Linux-Inotify2/Inotify2.pm

=head1 NAME

Linux::Inotify2 - scalable directory/file change notification

=head1 SYNOPSIS

=head2 Callback Interface

 use Linux::Inotify2;

 # create a new object
 my $inotify = new Linux::Inotify2
    or die "unable to create new inotify object: $!";
 
 # add watchers
 $inotify->watch ("/etc/passwd", IN_ACCESS, sub {
    my $e = shift;
    my $name = $e->fullname;
    print "$name was accessed\n" if $e->IN_ACCESS;
    print "$name is no longer mounted\n" if $e->IN_UNMOUNT;
    print "$name is gone\n" if $e->IN_IGNORED;
    print "events for $name have been lost\n" if $e->IN_Q_OVERFLOW;
 
    # cancel this watcher: remove no further events
    $e->w->cancel;
 });

 # integration into AnyEvent (works with EV, Glib, Tk, POE...)
 my $inotify_w = AE::io $inotify->fileno, 0, sub { $inotify->poll };

 # manual event loop
 1 while $inotify->poll;

=head2 Streaming Interface

 use Linux::Inotify2;

 # create a new object
 my $inotify = new Linux::Inotify2
    or die "Unable to create new inotify object: $!";

 # create watch
 $inotify->watch ("/etc/passwd", IN_ACCESS)
    or die "watch creation failed";

 while () {
   my @events = $inotify->read;
   unless (@events > 0) {
     print "read error: $!";
     last;
   }
   printf "mask\t%d\n", $_->mask foreach @events;
 }

=head1 DESCRIPTION

This module implements an interface to the Linux 2.6.13 and later Inotify
file/directory change notification system.

It has a number of advantages over the Linux::Inotify module:

   - it is portable (Linux::Inotify only works on x86)
   - the equivalent of fullname works correctly
   - it is better documented
   - it has callback-style interface, which is better suited for
     integration.

As for the inotify API itself - it is a very tricky, and somewhat
unreliable API. For a good overview of the challenges you might run into,
see this LWN article: L<https://lwn.net/Articles/605128/>.

=head2 The Linux::Inotify2 Class

=over 4

=cut

package Linux::Inotify2;

use Scalar::Util ();

use common::sense;

use Exporter qw(import);

BEGIN {
   our $VERSION = '1.23';
   our @EXPORT = qw(
      IN_ACCESS IN_MODIFY IN_ATTRIB IN_CLOSE_WRITE
      IN_CLOSE_NOWRITE IN_OPEN IN_MOVED_FROM IN_MOVED_TO
      IN_CREATE IN_DELETE IN_DELETE_SELF IN_MOVE_SELF
      IN_ALL_EVENTS
      IN_UNMOUNT IN_Q_OVERFLOW IN_IGNORED
      IN_CLOSE IN_MOVE
      IN_ISDIR IN_ONESHOT IN_MASK_ADD
      IN_DONT_FOLLOW IN_EXCL_UNLINK IN_ONLYDIR
   );

   require XSLoader;
   XSLoader::load Linux::Inotify2, $VERSION;
}

=item my $inotify = new Linux::Inotify2

Create a new notify object and return it. A notify object is kind of a
container that stores watches on file system names and is responsible for
handling event data.

On error, C<undef> is returned and C<$!> will be set accordingly. The
following errors are documented:

 ENFILE   The system limit on the total number of file descriptors has been reached.
 EMFILE   The user limit on the total number of inotify instances has been reached.
 ENOMEM   Insufficient kernel memory is available.

Example:

   my $inotify = new Linux::Inotify2
      or die "Unable to create new inotify object: $!";

=cut

sub new {
   my ($class) = @_;

   my $fd = inotify_init;

   return unless $fd >= 0;

   bless { fd => $fd }, $class
}

=item $watch = $inotify->watch ($name, $mask[, $cb])

Add a new watcher to the given notifier. The watcher will create events
on the pathname C<$name> as given in C<$mask>, which can be any of the
following constants (all exported by default) ORed together.

