Fix top level exception on unexpected event

lib/rb-kqueue/event.rb

@@ -3,6 +3,11 @@ module KQueue
   # Each {Watcher} can fire many events,
   # which are passed to that Watcher's callback.
   class Event
+
+    # Exception raised on an attempt to construct an {Event}
+    # from a native event with unexpected field values.
+    class UnexpectedEvent < Exception; end
+
     # Some integer data, the interpretation of which
     # is specific to each individual {Watcher}.
     # For specifics, see the individual Watcher subclasses.
@@ -64,7 +69,11 @@ def initialize(native, queue)
       @native = native
       @queue = queue
       @data = @native[:data]
-      @filter = KQueue::Native::Flags.from_flag("EVFILT", @native[:filter])
+      begin
+        @filter = KQueue::Native::Flags.from_flag("EVFILT", @native[:filter])
+      rescue Native::Flags::FlagNotFound
+        raise UnexpectedEvent
+      end
       @flags = Native::Flags.from_mask("EV", @native[:flags])
 
       KQueue.handle_error @native[:data] if @flags.include?(:error)

lib/rb-kqueue/native/flags.rb

@@ -97,6 +97,9 @@ module Flags
       NOTE_TIMER_NSECONDS = 0x00000004 # data is nanoseconds
       NOTE_TIMER_ABSOLUTE = 0x00000008 # absolute timeout
 
+      # Exception raised when a function fails to find a flag satisfying
+      # its given query.
+      class FlagNotFound < Exception; end
 
       # Converts a list of flags to the bitmask that the C API expects.
       #
@@ -143,6 +146,7 @@ def self.from_flag(prefix, flag)
           next unless c =~ re
           return c.to_s.sub("#{prefix}_", "").downcase.to_sym if const_get(c) == flag
         end
+        raise FlagNotFound
       end
     end
   end

lib/rb-kqueue/queue.rb

@@ -359,7 +359,13 @@ def read_events(blocking = true)
       res = Native.kevent(@fd, nil, 0, eventlist, size, timeout)
 
       KQueue.handle_error if res < 0
-      (0...res).map {|i| KQueue::Event.new(Native::KEvent.new(eventlist[i]), self)}
+      (0...res).map do |i|
+        begin
+          KQueue::Event.new(Native::KEvent.new(eventlist[i]), self)
+        rescue KQueue::Event::UnexpectedEvent
+          nil
+        end
+      end.compact
     end
   end
 end