Exception: Facter::Util::Windows::Error

Inherits:
RuntimeError
  • Object
show all
Extended by:
FFI::Library
Defined in:
lib/facter/util/windows/error.rb

Overview

represents an error resulting from a Win32 error code

Constant Summary collapse

ERROR_FILE_NOT_FOUND = 
2
ERROR_ACCESS_DENIED = 
5
FORMAT_MESSAGE_ALLOCATE_BUFFER = 
0x00000100
FORMAT_MESSAGE_IGNORE_INSERTS = 
0x00000200
FORMAT_MESSAGE_FROM_SYSTEM = 
0x00001000
FORMAT_MESSAGE_ARGUMENT_ARRAY = 
0x00002000
FORMAT_MESSAGE_MAX_WIDTH_MASK = 
0x000000FF

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(message, code = FFI.errno, original = nil) ⇒ Error

NOTE: FFI.errno only works properly when prior Win32 calls have been made through FFI bindings. Calls made through Win32API do not have their error codes captured by FFI.errno



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# File 'lib/facter/util/windows/error.rb', line 14

def initialize(message, code = FFI.errno, original = nil)
  @original = original
  super(message + ":  #{self.class.format_error_code(code)}")

  @code = code
end

Instance Attribute Details

#code ⇒ Object (readonly) 



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# File 'lib/facter/util/windows/error.rb', line 8

def code
  @code
end

#original ⇒ Object (readonly) 



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# File 'lib/facter/util/windows/error.rb', line 9

def original
  @original
end

Class Method Details

.format_error_code(code) ⇒ Object

Helper method that wraps FormatMessage that returns a human readable string.



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# File 'lib/facter/util/windows/error.rb', line 22

def self.format_error_code(code)
  # specifying 0 will look for LANGID in the following order
  # 1.Language neutral
  # 2.Thread LANGID, based on the thread's locale value
  # 3.User default LANGID, based on the user's default locale value
  # 4.System default LANGID, based on the system default locale value
  # 5.US English
  dwLanguageId = 0
  flags = FORMAT_MESSAGE_ALLOCATE_BUFFER |
      FORMAT_MESSAGE_FROM_SYSTEM |
      FORMAT_MESSAGE_ARGUMENT_ARRAY |
      FORMAT_MESSAGE_IGNORE_INSERTS |
      FORMAT_MESSAGE_MAX_WIDTH_MASK
  error_string = ''

  # this pointer actually points to a :lpwstr (pointer) since we're letting Windows allocate for us
  FFI::MemoryPointer.new(:pointer, 1) do |buffer_ptr|
    length = FormatMessageW(flags, FFI::Pointer::NULL, code, dwLanguageId,
                            buffer_ptr, 0, FFI::Pointer::NULL)

    if length == Facter::Util::Windows::FFI::WIN32_FALSE
      # can't raise same error type here or potentially recurse infinitely
      raise Facter::Error.new("FormatMessageW could not format code #{code}")
    end

    # returns an FFI::Pointer with autorelease set to false, which is what we want
    Facter::Util::Windows::FFI.read_win32_local_pointer(buffer_ptr) do |wide_string_ptr|
      if wide_string_ptr.null?
        raise Facter::Error.new("FormatMessageW failed to allocate buffer for code #{code}")
      end

      error_string = Facter::Util::Windows::FFI.read_wide_string(wide_string_ptr, length)
    end
  end

  error_string
end