"file" refers to any file system object in the watched object (always a
directory), that is files, directories, symlinks, device nodes etc., while
"object" refers to the object the watcher has been set on itself:

 IN_ACCESS            object was accessed
 IN_MODIFY            object was modified
 IN_ATTRIB            object metadata changed
 IN_CLOSE_WRITE       writable fd to file / to object was closed
 IN_CLOSE_NOWRITE     readonly fd to file / to object closed
 IN_OPEN              object was opened
 IN_MOVED_FROM        file was moved from this object (directory)
 IN_MOVED_TO          file was moved to this object (directory)
 IN_CREATE            file was created in this object (directory)
 IN_DELETE            file was deleted from this object (directory)
 IN_DELETE_SELF       object itself was deleted
 IN_MOVE_SELF         object itself was moved
 IN_ALL_EVENTS        all of the above events

 IN_ONESHOT           only send event once
 IN_ONLYDIR           only watch the path if it is a directory
 IN_DONT_FOLLOW       don't follow a sym link (Linux 2.6.15+)
 IN_EXCL_UNLINK       don't create events for unlinked objects (Linux 2.6.36+)
 IN_MASK_ADD          not supported with the current version of this module

 IN_CLOSE             same as IN_CLOSE_WRITE | IN_CLOSE_NOWRITE
 IN_MOVE              same as IN_MOVED_FROM | IN_MOVED_TO

C<$cb> is a perl code reference that, if given, is called for each
event. It receives a C<Linux::Inotify2::Event> object.

The returned C<$watch> object is of class C<Linux::Inotify2::Watch>.

On error, C<undef> is returned and C<$!> will be set accordingly. The
following errors are documented:

 EBADF    The given file descriptor is not valid.
 EINVAL   The given event mask contains no legal events.
 ENOMEM   Insufficient kernel memory was available.
 ENOSPC   The user limit on the total number of inotify watches was reached or the kernel failed to allocate a needed resource.
 EACCESS  Read access to the given file is not permitted.

Example, show when C</etc/passwd> gets accessed and/or modified once:

   $inotify->watch ("/etc/passwd", IN_ACCESS | IN_MODIFY, sub {
      my $e = shift;
      print "$e->{w}{name} was accessed\n" if $e->IN_ACCESS;
      print "$e->{w}{name} was modified\n" if $e->IN_MODIFY;
      print "$e->{w}{name} is no longer mounted\n" if $e->IN_UNMOUNT;
      print "events for $e->{w}{name} have been lost\n" if $e->IN_Q_OVERFLOW;

      $e->w->cancel;
   });

=cut

sub watch {
   my ($self, $name, $mask, $cb) = @_;

   my $wd = inotify_add_watch $self->{fd}, $name, $mask;

   return unless $wd >= 0;
   
   my $w = $self->{w}{$wd} = bless {
      inotify => $self,
      wd      => $wd,
      name    => $name,
      mask    => $mask,
      cb      => $cb,
   }, "Linux::Inotify2::Watch";

   Scalar::Util::weaken $w->{inotify};

   $w
}

=item $inotify->fileno

Returns the file descriptor for this notify object. When in non-blocking
mode, you are responsible for calling the C<poll> method when this file
descriptor becomes ready for reading.

=cut

sub fileno {
   $_[0]{fd}
}

=item $inotify->blocking ($blocking)

Clears ($blocking true) or sets ($blocking false) the C<O_NONBLOCK> flag on the file descriptor.

=cut

sub blocking {
   my ($self, $blocking) = @_;

   inotify_blocking $self->{fd}, $blocking;
}

=item $count = $inotify->poll

Reads events from the kernel and handles them. If the notify file
descriptor is blocking (the default), then this method waits for at least
one event (and thus returns true unless an error occurs). Otherwise it
returns immediately when no pending events could be read.

Returns the count of events that have been handled.

=cut

sub poll {
   scalar &read
}

=item @events = $inotify->read

Reads events from the kernel. Blocks when the file descriptor is in
blocking mode (default) until any event arrives. Returns list of
C<Linux::Inotify2::Event> objects or empty list if none (non-blocking
mode) or error occurred ($! should be checked).

Normally you shouldn't use this function, but instead use watcher
callbacks and call C<< ->poll >>.

