WindowsFile: Show the path when Win32Error is occured

In fluent#3325 we added Win32Error to show Windows specific errors correctly,
but it's not enough for debugging because it doesn't show which file
causes the error.

Signed-off-by: Takuro Ashie <ashie@clear-code.com>

lib/fluent/plugin/file_wrapper.rb

@@ -50,10 +50,11 @@ class Win32Error < StandardError
     require 'windows/error'
     include Windows::Error
 
-    attr_reader :errcode
+    attr_reader :errcode, :msg
 
-    def initialize(errcode)
+    def initialize(errcode, msg = nil)
       @errcode = errcode
+      @msg = msg
     end
 
     def format_english_message(errcode)
@@ -65,12 +66,14 @@ def format_english_message(errcode)
     end
 
     def message
-      "code: #{@errcode}, #{format_english_message(@errcode)}"
+      msg = "code: #{@errcode}, #{format_english_message(@errcode)}"
+      msg << ": #{@msg}" if @msg
+      msg
     end
 
     def ==(other)
       return false if other.class != Win32Error
-      @errcode == other.errcode
+      @errcode == other.errcode && @msg == other.msg
     end
   end
 
@@ -109,7 +112,7 @@ def initialize(path, mode='r', sharemode=FILE_SHARE_READ|FILE_SHARE_WRITE|FILE_S
         if err == ERROR_FILE_NOT_FOUND || err == ERROR_PATH_NOT_FOUND || err == ERROR_ACCESS_DENIED
           raise Errno::ENOENT
         end
-        raise Win32Error.new(err)
+        raise Win32Error.new(err, path)
       end
     end
 

test/plugin/test_file_wrapper.rb

@@ -19,15 +19,20 @@ def teardown
 
   sub_test_case 'Win32Error' do
     test 'equal' do
-      assert_equal(Fluent::Win32Error.new(ERROR_SHARING_VIOLATION),
-                   Fluent::Win32Error.new(ERROR_SHARING_VIOLATION))
+      assert_equal(Fluent::Win32Error.new(ERROR_SHARING_VIOLATION, "message"),
+                   Fluent::Win32Error.new(ERROR_SHARING_VIOLATION, "message"))
     end
 
     test 'different error code' do
       assert_not_equal(Fluent::Win32Error.new(ERROR_FILE_NOT_FOUND),
                        Fluent::Win32Error.new(ERROR_SHARING_VIOLATION))
     end
 
+    test 'different error message' do
+      assert_not_equal(Fluent::Win32Error.new(ERROR_FILE_NOT_FOUND, "message1"),
+                       Fluent::Win32Error.new(ERROR_FILE_NOT_FOUND, "message2"))
+    end
+
     test 'different class' do
       assert_not_equal(Errno::EPIPE,
                        Fluent::Win32Error.new(ERROR_SHARING_VIOLATION))
@@ -37,6 +42,12 @@ def teardown
       assert_equal(Fluent::Win32Error.new(ERROR_SHARING_VIOLATION).message,
                    "code: 32, The process cannot access the file because it is being used by another process.")
     end
+
+    test 'ERROR_SHARING_VIOLATION with a message' do
+      assert_equal(Fluent::Win32Error.new(ERROR_SHARING_VIOLATION, "cannot open the file").message,
+                   "code: 32, The process cannot access the file because it is being used by another process." +
+                   ": cannot open the file")
+    end
   end
 
   sub_test_case 'WindowsFile exceptions' do
@@ -71,7 +82,7 @@ def teardown
         path = "#{TMP_DIR}/test_windows_file.txt"
         file1 = file2 = nil
         file1 = File.open(path, "wb")
-        assert_raise(Fluent::Win32Error.new(ERROR_SHARING_VIOLATION)) do
+        assert_raise(Fluent::Win32Error.new(ERROR_SHARING_VIOLATION, path)) do
           file2 = Fluent::WindowsFile.new(path, 'r', FILE_SHARE_READ)
         ensure
           file2.close if file2