cvsroot/Linux-Inotify2/Inotify2.pm

=head1 NAME

Linux::Inotify2 - scalable directory/file change notification

=head1 SYNOPSIS

 use Linux::Inotify2;

 # create a new object
 my $inotify = new Linux::Inotify2
    or die "Unable to create new inotify object: $!";
 
 # for Event:
 Event->io (fd =>$inotify->fileno, poll => 'r', cb => sub { $inotify->poll });
 # for Glib:
 add_watch Glib::IO $inotify->fileno, in => sub { $inotify->poll };
 # manually:
 1 while $inotify->poll;

 # 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;
 });

=head1 DESCRIPTION

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

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.

=head2 The Linux::Inotify2 Class

=over 4

=cut

package Linux::Inotify2;

use Carp ();
use Scalar::Util ();

use base 'Exporter';

BEGIN {
   $VERSION = 0.2;

   @constants = 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_ALL_EVENTS
      IN_UNMOUNT IN_Q_OVERFLOW IN_IGNORED
      IN_CLOSE IN_MOVE
      IN_ISDIR IN_ONESHOT
   );

   @EXPORT = @constants;

   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 filesystem names and is responsible for
handling event data.

On error, C<undef> is returned and C<$!> will be set accordingly. The followign 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 filesystem object in the watch'ed object (always a
directory), that is files, directories, symlinks, device nodes etc., while
"object" refers to the object the watch 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_ALL_EVENTS        all of the above events

 IN_ONESHOT           only send event once

 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 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 fileno for this notify object. You are responsible for calling
the C<poll> method when this fileno becomes ready for reading.

=cut

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

=item $count = $inotify->poll

Reads events from the kernel and handles them. If the notify fileno 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 {
   my ($self) = @_;

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

   for (@ev) {
      my $w = $_->{w} = $self->{w}{$_->{wd}}
         or next; # no such watcher

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

      $w->{cb}->(bless $_, Linux::Inotify2::Event);
      # TODO: what about IN_ONESHOT?
      $w->cancel if $_->{mask} & (IN_IGNORED | IN_UNMOUNT);
   }

   delete $self->{ignore};

   scalar @ev
}

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

=back

=head2 The Linux::Inotify2::Event Class

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

=over 4

=item $event->w

=item $event->{w}

The watcher object for this event.

=item $event->name

=item $event->{name}

The path of the filesystem object, relative to the watch name.

=item $watch->fullname

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

=item $event->mask

=item $event->{mask}

The received event mask. In addition the 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 the following flags are set, then watchers are canceled automatically
 IN_UNMOUNT           filesystem for watch'ed object was unmounted
 IN_IGNORED           file was ignored/is gone (no more events are delivered)

=item $event->IN_xxx

Returns a boolean that returns true if the event mask matches the
event. All of the C<IN_xxx> constants can be used as methods.

=item $event->cookie

=item $event->{cookie}

The event cookie, can be used to synchronize two related events.

=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::constants) {
   my $mask = &{"Linux::Inotify2::$name"};

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

=head2 The Linux::Inotify2::Watch Class

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

It has the following members and methods:

=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 watch. Future events, even if already queued queued,
will not be handled and resources will be freed.

=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<Linux::Inotify>.

