bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Tassilo Horn]

Right now, (at least) the inotify version of `file-notify-rm-watch'
signals an error in case the given descriptor denotes a directory which
has been deleted in the meantime.  If it denotes a file which has been
deleted, no error is signaled.

Here's a receipe:

(require 'filenotify)
(let* ((flags '(change))
       (handler (lambda () nil))
       (file (make-temp-file "foo"))
       (file-watch (file-notify-add-watch file flags handler))
       (dir (make-temp-file "bar" t))
       (dir-watch (file-notify-add-watch dir flags handler)))
  (delete-file file)
  (delete-directory dir)
  (file-notify-rm-watch file-watch)    ;; works
  (message "Removed file watch")
  (file-notify-rm-watch dir-watch)     ;; signals an error
  (message "Removed directory watch"))

The documentation does not define any specific behavior for these
situation, so this is currently a gray area which makes it hard for
package developers to develop something which will work right accross
the different notification backends.

I don't have a strong opinion about what the right behavior would be but
at least it seems inconsistent that you get the error only with deleted
directories.  I guess the best solution was if `file-notify-rm-watch'
never signaled an error (then the docs can stay as they are), and there
would be some `file-notify-valid-p' predicate which would test if a
given descriptor still denotes a valid file or directory.  I guess the
latter has probably some function equivalent in the respective backend
APIs, and even if not, it can be implemented by inspecting
`file-notify-descriptors'.



In GNU Emacs 25.0.50.10 (x86_64-unknown-linux-gnu, GTK+ Version 3.16.6)
 of 2015-09-08
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Windowing system distributor 'The X.Org Foundation', version 11.0.11702000
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bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Tassilo Horn <tsdh@gnu.org> writes:

Hi Tassilo,

> I don't have a strong opinion about what the right behavior would be but
> at least it seems inconsistent that you get the error only with deleted
> directories.  I guess the best solution was if `file-notify-rm-watch'
> never signaled an error (then the docs can stay as they are), and there
> would be some `file-notify-valid-p' predicate which would test if a
> given descriptor still denotes a valid file or directory.  I guess the
> latter has probably some function equivalent in the respective backend
> APIs, and even if not, it can be implemented by inspecting
> `file-notify-descriptors'.

`file-notify-rm-watch' is just a cleanup function, it's not worth to add
some error handling. I will wrap the call of the native handlers by
catching `file-notify-error'. Alternatively, `inotify-rm-watch' could be
adapted not to raise an error in this case.

`file-notify-valid-p' is a nice idea; I will see how I could add it. At
least for the w32 case I would need some help from Eli, in order to
see whether the native library supports such a check.

Best regards, Michael.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Tassilo Horn]

Michael Albinus <michael.albinus@gmx.de> writes:

Hi Michael,

>> I don't have a strong opinion about what the right behavior would be
>> but at least it seems inconsistent that you get the error only with
>> deleted directories.  I guess the best solution was if
>> `file-notify-rm-watch' never signaled an error (then the docs can
>> stay as they are), and there would be some `file-notify-valid-p'
>> predicate which would test if a given descriptor still denotes a
>> valid file or directory.  I guess the latter has probably some
>> function equivalent in the respective backend APIs, and even if not,
>> it can be implemented by inspecting `file-notify-descriptors'.
>
> `file-notify-rm-watch' is just a cleanup function, it's not worth to
> add some error handling.  I will wrap the call of the native handlers
> by catching `file-notify-error'. Alternatively, `inotify-rm-watch'
> could be adapted not to raise an error in this case.

Great, thanks.

> `file-notify-valid-p' is a nice idea; I will see how I could add it.
> At least for the w32 case I would need some help from Eli, in order to
> see whether the native library supports such a check.

I just wanted to write that such a predicate would not strictly be
needed because if one really cares, she could determine when a
descriptor becomes invalid by handling all delete notifications.  But
that's not really true because when watching a directory, you only
receive events for the contents of the directory, not for the directory
itself.  That is, if you want to receive notifications about changes to
your watched directory itself, then you need to watch also its parent
directory.

Bye,
Tassilo

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Eli Zaretskii]

> From: Tassilo Horn <tsdh@gnu.org>
> Date: Tue, 08 Sep 2015 08:36:06 +0200
> 
> Right now, (at least) the inotify version of `file-notify-rm-watch'
> signals an error in case the given descriptor denotes a directory which
> has been deleted in the meantime.  If it denotes a file which has been
> deleted, no error is signaled.
> 
> Here's a receipe:
> 
> (require 'filenotify)
> (let* ((flags '(change))
>        (handler (lambda () nil))
>        (file (make-temp-file "foo"))
>        (file-watch (file-notify-add-watch file flags handler))
>        (dir (make-temp-file "bar" t))
>        (dir-watch (file-notify-add-watch dir flags handler)))
>   (delete-file file)
>   (delete-directory dir)
>   (file-notify-rm-watch file-watch)    ;; works
>   (message "Removed file watch")
>   (file-notify-rm-watch dir-watch)     ;; signals an error
>   (message "Removed directory watch"))
> 
> The documentation does not define any specific behavior for these
> situation, so this is currently a gray area which makes it hard for
> package developers to develop something which will work right accross
> the different notification backends.
> 
> I don't have a strong opinion about what the right behavior would be but
> at least it seems inconsistent that you get the error only with deleted
> directories.

