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

=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:	1.1
Committed:	Mon Aug 22 09:51:38 2005 UTC (21 years ago) by root
Branch:	MAIN
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			=over 4
14
15			=cut
16
17			package Linux::Inotify2;
18
19			use Carp ();
20			use Scalar::Util ();
21
22			use base 'Exporter';
23
24			BEGIN {
25			$VERSION = 0.1;
26
27			@constants = qw(
28			IN_ACCESS IN_MODIFY IN_ATTRIB IN_CLOSE_WRITE
29			IN_CLOSE_NOWRITE IN_OPEN IN_MOVED_FROM IN_MOVED_TO
30			IN_CREATE IN_DELETE IN_DELETE_SELF
31			IN_ALL_EVENTS
32			IN_UNMOUNT IN_Q_OVERFLOW IN_IGNORED
33			IN_CLOSE IN_MOVE
34			IN_ISDIR IN_ONESHOT
35			);
36
37			@EXPORT = @constants;
38
39			require XSLoader;
40			XSLoader::load Linux::Inotify2, $VERSION;
41			}
42
43			=item my $inotify = new Linux::Inotify2
44
45			Create a new notify object and return it. A notify object is kind of a
46			container that stores watches on filesystem names and is responsible for
47			handling event data.
48
49			On error, C<undef> is returned and C<$!> will be set accordingly. The followign errors
50			are documented:
51
52			ENFILE The system limit on the total number of file descriptors has been reached.
53			EMFILE The user limit on the total number of inotify instances has been reached.
54			ENOMEM Insufficient kernel memory is available.
55
56			=cut
57
58			sub new {
59			my ($class) = @_;
60
61			my $fd = inotify_init;
62
63			return unless $fd >= 0;
64
65			bless { fd => $fd }, $class
66			}
67
68			=item $watch = $inotify2->watch ($name, $mask, $cb)
69
70			Add a new watcher to the given notifier. The watcher will create events
71			on the pathname C<$name> as given in C<$mask>, which can be any of the
72			following constants (all exported by default) ORed together:
73
74			IN_ACCESS File was accessed
75			IN_MODIFY File was modified
76			IN_ATTRIB Metadata changed
77			IN_CLOSE_WRITE Writtable file was closed
78			IN_CLOSE_NOWRITE Unwrittable file closed
79			IN_OPEN File was opened
80			IN_MOVED_FROM File was moved from X
81			IN_MOVED_TO File was moved to Y
82			IN_CREATE Subfile was created
83			IN_DELETE Subfile was deleted
84			IN_DELETE_SELF Self was deleted
85			IN_ONESHOT only send event once
86			IN_ALL_EVENTS All of the above events
87
88			IN_CLOSE Same as IN_CLOSE_WRITE \| IN_CLOSE_NOWRITE
89			IN_MOVE Same as IN_MOVED_FROM \| IN_MOVED_TO
90
91			C<$cb> is a perl code reference that is called for each event. It receives
92			a C<Linux::Inotify2::Event> object.
93
94			The returned C<$watch> object is of class C<Linux::Inotify2::Watch>.
95
96			On error, C<undef> is returned and C<$!> will be set accordingly. The
97			following errors are documented:
98
99			EBADF The given file descriptor is not valid.
100			EINVAL The given event mask contains no legal events.
101			ENOMEM Insufficient kernel memory was available.
102			ENOSPC The user limit on the total number of inotify watches was reached or the kernel failed to allocate a needed resource.
103			EACCESS Read access to the given file is not permitted.
104
105			Example, show when C</etc/passwd> gets accessed and/or modified once:
106
107			$inotify->watch ("/etc/passwd", IN_ACCESS \| IN_MODIFY, sub {
108			my $e = shift;
109			print "$e->{w}{name} was accessed\n" if $e->IN_ACCESS;
110			print "$e->{w}{name} was modified\n" if $e->IN_MODIFY;
111			print "$e->{w}{name} is no longer mounted\n" if $e->IN_UNMOUNT;
112			print "events for $e->{w}{name} have been lost\n" if $e->IN_Q_OVERFLOW;
113
114			$e->w->cancel;
115			});
116
117			=cut
118
119			sub watch {
120			my ($self, $name, $mask, $cb) = @_;
121
122			my $wd = inotify_add_watch $self->{fd}, $name, $mask;
123
124			return unless $wd >= 0;
125
126			my $w = $self->{w}{$wd} = bless {
127			inotify => $self,
128			wd => $wd,
129			name => $name,
130			mask => $mask,
131			cb => $cb,
132			}, Linux::Inotify2::Watch;
133
134			Scalar::Util::weaken $w->{inotify};
135
136			$w
137			}
138
139			=item $inotify2->fileno
140
141			Returns the fileno for this notify object. You are responsible for calling
142			the C<poll> method when this fileno becomes ready for reading.