=head1 AUTHOR

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

=cut

1
Revision:	1.7
Committed:	Tue Aug 23 02:17:18 2005 UTC (18 years, 10 months ago) by root
Branch:	MAIN
Changes since 1.6:	+3 -1 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			use Linux::Inotify2;
8
9	root	1.4	# create a new object
10			my $inotify = new Linux::Inotify2
11			or die "Unable to create new inotify object: $!";
12
13			# for Event:
14			Event->io (fd =>$inotify->fileno, poll => 'r', cb => sub { $inotify->poll });
15			# for Glib:
16			add_watch Glib::IO $inotify->fileno, in => sub { $inotify->poll };
17			# manually:
18			1 while $inotify->poll;
19
20			# add watchers
21			$inotify->watch ("/etc/passwd", IN_ACCESS, sub {
22			my $e = shift;
23			my $name = $e->fullname;
24			print "$name was accessed\n" if $e->IN_ACCESS;
25			print "$name is no longer mounted\n" if $e->IN_UNMOUNT;
26			print "$name is gone\n" if $e->IN_IGNORED;
27			print "events for $name have been lost\n" if $e->IN_Q_OVERFLOW;
28
29			# cancel this watcheR: remove no further events
30			$e->w->cancel;
31			});
32
33	root	1.1	=head1 DESCRIPTION
34
35	root	1.3	This module implements an interface to the Linux 2.6.13 and later Inotify
36			file/directory change notification sytem.
37	root	1.2
38	root	1.3	It has a number of advantages over the Linux::Inotify module:
39	root	1.2
40			- it is portable (Linux::Inotify only works on x86)
41			- the equivalent of fullname works correctly
42			- it is better documented
43			- it has callback-style interface, which is better suited for
44			integration.
45
46	root	1.6	=head2 The Linux::Inotify2 Class
47
48	root	1.1	=over 4
49
50			=cut
51
52			package Linux::Inotify2;
53
54			use Carp ();
55			use Scalar::Util ();
56
57			use base 'Exporter';
58
59			BEGIN {
60	root	1.3	$VERSION = 0.2;
61	root	1.1
62			@constants = qw(
63			IN_ACCESS IN_MODIFY IN_ATTRIB IN_CLOSE_WRITE
64			IN_CLOSE_NOWRITE IN_OPEN IN_MOVED_FROM IN_MOVED_TO
65			IN_CREATE IN_DELETE IN_DELETE_SELF
66			IN_ALL_EVENTS
67			IN_UNMOUNT IN_Q_OVERFLOW IN_IGNORED
68			IN_CLOSE IN_MOVE
69			IN_ISDIR IN_ONESHOT
70			);
71
72			@EXPORT = @constants;
73
74			require XSLoader;
75			XSLoader::load Linux::Inotify2, $VERSION;
76			}
77
78			=item my $inotify = new Linux::Inotify2
79
80			Create a new notify object and return it. A notify object is kind of a
81			container that stores watches on filesystem names and is responsible for
82			handling event data.
83
84			On error, C<undef> is returned and C<$!> will be set accordingly. The followign errors
85			are documented:
86
87			ENFILE The system limit on the total number of file descriptors has been reached.
88			EMFILE The user limit on the total number of inotify instances has been reached.
89			ENOMEM Insufficient kernel memory is available.
90
91	root	1.4	Example:
92
93			my $inotify = new Linux::Inotify2
94			or die "Unable to create new inotify object: $!";
95
96	root	1.1	=cut
97
98			sub new {
99			my ($class) = @_;
100
101			my $fd = inotify_init;
102
103			return unless $fd >= 0;
104
105			bless { fd => $fd }, $class
106			}
107
108	root	1.4	=item $watch = $inotify->watch ($name, $mask, $cb)
109	root	1.1
110			Add a new watcher to the given notifier. The watcher will create events
111			on the pathname C<$name> as given in C<$mask>, which can be any of the
112	root	1.4	following constants (all exported by default) ORed together.
113
114			"file" refers to any filesystem object in the watch'ed object (always a
115			directory), that is files, directories, symlinks, device nodes etc., while
116			"object" refers to the object the watch has been set on itself:
117
118			IN_ACCESS object was accessed
119			IN_MODIFY object was modified
