Class: Cabriolet::CAB::Extractor::BlockReader

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

Overview

BlockReader wraps cabinet file handles and reads CFDATA blocks Handles multi-part cabinets by following the FolderData chain

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io_system, folder_data, num_blocks, salvage) ⇒ BlockReader

Returns a new instance of BlockReader.



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# File 'lib/cabriolet/cab/extractor.rb', line 329

def initialize(io_system, folder_data, num_blocks, salvage)
  @io_system = io_system
  @current_data = folder_data
  @num_blocks = num_blocks
  @salvage = salvage
  @current_block = 0
  @buffer = ""
  @buffer_pos = 0
  @cab_handle = nil

  # Cache ENV lookups once at initialization
  @debug_block = ENV.fetch("DEBUG_BLOCK", nil)

  # Open first cabinet and seek to data offset
  open_current_cabinet
end

Instance Attribute Details

#current_block ⇒ Object (readonly)

Returns the value of attribute current_block.



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# File 'lib/cabriolet/cab/extractor.rb', line 326

def current_block
  @current_block
end

#current_data ⇒ Object (readonly)

Returns the value of attribute current_data.



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# File 'lib/cabriolet/cab/extractor.rb', line 326

def current_data
  @current_data
end

#io_system ⇒ Object (readonly)

Returns the value of attribute io_system.



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# File 'lib/cabriolet/cab/extractor.rb', line 326

def io_system
  @io_system
end

#num_blocks ⇒ Object (readonly)

Returns the value of attribute num_blocks.



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# File 'lib/cabriolet/cab/extractor.rb', line 326

def num_blocks
  @num_blocks
end

#salvage ⇒ Object (readonly)

Returns the value of attribute salvage.



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# File 'lib/cabriolet/cab/extractor.rb', line 326

def salvage
  @salvage
end

Instance Method Details

#close ⇒ Object 



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# File 'lib/cabriolet/cab/extractor.rb', line 394

def close
  @cab_handle&.close
  @cab_handle = nil
end

#read(bytes) ⇒ Object 



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# File 'lib/cabriolet/cab/extractor.rb', line 346

def read(bytes)
  # Early return if we've already exhausted all blocks and buffer
  if @current_block >= @num_blocks && @buffer_pos >= @buffer.bytesize
    if @debug_block
      warn "DEBUG BlockReader.read(#{bytes}): Already exhausted, returning empty"
    end
    return +""
  end

  result = +""

  if @debug_block
    warn "DEBUG BlockReader.read(#{bytes}): buffer_size=#{@buffer.bytesize} buffer_pos=#{@buffer_pos} block=#{@current_block}/#{@num_blocks}"
  end

  while result.bytesize < bytes
    # Read more data if buffer is empty
    if (@buffer_pos >= @buffer.bytesize) && !read_next_block
      if @debug_block
        warn "DEBUG BlockReader.read: EXHAUSTED at result.bytesize=#{result.bytesize} (wanted #{bytes})"
      end
      break
    end

    # Copy from buffer
    available = @buffer.bytesize - @buffer_pos
    to_copy = [available, bytes - result.bytesize].min

    result << @buffer[@buffer_pos, to_copy]
    @buffer_pos += to_copy
  end

  if @debug_block
    warn "DEBUG BlockReader.read: returning #{result.bytesize} bytes"
  end

  result
end

#seek(_offset, _whence) ⇒ Object 



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# File 'lib/cabriolet/cab/extractor.rb', line 385

def seek(_offset, _whence)
  # Not implemented for block reader
  0
end

#tell ⇒ Object 



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# File 'lib/cabriolet/cab/extractor.rb', line 390

def tell
  0
end