=cut

sub read {
   my ($self) = @_;

   my @ev = inotify_read $self->{fd};
   my @res;

   for (@ev) {
      $_->{wd}=-1; $_->{mask} = IN_Q_OVERFLOW;#d#

      exists $self->{ignore}{$_->{wd}}
         and next; # watcher has been canceled

      push @res, bless $_, "Linux::Inotify2::Event";

      my $w = $_->{w} = $self->{w}{$_->{wd}}
         or do {
            # no such watcher, but maybe we can do overflow handling
            if ($_->{mask} & IN_Q_OVERFLOW) {
               if ($self->{on_overflow}) {
                  $self->{on_overflow}($_);
               } else {
                  $self->broadcast ($_);
               }
            }
            next;
         };

      $w->{cb}($_) if $w->{cb};
      $w->cancel if $_->{mask} & (IN_IGNORED | IN_UNMOUNT | IN_ONESHOT | IN_DELETE_SELF);
   }

   delete $self->{ignore};

   wantarray ? @res : scalar @res
}

=item $inotify->on_overflow ($cb->($ev))

Sets the callback to be used for overflow handling
(default: C<undef>): When C<read> receives an event with C<IN_Q_OVERFLOW>
set, it will invoke this callback with the event.

When the callback is C<undef>, then it broadcasts the event to all
registered watchers, i.e., C<undef> is equivalent to:

   sub { $inotify->broadcast ($_[0]) }

=cut

sub on_overflow {
   my $prev = $_[0]{on_overflow};

   $_[0]{on_overflow} = $_[1]
      if @_ >= 2;

   $prev
}

=item $inotify->broadcast ($ev)

Invokes all registered watcher callbacks and passes the given event to
them. Most useful in overflow handlers.

=cut

sub broadcast {
   my ($self, $ev) = @_;

   for my $w (values %{ $self->{w} }) {
      local $ev->{w} = $w;
      $w->{cb}($ev) if $w->{cb};
   }
}

sub DESTROY {
   inotify_close $_[0]{fd}
}

=back

=head2 The Linux::Inotify2::Event Class

Objects of this class are handed as first argument to the watcher
callback. It has the following members and methods:

=over 4

=item $event->w

=item $event->{w}

The watcher object for this event, if one is available. Generally, you cna
only rely on the value of this member inside watcher callbacks.

=item $event->name

=item $event->{name}

The path of the file system object, relative to the watched name.

=item $event->fullname

Returns the "full" name of the relevant object, i.e. including the C<name>
member of the watcher (if the watch object is on a directory and a
directory entry is affected), or simply the C<name> member itself when the
object is the watch object itself.

This call requires C<< $event->{w} >> to be valid, which is generally only
the case within watcher callbacks.

=item $event->mask

=item $event->{mask}

The received event mask. In addition to the events described for C<<
$inotify->watch >>, the following flags (exported by default) can be set:

 IN_ISDIR             event object is a directory
 IN_Q_OVERFLOW        event queue overflowed

 # when any of the following flags are set,
 # then watchers for this event are automatically canceled
 IN_UNMOUNT           filesystem for watched object was unmounted
 IN_IGNORED           file was ignored/is gone (no more events are delivered)
 IN_ONESHOT           only one event was generated
 IN_Q_OVERFLOW        queue overflow - event might not be specific to a watcher

=item $event->IN_xxx

Returns a boolean that returns true if the event mask contains any events
specified by the mask. All of the C<IN_xxx> constants can be used as
methods.

=item $event->cookie

=item $event->{cookie}

The event cookie to "synchronize two events". Normally zero, this value is
set when two events relating to the same file are generated. As far as I
know, this only happens for C<IN_MOVED_FROM> and C<IN_MOVED_TO> events, to
identify the old and new name of a file.

Note that the inotify API makes it impossible to know whether there will
be a C<IN_MOVED_TO> event - you might receive only one of the events,
and even if you receive both, there might be any number of events in
between. The best approach seems to be to implement a small timeout
after C<IN_MOVED_FROM> to see if a matching C<IN_MOVED_TO> event will be
received - 2ms seem to work relatively well.