There is no "right" behavior.  What you see is what the back-end
reports to us.  If we want Emacs to be smarter, it's the job of the
application, not of filenotify.el.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: 21432@debbugs.gnu.org, Eli Zaretskii <eliz@gnu.org>
> Date: Tue, 08 Sep 2015 09:47:07 +0200
> 
> `file-notify-valid-p' is a nice idea; I will see how I could add it. At
> least for the w32 case I would need some help from Eli, in order to
> see whether the native library supports such a check.

What happens on w32 when a watched directory is deleted is that the
thread which watches the changes exits (with an abnormal status), but
the object created to watch the changes still exists, and can be
easily tested for being "invalid".

So if you want to implement file-notify-valid-p, go ahead; the w32
side will be almost trivial.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Eli Zaretskii <eliz@gnu.org> writes:

>> I don't have a strong opinion about what the right behavior would be but
>> at least it seems inconsistent that you get the error only with deleted
>> directories.
>
> There is no "right" behavior.  What you see is what the back-end
> reports to us.  If we want Emacs to be smarter, it's the job of the
> application, not of filenotify.el.

Well, filenotify.el shall abstract from the different back-ends. Being
quite when the native rm-watch fails seems to be appropriate.

Best regards, Michael.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Michael Albinus <michael.albinus@gmx.de> writes:

> Eli Zaretskii <eliz@gnu.org> writes:
>
>>> I don't have a strong opinion about what the right behavior would be but
>>> at least it seems inconsistent that you get the error only with deleted
>>> directories.
>>
>> There is no "right" behavior.  What you see is what the back-end
>> reports to us.  If we want Emacs to be smarter, it's the job of the
>> application, not of filenotify.el.
>
> Well, filenotify.el shall abstract from the different back-ends. Being
> quiet when the native rm-watch fails seems to be appropriate.

I've checked, all three Emacs libraries inotify, gfilenotify and
w32notify return an error when *-rm-watch detects a problem.
`file-notify-rm-watch' could propagate this error. The manual
shall be extended then.

At least inotify removes a watch internally, when it detects that the
file/directoy to be watched does not exist any longer. gfilenotify and
w32notify do not seem to to care.

Shall we unify this behaviour? I'm not in favor of the inotify
behaviour, the libraries shall raise a final signal instead that the
watch is stopped. filenotify shall propagate this then, for example as
`stopped' event or something like this.

Last point, I've observed that inotify and gfilenotify raise a
`file-notify-error' when needed. w32notify raises a `file-error'.
Shouldn't it raise also `file-notify-error'?.

Best regards, Michael.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: Tassilo Horn <tsdh@gnu.org>,  21432@debbugs.gnu.org
> Date: Sat, 12 Sep 2015 12:18:01 +0200
> 
> Michael Albinus <michael.albinus@gmx.de> writes:
> 
> > Eli Zaretskii <eliz@gnu.org> writes:
> >
> >>> I don't have a strong opinion about what the right behavior would be but
> >>> at least it seems inconsistent that you get the error only with deleted
> >>> directories.
> >>
> >> There is no "right" behavior.  What you see is what the back-end
> >> reports to us.  If we want Emacs to be smarter, it's the job of the
> >> application, not of filenotify.el.
> >
> > Well, filenotify.el shall abstract from the different back-ends. Being
> > quiet when the native rm-watch fails seems to be appropriate.
> 
> I've checked, all three Emacs libraries inotify, gfilenotify and
> w32notify return an error when *-rm-watch detects a problem.
> `file-notify-rm-watch' could propagate this error. The manual
> shall be extended then.

But the issue comes up before you remove the watch.  You have a watch
that is in fact inoperable, but the application might not know about
that, or get hit by a signal out of nowhere.

So I think having a validation function is a good idea.

> At least inotify removes a watch internally, when it detects that the
> file/directoy to be watched does not exist any longer.

That's a bug, IMO: it shouldn't.

> gfilenotify and w32notify do not seem to to care.

In w32notify, I did that on purpose: it's not the business of the tail
to wag the dog.  Low-level functions has no business calling
higher-level APIs on their own.

> Shall we unify this behaviour? I'm not in favor of the inotify
> behaviour, the libraries shall raise a final signal instead that the
> watch is stopped. filenotify shall propagate this then, for example as
> `stopped' event or something like this.

I don't think you can easily raise a signal.  I think we should
provide a validate function for the applications to use.

> Last point, I've observed that inotify and gfilenotify raise a
> `file-notify-error' when needed. w32notify raises a `file-error'.
> Shouldn't it raise also `file-notify-error'?.

Yes, it should.  ('file-notify-error' didn't exist when I developed
w32notify.c.)

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Eli Zaretskii <eliz@gnu.org> writes:

>> I've checked, all three Emacs libraries inotify, gfilenotify and
>> w32notify return an error when *-rm-watch detects a problem.
>> `file-notify-rm-watch' could propagate this error. The manual
>> shall be extended then.
>
> But the issue comes up before you remove the watch.  You have a watch
> that is in fact inoperable, but the application might not know about
> that, or get hit by a signal out of nowhere.
>
> So I think having a validation function is a good idea.