120			IN_ATTRIB object metadata changed
121			IN_CLOSE_WRITE writable fd to file / to object was closed
122			IN_CLOSE_NOWRITE readonly fd to file / to object closed
123			IN_OPEN object was opened
124			IN_MOVED_FROM file was moved from this object (directory)
125			IN_MOVED_TO file was moved to this object (directory)
126			IN_CREATE file was created in this object (directory)
127			IN_DELETE file was deleted from this object (directory)
128			IN_DELETE_SELF object itself was deleted
129			IN_ALL_EVENTS all of the above events
130	root	1.1
131			IN_ONESHOT only send event once
132
133	root	1.4	IN_CLOSE same as IN_CLOSE_WRITE \| IN_CLOSE_NOWRITE
134			IN_MOVE same as IN_MOVED_FROM \| IN_MOVED_TO
135	root	1.1
136			C<$cb> is a perl code reference that is called for each event. It receives
137			a C<Linux::Inotify2::Event> object.
138
139			The returned C<$watch> object is of class C<Linux::Inotify2::Watch>.
140
141			On error, C<undef> is returned and C<$!> will be set accordingly. The
142			following errors are documented:
143
144			EBADF The given file descriptor is not valid.
145			EINVAL The given event mask contains no legal events.
146			ENOMEM Insufficient kernel memory was available.
147			ENOSPC The user limit on the total number of inotify watches was reached or the kernel failed to allocate a needed resource.
148			EACCESS Read access to the given file is not permitted.
149
150			Example, show when C</etc/passwd> gets accessed and/or modified once:
151
152			$inotify->watch ("/etc/passwd", IN_ACCESS \| IN_MODIFY, sub {
153			my $e = shift;
154			print "$e->{w}{name} was accessed\n" if $e->IN_ACCESS;
155			print "$e->{w}{name} was modified\n" if $e->IN_MODIFY;
156			print "$e->{w}{name} is no longer mounted\n" if $e->IN_UNMOUNT;
157			print "events for $e->{w}{name} have been lost\n" if $e->IN_Q_OVERFLOW;
158
159			$e->w->cancel;
160			});
161
162			=cut
163
164			sub watch {
165			my ($self, $name, $mask, $cb) = @_;
166
167			my $wd = inotify_add_watch $self->{fd}, $name, $mask;
168
169			return unless $wd >= 0;
170
171			my $w = $self->{w}{$wd} = bless {
172			inotify => $self,
173			wd => $wd,
174			name => $name,
175			mask => $mask,
176			cb => $cb,
177			}, Linux::Inotify2::Watch;
178
179			Scalar::Util::weaken $w->{inotify};
180
181			$w
182			}
183
184	root	1.4	=item $inotify->fileno
185	root	1.1
186			Returns the fileno for this notify object. You are responsible for calling
187			the C<poll> method when this fileno becomes ready for reading.
188
189			=cut
190
191			sub fileno {
192			$_[0]{fd}
193			}
194
195	root	1.4	=item $count = $inotify->poll
196	root	1.1
197	root	1.4	Reads events from the kernel and handles them. If the notify fileno is
198			blocking (the default), then this method waits for at least one event
199			(and thus returns true unless an error occurs). Otherwise it returns
200			immediately when no pending events could be read.
201	root	1.1
202			Returns the count of events that have been handled.
203
204			=cut
205
206			sub poll {
207			my ($self) = @_;
208
209	root	1.4	my @ev = inotify_read $self->{fd};
210
211			for (@ev) {
212			my $w = $_->{w} = $self->{w}{$_->{wd}}
213	root	1.1	or next; # no such watcher
214	root	1.4
215			exists $self->{ignore}{$_->{wd}}
216			and next; # watcher has been canceled
217
218			$w->{cb}->(bless $_, Linux::Inotify2::Event);
219	root	1.5	# TODO: what about IN_ONESHOT?
220	root	1.4	$w->cancel if $_->{mask} & (IN_IGNORED \| IN_UNMOUNT);
221	root	1.1	}
222	root	1.4
223			delete $self->{ignore};
224
225			scalar @ev
226	root	1.1	}
227
228			sub DESTROY {
229			inotify_close $_[0]{fd}
230			}
231
232			=back
233
234			=head2 The Linux::Inotify2::Event Class
235
