Class: Fanotify::Notifier

Inherits:
Object
  • Object
show all
Defined in:
lib/fanotify/notifier.rb

Overview

Owns a fanotify group and provides safe event iteration.

Constant Summary collapse

PERMISSION_EVENTS = 
%i[open_perm access_perm open_exec_perm pre_access].freeze
PERMISSION_MASK = 
PERMISSION_EVENTS.reduce(0) { |mask, event| mask | EVENT_MASKS.fetch(event) }
FID_EVENTS = 
%i[attrib create delete delete_self moved_from moved_to move_self rename].freeze
MARK_ACTIONS = 
{add: FAN_MARK_ADD, remove: FAN_MARK_REMOVE}.freeze
MARK_TARGETS = 
{inode: FAN_MARK_INODE, mount: FAN_MARK_MOUNT, filesystem: FAN_MARK_FILESYSTEM}.freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(**options) ⇒ Notifier

Returns a new instance of Notifier.

Raises:

  • (ArgumentError) 


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# File 'lib/fanotify/notifier.rb', line 75

def initialize(**options)
  klass = options.delete(:class) || :notif
  @report = Array(options.delete(:report)).map(&:to_sym)
  nonblock = options.key?(:nonblock) ? options.delete(:nonblock) : false
  @nonblock = nonblock
  unlimited_queue = options.key?(:unlimited_queue) ? options.delete(:unlimited_queue) : false
  unlimited_marks = options.key?(:unlimited_marks) ? options.delete(:unlimited_marks) : false
  audit = options.key?(:audit) ? options.delete(:audit) : false
  event_flags = Array(options.delete(:event_flags) || %i[rdonly largefile cloexec]).map(&:to_sym)
  @on_overflow = options.delete(:on_overflow)
  @on_error = options.delete(:on_error)
  @on_error = @on_error.nil? ? :allow : @on_error
  @on_error = @on_error.to_sym if @on_error.respond_to?(:to_sym)
  @response_timeout = options.key?(:response_timeout) ? options.delete(:response_timeout) : 5.0
  raise ArgumentError, "unknown options: #{options.keys.join(', ')}" unless options.empty?
  unless [nonblock, unlimited_queue, unlimited_marks, audit].all? { |value| value == true || value == false }
    raise ArgumentError, "boolean options must be true or false"
  end
  unless @on_overflow.nil? || @on_overflow.respond_to?(:call)
    raise ArgumentError, "on_overflow must be callable or nil"
  end
  raise ArgumentError, "on_error must be :allow or :deny" unless %i[allow deny].include?(@on_error)
  unless @response_timeout.nil? || (@response_timeout.is_a?(Numeric) && @response_timeout.real? &&
    @response_timeout.finite? && @response_timeout.positive?)
    raise ArgumentError, "response_timeout must be positive or nil"
  end

  @class = klass.to_sym
  validate_report!
  access_modes = event_flags & %i[rdonly wronly rdwr]
  raise ArgumentError, "event_flags require exactly one access mode" unless access_modes.one?
  flags = fetch(CLASS_FLAGS, @class, "class") | flags_for(@report, REPORT_FLAGS, "report")
  flags |= FAN_NONBLOCK if nonblock
  flags |= FAN_UNLIMITED_QUEUE if unlimited_queue
  flags |= FAN_UNLIMITED_MARKS if unlimited_marks
  flags |= FAN_ENABLE_AUDIT if audit
  @handle = Native.open(flags, flags_for(event_flags, EVENT_FLAGS, "event flag"))
  @pending = {}
  @pending_mutex = Mutex.new
  @response_mutex = Mutex.new
  @readers = {}
  @readers_condition = ConditionVariable.new
  @closing = false
  @exclude_self = false
end

Instance Attribute Details

#report ⇒ Object (readonly)

Returns the value of attribute report.



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# File 'lib/fanotify/notifier.rb', line 62

def report
  @report
end

Class Method Details

.open(**options) ⇒ Object 



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# File 'lib/fanotify/notifier.rb', line 64

def self.open(**options)
  notifier = new(**options)
  return notifier unless block_given?

  begin
    yield notifier
  ensure
    notifier.close
  end
end

Instance Method Details

#close ⇒ Object 



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# File 'lib/fanotify/notifier.rb', line 225

def close
  close_token = Object.new
  @response_mutex.synchronize do
    return if @closing || closed?