Yes. I've started to write a prototype for inotify.c, will show when it
works (slow progress, you know :-( )

>> At least inotify removes a watch internally, when it detects that the
>> file/directoy to be watched does not exist any longer.
>
> That's a bug, IMO: it shouldn't.

I tend to agree. Will check further with inotify.c, but likely we should
discard this "feature".

>> Shall we unify this behaviour? I'm not in favor of the inotify
>> behaviour, the libraries shall raise a final signal instead that the
>> watch is stopped. filenotify shall propagate this then, for example as
>> `stopped' event or something like this.
>
> I don't think you can easily raise a signal.  I think we should
> provide a validate function for the applications to use.

At least for inotify, it is built-in. It sends the `ignored' signal when
the directory or file being watch disappears, due to a delete, rename, or
unmount, whatever:

--8<---------------cut here---------------start------------->8---
(progn
  (trace-function 'file-notify-handle-event)
  (write-region "any text" nil "/tmp/xxx")
  (inotify-add-watch "/tmp/xxx" 'all-events 'ignore)
  (delete-file "/tmp/xxx"))

======================================================================
1 -> (file-notify-handle-event (file-notify (1 (attrib) nil 0) ignore))
1 <- file-notify-handle-event: nil
======================================================================
1 -> (file-notify-handle-event (file-notify (1 (delete-self) nil 0) ignore))
1 <- file-notify-handle-event: nil
======================================================================
1 -> (file-notify-handle-event (file-notify (1 (ignored) nil 0) ignore))
1 <- file-notify-handle-event: nil
--8<---------------cut here---------------end--------------->8---

For gfilenotify it isn't such simple, unfortunately.

Best regards, Michael.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Michael Albinus <michael.albinus@gmx.de> writes:

>> So I think having a validation function is a good idea.
>
> Yes. I've started to write a prototype for inotify.c, will show when it
> works (slow progress, you know :-( )

I've committed a patch to the trunk, adding `file-notify-valid-p' and
its native implementations in inotify.c and tramp.el. Comments welcome.

I know, documentation in the elisp manual is missing. I'll add it later,
and also the native implementation in gfilenotify.c.

Test cases, anywhere?

Best regards, Michael.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Tassilo Horn]

Michael Albinus <michael.albinus@gmx.de> writes:

Hi Michael,

>>> So I think having a validation function is a good idea.
>>
>> Yes. I've started to write a prototype for inotify.c, will show when
>> it works (slow progress, you know :-( )
>
> I've committed a patch to the trunk, adding `file-notify-valid-p' and
> its native implementations in inotify.c and tramp.el. Comments
> welcome.
>
> I know, documentation in the elisp manual is missing. I'll add it
> later, and also the native implementation in gfilenotify.c.
>
> Test cases, anywhere?

I've added two tests, one for plain files and one for directories.  They
are "green" right now but I think they should not.

What seems wrong to me is that the descriptors stay valid even when the
watched file or directory is deleted.  For files this might be ok
(though maybe inotify-specific) because when I create a new file with
the same name, the watch will trigger.

However, the current hehavior is certainly wrong for directories.  When
I deleted the watched directory, the descriptor is still valid, but
calling file-notify-rm-watch on it signals an error.

Bye,
Tassilo

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Eli Zaretskii]

> From: Tassilo Horn <tsdh@gnu.org>
> Cc: Eli Zaretskii <eliz@gnu.org>,  21432@debbugs.gnu.org
> Date: Mon, 14 Sep 2015 08:08:20 +0200
> 
> Michael Albinus <michael.albinus@gmx.de> writes:
> 
> Hi Michael,
> 
> >>> So I think having a validation function is a good idea.
> >>
> >> Yes. I've started to write a prototype for inotify.c, will show when
> >> it works (slow progress, you know :-( )
> >
> > I've committed a patch to the trunk, adding `file-notify-valid-p' and
> > its native implementations in inotify.c and tramp.el. Comments
> > welcome.

I've added a w32 implementation in w32notify.c.

> I've added two tests, one for plain files and one for directories.  They
> are "green" right now but I think they should not.

I think you are testing this incorrectly.

> What seems wrong to me is that the descriptors stay valid even when the
> watched file or directory is deleted.  For files this might be ok
> (though maybe inotify-specific) because when I create a new file with
> the same name, the watch will trigger.
> 
> However, the current hehavior is certainly wrong for directories.  When
> I deleted the watched directory, the descriptor is still valid, but
> calling file-notify-rm-watch on it signals an error.

AFAIR, filenotify.el watches the parent directory of the
file/directory you asked it to watch.  So to see the invalid-p method
in action you need to remove the parent, not the directory itself.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Eli Zaretskii]

> Date: Sat, 12 Sep 2015 18:11:37 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 21432@debbugs.gnu.org, tsdh@gnu.org
> 
> > Last point, I've observed that inotify and gfilenotify raise a
> > `file-notify-error' when needed. w32notify raises a `file-error'.
> > Shouldn't it raise also `file-notify-error'?.
> 
> Yes, it should.

I've done that now.

