Module: Omnizip::Formats::Bzip2File

Defined in:
lib/omnizip/formats/bzip2_file.rb

Overview

BZIP2 file format

BZIP2 is a file compression format that uses the BZip2 algorithm with block-sorting compression (Burrows-Wheeler Transform).

Format structure:

  • Magic bytes: "BZh" (0x42 0x5A 0x68)
  • Block size indicator: '1'-'9' (100KB - 900KB)
  • Compressed blocks
  • End-of-stream marker

The format supports multiple compressed blocks, each with its own CRC32 checksum for data integrity verification.

Constant Summary collapse

BZIP2_MAGIC =

BZIP2 magic bytes

"BZh"
BLOCK_SIZE_MIN =

Block size markers ('1' to '9')

1
BLOCK_SIZE_MAX = 
9
STREAM_MAGIC =

Stream markers

0x314159265359
BLOCK_MAGIC =

π in hex

0x177245385090
STREAM_END_MAGIC =

Block start marker

0x177245385090

Class Method Summary collapse

Class Method Details

.compress(input_path, output_path, options = {}) ⇒ Object

Compress a file with BZIP2

Parameters:

  • input_path (String) —

    Input file path

  • output_path (String) —

    Output BZIP2 file path

  • options (Hash) (defaults to: {}) —

    Compression options

Options Hash (options):

  • :level (Integer) —

    Compression level (1-9)



40
41
42
43
44
45
46
 
# File 'lib/omnizip/formats/bzip2_file.rb', line 40

def compress(input_path, output_path, options = {})
  input_data = File.binread(input_path)

  File.open(output_path, "wb") do |output|
    compress_stream(StringIO.new(input_data), output, options)
  end
end

.compress_stream(input_io, output_io, options = {}) ⇒ Object

Compress data stream with BZIP2

Parameters:

  • input_io (IO) —

    Input stream

  • output_io (IO) —

    Output stream

  • options (Hash) (defaults to: {}) —

    Compression options



65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
 
# File 'lib/omnizip/formats/bzip2_file.rb', line 65

def compress_stream(input_io, output_io, options = {})
  level = options[:level] || 9
  level = level.clamp(BLOCK_SIZE_MIN, BLOCK_SIZE_MAX)

  input_data = input_io.read

  # Write BZIP2 header
  write_header(output_io, level)

  # Get BZip2 algorithm
  bzip2 = AlgorithmRegistry.get(:bzip2).new

  # Compress data
  compressed_io = StringIO.new
  compressed_io.set_encoding(Encoding::BINARY)

  bzip2.compress(
    StringIO.new(input_data),
    compressed_io,
    build_compression_options(level),
  )

  # Write compressed data
  compressed_io.rewind
  compressed_data = compressed_io.read
  output_io.write(compressed_data)
end

.decompress(input_path, output_path) ⇒ Object

Decompress a BZIP2 file

Parameters:

  • input_path (String) —

    Input BZIP2 file path

  • output_path (String) —

    Output file path



52
53
54
55
56
57
58
 
# File 'lib/omnizip/formats/bzip2_file.rb', line 52

def decompress(input_path, output_path)
  File.open(input_path, "rb") do |input|
    File.open(output_path, "wb") do |output|
      decompress_stream(input, output)
    end
  end
end

.decompress_stream(input_io, output_io) ⇒ Object

Decompress BZIP2 stream

Parameters:

  • input_io (IO) —

    Input stream

  • output_io (IO) —

    Output stream



97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
 
# File 'lib/omnizip/formats/bzip2_file.rb', line 97

def decompress_stream(input_io, output_io)
  # Read and verify header
  read_header(input_io)

  # Get BZip2 algorithm
  bzip2 = AlgorithmRegistry.get(:bzip2).new

  # Decompress data
  decompressed_io = StringIO.new
  decompressed_io.set_encoding(Encoding::BINARY)

  bzip2.decompress(input_io, decompressed_io)

  # Write decompressed data
  decompressed_io.rewind
  output_io.write(decompressed_io.read)
end

.register! ⇒ Object

Register BZIP2 format when loaded



116
117
118
119
 
# File 'lib/omnizip/formats/bzip2_file.rb', line 116

def register!
  FormatRegistry.register(".bz2", Omnizip::Formats::Bzip2File)
  FormatRegistry.register(".bzip2", Omnizip::Formats::Bzip2File)
end