143
144			=cut
145
146			sub fileno {
147			$_[0]{fd}
148			}
149
150			=item $count = $inotify2->poll
151
152			Reads events from the kernel and handles them. If the notify fileno
153			is blocking (the default), then this method waits for at least one
154			event. Otherwise it returns immediately when no pending events could be
155			read.
156
157			Returns the count of events that have been handled.
158
159			=cut
160
161			# TODO: potential race with recently-canceled watchers
162
163			sub poll {
164			my ($self) = @_;
165
166			for (inotify_read $self->{fd}) {
167			$_->{w} = $self->{w}{$_->{wd}}
168			or next; # no such watcher
169			$_->{w}{cb}->(bless $_, Linux::Inotify2::Event);
170			}
171			}
172
173			sub DESTROY {
174			inotify_close $_[0]{fd}
175			}
176
177			=back
178
179			=head2 The Linux::Inotify2::Event Class
180
181			Objects of this class are handed as first argument to the watch
182			callback. It has the following members and methods:
183
184			=over 4
185
186			=item $event->w
187
188			=item $event->{w}
189
190			The watcher object for this event.
191
192			=item $event->name
193
194			=item $event->{name}
195
196			The path of the filesystem object, relative to the watch name.
197
198			=item $watch->fullname
199
200			Returns the "full" name of the relevant object, i.e. including the C<name>
201			component of the watcher.
202
203			=item $event->mask
204
205			=item $event->{mask}
206
207			The received event mask. In addition the the events described for
208			C<$inotify->watch>, the following flags (exported by default) can be set:
209
210			IN_ISDIR event occurred against dir
211
212			IN_UNMOUNT Backing fs was unmounted
213			IN_Q_OVERFLOW Event queued overflowed
214			IN_IGNORED File was ignored (no more events will be delivered)
215
216			=item $event->IN_xxx
217
218			Returns a boolean that returns true if the event mask matches the
219			event. All of the C<IN_xxx> constants can be used as methods.
220
221			=item $event->cookie
222
223			=item $event->{cookie}
224
225			The event cookie, can be used to synchronize two related events.
226
227			=back
228
229			=cut
230
231			package Linux::Inotify2::Event;
232
233			sub w { $_[0]{w} }
234			sub name { $_[0]{name} }
235			sub mask { $_[0]{mask} }
236			sub cookie { $_[0]{cookie} }
237
238			sub fullname {
239			length $_[0]{name}
240			? "$_[0]{w}{name}/$_[0]{name}"
241			: $_[0]{w}{name};
242			}
243
244			for my $name (@Linux::Inotify2::constants) {
245			my $mask = &{"Linux::Inotify2::$name"};
246
247			*$name = sub { ($_[0]{mask} & $mask) == $mask };
248			}
249
250			=head2 The Linux::Inotify2::Watch Class
251
252			Watch objects are created by calling the C<watch> method of a notifier.
253
254			It has the following members and methods:
255
256			=item $watch->name
257
258			=item $watch->{name}
259
260			The name as specified in the C<watch> call. For the object itself, this is
261			the empty string. For directory watches, this is the name of the entry
262			without leading path elements.
263
264			=item $watch->mask
265
266			=item $watch->{mask}
267
268			The mask as specified in the C<watch> call.
269
270			=item $watch->cb ([new callback])
271
272			=item $watch->{cb}
273
274			The callback as specified in the C<watch> call. Can optionally be changed.
275
276			=item $watch->cancel
277
278			Cancels/removes this watch. Future events, even if already queued queued,
279			will not be handled and resources will be freed.
280
281			=cut
282
283			package Linux::Inotify2::Watch;
284
285			sub name { $_[0]{name} }
286			sub mask { $_[0]{mask} }
287
288			sub cb {
289			$_[0]{cb} = $_[1] if @_ > 1;
290			$_[0]{cb}
291			}
292
293			sub cancel {
294			my ($self) = @_;
295
296			(Linux::Inotify2::inotify_rm_watch $self->{inotify}{fd}, $self->{wd})
297			? 1 : undef
298			}
299
300			=head1 SEE ALSO
301
302			L<Linux::Inotify>.
303
304			=head1 AUTHOR
305
306			Marc Lehmann <schmorp@schmorp.de>
307			http://home.schmorp.de/
308
309			=cut
310
311			1