I find the way inotify.c and gfilenotify.c report errors suboptimal:
they don't report the errno value and the related data, so the error
messages tell less than they could.  I went the way similar to
report_file_error instead.  Maybe the other back-ends should follow
suit.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Eli Zaretskii <eliz@gnu.org> writes:

> I find the way inotify.c and gfilenotify.c report errors suboptimal:
> they don't report the errno value and the related data, so the error
> messages tell less than they could.  I went the way similar to
> report_file_error instead.  Maybe the other back-ends should follow
> suit.

Will do.

Best regards, Michael.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Tassilo Horn]

Eli Zaretskii <eliz@gnu.org> writes:

>> What seems wrong to me is that the descriptors stay valid even when
>> the watched file or directory is deleted.  For files this might be ok
>> (though maybe inotify-specific) because when I create a new file with
>> the same name, the watch will trigger.
>> 
>> However, the current hehavior is certainly wrong for directories.
>> When I deleted the watched directory, the descriptor is still valid,
>> but calling file-notify-rm-watch on it signals an error.
>
> AFAIR, filenotify.el watches the parent directory of the
> file/directory you asked it to watch.  So to see the invalid-p method
> in action you need to remove the parent, not the directory itself.

Ah, I see.  I'll adapt the tests accordingly.

Bye,
Tassilo

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Tassilo Horn]

Tassilo Horn <tsdh@gnu.org> writes:

>>> What seems wrong to me is that the descriptors stay valid even when
>>> the watched file or directory is deleted.  For files this might be
>>> ok (though maybe inotify-specific) because when I create a new file
>>> with the same name, the watch will trigger.
>>> 
>>> However, the current hehavior is certainly wrong for directories.
>>> When I deleted the watched directory, the descriptor is still valid,
>>> but calling file-notify-rm-watch on it signals an error.
>>
>> AFAIR, filenotify.el watches the parent directory of the
>> file/directory you asked it to watch.  So to see the invalid-p method
>> in action you need to remove the parent, not the directory itself.
>
> Ah, I see.  I'll adapt the tests accordingly.

Done, however the descriptors still don't become invalid when deleting
the parent directory of the watched file or directory.  I guess, that's
a problem in the inotify and TRAMP implementations then.

Bye,
Tassilo

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Eli Zaretskii]

> From: Tassilo Horn <tsdh@gnu.org>
> Cc: michael.albinus@gmx.de,  21432@debbugs.gnu.org
> Date: Mon, 14 Sep 2015 09:56:12 +0200
> 
> >> AFAIR, filenotify.el watches the parent directory of the
> >> file/directory you asked it to watch.  So to see the invalid-p method
> >> in action you need to remove the parent, not the directory itself.
> >
> > Ah, I see.  I'll adapt the tests accordingly.
> 
> Done, however the descriptors still don't become invalid when deleting
> the parent directory of the watched file or directory.  I guess, that's
> a problem in the inotify and TRAMP implementations then.

No, I think it's a problem with our mental model of what happens.  The
file notifications use the Emacs event loop, and Emacs won't check for
events until it's idle.  So calling file-notify-valid-p as part of the
test ends up doing that _before_ the directory deletion notification
is read by Emacs and invalidates the watch.  I actually see the
message saying the watch is valid before the notification comes in and
its message is inserted into *Messages*.

The following simple test case works with w32notify:

  (setq mydir "/tmp/x")
  (make-directory mydir t)
  (setq myfile "/tmp/x/y")
  (write-region "foo\n" nil myfile)
  (setq w (w32notify-add-watch mydir '(file-name attributes size last-write-time)
			       (lambda (event) (message "%s" event))))
  (message "valid: %s" (w32notify-valid-p w))
  (delete-directory mydir t)
  (run-with-idle-timer 1 nil
		       (lambda ()
			 (message "valid: %s" (w32notify-valid-p w))))

When I run the above snippet with eval-region, I see these messages in
*Messages*:

  Wrote d:/tmp/x/y
  valid: t
  (100161480 modified y)
  (100161480 removed y)
  valid: nil

Try something similar with inotify and see if you see the same basic
issue.  If you do, I trust you will think of a way to modify the tests
so that validation does do its thing.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Eli Zaretskii <eliz@gnu.org> writes:

> No, I think it's a problem with our mental model of what happens.  The
> file notifications use the Emacs event loop, and Emacs won't check for
> events until it's idle.  So calling file-notify-valid-p as part of the
> test ends up doing that _before_ the directory deletion notification
> is read by Emacs and invalidates the watch.  I actually see the
> message saying the watch is valid before the notification comes in and
> its message is inserted into *Messages*.
>
> Try something similar with inotify and see if you see the same basic
> issue.  If you do, I trust you will think of a way to modify the tests
> so that validation does do its thing.

I've adapted `file-notify-test04-file-validity' and
`file-notify-test05-dir-validity', and they pass the tests now for the
inotify case. Hopefully, it is the same for w32notify.

Implementation for gfilenotify and Tramp will follow.

While being there, I have made also `file-notify-rm-watch' more robust
by ignoring all `file-notify-error's. This was the initial trigger for
bug#21432.

