Class: Omnizip::FormatDetector

Inherits:
Object
  • Object
show all
Defined in:
lib/omnizip/format_detector.rb

Overview

Detects archive format from file signature/magic bytes

This class identifies archive formats based on their file signatures. It distinguishes between XZ Utils format (.xz) and 7-Zip format (.7z) which are DIFFERENT implementations of LZMA/LZMA2 compression.

Examples:

Basic usage

format = Omnizip::FormatDetector.detect("archive.xz")
case format
when :xz
  # Use XZ Utils implementation
when :seven_zip
  # Use 7-Zip implementation
end

Constant Summary collapse

XZ_SIGNATURE =

XZ Utils format signature: "\xFD7zXZ\x00"

[0xFD, 0x37, 0x7A, 0x58, 0x5A, 0x00].freeze
SEVEN_ZIP_SIGNATURE =

7-Zip format signature: "7z\xBC\xAF\x27\x1C"

[0x37, 0x7A, 0xBC, 0xAF, 0x27, 0x1C].freeze
RAR5_SIGNATURE =

RAR5 format signature: "Rar!\x1A\x07\x01\x00"

[0x52, 0x61, 0x72, 0x21, 0x1A, 0x07, 0x01, 0x00].freeze
RAR4_SIGNATURE =

RAR4 format signature: "Rar!\x1A\x07\x00"

[0x52, 0x61, 0x72, 0x21, 0x1A, 0x07, 0x00].freeze
ZIP_SIGNATURE =

ZIP format signature: "PK\x03\x04"

[0x50, 0x4B, 0x03, 0x04].freeze
GZIP_SIGNATURE =

GZIP format signature: "\x1F\x8B"

[0x1F, 0x8B].freeze
BZIP2_SIGNATURE =

BZIP2 format signature: "BZ"

[0x42, 0x5A].freeze
READER_FOR_FORMAT =

Mapping of detected format symbols to (extension, constant-path) tuples. The constant path is resolved lazily so autoload fires only when a format is actually requested.

{
  xz: ["omnizip/formats/xz", "Omnizip::Formats::Xz"],
  seven_zip: ["omnizip/formats/seven_zip", "Omnizip::Formats::SevenZip::Reader"],
  rar5: ["omnizip/formats/rar5", "Omnizip::Formats::Rar5::Reader"],
  rar4: ["omnizip/formats/rar3", "Omnizip::Formats::Rar3::Reader"],
  zip: ["omnizip/formats/zip", "Omnizip::Formats::Zip::Reader"],
  gzip: ["omnizip/formats/gzip", "Omnizip::Formats::Gzip"],
  bzip2: ["omnizip/formats/bzip2_file", "Omnizip::Formats::Bzip2File"],
}.freeze

Class Method Summary collapse

Class Method Details

.detect(file_path) ⇒ Symbol?

Detect archive format from file path

Parameters:

  • file_path (String) —

    Path to the archive file

Returns:

  • (Symbol, nil) —

    Format identifier (:xz, :seven_zip, :rar5, :rar4, :zip, :gzip, :bzip2, :lzma_alone) or nil if unknown



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# File 'lib/omnizip/format_detector.rb', line 46

def self.detect(file_path)
  return nil unless File.exist?(file_path)

  header = File.binread(file_path, 16)
  return nil if header.nil? || header.empty?

  bytes = header.bytes

  case bytes
  in [0xFD, 0x37, 0x7A, 0x58, 0x5A, 0x00, *]
    :xz
  in [0x37, 0x7A, 0xBC, 0xAF, 0x27, 0x1C, *]
    :seven_zip
  in [0x52, 0x61, 0x72, 0x21, 0x1A, 0x07, 0x01, 0x00, *]
    :rar5
  in [0x52, 0x61, 0x72, 0x21, 0x1A, 0x07, 0x00, *]
    :rar4
  in [0x50, 0x4B, 0x03, 0x04, *]
    :zip
  in [0x1F, 0x8B, *]
    :gzip
  in [0x42, 0x5A, *]
    :bzip2
  else
    # Check for LZMA_Alone format (13-byte header with properties)
    detect_lzma_alone(bytes)
  end
end

.rar4?(file_path) ⇒ Boolean

Check if file is RAR4 format

Parameters:

  • file_path (String) —

    Path to the file

Returns:

  • (Boolean) —

    true if RAR4 format



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# File 'lib/omnizip/format_detector.rb', line 103

def self.rar4?(file_path)
  detect(file_path) == :rar4
end

.rar5?(file_path) ⇒ Boolean

Check if file is RAR5 format

Parameters:

  • file_path (String) —

    Path to the file

Returns:

  • (Boolean) —

    true if RAR5 format



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# File 'lib/omnizip/format_detector.rb', line 95

def self.rar5?(file_path)
  detect(file_path) == :rar5
end

.reader_for(file_path) ⇒ Class?

Get the appropriate reader class for the format

Parameters:

  • file_path (String) —

    Path to the archive file

Returns:

  • (Class, nil) —

    Reader class or nil if unknown format



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# File 'lib/omnizip/format_detector.rb', line 124

def self.reader_for(file_path)
  format = detect(file_path)
  return nil unless format

  mapping = READER_FOR_FORMAT[format]
  return nil unless mapping

  _path, const_path = mapping
  Object.const_get(const_path)
end

.seven_zip?(file_path) ⇒ Boolean

Check if file is 7-Zip format

Parameters:

  • file_path (String) —

    Path to the file

Returns:

  • (Boolean) —

    true if 7-Zip format



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# File 'lib/omnizip/format_detector.rb', line 87

def self.seven_zip?(file_path)
  detect(file_path) == :seven_zip
end

.xz?(file_path) ⇒ Boolean

Check if file is XZ Utils format

Parameters:

  • file_path (String) —

    Path to the file

Returns:

  • (Boolean) —

    true if XZ format



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# File 'lib/omnizip/format_detector.rb', line 79

def self.xz?(file_path)
  detect(file_path) == :xz
end