Extract MSI Installer

Purpose

Complete example of extracting files from a Windows Installer (MSI) package.

Problem

You need to extract files from an MSI installer to analyze its contents or access specific files without running the installer.

Solution

Use Excavate with recursive extraction to handle the nested CAB archives:

require 'excavate'

# Create archive instance
archive = Excavate::Archive.new('installer.msi')

# Extract with recursive option to get all files
archive.extract(recursive_packages: true)

Complete Example

require 'excavate'
require 'fileutils'

class MsiExtractor
  def initialize(msi_path)
    @msi_path = msi_path
    @archive = Excavate::Archive.new(msi_path)
  end

  def extract_all(target = nil)
    target ||= default_target

    # Remove existing target if any
    FileUtils.rm_rf(target) if File.exist?(target)

    # Extract with recursive option
    @archive.extract(target, recursive_packages: true)

    puts "Extracted to: #{target}"
    target
  end

  def extract_files(file_patterns, target = nil)
    target ||= default_target

    # Extract specific files
    extracted = @archive.extract(
      target,
      recursive_packages: true,
      files: file_patterns
    )

    puts "Extracted #{extracted.size} files"
    extracted
  end

  def extract_by_filter(pattern, target = nil)
    target ||= default_target

    # Extract matching files
    extracted = @archive.extract(
      target,
      recursive_packages: true,
      filter: pattern
    )

    puts "Extracted #{extracted.size} files matching #{pattern}"
    extracted
  end

  def list_contents
    files = []

    @archive.files(recursive_packages: true) do |path|
      files << path
    end

    files.sort
  end

  private

  def default_target
    File.basename(@msi_path, '.msi')
  end
end

# Usage
extractor = MsiExtractor.new('installer.msi')

# List contents
puts "Contents:"
extractor.list_contents.each { |f| puts "  #{f}" }

# Extract everything
extractor.extract_all

# Extract only DLLs
extractor.extract_by_filter('**/*.dll')

# Extract specific files
extractor.extract_files(['data1.cab/config.ini', 'data1.cab/README.txt'])

CLI Alternative

# Extract everything
excavate -r installer.msi

# Extract only DLLs
excavate -r --filter "**/*.dll" installer.msi

# Extract specific files
excavate -r installer.msi data1.cab/config.ini

Notes

• MSI files contain CAB archives that are automatically extracted

• Use recursive_packages: true to get actual file contents

• Without recursive option, you get the CAB files but not their contents