Best regards, Michael.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Tassilo Horn]

Eli Zaretskii <eliz@gnu.org> writes:

>> Done, however the descriptors still don't become invalid when
>> deleting the parent directory of the watched file or directory.  I
>> guess, that's a problem in the inotify and TRAMP implementations
>> then.
>
> No, I think it's a problem with our mental model of what happens.  The
> file notifications use the Emacs event loop, and Emacs won't check for
> events until it's idle.  So calling file-notify-valid-p as part of the
> test ends up doing that _before_ the directory deletion notification
> is read by Emacs and invalidates the watch.

Yes, you are right.  Michael already fixed the tests by waiting for the
file notifications before calling `file-notify-valid-p' and then we get
the expected results (well, not yet with remote files).

Bye,
Tassilo

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: Tassilo Horn <tsdh@gnu.org>,  21432@debbugs.gnu.org
> Date: Mon, 14 Sep 2015 22:23:36 +0200
> 
> I've adapted `file-notify-test04-file-validity' and
> `file-notify-test05-dir-validity', and they pass the tests now for the
> inotify case. Hopefully, it is the same for w32notify.

No, it fails:

  Test file-notify-test04-file-validity condition:
      (ert-test-failed
       ((should
	 (equal '...
	  (mapcar ... events)))
	:form
	(equal
	 (created changed deleted)
	 nil)
	:value nil :explanation
	(different-types
	 (created changed deleted)
	 nil)))
     FAILED   9/12  file-notify-test04-file-validity

I guess the file-notify--test-with-events macro doesn't allow events
to come in on w32, but I have no idea how to debug this.

Moreover, file-notify-test05-dir-validity also fails:

  Test file-notify-test05-dir-validity condition:
      (ert-test-failed
       ((should-not
	 (file-notify-valid-p file-notify--test-desc))
	:form
	(file-notify-valid-p 91670672)
	:value t))
     FAILED  11/12  file-notify-test05-dir-validity

The latter could be because of the batch mode (it passes when I invoke
it interactively).  But the former fails in interactive session as
well, so it's a real problem.  Suggestions for debugging it are
welcome.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Eli Zaretskii <eliz@gnu.org> writes:

>> I've adapted `file-notify-test04-file-validity' and
>> `file-notify-test05-dir-validity', and they pass the tests now for the
>> inotify case. Hopefully, it is the same for w32notify.
>
> No, it fails:
>
>   Test file-notify-test04-file-validity condition:
>       (ert-test-failed
>        ((should
> 	 (equal '...
> 	  (mapcar ... events)))
> 	:form
> 	(equal
> 	 (created changed deleted)
> 	 nil)
> 	:value nil :explanation
> 	(different-types
> 	 (created changed deleted)
> 	 nil)))
>      FAILED   9/12  file-notify-test04-file-validity
>
> I guess the file-notify--test-with-events macro doesn't allow events
> to come in on w32, but I have no idea how to debug this.

After loading file-notify-tests.el, trace-function for
file-notify-handle-event, file-notify-callback,
file-notify--test-event-handler. Run only file-notify-test04-file-validity.
Show the trace buffer.

Best regards, Michael.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: tsdh@gnu.org,  21432@debbugs.gnu.org
> Date: Tue, 15 Sep 2015 10:00:10 +0200
> 
> > I guess the file-notify--test-with-events macro doesn't allow events
> > to come in on w32, but I have no idea how to debug this.
> 
> After loading file-notify-tests.el, trace-function for
> file-notify-handle-event, file-notify-callback,
> file-notify--test-event-handler. Run only file-notify-test04-file-validity.
> Show the trace buffer.

Here:

  ======================================================================
  1 -> (file-notify-handle-event (file-notify (100272320 added ".#-emacsa05420") file-notify-callback))
  | 2 -> (file-notify-callback (100272320 added ".#-emacsa05420"))
  | 2 <- file-notify-callback: nil
  1 <- file-notify-handle-event: nil
  ======================================================================
  1 -> (file-notify-handle-event (file-notify (100272320 modified ".#-emacsa05420") file-notify-callback))
  | 2 -> (file-notify-callback (100272320 modified ".#-emacsa05420"))
  | 2 <- file-notify-callback: nil
  1 <- file-notify-handle-event: nil

I'm confused: why does it mention a lock file instead of some file in
temporary-file-directory?  Is some variable missing a value?

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Eli Zaretskii <eliz@gnu.org> writes:

>   ======================================================================
>   1 -> (file-notify-handle-event (file-notify (100272320 added
> ".#-emacsa05420") file-notify-callback))
>   | 2 -> (file-notify-callback (100272320 added ".#-emacsa05420"))
>   | 2 <- file-notify-callback: nil
>   1 <- file-notify-handle-event: nil
>   ======================================================================
>   1 -> (file-notify-handle-event (file-notify (100272320 modified
> ".#-emacsa05420") file-notify-callback))
>   | 2 -> (file-notify-callback (100272320 modified ".#-emacsa05420"))
>   | 2 <- file-notify-callback: nil
>   1 <- file-notify-handle-event: nil
>
> I'm confused: why does it mention a lock file instead of some file in
> temporary-file-directory?  Is some variable missing a value?

