#!/usr/bin/ruby

 # This script watches modifications on the given directory, using the new # FSEvents API in Leopard.

 require 'osx/foundation'

 OSX.require_framework '/System/Library/Frameworks/CoreServices.framework/Frameworks/CarbonCore.framework'

 include OSX

 require 'set'

 require 'optparse'

 require 'ostruct'

 $COMMAND = File.basename($0)

 $USAGE = "Usage: #{$COMMAND} [OPTIONS] <command> [<args> ...]"

 def die(s)

   $stderr.puts s

   exit 1

 end

 def run_command(*args)

   fork do

     begin

       exec(*args)

     rescue SystemCallError  => e

       puts e.message

       exit 127

     end

   end

   pid = Process.wait

   returnCode = $? >> 8

   sleep(0.1)

   return returnCode

 end

 def wait_until_interrupt

   begin

     $stderr.puts "Press Control-C to stop monitoring"

     sleep(1.0) while (true)

   rescue Interrupt

     puts

   end

 end

 options = OpenStruct.new

 options.directoriesOnly = false

 options.outputFile = "-"

 options.wait = false

 options.show_current_id = false

 options.start_id = nil

 options.path = "/"

 opts = OptionParser.new do |opts|

   opts.banner = $USAGE

   opts.separator ""

   opts.separator "Specific options:"

   opts.on("-d", "--dir-only", "Only display directories") do

     options.directoriesOnly = true

   end

   opts.on("-o", "--output FILE", "Write output to a file") do |fileName|

     options.outputFile = fileName

   end

   opts.on("-w", "--wait", "Wait until interrupted") do

     options.wait = true

   end

   opts.on("-c", "--current-id", "Show current id and exit") do

     options.show_current_id = true

   end

   opts.on("-C", "--use-start-id START_ID", "Use start ID") do |start_id|

     options.start_id = start_id

   end

   opts.on("-p", "--path PATH", "Path to show") do |path|

     options.path = path

   end

   opts.on_tail("-h", "--help", "Show this message") do

     puts opts

     exit

   end

 end

 opts.parse!(ARGV)

 if !options.wait and ARGV == 0

   die $USAGE

 end

 if options.outputFile == "-"

   outputHandle = $stdout.clone

 else

   outputHandle = File.open(options.outputFile, "w")

 end

 path = options.path

 startId = FSEventsGetCurrentEventId()

 # Used to compare with mtime, which only has second accuracy

 startTime = Time.now.to_i

 if (options.show_current_id)

   puts "#{startId}:#{startTime}"

   exit 0

 end

 if !options.start_id.nil? then

   startId, startTime = options.start_id.split(':').map { |s| s.to_i }

   returnCode = 0

 elsif options.wait then

   wait_until_interrupt

   returnCode = 0

 else

   returnCode = run_command(*ARGV)

 end

 allPaths = Set.new

 fsevents_cb = proc do |stream, ctx, numEvents, paths, marks, eventIDs|

   paths.regard_as('*')

   numEvents.times do |n|

     allPaths.add(paths[n])

   end

 end

 stream = FSEventStreamCreate(

   KCFAllocatorDefault,

   fsevents_cb,

   nil,

   [path],

   startId,

   1.0,

   KFSEventStreamCreateFlagNoDefer)

 die "Failed to create the FSEventStream" unless stream

 FSEventStreamScheduleWithRunLoop(

   stream,

   CFRunLoopGetCurrent(),

   KCFRunLoopDefaultMode)

 ok = FSEventStreamStart(stream)

 die "Failed to start the FSEventStream" unless ok

 FSEventStreamFlushSync(stream)

 puts allPaths.to_a

 puts

 allPaths.sort.each do |path|

   if File.exists?(path)

     outputHandle.puts path

     if (!options.directoriesOnly)

       Dir.foreach(path) do |file|

         fullPath = File.join(path, file)

         stat = File.stat(fullPath)

         if (stat.mtime.to_i >= startTime)

           outputHandle.puts "  #{file}"

         end

       end

     end

   else

     outputHandle.puts "#{path} !"

   end

 end

 FSEventStreamStop(stream)

 FSEventStreamInvalidate(stream)

 FSEventStreamRelease(stream)

 outputHandle.flush

 exit(returnCode)