Fix Errno::EACCES which occurs while testing on Ruby 3.2

lib/fluent/file_wrapper.rb

@@ -0,0 +1,137 @@
+#
+# Fluentd
+#
+#    Licensed under the Apache License, Version 2.0 (the "License");
+#    you may not use this file except in compliance with the License.
+#    You may obtain a copy of the License at
+#
+#        http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS,
+#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#    See the License for the specific language governing permissions and
+#    limitations under the License.
+#
+
+unless Fluent.windows?
+  Fluent::FileWrapper = File
+else
+  require 'fluent/win32api'
+
+  module Fluent
+    module FileWrapper
+      def self.open(path, mode='r')
+        io = WindowsFile.new(path, mode).io
+        if block_given?
+          v = yield io
+          io.close
+          v
+        else
+          io
+        end
+      end
+
+      def self.stat(path)
+        f = WindowsFile.new(path)
+        s = f.stat
+        f.close
+        s
+      end
+    end
+
+    class WindowsFile
+      include File::Constants
+
+      attr_reader :io
+
+      INVALID_HANDLE_VALUE = -1
+
+      def initialize(path, mode_enc='r')
+        @path = path
+        mode, enc = mode_enc.split(":", 2)
+        @io = File.open(path, mode2flags(mode))
+        @io.set_encoding(enc) if enc
+        @file_handle = Win32API._get_osfhandle(@io.to_i)
+        @io.instance_variable_set(:@file_index, self.ino)
+        def @io.ino
+          @file_index
+        end
+      end
+
+      def close
+        @io.close
+        @file_handle = INVALID_HANDLE_VALUE
+      end
+
+      # To keep backward compatibility, we continue to use GetFileInformationByHandle()
+      # to get file id.
+      # Note that Ruby's File.stat uses GetFileInformationByHandleEx() with FileIdInfo
+      # and returned value is different with above one, former one is 64 bit while
+      # later one is 128bit.
+      def ino
+        by_handle_file_information = '\0'*(4+8+8+8+4+4+4+4+4+4)   #72bytes
+
+        unless Win32API.GetFileInformationByHandle(@file_handle, by_handle_file_information)
+          return 0
+        end
+
+        by_handle_file_information.unpack("I11Q1")[11] # fileindex
+      end
+
+      def stat
+        raise Errno::ENOENT if delete_pending
+        s = File.stat(@path)
+        s.instance_variable_set :@ino, self.ino
+        def s.ino; @ino; end
+        s
+      end
+
+      private
+
+      def mode2flags(mode)
+        # Always inject File::Constants::SHARE_DELETE
+        # https://github.com/fluent/fluentd/pull/3585#issuecomment-1101502617
+        # To enable SHARE_DELETE, BINARY is also required.
+        # https://bugs.ruby-lang.org/issues/11218
+        # https://github.com/ruby/ruby/blob/d6684f063bc53e3cab025bd39526eca3b480b5e7/win32/win32.c#L6332-L6345
+        flags = BINARY | SHARE_DELETE
+        case mode.delete("b")
+        when "r"
+          flags |= RDONLY
+        when "r+"
+          flags |= RDWR
+        when "w"
+          flags |= WRONLY | CREAT | TRUNC
+        when "w+"
+          flags |= RDWR | CREAT | TRUNC
+        when "a"
+          flags |= WRONLY | CREAT | APPEND
+        when "a+"
+          flags |= RDWR | CREAT | APPEND
+        else
+          raise Errno::EINVAL.new("Unsupported mode by Fluent::FileWrapper: #{mode}")
+        end
+      end
+
+      # DeletePending is a Windows-specific file state that roughly means
+      # "this file is queued for deletion, so close any open handlers"
+      #
+      # This flag can be retrieved via GetFileInformationByHandleEx().
+      #
+      # https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-getfileinformationbyhandleex
+      #
+      def delete_pending
+        file_standard_info = 0x01
+        bufsize = 1024
+        buf = '\0' * bufsize
+
+        unless Win32API.GetFileInformationByHandleEx(@file_handle, file_standard_info, buf, bufsize)
+          return false
+        end
+
+        return buf.unpack("QQICC")[3] != 0
+      end
+    end
+  end
+end

lib/fluent/plugin/in_tail.rb

@@ -25,12 +25,7 @@
 require 'fluent/capability'
 require 'fluent/plugin/in_tail/position_file'
 require 'fluent/plugin/in_tail/group_watch'
-
-if Fluent.windows?
-  require_relative 'file_wrapper'
-else
-  Fluent::FileWrapper = File
-end
+require 'fluent/file_wrapper'
 
 module Fluent::Plugin
   class TailInput < Fluent::Plugin::Input