Well, the lock files are from the write-region call. I see something
similar for inotify:

======================================================================
1 -> (file-notify-handle-event (file-notify (2 (create) ".#file-notify-test20231Yhx" 0) file-notify-callback))
| 2 -> (file-notify-callback (2 (create) ".#file-notify-test20231Yhx" 0))
| 2 <- file-notify-callback: nil
1 <- file-notify-handle-event: nil
======================================================================
1 -> (file-notify-handle-event (file-notify (2 (create) "file-notify-test20231Yhx" 0) file-notify-callback))
| 2 -> (file-notify-callback (2 (create) "file-notify-test20231Yhx" 0))
| | 3 -> (file-notify--test-event-handler ((2 . "file-notify-test20231Yhx") created "/tmp/file-notify-test-parent20231LXr/file-notify-test20231Yhx"))
| | 3 <- file-notify--test-event-handler: ([cl-struct-ert-test-passed #2="" ((#3=(should (equal (car file-notify--test-event) file-notify--test-desc)) :form (equal (1 . #1="file-notify-test20231-Ml") #4=(1 . #1#)) :value t :explanation nil) (#5=(should (string-equal (file-notify--event-file-name file-notify--test-event) file-notify--test-tmpfile)) :form (string-equal "/tmp/file-notify-test-parent20231MPA/file-notify-test20231-Ml" #6="/tmp/file-notify-test-parent20231MPA/file-notify-test20231-Ml") :value t))] [cl-struct-ert-test-passed #2# ((#3# :form (equal (1 . #1#) #4#) :value t :explanation nil) (#5# :form (string-equal "/tmp/file-notify-test-parent20231MPA/file-notify-test20231-Ml" #6#) :value t))] [cl-struct-ert-test-passed #2# ((#3# :form (equal (1 . #1#) #4#) :value t :explanation nil) (#5# :form (string-equal "/tmp/file-notify-test-parent20231MPA/file-notify-test20231-Ml" #6#) :value t))] [cl-struct-ert-test-passed #2# ((#3# :form (equal (2 . #7="file-notify-test20231Yhx") (2 . #7#)) :value t :explanation nil) (#5# :form (string-equal "/tmp/file-notify-test-parent20231LXr/file-notify-test20231Yhx" "/tmp/file-notify-test-parent20231LXr/file-notify-test20231Yhx") :value t))])
| 2 <- file-notify-callback: nil
1 <- file-notify-handle-event: nil
======================================================================
1 -> (file-notify-handle-event (file-notify (2 (modify) "file-notify-test20231Yhx" 0) file-notify-callback))
| 2 -> (file-notify-callback (2 (modify) "file-notify-test20231Yhx" 0))
| | 3 -> (file-notify--test-event-handler ((2 . "file-notify-test20231Yhx") changed "/tmp/file-notify-test-parent20231LXr/file-notify-test20231Yhx"))
| | 3 <- file-notify--test-event-handler: ([cl-struct-ert-test-passed #2="" ((#3=(should (equal (car file-notify--test-event) file-notify--test-desc)) :form (equal (1 . #1="file-notify-test20231-Ml") #4=(1 . #1#)) :value t :explanation nil) (#5=(should (string-equal (file-notify--event-file-name file-notify--test-event) file-notify--test-tmpfile)) :form (string-equal "/tmp/file-notify-test-parent20231MPA/file-notify-test20231-Ml" #6="/tmp/file-notify-test-parent20231MPA/file-notify-test20231-Ml") :value t))] [cl-struct-ert-test-passed #2# ((#3# :form (equal (1 . #1#) #4#) :value t :explanation nil) (#5# :form (string-equal "/tmp/file-notify-test-parent20231MPA/file-notify-test20231-Ml" #6#) :value t))] [cl-struct-ert-test-passed #2# ((#3# :form (equal (1 . #1#) #4#) :value t :explanation nil) (#5# :form (string-equal "/tmp/file-notify-test-parent20231MPA/file-notify-test20231-Ml" #6#) :value t))] [cl-struct-ert-test-passed #2# ((#3# :form (equal (2 . #7="file-notify-test20231Yhx") #8=(2 . #7#)) :value t :explanation nil) (#5# :form (string-equal "/tmp/file-notify-test-parent20231LXr/file-notify-test20231Yhx" #9="/tmp/file-notify-test-parent20231LXr/file-notify-test20231Yhx") :value t))] [cl-struct-ert-test-passed #2# ((#3# :form (equal (2 . #7#) #8#) :value t :explanation nil) (#5# :form (string-equal "/tmp/file-notify-test-parent20231LXr/file-notify-test20231Yhx" #9#) :value t))])
| 2 <- file-notify-callback: nil
1 <- file-notify-handle-event: nil
======================================================================
1 -> (file-notify-handle-event (file-notify (2 (delete) ".#file-notify-test20231Yhx" 0) file-notify-callback))
| 2 -> (file-notify-callback (2 (delete) ".#file-notify-test20231Yhx" 0))
| 2 <- file-notify-callback: nil
1 <- file-notify-handle-event: nil
======================================================================
1 -> (file-notify-handle-event (file-notify (2 (delete) "file-notify-test20231Yhx" 0) file-notify-callback))
| 2 -> (file-notify-callback (2 (delete) "file-notify-test20231Yhx" 0))
| | 3 -> (file-notify--test-event-handler ((2 . "file-notify-test20231Yhx") deleted "/tmp/file-notify-test-parent20231LXr/file-notify-test20231Yhx"))
| | 3 <- file-notify--test-event-handler: ([cl-struct-ert-test-passed #2="" ((#3=(should (equal (car file-notify--test-event) file-notify--test-desc)) :form (equal (1 . #1="file-notify-test20231-Ml") #4=(1 . #1#)) :value t :explanation nil) (#5=(should (string-equal (file-notify--event-file-name file-notify--test-event) file-notify--test-tmpfile)) :form (string-equal "/tmp/file-notify-test-parent20231MPA/file-notify-test20231-Ml" #6="/tmp/file-notify-test-parent20231MPA/file-notify-test20231-Ml") :value t))] [cl-struct-ert-test-passed #2# ((#3# :form (equal (1 . #1#) #4#) :value t :explanation nil) (#5# :form (string-equal "/tmp/file-notify-test-parent20231MPA/file-notify-test20231-Ml" #6#) :value t))] [cl-struct-ert-test-passed #2# ((#3# :form (equal (1 . #1#) #4#) :value t :explanation nil) (#5# :form (string-equal "/tmp/file-notify-test-parent20231MPA/file-notify-test20231-Ml" #6#) :value t))] [cl-struct-ert-test-passed #2# ((#3# :form (equal (2 . #7="file-notify-test20231Yhx") #8=(2 . #7#)) :value t :explanation nil) (#5# :form (string-equal "/tmp/file-notify-test-parent20231LXr/file-notify-test20231Yhx" #9="/tmp/file-notify-test-parent20231LXr/file-notify-test20231Yhx") :value t))] [cl-struct-ert-test-passed #2# ((#3# :form (equal (2 . #7#) #8#) :value t :explanation nil) (#5# :form (string-equal "/tmp/file-notify-test-parent20231LXr/file-notify-test20231Yhx" #9#) :value t))] [cl-struct-ert-test-passed #2# ((#3# :form (equal (2 . #7#) #8#) :value t :explanation nil) (#5# :form (string-equal "/tmp/file-notify-test-parent20231LXr/file-notify-test20231Yhx" #9#) :value t))])
| 2 <- file-notify-callback: nil
1 <- file-notify-handle-event: nil
======================================================================
1 -> (file-notify-handle-event (file-notify (2 (ignored) nil 0) file-notify-callback))
| 2 -> (file-notify-callback (2 (ignored) nil 0))
| 2 <- file-notify-callback: nil
1 <- file-notify-handle-event: nil