=back

=cut

package Linux::Inotify2::Event;

sub w       { $_[0]{w}      }
sub name    { $_[0]{name}   }
sub mask    { $_[0]{mask}   }
sub cookie  { $_[0]{cookie} }

sub fullname {
   length $_[0]{name}
      ? "$_[0]{w}{name}/$_[0]{name}"
      : $_[0]{w}{name};
}

for my $name (@Linux::Inotify2::EXPORT) {
   my $mask = &{"Linux::Inotify2::$name"};

   *$name = sub { $_[0]{mask} & $mask };
}

=head2 The Linux::Inotify2::Watch Class

Watcher objects are created by calling the C<watch> method of a notifier.

It has the following members and methods:

=over 4

=item $watch->name

=item $watch->{name}

The name as specified in the C<watch> call. For the object itself, this is
the empty string.  For directory watches, this is the name of the entry
without leading path elements.

=item $watch->mask

=item $watch->{mask}

The mask as specified in the C<watch> call.

=item $watch->cb ([new callback])

=item $watch->{cb}

The callback as specified in the C<watch> call. Can optionally be changed.

=item $watch->cancel

Cancels/removes this watcher. Future events, even if already queued queued,
will not be handled and resources will be freed.

=back

=cut

package Linux::Inotify2::Watch;

sub name    { $_[0]{name} }
sub mask    { $_[0]{mask} }

sub cb {
   $_[0]{cb} = $_[1] if @_ > 1;
   $_[0]{cb}
}

sub cancel {
   my ($self) = @_;

   my $inotify = delete $self->{inotify}
      or return 1; # already canceled

   delete $inotify->{w}{$self->{wd}}; # we are no longer there
   $inotify->{ignore}{$self->{wd}} = 1; # ignore further events for one poll

   (Linux::Inotify2::inotify_rm_watch $inotify->{fd}, $self->{wd})
      ? 1 : undef
}

=head1 SEE ALSO

L<AnyEvent>, L<Linux::Inotify>.

