/* Filesystem notifications support with kqueue API.
Copyright (C) 2015-2016 Free Software Foundation, Inc.
This file is part of GNU Emacs.
GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
#include <config.h>
#ifdef HAVE_KQUEUE
#include <stdio.h>
#include <sys/types.h>
#include <sys/event.h>
#include <sys/time.h>
#include <sys/file.h>
#include "lisp.h"
#include "keyboard.h"
#include "process.h"
/* File handle for kqueue. */
static int kqueuefd = -1;
/* This is a list, elements are (DESCRIPTOR FILE FLAGS CALLBACK [DIRLIST]). */
static Lisp_Object watch_list;
/* Generate a list from the directory_files_internal output.
Items are (INODE FILE-NAME LAST-MOD LAST-STATUS-MOD SIZE). */
Lisp_Object
kqueue_directory_listing (Lisp_Object directory_files)
{
Lisp_Object dl, result = Qnil;
for (dl = directory_files; ! NILP (dl); dl = XCDR (dl)) {
/* We ignore "." and "..". */
if ((strcmp (".", SSDATA (XCAR (XCAR (dl)))) == 0) ||
(strcmp ("..", SSDATA (XCAR (XCAR (dl)))) == 0))
continue;
result = Fcons
(list5 (/* inode. */
Fnth (make_number (11), XCAR (dl)),
/* filename. */
XCAR (XCAR (dl)),
/* last modification time. */
Fnth (make_number (6), XCAR (dl)),
/* last status change time. */
Fnth (make_number (7), XCAR (dl)),
/* size. */
Fnth (make_number (8), XCAR (dl))),
result);
}
return result;
}
/* Generate a file notification event. */
static void
kqueue_generate_event (Lisp_Object watch_object, Lisp_Object actions,
Lisp_Object file, Lisp_Object file1)
{
Lisp_Object flags, action, entry;
struct input_event event;
/* Check, whether all actions shall be monitored. */
flags = Fnth (make_number (2), watch_object);
action = actions;
do {
if (NILP (action))
break;
entry = XCAR (action);
if (NILP (Fmember (entry, flags))) {
action = XCDR (action);
actions = Fdelq (entry, actions);
} else
action = XCDR (action);
} while (1);
/* Store it into the input event queue. */
if (! NILP (actions)) {
EVENT_INIT (event);
event.kind = FILE_NOTIFY_EVENT;
event.frame_or_window = Qnil;
event.arg = list2 (Fcons (XCAR (watch_object),
Fcons (actions,
NILP (file1)
? Fcons (file, Qnil)
: list2 (file, file1))),
Fnth (make_number (3), watch_object));
kbd_buffer_store_event (&event);
}
}
/* This compares two directory listings in case of a `write' event for
a directory. Generate resulting file notification events. The old
directory listing is retrieved from watch_object, it will be
replaced by the new directory listing at the end of this
function. */
static void
kqueue_compare_dir_list (Lisp_Object watch_object)
{
Lisp_Object dir, pending_dl, deleted_dl;
Lisp_Object old_directory_files, old_dl, new_directory_files, new_dl, dl;
dir = XCAR (XCDR (watch_object));
pending_dl = Qnil;
deleted_dl = Qnil;
old_directory_files = Fnth (make_number (4), watch_object);
old_dl = kqueue_directory_listing (old_directory_files);
/* When the directory is not accessible anymore, it has been deleted. */
if (NILP (Ffile_directory_p (dir))) {
kqueue_generate_event (watch_object, Fcons (Qdelete, Qnil), dir, Qnil);
return;
}
new_directory_files =
directory_files_internal (dir, Qnil, Qnil, Qnil, 1, Qnil);
new_dl = kqueue_directory_listing (new_directory_files);
/* Parse through the old list. */
dl = old_dl;
while (1) {
Lisp_Object old_entry, new_entry, dl1;
if (NILP (dl))
break;
/* Search for an entry with the same inode. */
old_entry = XCAR (dl);
new_entry = assq_no_quit (XCAR (old_entry), new_dl);
if (! NILP (Fequal (old_entry, new_entry))) {
/* Both entries are identical. Nothing to do. */
new_dl = Fdelq (new_entry, new_dl);
goto the_end;
}
/* Both entries have the same inode. */
if (! NILP (new_entry)) {
/* Both entries have the same file name. */
if (strcmp (SSDATA (XCAR (XCDR (old_entry))),
SSDATA (XCAR (XCDR (new_entry)))) == 0) {
/* Modification time has been changed, the file has been written. */
if (NILP (Fequal (Fnth (make_number (2), old_entry),
Fnth (make_number (2), new_entry))))
kqueue_generate_event
(watch_object, Fcons (Qwrite, Qnil), XCAR (XCDR (old_entry)), Qnil);
/* Status change time has been changed, the file attributes
have changed. */
if (NILP (Fequal (Fnth (make_number (3), old_entry),
Fnth (make_number (3), new_entry))))
kqueue_generate_event
(watch_object, Fcons (Qattrib, Qnil),
XCAR (XCDR (old_entry)), Qnil);
} else {
/* The file has been renamed. */
kqueue_generate_event
(watch_object, Fcons (Qrename, Qnil),