`file-notify--test-event-handler' hasn't been called for the lock files,
because it was enabled for the test file only (that's the intention of
this test case). It isn't clear to me why
`file-notify--test-event-handler' hasn't been called for your test
file. That must be something in w32notify.c.

Best regards, Michael.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: tsdh@gnu.org,  21432@debbugs.gnu.org
> Date: Tue, 15 Sep 2015 13:54:08 +0200
> 
> It isn't clear to me why `file-notify--test-event-handler' hasn't
> been called for your test file. That must be something in
> w32notify.c.

What kind of "something"?  Notifications do work, and the rest of the
tests pass.  So it must be something with this particular test.

I think the problem is due to the fact that the directory is deleted
inside the file-notify--test-with-events form: doing that invalidates
the watch, so the events are not reported.  If I remove this line from
the macro body:

          (delete-directory temporary-file-directory t)

then the notifications are received as expected:

  Test file-notify-test04-file-validity condition:
      (ert-test-failed
       ((should
	 (equal '...
	  (mapcar ... events)))
	:form
	(equal
	 (created changed deleted)
	 (created changed))
	:value nil :explanation
	(proper-lists-of-different-length 3 2
					  (created changed deleted)
					  (created changed)
					  first-mismatch-at 2)))


(There's no "deleted" because it's caused by delete-directory call
which I removed.)

So I modified the test to have the directory deletion outside of the
macro, and the test now passes.  I also increased the timeout of
read-event, because 0.1 was borderline: it sometimes worked and
sometimes didn't.

Please see if the modified tests work with inotify (they did for me on
GNU/Linux).

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Eli Zaretskii <eliz@gnu.org> writes:

> So I modified the test to have the directory deletion outside of the
> macro, and the test now passes.  I also increased the timeout of
> read-event, because 0.1 was borderline: it sometimes worked and
> sometimes didn't.
>
> Please see if the modified tests work with inotify (they did for me on
> GNU/Linux).

Works here. And also `file-notify-test04-file-validity-remote', which
did fail before. Thanks.

Best regards, Michael.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Eli Zaretskii <eliz@gnu.org> writes:

> I find the way inotify.c and gfilenotify.c report errors suboptimal:
> they don't report the errno value and the related data, so the error
> messages tell less than they could.  I went the way similar to
> report_file_error instead.  Maybe the other back-ends should follow
> suit.

I've changed it in inotify.c. I've simply cloned your
report_w32notify_error, called it report_inotify_error, and adapted all
error reporting places.

However, wouldn't it be better to have a common function the three
backends will use? A report_filenotify_error function in fileio.c?

Best regards, Michael.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: 21432@debbugs.gnu.org,  tsdh@gnu.org
> Date: Tue, 15 Sep 2015 15:02:01 +0200
> 
> However, wouldn't it be better to have a common function the three
> backends will use? A report_filenotify_error function in fileio.c?