=head1 AUTHOR

 Marc Lehmann <schmorp@schmorp.de>
 http://home.schmorp.de/

=cut

1
Revision:	1.30
Committed:	Thu Oct 25 01:13:07 2018 UTC (7 years, 11 months ago) by root
Branch:	MAIN
Changes since 1.29:	+4 -0 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	=head1 NAME
2
3			Linux::Inotify2 - scalable directory/file change notification
4
5			=head1 SYNOPSIS
6
7	root	1.19	=head2 Callback Interface
8	root	1.11
9	root	1.1	use Linux::Inotify2;
10
11	root	1.4	# create a new object
12			my $inotify = new Linux::Inotify2
13	root	1.19	or die "unable to create new inotify object: $!";
14	root	1.4
15			# add watchers
16			$inotify->watch ("/etc/passwd", IN_ACCESS, sub {
17			my $e = shift;
18			my $name = $e->fullname;
19			print "$name was accessed\n" if $e->IN_ACCESS;
20			print "$name is no longer mounted\n" if $e->IN_UNMOUNT;
21			print "$name is gone\n" if $e->IN_IGNORED;
22			print "events for $name have been lost\n" if $e->IN_Q_OVERFLOW;
23
24	root	1.11	# cancel this watcher: remove no further events
25	root	1.4	$e->w->cancel;
26			});
27
28	root	1.20	# integration into AnyEvent (works with EV, Glib, Tk, POE...)
29	root	1.25	my $inotify_w = AE::io $inotify->fileno, 0, sub { $inotify->poll };
30	root	1.17
31			# manual event loop
32			1 while $inotify->poll;
33
34	root	1.11	=head2 Streaming Interface
35
36	root	1.27	use Linux::Inotify2;
37	root	1.11
38			# create a new object
39			my $inotify = new Linux::Inotify2
40	root	1.27	or die "Unable to create new inotify object: $!";
41	root	1.11
42			# create watch
43			$inotify->watch ("/etc/passwd", IN_ACCESS)
44	root	1.27	or die "watch creation failed";
45	root	1.11
46			while () {
47			my @events = $inotify->read;
48			unless (@events > 0) {
49			print "read error: $!";
50	root	1.27	last;
51	root	1.11	}
52	root	1.27	printf "mask\t%d\n", $_->mask foreach @events;
53	root	1.11	}
54
55	root	1.1	=head1 DESCRIPTION
56
57	root	1.3	This module implements an interface to the Linux 2.6.13 and later Inotify
58	root	1.24	file/directory change notification system.
59	root	1.2
60	root	1.3	It has a number of advantages over the Linux::Inotify module:
61	root	1.2
62			- it is portable (Linux::Inotify only works on x86)
63			- the equivalent of fullname works correctly
64			- it is better documented
65			- it has callback-style interface, which is better suited for
66			integration.
67
68	root	1.30	As for the inotify API itself - it is a very tricky, and somewhat
69			unreliable API. For a good overview of the challenges you might run into,
70			see this LWN article: L<https://lwn.net/Articles/605128/>.
71
72	root	1.6	=head2 The Linux::Inotify2 Class
73
74	root	1.1	=over 4
75
76			=cut
77
78			package Linux::Inotify2;
79
80			use Scalar::Util ();
81
82	root	1.20	use common::sense;
83
84	root	1.26	use Exporter qw(import);
85	root	1.1
86			BEGIN {
87	root	1.28	our $VERSION = '1.23';
88	root	1.20	our @EXPORT = qw(
89	root	1.1	IN_ACCESS IN_MODIFY IN_ATTRIB IN_CLOSE_WRITE
90			IN_CLOSE_NOWRITE IN_OPEN IN_MOVED_FROM IN_MOVED_TO
91	root	1.9	IN_CREATE IN_DELETE IN_DELETE_SELF IN_MOVE_SELF
92	root	1.1	IN_ALL_EVENTS
93			IN_UNMOUNT IN_Q_OVERFLOW IN_IGNORED
94			IN_CLOSE IN_MOVE
95	root	1.28	IN_ISDIR IN_ONESHOT IN_MASK_ADD
96			IN_DONT_FOLLOW IN_EXCL_UNLINK IN_ONLYDIR
97	root	1.1	);
98
99			require XSLoader;
100			XSLoader::load Linux::Inotify2, $VERSION;
101			}
102
103			=item my $inotify = new Linux::Inotify2
104
105			Create a new notify object and return it. A notify object is kind of a
106	root	1.24	container that stores watches on file system names and is responsible for
107	root	1.1	handling event data.
108
109	root	1.22	On error, C<undef> is returned and C<$!> will be set accordingly. The
110			following errors are documented:
111	root	1.1
112			ENFILE The system limit on the total number of file descriptors has been reached.
113			EMFILE The user limit on the total number of inotify instances has been reached.
114			ENOMEM Insufficient kernel memory is available.
115
116	root	1.4	Example:
117
118			my $inotify = new Linux::Inotify2
119			or die "Unable to create new inotify object: $!";
120
121	root	1.1	=cut
