Class: Cabriolet::CAB::Decompressor

Inherits:
Object
  • Object
show all
Defined in:
lib/cabriolet/cab/decompressor.rb

Overview

Decompressor is the main interface for CAB file operations

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io_system = nil, algorithm_factory = nil) ⇒ Decompressor

Initialize a new CAB decompressor

Parameters:

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

    Custom I/O system or nil for default

  • algorithm_factory (AlgorithmFactory, nil) (defaults to: nil) —

    Custom algorithm factory or nil for default



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# File 'lib/cabriolet/cab/decompressor.rb', line 14

def initialize(io_system = nil, algorithm_factory = nil)
  @io_system = io_system || System::IOSystem.new
  @algorithm_factory = algorithm_factory || Cabriolet.algorithm_factory
  @parser = Parser.new(@io_system)
  @buffer_size = Cabriolet.default_buffer_size
  @fix_mszip = false
  @salvage = false
  @search_buffer_size = 32_768
end

Instance Attribute Details

#buffer_size ⇒ Object

Returns the value of attribute buffer_size.



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# File 'lib/cabriolet/cab/decompressor.rb', line 8

def buffer_size
  @buffer_size
end

#fix_mszip ⇒ Object

Returns the value of attribute fix_mszip.



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# File 'lib/cabriolet/cab/decompressor.rb', line 8

def fix_mszip
  @fix_mszip
end

#io_system ⇒ Object (readonly)

Returns the value of attribute io_system.



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# File 'lib/cabriolet/cab/decompressor.rb', line 7

def io_system
  @io_system
end

#parser ⇒ Object (readonly)

Returns the value of attribute parser.



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# File 'lib/cabriolet/cab/decompressor.rb', line 7

def parser
  @parser
end

#salvage ⇒ Object

Returns the value of attribute salvage.



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# File 'lib/cabriolet/cab/decompressor.rb', line 8

def salvage
  @salvage
end

#search_buffer_size ⇒ Object

Returns the value of attribute search_buffer_size.



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# File 'lib/cabriolet/cab/decompressor.rb', line 8

def search_buffer_size
  @search_buffer_size
end

Instance Method Details

#append(cabinet, next_cabinet) ⇒ Boolean

Append a cabinet to another, merging their folders and files

Parameters:

Returns:

  • (Boolean) —

    true if successful

Raises:



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# File 'lib/cabriolet/cab/decompressor.rb', line 81

def append(cabinet, next_cabinet)
  merge_cabinets(cabinet, next_cabinet)
end

#create_decompressor(folder, input, output) ⇒ Decompressors::Base

Create appropriate decompressor for a folder

Parameters:

Returns:



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# File 'lib/cabriolet/cab/decompressor.rb', line 61

def create_decompressor(folder, input, output)
  @algorithm_factory.create(
    folder.compression_method,
    :decompressor,
    @io_system,
    input,
    output,
    @buffer_size,
    fix_mszip: @fix_mszip,
    salvage: @salvage,
    window_bits: folder.compression_level,
  )
end

#extract_all(cabinet, output_dir, **options) ⇒ Integer

Extract all files from the cabinet

Parameters:

  • cabinet (Models::Cabinet) —

    Cabinet to extract from

  • output_dir (String) —

    Directory to extract to

  • options (Hash) —

    Extraction options

Returns:

  • (Integer) —

    Number of files extracted



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# File 'lib/cabriolet/cab/decompressor.rb', line 50

def extract_all(cabinet, output_dir, **options)
  extractor = Extractor.new(@io_system, self)
  extractor.extract_all(cabinet, output_dir, **options)
end

#extract_file(file, output_path, **options) ⇒ Integer

Extract a single file from the cabinet

Parameters:

  • file (Models::File) —

    File to extract

  • output_path (String) —

    Where to write the file

  • options (Hash) —

    Extraction options

Returns:

  • (Integer) —

    Number of bytes extracted



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# File 'lib/cabriolet/cab/decompressor.rb', line 39

def extract_file(file, output_path, **options)
  extractor = Extractor.new(@io_system, self)
  extractor.extract_file(file, output_path, **options)
end

#open(filename) ⇒ Models::Cabinet

Open and parse a CAB file

Parameters:

  • filename (String) —

    Path to the CAB file

Returns:

Raises:



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# File 'lib/cabriolet/cab/decompressor.rb', line 29

def open(filename)
  @parser.parse(filename)
end

#prepend(cabinet, prev_cabinet) ⇒ Boolean

Prepend a cabinet to another, merging their folders and files

Parameters:

Returns:

  • (Boolean) —

    true if successful

Raises:



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# File 'lib/cabriolet/cab/decompressor.rb', line 91

def prepend(cabinet, prev_cabinet)
  merge_cabinets(prev_cabinet, cabinet)
end

#search(filename) ⇒ Models::Cabinet?

Search for embedded CAB files within a file

Parameters:

  • filename (String) —

    Path to file to search

Returns:



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# File 'lib/cabriolet/cab/decompressor.rb', line 99

def search(filename)
  # Reuse search buffer across searches for better performance
  search_buf = @search_buffer ||= Array.new(@search_buffer_size)
  first_cabinet = nil
  link_cabinet = nil
  first_len = 0
  false_cabs = 0

  handle = @io_system.open(filename, Constants::MODE_READ)
  file_length = handle.size

  # Check for InstallShield header at start of file
  if file_length >= 4
    header = @io_system.read(handle, 4)
    @io_system.seek(handle, 0, Constants::SEEK_START)
    if header.unpack1("V") == 0x28635349
      @io_system.message(handle, "WARNING; found InstallShield header. Use unshield " \
                                 "(https://github.com/twogood/unshield) to unpack this file")
    end
  end

  offset = 0
  while offset < file_length
    # Calculate read length
    length = [file_length - offset, @search_buffer_size].min

    # Read chunk
    @io_system.seek(handle, offset, Constants::SEEK_START)
    bytes_read = @io_system.read(handle, length)
    break if bytes_read.nil? || bytes_read.empty?

    search_buf[0, bytes_read.bytesize] = bytes_read.bytes

    # Search for cabinets in this chunk
    cab_offset = find_cabinet_in_buffer(search_buf, bytes_read.size,
                                        offset, handle, filename, file_length)

    if cab_offset
      # Try to parse cabinet at this offset
      cabinet = try_parse_cab_at_offset(handle, filename, cab_offset)

      if cabinet
        # Capture first cabinet length
        first_len = cabinet.length if cab_offset.zero?

        # Link into list
        if first_cabinet.nil?
          first_cabinet = cabinet
        else
          link_cabinet.next = cabinet
        end
        link_cabinet = cabinet

        # Continue searching after this cabinet
        offset = cab_offset + cabinet.length
      else
        false_cabs += 1
        # Restart search after signature
        offset = cab_offset + 4
      end
    else
      # No cabinet found in this chunk, move to next
      offset += length
    end
  end

  @io_system.close(handle)

  # Warn about truncated/extra data
  if first_len.positive? && first_len != file_length && (first_cabinet.nil? || first_cabinet.base_offset.zero?)
    if first_len < file_length
      @io_system.message(handle,
                         "WARNING; possible #{file_length - first_len} extra bytes at end of file.")
    else
      @io_system.message(handle,
                         "WARNING; file possibly truncated by #{first_len - file_length} bytes.")
    end
  end

  if false_cabs.positive? && Cabriolet.verbose
    @io_system.message(handle,
                       "#{false_cabs} false cabinets found")
  end

  first_cabinet
rescue StandardError
  @io_system.close(handle) if handle
  raise
end