Add warning for directory permission to in_tail.rb

Signed-off-by: Tomoaki Kobayashi <tomoaki.kobayashi.t3@alumni.tohoku.ac.jp>

Author: moatom

lib/fluent/plugin/in_tail.rb

@@ -253,7 +253,7 @@ def start
         FileUtils.mkdir_p(pos_file_dir, mode: @dir_perm) unless Dir.exist?(pos_file_dir)
         @pf_file = File.open(@pos_file, File::RDWR|File::CREAT|File::BINARY, @file_perm)
         @pf_file.sync = true
-        @pf = PositionFile.load(@pf_file, @follow_inodes, expand_paths, logger: log)
+        @pf = PositionFile.load(@pf_file, @follow_inodes, expand_paths(true), logger: log)
 
         if @pos_file_compaction_interval
           timer_execute(:in_tail_refresh_compact_pos_file, @pos_file_compaction_interval) do
@@ -321,7 +321,7 @@ def use_glob?(path)
       end
     end
 
-    def expand_paths
+    def expand_paths(check_permission = false)
       date = Fluent::EventTime.now
       paths = []
       @paths.each { |path|
@@ -370,6 +370,19 @@ def expand_paths
       # filter out non existing files, so in case pattern is without '*' we don't do unnecessary work
       hash = {}
       (paths - excluded).select { |path|
+        if check_permission && !FileTest.readable?(path)
+          is_bad_permission = begin
+            current_path = File.expand_path(path)
+            loop do
+              current_path = File.dirname(current_path)
+              break true unless FileTest.executable?(current_path)
+              break false if current_path == "/"
+            end
+          end
+          if is_bad_permission
+            $log.warn "Skip #{path} because a directory in the path lacks execute permission."
+          end
+        end
         FileTest.exist?(path)
       }.each { |path|
         # Even we just checked for existence, there is a race condition here as

test/plugin/test_in_tail.rb

@@ -2591,6 +2591,60 @@ def test_EACCES
     d.instance_shutdown if d && d.instance
   end
 
+  def test_warn_without_directory_permission
+    omit "Cannot test with root user" if Process::UID.eid == 0
+    path = "#{@tmp_dir}/noaccess/tail.txt"
+    begin
+      FileUtils.mkdir_p("#{@tmp_dir}/noaccess")
+      FileUtils.touch(path)
+      FileUtils.chmod(0400, path)
+      FileUtils.chmod(0600, "#{@tmp_dir}/noaccess")
+      config = config_element('', '', {
+                                'tag' => "tail",
+                                'path' => path,
+                                'format' => 'none',
+                                "pos_file" => "#{@tmp_dir}/tail.pos",
+                              })
+      d = create_driver(config, false)
+      assert_nothing_raised do
+        d.run(shutdown: false) {}
+      end
+      assert($log.out.logs.any?{|log| log.include?("Skip #{path} because a directory in the path lacks execute permission.\n") })
+    end
+  ensure
+    d.instance_shutdown if d && d.instance
+    FileUtils.chmod(0755, "#{@tmp_dir}/noaccess")
+    if File.exist?("#{@tmp_dir}/noaccess")
+      FileUtils.rm_rf("#{@tmp_dir}/noaccess")
+    end
+  end unless Fluent.windows?
+
+  def test_no_warn_with_directory_permission
+    omit "Cannot test with root user" if Process::UID.eid == 0
+    path = "#{@tmp_dir}/noaccess/tail.txt"
+    begin
+      FileUtils.mkdir_p("#{@tmp_dir}/noaccess")
+      FileUtils.chmod(0100, "#{@tmp_dir}/noaccess")
+      config = config_element('', '', {
+                                'tag' => "tail",
+                                'path' => path,
+                                'format' => 'none',
+                                "pos_file" => "#{@tmp_dir}/tail.pos",
+                              })
+      d = create_driver(config, false)
+      assert_nothing_raised do
+        d.run(shutdown: false) {}
+      end
+      assert($log.out.logs.all?{|log| !log.include?("Skip #{path} because a directory in the path lacks execute permission.\n") })
+    end
+  ensure
+    d.instance_shutdown if d && d.instance
+    FileUtils.chmod(0755, "#{@tmp_dir}/noaccess")
+    if File.exist?("#{@tmp_dir}/noaccess")
+      FileUtils.rm_rf("#{@tmp_dir}/noaccess")
+    end
+  end unless Fluent.windows?
+
   def test_shutdown_timeout
     Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "wb") do |f|
       # Should be large enough to take too long time to consume