122
123			sub new {
124			my ($class) = @_;
125
126			my $fd = inotify_init;
127
128			return unless $fd >= 0;
129
130			bless { fd => $fd }, $class
131			}
132
133	root	1.11	=item $watch = $inotify->watch ($name, $mask[, $cb])
134	root	1.1
135			Add a new watcher to the given notifier. The watcher will create events
136			on the pathname C<$name> as given in C<$mask>, which can be any of the
137	root	1.4	following constants (all exported by default) ORed together.
138
139	root	1.24	"file" refers to any file system object in the watched object (always a
140	root	1.4	directory), that is files, directories, symlinks, device nodes etc., while
141	root	1.24	"object" refers to the object the watcher has been set on itself:
142	root	1.4
143			IN_ACCESS object was accessed
144			IN_MODIFY object was modified
145			IN_ATTRIB object metadata changed
146			IN_CLOSE_WRITE writable fd to file / to object was closed
147			IN_CLOSE_NOWRITE readonly fd to file / to object closed
148			IN_OPEN object was opened
149			IN_MOVED_FROM file was moved from this object (directory)
150			IN_MOVED_TO file was moved to this object (directory)
151			IN_CREATE file was created in this object (directory)
152			IN_DELETE file was deleted from this object (directory)
153			IN_DELETE_SELF object itself was deleted
154	root	1.9	IN_MOVE_SELF object itself was moved
155	root	1.4	IN_ALL_EVENTS all of the above events
156	root	1.1
157			IN_ONESHOT only send event once
158	root	1.15	IN_ONLYDIR only watch the path if it is a directory
159	root	1.28	IN_DONT_FOLLOW don't follow a sym link (Linux 2.6.15+)
160			IN_EXCL_UNLINK don't create events for unlinked objects (Linux 2.6.36+)
161	root	1.15	IN_MASK_ADD not supported with the current version of this module
162	root	1.1
163	root	1.4	IN_CLOSE same as IN_CLOSE_WRITE \| IN_CLOSE_NOWRITE
164			IN_MOVE same as IN_MOVED_FROM \| IN_MOVED_TO
165	root	1.1
166	root	1.11	C<$cb> is a perl code reference that, if given, is called for each
167			event. It receives a C<Linux::Inotify2::Event> object.
168	root	1.1
169			The returned C<$watch> object is of class C<Linux::Inotify2::Watch>.
170
171			On error, C<undef> is returned and C<$!> will be set accordingly. The
172			following errors are documented:
173
174			EBADF The given file descriptor is not valid.
175			EINVAL The given event mask contains no legal events.
176			ENOMEM Insufficient kernel memory was available.
177			ENOSPC The user limit on the total number of inotify watches was reached or the kernel failed to allocate a needed resource.
178			EACCESS Read access to the given file is not permitted.
179
180			Example, show when C</etc/passwd> gets accessed and/or modified once:
181
182			$inotify->watch ("/etc/passwd", IN_ACCESS \| IN_MODIFY, sub {
183			my $e = shift;
184			print "$e->{w}{name} was accessed\n" if $e->IN_ACCESS;
185			print "$e->{w}{name} was modified\n" if $e->IN_MODIFY;
186			print "$e->{w}{name} is no longer mounted\n" if $e->IN_UNMOUNT;
187			print "events for $e->{w}{name} have been lost\n" if $e->IN_Q_OVERFLOW;
188
189			$e->w->cancel;
190			});
191
192			=cut
193
194			sub watch {
195			my ($self, $name, $mask, $cb) = @_;
196
197			my $wd = inotify_add_watch $self->{fd}, $name, $mask;
198
199			return unless $wd >= 0;
200
201			my $w = $self->{w}{$wd} = bless {
202			inotify => $self,
203			wd => $wd,
204			name => $name,
205			mask => $mask,
206			cb => $cb,
207	root	1.13	}, "Linux::Inotify2::Watch";
208	root	1.1
209			Scalar::Util::weaken $w->{inotify};
210
211			$w
212			}
213
214	root	1.4	=item $inotify->fileno
215	root	1.1
216	root	1.24	Returns the file descriptor for this notify object. When in non-blocking
217			mode, you are responsible for calling the C<poll> method when this file
218			descriptor becomes ready for reading.
219	root	1.1
220			=cut
221
222			sub fileno {
223			$_[0]{fd}
224			}
225
226	root	1.11	=item $inotify->blocking ($blocking)
227
228			Clears ($blocking true) or sets ($blocking false) the C<O_NONBLOCK> flag on the file descriptor.
229
230			=cut
231
232			sub blocking {
233			my ($self, $blocking) = @_;
234
