Class: Cabriolet::HLP::Compressor

Inherits:
Object
  • Object
show all
Defined in:
lib/cabriolet/hlp/compressor.rb

Overview

Compressor creates HLP (Windows Help) compressed archives

HLP files contain an internal file system where files can be compressed using LZSS MODE_MSHELP compression. The compressor builds the archive structure and compresses files as needed.

NOTE: This implementation is based on the knowledge that HLP files use LZSS compression with MODE_MSHELP, but cannot be fully validated due to lack of test fixtures and incomplete libmspack implementation.

Constant Summary collapse

DEFAULT_BUFFER_SIZE =

Default buffer size for I/O operations

2048

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io_system = nil) ⇒ Compressor

Initialize a new HLP compressor

Parameters:

  • io_system (System::IOSystem, nil) (defaults to: nil) —

    Custom I/O system or nil for default



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# File 'lib/cabriolet/hlp/compressor.rb', line 24

def initialize(io_system = nil)
  @io_system = io_system || System::IOSystem.new
  @files = []
end

Instance Attribute Details

#io_system ⇒ Object (readonly)

Returns the value of attribute io_system.



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# File 'lib/cabriolet/hlp/compressor.rb', line 15

def io_system
  @io_system
end

Instance Method Details

#add_data(data, hlp_path, compress: true) ⇒ void

This method returns an undefined value.

Add data from memory to the HLP archive

Parameters:

  • data (String) —

    Data to add

  • hlp_path (String) —

    Path within HLP archive

  • compress (Boolean) (defaults to: true) —

    Whether to compress the data



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# File 'lib/cabriolet/hlp/compressor.rb', line 49

def add_data(data, hlp_path, compress: true)
  @files << {
    data: data,
    hlp_path: hlp_path,
    compress: compress,
  }
end

#add_file(source_path, hlp_path, compress: true) ⇒ void

This method returns an undefined value.

Add a file to the HLP archive

Parameters:

  • source_path (String) —

    Path to source file

  • hlp_path (String) —

    Path within HLP archive

  • compress (Boolean) (defaults to: true) —

    Whether to compress the file



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# File 'lib/cabriolet/hlp/compressor.rb', line 35

def add_file(source_path, hlp_path, compress: true)
  @files << {
    source: source_path,
    hlp_path: hlp_path,
    compress: compress,
  }
end

#generate(output_file, **options) ⇒ Integer

Generate HLP archive

Parameters:

  • output_file (String) —

    Path to output HLP file

  • options (Hash) —

    Compression options

Options Hash (**options):

  • :version (Integer) —

    HLP format version (default: 1)

Returns:

  • (Integer) —

    Bytes written to output file

Raises:

  • (Errors::CompressionError) —

    if compression fails



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# File 'lib/cabriolet/hlp/compressor.rb', line 64

def generate(output_file, **options)
  version = options.fetch(:version, 1)

  output_handle = @io_system.open(output_file, Constants::MODE_WRITE)

  begin
    # Compress all files and collect metadata
    compressed_files = compress_all_files

    # Calculate directory size first
    directory_size = calculate_directory_size(compressed_files)

    # Calculate offsets
    header_size = 18 # Header structure size
    directory_offset = header_size
    data_offset = header_size + directory_size

    # Assign file offsets
    current_offset = data_offset
    compressed_files.each do |file_info|
      file_info[:offset] = current_offset
      current_offset += file_info[:compressed_data].bytesize
    end

    # Write header
    header_bytes = write_header(
      output_handle,
      version,
      compressed_files.size,
      directory_offset,
    )

    # Write directory
    directory_bytes = write_directory(output_handle, compressed_files)

    # Write file data
    data_bytes = write_file_data(output_handle, compressed_files)

    header_bytes + directory_bytes + data_bytes
  ensure
    @io_system.close(output_handle) if output_handle
  end
end