Quick script to read a property from a Windows Installer file

msiprop.rb

#!/usr/bin/env ruby

current_dir = File.dirname(__FILE__)

require 'ffi'

module Win32
  extend FFI::Library
  ffi_lib 'msi'
  attach_function :msi_open_package_ex,
  :MsiOpenPackageExA, [:string, :long, :pointer], :int
end

module Win32
  extend FFI::Library
  ffi_lib 'msi'
  attach_function :msi_close_handle,
  :MsiCloseHandle, [:pointer], :int
end

module Win32
  extend FFI::Library
  ffi_lib 'kernel32'
  attach_function :local_free,
  :LocalFree, [ :pointer ], :long
end

module Win32
  extend FFI::Library
  ffi_lib 'msi'
  attach_function :msi_get_product_property,
  :MsiGetProductPropertyA, [:pointer, :pointer, :pointer, :pointer], :int
end

module Win32
  extend FFI::Library
  ffi_lib 'msi'
  attach_function :msi_open_database,
  :MsiOpenDatabaseA, [:pointer, :pointer, :pointer], :int
end


def print_usage
  puts "Usage:\n"
  puts "\tmsiprop <package path> <property name> [property name2] [property name 3]...\n"
  puts
end

if ( ARGV.length < 2 )
  print_usage
  exit 1
end

package_path = ARGV[0]
properties = Array.new(ARGV.length - 1)

properties.length.times do | index |
  properties[index] = ARGV[index + 1]
end

def show_package_properties(package_path, property_names)
  properties = get_package_properties(package_path, property_names)

  properties.each_pair do | property |
    puts "#{property[0]}:\t #{property[1]}"
  end

  puts
end

def get_package_properties(package_path, property_names)
  package_handle_result = FFI::MemoryPointer.new(:pointer, 4)

  status = Win32.msi_open_package_ex(package_path, 1, package_handle_result)

#  status = Win32.msi_open_database(package_path, nil, package_handle_result)
  
  raise RuntimeError, "MsiOpenPackageEx failed with status #{status}" if status != 0

  results = {}
  begin
    property_names.each do | property_name |
      property_value = get_package_property(package_handle_result.read_pointer, property_name)
      if property_value && ! property_value.empty?
        results[property_name] = property_value
      end
    end
  ensure
    Win32.msi_close_handle(package_handle_result.read_pointer)
  end

  results
end

def get_package_property(msi_handle, property_name)
  property_value = 0.chr
  property_length = FFI::Buffer.new(:long).write_long(0)
    
  status = Win32.msi_get_product_property(
                           msi_handle,
                           property_name,
                           property_value,
                           property_length)

  
  if ( status != 234 )
    raise "Unexpected status #{status}"
  end

  new_property_size = FFI::Buffer.new(:long).write_long(property_length.read_long + 1)

  property_value = 0.chr * new_property_size.read_long
  
  status = Win32.msi_get_product_property(
                           msi_handle,
                           property_name,
                           property_value,
                           new_property_size)

  if status != 0
    raise RuntimeError, "MsiGetProductProperty Failed with status #{status}"
  end

  property_value
end

show_package_properties(package_path, properties)