Class: Cabriolet::OAB::Decompressor

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

Overview

Decompressor for OAB (Outlook Offline Address Book) files

OAB files use LZX compression and come in two formats:

  • Full files (version 3.1): Complete address book data

  • Incremental patches (version 3.2): Binary patches applied to base file

This implementation is based on libmspack’s oabd.c

NOTE: This implementation cannot be fully validated due to lack of test fixtures. OAB files are specialized Outlook data files. Testing relies on round-trip compression/decompression.

Constant Summary collapse

DEFAULT_BUFFER_SIZE =

Default buffer size for I/O operations

4096

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io_system = nil) ⇒ Decompressor

Initialize OAB decompressor

Parameters:

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

    I/O system or nil for default



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# File 'lib/cabriolet/oab/decompressor.rb', line 28

def initialize(io_system = nil)
  @io_system = io_system || System::IOSystem.new
  @buffer_size = DEFAULT_BUFFER_SIZE
end

Instance Attribute Details

#buffer_size ⇒ Object

Returns the value of attribute buffer_size.



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# File 'lib/cabriolet/oab/decompressor.rb', line 20

def buffer_size
  @buffer_size
end

#io_system ⇒ Object (readonly)

Returns the value of attribute io_system.



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# File 'lib/cabriolet/oab/decompressor.rb', line 19

def io_system
  @io_system
end

Instance Method Details

#decompress(input_file, output_file) ⇒ Integer

Decompress a full OAB file

Parameters:

  • input_file (String) —

    Compressed OAB file path

  • output_file (String) —

    Decompressed output path

Returns:

  • (Integer) —

    Bytes written

Raises:

  • (Error) —

    if decompression fails



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

def decompress(input_file, output_file)
  input_handle = @io_system.open(input_file, Constants::MODE_READ)
  output_handle = @io_system.open(output_file, Constants::MODE_WRITE)

  begin
    # Read and validate header
    header_data = @io_system.read(input_handle, 16)
    raise Error, "Failed to read OAB header" if header_data.length < 16

    header = Binary::OABStructures::FullHeader.read(header_data)
    raise Error, "Invalid OAB header" unless header.valid?

    block_max = header.block_max
    target_size = header.target_size
    total_written = 0

    # Process blocks until target size reached
    while target_size.positive?
      total_written += decompress_block(
        input_handle, output_handle, block_max, target_size
      )
      target_size -= [block_max, target_size].min
    end

    total_written
  ensure
    @io_system.close(input_handle) if input_handle
    @io_system.close(output_handle) if output_handle
  end
end

#decompress_incremental(patch_file, base_file, output_file) ⇒ Integer

Decompress an incremental patch file

Parameters:

  • patch_file (String) —

    Compressed patch file path

  • base_file (String) —

    Base (uncompressed) file path

  • output_file (String) —

    Output file path

Returns:

  • (Integer) —

    Bytes written

Raises:

  • (Error) —

    if decompression fails



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# File 'lib/cabriolet/oab/decompressor.rb', line 77

def decompress_incremental(patch_file, base_file, output_file)
  patch_handle = @io_system.open(patch_file, Constants::MODE_READ)
  base_handle = @io_system.open(base_file, Constants::MODE_READ)
  output_handle = @io_system.open(output_file, Constants::MODE_WRITE)

  begin
    # Read and validate patch header
    header_data = @io_system.read(patch_handle, 28)
    if header_data.length < 28
      raise Error,
            "Failed to read OAB patch header"
    end

    header = Binary::OABStructures::PatchHeader.read(header_data)
    raise Error, "Invalid OAB patch header" unless header.valid?

    block_max = [header.block_max, 16].max # At least 16 for header
    target_size = header.target_size
    total_written = 0

    # Process patch blocks until target size reached
    while target_size.positive?
      total_written += decompress_patch_block(
        patch_handle, base_handle, output_handle, block_max, target_size
      )
      target_size = header.target_size - total_written
    end

    total_written
  ensure
    @io_system.close(patch_handle) if patch_handle
    @io_system.close(base_handle) if base_handle
    @io_system.close(output_handle) if output_handle
  end
end