {:error, term()}

Decode a CAR file into a map of CID → decoded data.

Returns {:ok, %{cid => data}} on success.

get_block(blocks, cid)

@spec get_block(block_map(), Exosphere.ATProto.CID.t() | String.t()) :: term() | nil

Get a block by CID from the parsed blocks map.

Returns the decoded CBOR data if found.