cvsroot/Linux-Inotify2/Inotify2.pm

=head1 NAME

Linux::Inotify2 - scalable directory/file change notification

=head1 SYNOPSIS

 use Linux::Inotify2;

=head1 DESCRIPTION

=head2 The Linux::Inotify2 Class

This module implements an interface to the linux inotify file/directory
change notification sytem.

It has a number of advantages over the Linux::Inotfy 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.

=over 4

=cut

package Linux::Inotify2;

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

use base 'Exporter';

BEGIN {
   $VERSION = 0.1;

   @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.

=cut

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

   my $fd = inotify_init;

   return unless $fd >= 0;

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

=item $watch = $inotify2->watch ($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:

 IN_ACCESS            File was accessed
 IN_MODIFY            File was modified
 IN_ATTRIB            Metadata changed
 IN_CLOSE_WRITE       Writtable file was closed
 IN_CLOSE_NOWRITE     Unwrittable file closed
 IN_OPEN              File was opened
 IN_MOVED_FROM        File was moved from X
 IN_MOVED_TO          File was moved to Y
 IN_CREATE            Subfile was created
 IN_DELETE            Subfile was deleted
 IN_DELETE_SELF       Self was deleted
 IN_ONESHOT           only send event once
 IN_ALL_EVENTS        All of the above events

 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 $inotify2->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 = $inotify2->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. Otherwise it returns immediately when no pending events could be
read.

Returns the count of events that have been handled.

=cut

# TODO: potential race with recently-canceled watchers

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

   for (inotify_read $self->{fd}) {
      $_->{w} = $self->{w}{$_->{wd}}
         or next; # no such watcher
      $_->{w}{cb}->(bless $_, Linux::Inotify2::Event);
   }
}

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>
component of the watcher.

=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 occurred against dir

 IN_UNMOUNT           Backing fs was unmounted
 IN_Q_OVERFLOW        Event queued overflowed
 IN_IGNORED           File was ignored (no more events will be 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) = @_;

