Only try and set permissions if permissions have changed.

CHANGELOG.md

@@ -1,3 +1,10 @@
+## 4.3.1
+  - Add extra safety to `chown` call in `atomic_write`, avoiding plugin crashes and falling back to a 
+  `non_atomic_write` in the event of failure [#295](https://github.com/logstash-plugins/logstash-input-file/pull/295)
+  - Refactor: unify event updates to happen in one place [#297](https://github.com/logstash-plugins/logstash-input-file/pull/297)
+  - Test: Actually retry tests on `RSpec::Expectations::ExpectationNotMetError` and retry instead of relying on timeout
+  [#297](https://github.com/logstash-plugins/logstash-input-file/pull/297)
+
 ## 4.3.0
   - Add ECS Compatibility Mode [#291](https://github.com/logstash-plugins/logstash-input-file/pull/291)
 

lib/filewatch/helper.rb

@@ -30,15 +30,18 @@ def write_atomically(file_name)
     temp_file.binmode
     return_val = yield temp_file
     temp_file.close
+    new_stat = File.stat(temp_file)
 
     # Overwrite original file with temp file
     File.rename(temp_file.path, file_name)
 
     # Unable to get permissions of the original file => return
     return return_val if old_stat.nil?
 
-    # Set correct uid/gid on new file
-    File.chown(old_stat.uid, old_stat.gid, file_name) if old_stat
+    # Set correct uid/gid on new file if ownership is different.
+    if old_stat && (old_stat.gid != new_stat.gid || old_stat.uid != new_stat.uid)
+      File.chown(old_stat.uid, old_stat.gid, file_name) if old_stat
+    end
 
     return_val
   end

lib/filewatch/sincedb_collection.rb

@@ -225,13 +225,24 @@ def sincedb_write(time = Time.now)
 
     # @return expired keys
     def atomic_write(time)
-      FileHelper.write_atomically(@full_path) do |io|
-        @serializer.serialize(@sincedb, io, time.to_f)
+      logger.trace? && logger.trace("non_atomic_write: ", :time => time)
+      begin
+        FileHelper.write_atomically(@full_path) do |io|
+          @serializer.serialize(@sincedb, io, time.to_f)
+        end
+      rescue Errno::EPERM, Errno::EACCES => e
+        logger.warn("sincedb_write: unable to write atomically due to permissions error, falling back to non-atomic write: #{path} error:", :exception => e.class, :message => e.message)
+        @write_method = method(:non_atomic_write)
+        non_atomic_write(time)
+      rescue => e
+        logger.warn("sincedb_write: unable to write atomically, attempting non-atomic write: #{path} error:", :exception => e.class, :message => e.message)
+        non_atomic_write(time)
       end
     end
 
     # @return expired keys
     def non_atomic_write(time)
+      logger.trace? && logger.trace("non_atomic_write: ", :time => time)
       File.open(@full_path, "w+") do |io|
         @serializer.serialize(@sincedb, io, time.to_f)
       end

logstash-input-file.gemspec

@@ -1,7 +1,7 @@
 Gem::Specification.new do |s|
 
   s.name            = 'logstash-input-file'
-  s.version         = '4.3.0'
+  s.version         = '4.3.1'
   s.licenses        = ['Apache-2.0']
   s.summary         = "Streams events from files"
   s.description     = "This gem is a Logstash plugin required to be installed on top of the Logstash core pipeline using $LS_HOME/bin/logstash-plugin install gemname. This gem is not a stand-alone program"