Windows registry test, MRI vs JRuby

reg_test.r

require 'Win32API'
hkey = 'SYSTEM\CurrentControlSet\Services\Tcpip\Parameters'

WCHAR = Encoding::UTF_16LE
HKEY_LOCAL_MACHINE = 0x80000002
STANDARD_RIGHTS_READ = 0x00020000
KEY_QUERY_VALUE = 0x0001
KEY_ENUMERATE_SUB_KEYS = 0x0008
KEY_NOTIFY = 0x0010
KEY_READ = STANDARD_RIGHTS_READ |
   KEY_QUERY_VALUE |
   KEY_ENUMERATE_SUB_KEYS |
   KEY_NOTIFY

RegOpenKeyExA = Win32API.new('advapi32', 'RegOpenKeyExA', 'LPLLP', 'L')
RegQueryValueExA = Win32API.new('advapi32', 'RegQueryValueExA', 'LPLPPP', 'L')
RegQueryValueExW = Win32API.new('advapi32', 'RegQueryValueExW', 'LPLPPP', 'L')

handle = [0].pack('L')

rv = RegOpenKeyExA.call(
  HKEY_LOCAL_MACHINE,
  hkey,
  0,
  KEY_READ,
  handle
)

if rv != 0
  raise "RegOpenKeyExA failed"
end

handle = handle.unpack('L').first
name = "DataBasePath"
wname = name.encode(WCHAR)

# First call, get size
size = [0].pack('L')
type = [0].pack('L')
#RegQueryValueExA.call(handle, name, 0, type, 0, size)
rv = RegQueryValueExW.call(handle, wname, 0, type, 0, size)

# JRuby fails here
if rv != 0 && rv != ERROR_MORE_DATA
  raise SystemCallError.new('RegQueryValueEx', rv)
end

# Now use that data for second call
#data = 0.chr * size.unpack('L').first
data = "\0".force_encoding('ASCII-8BIT') * size.unpack('L').first
#RegQueryValueExA.call(handle, name, 0, type, data, size)
rv = RegQueryValueExW.call(handle, wname, 0, type, data, size)

if rv != 0
  raise "RegQueryValueEx failed"
end

p data