   (Linux::Inotify2::inotify_rm_watch $self->{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:	1.2
Committed:	Mon Aug 22 10:00:10 2005 UTC (18 years, 10 months ago) by root
Branch:	MAIN
Changes since 1.1:	+11 -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			use Linux::Inotify2;
8
9			=head1 DESCRIPTION
10
11			=head2 The Linux::Inotify2 Class
12
13	root	1.2	This module implements an interface to the linux inotify file/directory
14			change notification sytem.
15
16			It has a number of advantages over the Linux::Inotfy module:
17
18			- it is portable (Linux::Inotify only works on x86)
19			- the equivalent of fullname works correctly
20			- it is better documented
21			- it has callback-style interface, which is better suited for
22			integration.
23
24	root	1.1	=over 4
25
26			=cut
27
28			package Linux::Inotify2;
29
30			use Carp ();
31			use Scalar::Util ();
32
33			use base 'Exporter';
34
35			BEGIN {
36			$VERSION = 0.1;
37
38			@constants = qw(
39			IN_ACCESS IN_MODIFY IN_ATTRIB IN_CLOSE_WRITE
40			IN_CLOSE_NOWRITE IN_OPEN IN_MOVED_FROM IN_MOVED_TO
41			IN_CREATE IN_DELETE IN_DELETE_SELF
42			IN_ALL_EVENTS
43			IN_UNMOUNT IN_Q_OVERFLOW IN_IGNORED
44			IN_CLOSE IN_MOVE
45			IN_ISDIR IN_ONESHOT
46			);
47
48			@EXPORT = @constants;
49
50			require XSLoader;
51			XSLoader::load Linux::Inotify2, $VERSION;
52			}
53
54			=item my $inotify = new Linux::Inotify2
55
56			Create a new notify object and return it. A notify object is kind of a
57			container that stores watches on filesystem names and is responsible for
58			handling event data.
59
60			On error, C<undef> is returned and C<$!> will be set accordingly. The followign errors
61			are documented:
62
63			ENFILE The system limit on the total number of file descriptors has been reached.
64			EMFILE The user limit on the total number of inotify instances has been reached.
65			ENOMEM Insufficient kernel memory is available.
66
67			=cut
68
69			sub new {
70			my ($class) = @_;
71
72			my $fd = inotify_init;
73
74			return unless $fd >= 0;
75
76			bless { fd => $fd }, $class
77			}
78
79			=item $watch = $inotify2->watch ($name, $mask, $cb)
80
81			Add a new watcher to the given notifier. The watcher will create events
82			on the pathname C<$name> as given in C<$mask>, which can be any of the
83			following constants (all exported by default) ORed together:
84
85			IN_ACCESS File was accessed
86			IN_MODIFY File was modified
87			IN_ATTRIB Metadata changed
88			IN_CLOSE_WRITE Writtable file was closed
89			IN_CLOSE_NOWRITE Unwrittable file closed
90			IN_OPEN File was opened
91			IN_MOVED_FROM File was moved from X
92			IN_MOVED_TO File was moved to Y
93			IN_CREATE Subfile was created
94			IN_DELETE Subfile was deleted
95			IN_DELETE_SELF Self was deleted
96			IN_ONESHOT only send event once
97			IN_ALL_EVENTS All of the above events
98
99			IN_CLOSE Same as IN_CLOSE_WRITE \| IN_CLOSE_NOWRITE
100			IN_MOVE Same as IN_MOVED_FROM \| IN_MOVED_TO
101
102			C<$cb> is a perl code reference that is called for each event. It receives
103			a C<Linux::Inotify2::Event> object.
104
105			The returned C<$watch> object is of class C<Linux::Inotify2::Watch>.
106
107			On error, C<undef> is returned and C<$!> will be set accordingly. The
108			following errors are documented:
109
110			EBADF The given file descriptor is not valid.
111			EINVAL The given event mask contains no legal events.
112			ENOMEM Insufficient kernel memory was available.
113			ENOSPC The user limit on the total number of inotify watches was reached or the kernel failed to allocate a needed resource.
114			EACCESS Read access to the given file is not permitted.
115
116			Example, show when C</etc/passwd> gets accessed and/or modified once:
117
118			$inotify->watch ("/etc/passwd", IN_ACCESS \| IN_MODIFY, sub {
119			my $e = shift;
120			print "$e->{w}{name} was accessed\n" if $e->IN_ACCESS;
121			print "$e->{w}{name} was modified\n" if $e->IN_MODIFY;
122			print "$e->{w}{name} is no longer mounted\n" if $e->IN_UNMOUNT;
123			print "events for $e->{w}{name} have been lost\n" if $e->IN_Q_OVERFLOW;
124
125			$e->w->cancel;
126			});
127
128			=cut
129
130			sub watch {
131			my ($self, $name, $mask, $cb) = @_;
132
133			my $wd = inotify_add_watch $self->{fd}, $name, $mask;
134
135			return unless $wd >= 0;
136
137			my $w = $self->{w}{$wd} = bless {
138			inotify => $self,