235			inotify_blocking $self->{fd}, $blocking;
236			}
237
238	root	1.4	=item $count = $inotify->poll
239	root	1.1
240	root	1.24	Reads events from the kernel and handles them. If the notify file
241			descriptor is blocking (the default), then this method waits for at least
242			one event (and thus returns true unless an error occurs). Otherwise it
243			returns immediately when no pending events could be read.
244	root	1.1
245			Returns the count of events that have been handled.
246
247			=cut
248
249			sub poll {
250	root	1.11	scalar &read
251			}
252
253	root	1.24	=item @events = $inotify->read
254	root	1.11
255	root	1.24	Reads events from the kernel. Blocks when the file descriptor is in
256			blocking mode (default) until any event arrives. Returns list of
257			C<Linux::Inotify2::Event> objects or empty list if none (non-blocking
258			mode) or error occurred ($! should be checked).
259
260			Normally you shouldn't use this function, but instead use watcher
261			callbacks and call C<< ->poll >>.
262	root	1.11
263			=cut
264
265			sub read {
266	root	1.1	my ($self) = @_;
267
268	root	1.4	my @ev = inotify_read $self->{fd};
269	root	1.11	my @res;
270	root	1.4
271			for (@ev) {
272	root	1.29	$_->{wd}=-1; $_->{mask} = IN_Q_OVERFLOW;#d#
273	root	1.4
274			exists $self->{ignore}{$_->{wd}}
275			and next; # watcher has been canceled
276
277	root	1.29	push @res, bless $_, "Linux::Inotify2::Event";
278	root	1.12
279	root	1.29	my $w = $_->{w} = $self->{w}{$_->{wd}}
280			or do {
281			# no such watcher, but maybe we can do overflow handling
282			if ($_->{mask} & IN_Q_OVERFLOW) {
283			if ($self->{on_overflow}) {
284			$self->{on_overflow}($_);
285			} else {
286			$self->broadcast ($_);
287			}
288			}
289			next;
290			};
291	root	1.11
292	root	1.29	$w->{cb}($_) if $w->{cb};
293	root	1.16	$w->cancel if $_->{mask} & (IN_IGNORED \| IN_UNMOUNT \| IN_ONESHOT \| IN_DELETE_SELF);
294	root	1.1	}
295	root	1.4
296			delete $self->{ignore};
297
298	root	1.29	wantarray ? @res : scalar @res
299			}
300
301			=item $inotify->on_overflow ($cb->($ev))
302
303			Sets the callback to be used for overflow handling
304			(default: C<undef>): When C<read> receives an event with C<IN_Q_OVERFLOW>
305			set, it will invoke this callback with the event.
306
307			When the callback is C<undef>, then it broadcasts the event to all
308			registered watchers, i.e., C<undef> is equivalent to:
309
310			sub { $inotify->broadcast ($_[0]) }
311
312			=cut
313
314			sub on_overflow {
315			my $prev = $_[0]{on_overflow};
316
317			$_[0]{on_overflow} = $_[1]
318			if @_ >= 2;
319
320			$prev
321			}
322
323			=item $inotify->broadcast ($ev)
324
325			Invokes all registered watcher callbacks and passes the given event to
326			them. Most useful in overflow handlers.
327
328			=cut
329
330			sub broadcast {
331			my ($self, $ev) = @_;
332
333			for my $w (values %{ $self->{w} }) {
334			local $ev->{w} = $w;
335			$w->{cb}($ev) if $w->{cb};
336			}
337	root	1.1	}
338
339			sub DESTROY {
340			inotify_close $_[0]{fd}
341			}
342
343			=back
344
345			=head2 The Linux::Inotify2::Event Class
346
347	root	1.24	Objects of this class are handed as first argument to the watcher
348	root	1.1	callback. It has the following members and methods:
349
350			=over 4
351
352			=item $event->w
353
354			=item $event->{w}
355
356	root	1.29	The watcher object for this event, if one is available. Generally, you cna
357			only rely on the value of this member inside watcher callbacks.
358	root	1.1
359			=item $event->name
360
361			=item $event->{name}
362
363	root	1.24	The path of the file system object, relative to the watched name.
364	root	1.1
365	root	1.23	=item $event->fullname
366	root	1.1
367			Returns the "full" name of the relevant object, i.e. including the C<name>
368	root	1.24	member of the watcher (if the watch object is on a directory and a
369			directory entry is affected), or simply the C<name> member itself when the
370			object is the watch object itself.
371	root	1.1
372	root	1.29	This call requires C<< $event->{w} >> to be valid, which is generally only
373			the case within watcher callbacks.