    @closing = close_token
    @readers.each_key do |reader|
      reader.raise(Error, "notifier is closed") unless reader == Thread.current
    rescue ThreadError
      nil
    end
  end
  @response_mutex.synchronize do
    @readers_condition.wait(@response_mutex) while @readers.any? { |reader, _| reader != Thread.current }
  end

  if @watchdog && @watchdog != Thread.current
    @watchdog.kill
    @watchdog.join
    @watchdog = nil
  end
  pending_events.each { |event| finish_event(event, :allow, suppress_errors: true) }
  @pending_mutex.synchronize { @pending.keys }.each { |token| finalize_deferred(token) }
  nil
ensure
  if @closing.equal?(close_token)
    active_error = $!
    close_error = nil
    @response_mutex.synchronize do
      [@io, @handle].each do |resource|
        resource&.close unless resource&.closed?
      rescue StandardError => error
        close_error ||= error
      end
    end
    raise close_error if !active_error && close_error
  end
end

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/fanotify/notifier.rb', line 223

def closed? = @handle.closed?

#each_event ⇒ Object 



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# File 'lib/fanotify/notifier.rb', line 173

def each_event
  return enum_for(__method__) unless block_given?

  loop do
    events = read_events(timeout: @nonblock ? 0.1 : nil)
    begin
      events.each do |event|
        if @exclude_self && event.pid == Process.pid
          finish_event(event, :allow)
          next
        end

        begin
          yield event
        ensure
          handling_error = !$!.nil?
          if handling_error || !event.deferred?
            finish_event(event, handling_error ? @on_error : :allow, suppress_errors: handling_error)
          end
        end
      end
    ensure
      events.each do |event|
        finish_event(event, :allow, suppress_errors: true) unless event.closed? || event.deferred?
      end
    end
  end
end

#exclude_self! ⇒ Object 



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# File 'lib/fanotify/notifier.rb', line 202

def exclude_self!
  @exclude_self = true
  self
end

#fileno ⇒ Object 



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# File 'lib/fanotify/notifier.rb', line 222

def fileno = @handle.fileno

#flush(on = :inode) ⇒ Object 



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# File 'lib/fanotify/notifier.rb', line 135

def flush(on = :inode)
  @handle.mark(FAN_MARK_FLUSH | fetch(MARK_TARGETS, on.to_sym, "mark target"), 0, AT_FDCWD, nil)
  self
end

#mark(action, path, events:, on: :inode, follow: true, only_dir: false) ⇒ Object 



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# File 'lib/fanotify/notifier.rb', line 121

def mark(action, path, events:, on: :inode, follow: true, only_dir: false)
  unless [follow, only_dir].all? { |value| value == true || value == false }
    raise ArgumentError, "follow and only_dir must be true or false"
  end
  mark = Mark.new(action: action.to_sym, path: File.path(path), events: Array(events).map(&:to_sym),
                  on: on.to_sym, follow:, only_dir:)
  validate_mark!(mark)
  flags = fetch(MARK_ACTIONS, mark.action, "mark action") | fetch(MARK_TARGETS, mark.on, "mark target")
  flags |= FAN_MARK_DONT_FOLLOW unless mark.follow
  flags |= FAN_MARK_ONLYDIR if mark.only_dir
  @handle.mark(flags, flags_for(mark.events, EVENT_MASKS, "event"), AT_FDCWD, mark.path)
  self
end

#pending_events ⇒ Object 



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# File 'lib/fanotify/notifier.rb', line 207

def pending_events
  @pending_mutex.synchronize do
    @pending.values.filter_map { |reference, _deadline| dereference(reference) }
  end
end

#read_events(timeout: nil) ⇒ Object 



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# File 'lib/fanotify/notifier.rb', line 140

def read_events(timeout: nil)
  unless timeout.nil? || (timeout.is_a?(Numeric) && timeout.real? && timeout.finite? &&
    timeout >= 0 && timeout * 1000 <= 2_147_483_647)
    raise ArgumentError, "timeout must be a non-negative finite number or nil"
  end

  buffer = read_buffer(timeout)
  return [] unless buffer

  begin
    events = Event.__send__(:parse_owned, buffer, notifier: self)
  rescue Exception # Closing the group releases permission events that could not be parsed.
    begin
      close
    rescue Exception
      nil
    end
    raise
  end
  begin
    events.each do |event|
      next unless event.overflow?

      safely_warn "fanotify event queue overflowed; events were lost"
      @on_overflow&.call(event)
    end
  rescue Exception # SystemExit and Interrupt must not strand permission events.
    events.each { |event| finish_event(event, :allow, suppress_errors: true) }
    raise
  end
  events
end

#to_io ⇒ Object 



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# File 'lib/fanotify/notifier.rb', line 213

def to_io
  @response_mutex.synchronize do
    raise Error, "notifier is closed" if @closing || closed?

    @io = @handle.to_io.dup unless @io && !@io.closed?
    @io
  end
end