139			wd => $wd,
140			name => $name,
141			mask => $mask,
142			cb => $cb,
143			}, Linux::Inotify2::Watch;
144
145			Scalar::Util::weaken $w->{inotify};
146
147			$w
148			}
149
150			=item $inotify2->fileno
151
152			Returns the fileno for this notify object. You are responsible for calling
153			the C<poll> method when this fileno becomes ready for reading.
154
155			=cut
156
157			sub fileno {
158			$_[0]{fd}
159			}
160
161			=item $count = $inotify2->poll
162
163			Reads events from the kernel and handles them. If the notify fileno
164			is blocking (the default), then this method waits for at least one
165			event. Otherwise it returns immediately when no pending events could be
166			read.
167
168			Returns the count of events that have been handled.
169
170			=cut
171
172			# TODO: potential race with recently-canceled watchers
173
174			sub poll {
175			my ($self) = @_;
176
177			for (inotify_read $self->{fd}) {
178			$_->{w} = $self->{w}{$_->{wd}}
179			or next; # no such watcher
180			$_->{w}{cb}->(bless $_, Linux::Inotify2::Event);
181			}
182			}
183
184			sub DESTROY {
185			inotify_close $_[0]{fd}
186			}
187
188			=back
189
190			=head2 The Linux::Inotify2::Event Class
191
192			Objects of this class are handed as first argument to the watch
193			callback. It has the following members and methods:
194
195			=over 4
196
197			=item $event->w
198
199			=item $event->{w}
200
201			The watcher object for this event.
202
203			=item $event->name
204
205			=item $event->{name}
206
207			The path of the filesystem object, relative to the watch name.
208
209			=item $watch->fullname
210
211			Returns the "full" name of the relevant object, i.e. including the C<name>
212			component of the watcher.
213
214			=item $event->mask
215
216			=item $event->{mask}
217
218			The received event mask. In addition the the events described for
219			C<$inotify->watch>, the following flags (exported by default) can be set:
220
221			IN_ISDIR event occurred against dir
222
223			IN_UNMOUNT Backing fs was unmounted
224			IN_Q_OVERFLOW Event queued overflowed
225			IN_IGNORED File was ignored (no more events will be delivered)
226
227			=item $event->IN_xxx
228
229			Returns a boolean that returns true if the event mask matches the
230			event. All of the C<IN_xxx> constants can be used as methods.
231
232			=item $event->cookie
233
234			=item $event->{cookie}
235
236			The event cookie, can be used to synchronize two related events.
237
238			=back
239
240			=cut
241
242			package Linux::Inotify2::Event;
243
244			sub w { $_[0]{w} }
245			sub name { $_[0]{name} }
246			sub mask { $_[0]{mask} }
247			sub cookie { $_[0]{cookie} }
248
249			sub fullname {
250			length $_[0]{name}
251			? "$_[0]{w}{name}/$_[0]{name}"
252			: $_[0]{w}{name};
253			}
254
255			for my $name (@Linux::Inotify2::constants) {
256			my $mask = &{"Linux::Inotify2::$name"};
257
258			*$name = sub { ($_[0]{mask} & $mask) == $mask };
259			}
260
261			=head2 The Linux::Inotify2::Watch Class
262
263			Watch objects are created by calling the C<watch> method of a notifier.
264
265			It has the following members and methods:
266
267			=item $watch->name
268
269			=item $watch->{name}
270
271			The name as specified in the C<watch> call. For the object itself, this is
272			the empty string. For directory watches, this is the name of the entry
273			without leading path elements.
274
275			=item $watch->mask
276
277			=item $watch->{mask}
278
279			The mask as specified in the C<watch> call.
280
281			=item $watch->cb ([new callback])
282
283			=item $watch->{cb}
284
285			The callback as specified in the C<watch> call. Can optionally be changed.
286
287			=item $watch->cancel
288
289			Cancels/removes this watch. Future events, even if already queued queued,
290			will not be handled and resources will be freed.
291
292			=cut
293
294			package Linux::Inotify2::Watch;
295
296			sub name { $_[0]{name} }
297			sub mask { $_[0]{mask} }
298
299			sub cb {
300			$_[0]{cb} = $_[1] if @_ > 1;
301			$_[0]{cb}
302			}
303
304			sub cancel {
305			my ($self) = @_;
306
307			(Linux::Inotify2::inotify_rm_watch $self->{inotify}{fd}, $self->{wd})
308			? 1 : undef
309			}
310
311			=head1 SEE ALSO
312
313			L<Linux::Inotify>.
314
315			=head1 AUTHOR
316
317			Marc Lehmann <schmorp@schmorp.de>
318			http://home.schmorp.de/
319
320			=cut
321
322			1