# `ExCodecs.Compression.Bzip2`
[🔗](https://github.com/AnimaLogica/codecs/blob/v0.2.4/lib/ex_codecs/compression/bzip2.ex#L1)

Bzip2 compression codec (pure-Rust backend).

## Options

  * `:block_size` — 1..9 (default 9)
  * `:max_output_size` — Maximum allowed decompressed size in bytes
    (default: 256 MiB)

## Security

Do not decompress untrusted inputs without a tight `:max_output_size`.

## Examples

    iex> {:ok, compressed} = ExCodecs.encode(:bzip2, "hello world")
    iex> {:ok, decompressed} = ExCodecs.decode(:bzip2, compressed)
    iex> decompressed
    "hello world"

    iex> {:ok, compressed} = ExCodecs.encode(:bzip2, "hello world", block_size: 6)
    iex> is_binary(compressed)
    true

# `__codec_info__`

Returns the registry metadata for the Bzip2 codec.

## Arguments

This function takes no arguments.

## Returns

An `ExCodecs.Codec.t()` with these Bzip2-specific fields:

  * `name: :bzip2` and `category: :compression`
  * `module: ExCodecs.Compression.Bzip2`
  * `native?: true` because compression runs in a NIF
  * `streaming?: false` because only complete payloads are supported
  * `configurable?: true` because `encode/2` accepts `:block_size`
  * `version: "bzip2-0.6/libbz2-rs"` for the backend implementation

## Raises / Exceptions

This function does not invoke the NIF and does not raise.

## Examples

    iex> ExCodecs.Compression.Bzip2.__codec_info__()
    %ExCodecs.Codec{
      name: :bzip2,
      category: :compression,
      module: ExCodecs.Compression.Bzip2,
      native?: true,
      streaming?: false,
      configurable?: true,
      version: "bzip2-0.6/libbz2-rs"
    }

# `decode`

Decompresses Bzip2 data.

## Arguments

  * `data` (`binary()`) — a complete Bzip2 stream
  * `opts` (`keyword()`) — optional `:max_output_size` (positive integer
    bytes, default 256 MiB)

## Returns

  * `{:ok, decompressed :: binary()}` on success
  * `{:error, %ExCodecs.Error{reason: :invalid_data}}` when `data` is not a
    binary, `opts` is not a list, or the NIF raises an argument error
  * `{:error, %ExCodecs.Error{reason: :invalid_options}}` when
    `:max_output_size` is not a positive integer
  * `{:error, %ExCodecs.Error{reason: :output_limit_exceeded}}` when the
    decompressed size would exceed `:max_output_size`
  * `{:error, %ExCodecs.Error{reason: :decompression_failed}}` when `data`
    is corrupt, truncated, or not a Bzip2 stream
  * `{:error, %ExCodecs.Error{reason: :nif_not_loaded}}` when the native
    library is unavailable

## Raises / Exceptions

Guard failures and `ErlangError`/`ArgumentError` exceptions from the NIF
call are converted to error tuples. Unexpected exception classes may
propagate.

## Examples

    iex> payload = "quarterly results"
    iex> {:ok, compressed} = ExCodecs.Compression.Bzip2.encode(payload, [])
    iex> ExCodecs.Compression.Bzip2.decode(compressed, [])
    {:ok, "quarterly results"}

    iex> {:error, error} = ExCodecs.Compression.Bzip2.decode("not bzip2", [])
    iex> error.reason
    :decompression_failed

# `encode`

Compresses a binary with Bzip2.

## Arguments

  * `data` (`binary()`) — uncompressed bytes
  * `opts` (`keyword()`) — options containing `:block_size`, an integer from
    `1` (100 KiB blocks) through `9` (900 KiB blocks); defaults to `9`.
    Unknown keys are ignored.

## Returns

  * `{:ok, compressed :: binary()}` containing a Bzip2 stream
  * `{:error, %ExCodecs.Error{reason: :invalid_data}}` when `data` is not a
    binary, `opts` is not a list, or the NIF raises an argument error
  * `{:error, %ExCodecs.Error{reason: :invalid_options}}` when `:block_size`
    is not an integer in `1..9`
  * `{:error, %ExCodecs.Error{reason: :compression_failed}}` when the native
    compressor fails
  * `{:error, %ExCodecs.Error{reason: :nif_not_loaded}}` when the native
    library is unavailable

## Raises / Exceptions

Guard/option validation failures and `ErlangError`/`ArgumentError`
exceptions from the NIF call are converted to error tuples. Unexpected
exception classes may propagate.

## Examples

    iex> payload = :binary.copy("daily-report,", 10)
    iex> {:ok, compressed} =
    ...>   ExCodecs.Compression.Bzip2.encode(payload, block_size: 6)
    iex> is_binary(compressed)
    true
    iex> ExCodecs.Compression.Bzip2.decode(compressed, [])
    {:ok, payload}

    iex> {:error, error} = ExCodecs.Compression.Bzip2.encode("data", block_size: 10)
    iex> error.reason
    :invalid_options

---

*Consult [api-reference.md](api-reference.md) for complete listing*