Yes, of course.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Eli Zaretskii <eliz@gnu.org> writes:

>> However, wouldn't it be better to have a common function the three
>> backends will use? A report_filenotify_error function in fileio.c?
>
> Yes, of course.

Done.

Best regards, Michael.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Eli Zaretskii <eliz@gnu.org> writes:

> I think the problem is due to the fact that the directory is deleted
> inside the file-notify--test-with-events form: doing that invalidates
> the watch, so the events are not reported.  If I remove this line from
> the macro body:
>
> So I modified the test to have the directory deletion outside of the
> macro, and the test now passes.  I also increased the timeout of
> read-event, because 0.1 was borderline: it sometimes worked and
> sometimes didn't.

I've checked further. In `file-notify-test04-file-validity', you have
also removed the final check for `file-notify-valid-p':

         ;; After deleting the parent, the descriptor must not be valid
         ;; anymore.
-        (should-not (file-notify-valid-p file-notify--test-desc)))
+        (delete-directory temporary-file-directory t)
+        (read-event nil nil 0.5))

Was this by intention? The whole test case is about this check. And
maybe this is also the reason that it passes now the remote test case,
surprisingly.

Best regards, Michael.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: tsdh@gnu.org,  21432@debbugs.gnu.org
> Date: Wed, 16 Sep 2015 16:45:56 +0200
> 
> I've checked further. In `file-notify-test04-file-validity', you have
> also removed the final check for `file-notify-valid-p':
> 
>          ;; After deleting the parent, the descriptor must not be valid
>          ;; anymore.
> -        (should-not (file-notify-valid-p file-notify--test-desc)))
> +        (delete-directory temporary-file-directory t)
> +        (read-event nil nil 0.5))

Oops!

> Was this by intention?

No.

> The whole test case is about this check. And maybe this is also the
> reason that it passes now the remote test case, surprisingly.

Does it work for you if you add the test after read-event?  It fails
here, i.e. the watch is still valid.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Eli Zaretskii <eliz@gnu.org> writes:

>> The whole test case is about this check. And maybe this is also the
>> reason that it passes now the remote test case, surprisingly.
>
> Does it work for you if you add the test after read-event?  It fails
> here, i.e. the watch is still valid.

Yes, it works for inotify. And `file-notify-test04-file-validity-remote'
fails as expected, 'cos I haven't fixed it yet in Tramp.

For inotify it is obvious that it shall work. All inotify watches are
based on inodes. If a file is watched by inotify, and the parent
directory of the file is deleted, the inode of the file itself disappears.

I don't know how it works with w32notify internally. And I don't know
yet how it will behave with gfilenotify, all checks for that backend I
have moved to later.

Best regards, Michael.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: tsdh@gnu.org,  21432@debbugs.gnu.org
> Date: Wed, 16 Sep 2015 19:26:50 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> The whole test case is about this check. And maybe this is also the
> >> reason that it passes now the remote test case, surprisingly.
> >
> > Does it work for you if you add the test after read-event?  It fails
> > here, i.e. the watch is still valid.
> 
> Yes, it works for inotify. And `file-notify-test04-file-validity-remote'
> fails as expected, 'cos I haven't fixed it yet in Tramp.
> 
> For inotify it is obvious that it shall work. All inotify watches are
> based on inodes. If a file is watched by inotify, and the parent
> directory of the file is deleted, the inode of the file itself disappears.
> 
> I don't know how it works with w32notify internally. And I don't know
> yet how it will behave with gfilenotify, all checks for that backend I
> have moved to later.

It works for w32notify if I run the test in an interactive session.
It only fails in batch mode.  Since the batch-mode operation of
w32notify is fragile (there's no input threads to send the message
to), and we have already wasted too much time on this tiny feature,
feel free to skip that test when in batch mode and w32notify back-end
is used.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Eli Zaretskii <eliz@gnu.org> writes:

> It works for w32notify if I run the test in an interactive session.
> It only fails in batch mode.  Since the batch-mode operation of
> w32notify is fragile (there's no input threads to send the message
> to), and we have already wasted too much time on this tiny feature,
> feel free to skip that test when in batch mode and w32notify back-end
> is used.

Done.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Tassilo Horn <tsdh@gnu.org> writes:

> Right now, (at least) the inotify version of `file-notify-rm-watch'
> signals an error in case the given descriptor denotes a directory which
> has been deleted in the meantime.  If it denotes a file which has been
> deleted, no error is signaled.

I believe, everything what has been discussed in the course of this bug
has been fixed now. I've committed a final patch for the Tramp case, and
I have extended the test cases slightly with this patch. Inotify and
Tramp tests pass all test cases.

If there's no problem left for w32notify, I believe we can close this bug.

There is still something to do for the gfilenotify case, but this I
could do outside this report.

Best regards, Michael.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Date: Sun, 20 Sep 2015 19:23:56 +0200
> Cc: 21432@debbugs.gnu.org
> 
> If there's no problem left for w32notify, I believe we can close this bug.

I don't believe there are any w32notify problems left we know about.

bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Michael Albinus]

Eli Zaretskii <eliz@gnu.org> writes:

>> If there's no problem left for w32notify, I believe we can close this bug.
>
> I don't believe there are any w32notify problems left we know about.

So I'm closing the bug.

Best regards, Michael.