236			Objects of this class are handed as first argument to the watch
237			callback. It has the following members and methods:
238
239			=over 4
240
241			=item $event->w
242
243			=item $event->{w}
244
245			The watcher object for this event.
246
247			=item $event->name
248
249			=item $event->{name}
250
251			The path of the filesystem object, relative to the watch name.
252
253			=item $watch->fullname
254
255			Returns the "full" name of the relevant object, i.e. including the C<name>
256	root	1.7	member of the watcher (if the the watch is on a directory and a dir entry
257			is affected), or simply the C<name> member itself when the object is the
258			watch object itself.
259	root	1.1
260			=item $event->mask
261
262			=item $event->{mask}
263
264			The received event mask. In addition the the events described for
265			C<$inotify->watch>, the following flags (exported by default) can be set:
266
267	root	1.4	IN_ISDIR event object is a directory
268	root	1.1
269	root	1.4	IN_Q_OVERFLOW event queue overflowed
270
271			# when the following flags are set, then watchers are canceled automatically
272			IN_UNMOUNT filesystem for watch'ed object was unmounted
273			IN_IGNORED file was ignored/is gone (no more events are delivered)
274	root	1.1
275			=item $event->IN_xxx
276
277			Returns a boolean that returns true if the event mask matches the
278			event. All of the C<IN_xxx> constants can be used as methods.
279
280			=item $event->cookie
281
282			=item $event->{cookie}
283
284			The event cookie, can be used to synchronize two related events.
285
286			=back
287
288			=cut
289
290			package Linux::Inotify2::Event;
291
292			sub w { $_[0]{w} }
293			sub name { $_[0]{name} }
294			sub mask { $_[0]{mask} }
295			sub cookie { $_[0]{cookie} }
296
297			sub fullname {
298			length $_[0]{name}
299			? "$_[0]{w}{name}/$_[0]{name}"
300			: $_[0]{w}{name};
301			}
302
303			for my $name (@Linux::Inotify2::constants) {
304			my $mask = &{"Linux::Inotify2::$name"};
305
306			*$name = sub { ($_[0]{mask} & $mask) == $mask };
307			}
308
309			=head2 The Linux::Inotify2::Watch Class
310
311			Watch objects are created by calling the C<watch> method of a notifier.
312
313			It has the following members and methods:
314
315			=item $watch->name
316
317			=item $watch->{name}
318
319			The name as specified in the C<watch> call. For the object itself, this is
320			the empty string. For directory watches, this is the name of the entry
321			without leading path elements.
322
323			=item $watch->mask
324
325			=item $watch->{mask}
326
327			The mask as specified in the C<watch> call.
328
329			=item $watch->cb ([new callback])
330
331			=item $watch->{cb}
332
333			The callback as specified in the C<watch> call. Can optionally be changed.
334
335			=item $watch->cancel
336
337			Cancels/removes this watch. Future events, even if already queued queued,
338			will not be handled and resources will be freed.
339
340			=cut
341
342			package Linux::Inotify2::Watch;
343
344			sub name { $_[0]{name} }
345			sub mask { $_[0]{mask} }
346
347			sub cb {
348			$_[0]{cb} = $_[1] if @_ > 1;
349			$_[0]{cb}
350			}
351
352			sub cancel {
353			my ($self) = @_;
354
355	root	1.4	my $inotify = delete $self->{inotify}
356			or return 1; # already canceled
357
358			delete $inotify->{w}{$self->{wd}}; # we are no longer there
359			$inotify->{ignore}{$self->{wd}} = 1; # ignore further events for one poll
360
361			(Linux::Inotify2::inotify_rm_watch $inotify->{fd}, $self->{wd})
362	root	1.1	? 1 : undef
363			}
364
365			=head1 SEE ALSO
366
367			L<Linux::Inotify>.
368
369			=head1 AUTHOR
370
371			Marc Lehmann <schmorp@schmorp.de>
372			http://home.schmorp.de/
373
374			=cut
375
376			1