Merge pull request #2695 from Iristyle/ticket/master/PUP-2657-FFI-Pup…

…pet-Util-Windows-Error

(PUP-2657) FFI Puppet::Util::Windows:Error

lib/puppet/util/windows/api_types.rb

@@ -16,9 +16,7 @@ def attach_function_private(*args)
 
   class ::FFI::Pointer
     NULL_HANDLE = 0
-  end
 
-  class ::FFI::MemoryPointer
     def self.from_string_to_wide_string(str)
       str = Puppet::Util::Windows::String.wide_string(str)
       ptr = FFI::MemoryPointer.new(:byte, str.bytesize)
@@ -75,6 +73,7 @@ def read_wide_string(char_length)
 
   # pointer in FFI is platform specific
   # NOTE: for API calls with reserved lpvoid parameters, pass a FFI::Pointer::NULL
+  FFI.typedef :pointer, :lpcvoid
   FFI.typedef :pointer, :lpvoid
   FFI.typedef :pointer, :lpword
   FFI.typedef :pointer, :lpdword

lib/puppet/util/windows/error.rb

@@ -2,15 +2,97 @@
 
 # represents an error resulting from a Win32 error code
 class Puppet::Util::Windows::Error < Puppet::Error
-  require 'windows/error'
-  include ::Windows::Error
+  require 'ffi'
+  extend FFI::Library
 
   attr_reader :code
 
-  def initialize(message, code = GetLastError.call, original = nil)
-    super(message + ":  #{get_last_error(code)}", original)
+  def initialize(message, code = @@GetLastError.call(), original = nil)
+    super(message + ":  #{self.class.format_error_code(code)}", original)
 
     @code = code
   end
-end
 
+  # Helper method that wraps FormatMessage that returns a human readable string.
+  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
+    # this pointer actually points to a :lpwstr (pointer) since we're letting Windows allocate for us
+    buffer_ptr = FFI::MemoryPointer.new(:pointer, 1)
+
+    begin
+      length = FormatMessageW(flags, FFI::Pointer::NULL, code, dwLanguageId,
+        buffer_ptr, 0, FFI::Pointer::NULL)
+
+      if length == FFI::WIN32_FALSE
+        # can't raise same error type here or potentially recurse infinitely
+        raise Puppet::Error.new("FormatMessageW could not format code #{code}")
+      end
+
+      # returns an FFI::Pointer with autorelease set to false, which is what we want
+      wide_string_ptr = buffer_ptr.read_pointer
+
+      if wide_string_ptr.null?
+        raise Puppet::Error.new("FormatMessageW failed to allocate buffer for code #{code}")
+      end
+
+      return wide_string_ptr.read_wide_string(length)
+    ensure
+      if ! wide_string_ptr.nil? && ! wide_string_ptr.null?
+        if LocalFree(wide_string_ptr.address) != FFI::Pointer::NULL_HANDLE
+          Puppet.debug "LocalFree memory leak"
+        end
+      end
+    end
+  end
+
+  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
+
+  ffi_convention :stdcall
+
+  # NOTE: It seems like FFI.errno is already implemented as GetLastError... or is it?
+  # http://msdn.microsoft.com/en-us/library/windows/desktop/ms679360(v=vs.85).aspx
+  # DWORD WINAPI GetLastError(void);
+  # HACK: unfortunately using FFI.errno or attach_function to hook GetLastError in
+  # FFI like the following will not work.  Something internal to FFI appears to
+  # be stomping out the value of GetLastError when calling via FFI.
+  # attach_function_private :GetLastError, [], :dword
+  require 'Win32API'
+  @@GetLastError = Win32API.new('kernel32', 'GetLastError', [], 'L')
+
+  # http://msdn.microsoft.com/en-us/library/windows/desktop/ms679351(v=vs.85).aspx
+  # DWORD WINAPI FormatMessage(
+  #   _In_      DWORD dwFlags,
+  #   _In_opt_  LPCVOID lpSource,
+  #   _In_      DWORD dwMessageId,
+  #   _In_      DWORD dwLanguageId,
+  #   _Out_     LPTSTR lpBuffer,
+  #   _In_      DWORD nSize,
+  #   _In_opt_  va_list *Arguments
+  # );
+  # NOTE: since we're not preallocating the buffer, use a :pointer for lpBuffer
+  ffi_lib :kernel32
+  attach_function_private :FormatMessageW,
+    [:dword, :lpcvoid, :dword, :dword, :pointer, :dword, :pointer], :dword
+
+  # http://msdn.microsoft.com/en-us/library/windows/desktop/aa366730(v=vs.85).aspx
+  # HLOCAL WINAPI LocalFree(
+  #   _In_  HLOCAL hMem
+  # );
+  ffi_lib :kernel32
+  attach_function_private :LocalFree, [:handle], :handle
+end