374
375	root	1.1	=item $event->mask
376
377			=item $event->{mask}
378
379	root	1.24	The received event mask. In addition to the events described for C<<
380			$inotify->watch >>, the following flags (exported by default) can be set:
381	root	1.1
382	root	1.4	IN_ISDIR event object is a directory
383			IN_Q_OVERFLOW event queue overflowed
384
385	root	1.10	# when any of the following flags are set,
386			# then watchers for this event are automatically canceled
387	root	1.24	IN_UNMOUNT filesystem for watched object was unmounted
388	root	1.4	IN_IGNORED file was ignored/is gone (no more events are delivered)
389	root	1.10	IN_ONESHOT only one event was generated
390	root	1.29	IN_Q_OVERFLOW queue overflow - event might not be specific to a watcher
391	root	1.1
392			=item $event->IN_xxx
393
394	root	1.24	Returns a boolean that returns true if the event mask contains any events
395			specified by the mask. All of the C<IN_xxx> constants can be used as
396			methods.
397	root	1.1
398			=item $event->cookie
399
400			=item $event->{cookie}
401
402	root	1.10	The event cookie to "synchronize two events". Normally zero, this value is
403			set when two events relating to the same file are generated. As far as I
404			know, this only happens for C<IN_MOVED_FROM> and C<IN_MOVED_TO> events, to
405			identify the old and new name of a file.
406	root	1.1
407	root	1.29	Note that the inotify API makes it impossible to know whether there will
408			be a C<IN_MOVED_TO> event - you might receive only one of the events,
409			and even if you receive both, there might be any number of events in
410			between. The best approach seems to be to implement a small timeout
411			after C<IN_MOVED_FROM> to see if a matching C<IN_MOVED_TO> event will be
412			received - 2ms seem to work relatively well.
413
414	root	1.1	=back
415
416			=cut
417
418			package Linux::Inotify2::Event;
419
420			sub w { $_[0]{w} }
421			sub name { $_[0]{name} }
422			sub mask { $_[0]{mask} }
423			sub cookie { $_[0]{cookie} }
424
425			sub fullname {
426			length $_[0]{name}
427			? "$_[0]{w}{name}/$_[0]{name}"
428			: $_[0]{w}{name};
429			}
430
431	root	1.20	for my $name (@Linux::Inotify2::EXPORT) {
432	root	1.1	my $mask = &{"Linux::Inotify2::$name"};
433
434	root	1.24	*$name = sub { $_[0]{mask} & $mask };
435	root	1.1	}
436
437			=head2 The Linux::Inotify2::Watch Class
438
439	root	1.24	Watcher objects are created by calling the C<watch> method of a notifier.
440	root	1.1
441			It has the following members and methods:
442
443	root	1.14	=over 4
444
445	root	1.1	=item $watch->name
446
447			=item $watch->{name}
448
449			The name as specified in the C<watch> call. For the object itself, this is
450			the empty string. For directory watches, this is the name of the entry
451			without leading path elements.
452
453			=item $watch->mask
454
455			=item $watch->{mask}
456
457			The mask as specified in the C<watch> call.
458
459			=item $watch->cb ([new callback])
460
461			=item $watch->{cb}
462
463			The callback as specified in the C<watch> call. Can optionally be changed.
464
465			=item $watch->cancel
466
467	root	1.24	Cancels/removes this watcher. Future events, even if already queued queued,
468	root	1.1	will not be handled and resources will be freed.
469
470	root	1.14	=back
471
472	root	1.1	=cut
473
474			package Linux::Inotify2::Watch;
475
476			sub name { $_[0]{name} }
477			sub mask { $_[0]{mask} }
478
479			sub cb {
480			$_[0]{cb} = $_[1] if @_ > 1;
481			$_[0]{cb}
482			}
483
484			sub cancel {
485			my ($self) = @_;
486
487	root	1.4	my $inotify = delete $self->{inotify}
488			or return 1; # already canceled
489
490			delete $inotify->{w}{$self->{wd}}; # we are no longer there
491			$inotify->{ignore}{$self->{wd}} = 1; # ignore further events for one poll
492
493			(Linux::Inotify2::inotify_rm_watch $inotify->{fd}, $self->{wd})
494	root	1.1	? 1 : undef
495			}
496
497			=head1 SEE ALSO
498
499	root	1.19	L<AnyEvent>, L<Linux::Inotify>.
500	root	1.1
501			=head1 AUTHOR
502
503			Marc Lehmann <schmorp@schmorp.de>
504			http://home.schmorp.de/
505
506			=cut
507
508			1