XCAR (XCDR (old_entry)), XCAR (XCDR (new_entry)));
deleted_dl = Fcons (new_entry, deleted_dl);
}
new_dl = Fdelq (new_entry, new_dl);
goto the_end;
}
/* Search, whether there is a file with the same name but another
inode. */
for (dl1 = new_dl; ! NILP (dl1); dl1 = XCDR (dl1)) {
new_entry = XCAR (dl1);
if (strcmp (SSDATA (XCAR (XCDR (old_entry))),
SSDATA (XCAR (XCDR (new_entry)))) == 0) {
pending_dl = Fcons (new_entry, pending_dl);
new_dl = Fdelq (new_entry, new_dl);
goto the_end;
}
}
/* Check, whether this a pending file. */
new_entry = assq_no_quit (XCAR (old_entry), pending_dl);
if (NILP (new_entry)) {
/* Check, whether this is an already deleted file (by rename). */
for (dl1 = deleted_dl; ! NILP (dl1); dl1 = XCDR (dl1)) {
new_entry = XCAR (dl1);
if (strcmp (SSDATA (XCAR (XCDR (old_entry))),
SSDATA (XCAR (XCDR (new_entry)))) == 0) {
deleted_dl = Fdelq (new_entry, deleted_dl);
goto the_end;
}
}
/* The file has been deleted. */
kqueue_generate_event
(watch_object, Fcons (Qdelete, Qnil), XCAR (XCDR (old_entry)), Qnil);
} else {
/* The file has been renamed. */
kqueue_generate_event
(watch_object, Fcons (Qrename, Qnil),
XCAR (XCDR (old_entry)), XCAR (XCDR (new_entry)));
pending_dl = Fdelq (new_entry, pending_dl);
}
the_end:
dl = XCDR (dl);
old_dl = Fdelq (old_entry, old_dl);
}
/* Parse through the resulting new list. */
dl = new_dl;
while (1) {
Lisp_Object entry;
if (NILP (dl))
break;
/* A new file has appeared. */
entry = XCAR (dl);
kqueue_generate_event
(watch_object, Fcons (Qcreate, Qnil), XCAR (XCDR (entry)), Qnil);
/* Check size of that file. */
Lisp_Object size = Fnth (make_number (4), entry);
if (FLOATP (size) || (XINT (size) > 0))
kqueue_generate_event
(watch_object, Fcons (Qwrite, Qnil), XCAR (XCDR (entry)), Qnil);
dl = XCDR (dl);
new_dl = Fdelq (entry, new_dl);
}
/* Parse through the resulting pending_dl list. */
dl = pending_dl;
while (1) {
Lisp_Object entry;
if (NILP (dl))
break;
/* A file is still pending. Assume it was a write. */
entry = XCAR (dl);
kqueue_generate_event
(watch_object, Fcons (Qwrite, Qnil), XCAR (XCDR (entry)), Qnil);
dl = XCDR (dl);
pending_dl = Fdelq (entry, pending_dl);
}
/* At this point, old_dl, new_dl and pending_dl shall be empty.
deleted_dl might not be empty when there was a rename to a
nonexistent file. Let's make a check for this (might be removed
once the code is stable). */
if (! NILP (old_dl))
report_file_error ("Old list not empty", old_dl);
if (! NILP (new_dl))
report_file_error ("New list not empty", new_dl);
if (! NILP (pending_dl))
report_file_error ("Pending events list not empty", pending_dl);
/* Replace old directory listing with the new one. */
XSETCDR (Fnthcdr (make_number (3), watch_object),
Fcons (new_directory_files, Qnil));
return;
}
/* This is the callback function for arriving input on kqueuefd. It
shall create a Lisp event, and put it into the Emacs input queue. */
static void
kqueue_callback (int fd, void *data)
{
for (;;) {
struct kevent kev;
static const struct timespec nullts = { 0, 0 };
Lisp_Object descriptor, watch_object, file, actions;
/* Read one event. */
int ret = kevent (kqueuefd, NULL, 0, &kev, 1, &nullts);
if (ret < 1) {
/* All events read. */
return;
}
/* Determine descriptor and file name. */
descriptor = make_number (kev.ident);
watch_object = assq_no_quit (descriptor, watch_list);
if (CONSP (watch_object))
file = XCAR (XCDR (watch_object));
else
continue;
/* Determine event actions. */
actions = Qnil;
if (kev.fflags & NOTE_DELETE)
actions = Fcons (Qdelete, actions);
if (kev.fflags & NOTE_WRITE) {
/* Check, whether this is a directory event. */
if (NILP (Fnth (make_number (4), watch_object)))
actions = Fcons (Qwrite, actions);
else
kqueue_compare_dir_list (watch_object);
}
if (kev.fflags & NOTE_EXTEND)
actions = Fcons (Qextend, actions);
if (kev.fflags & NOTE_ATTRIB)
actions = Fcons (Qattrib, actions);
if (kev.fflags & NOTE_LINK)
actions = Fcons (Qlink, actions);
/* It would be useful to know the target of the rename operation.
At this point, it is not possible. Happens only when the upper
directory is monitored. */
if (kev.fflags & NOTE_RENAME)
actions = Fcons (Qrename, actions);
/* Create the event. */
if (! NILP (actions))
kqueue_generate_event (watch_object, actions, file, Qnil);
/* Cancel monitor if file or directory is deleted or renamed. */
if (kev.fflags & (NOTE_DELETE | NOTE_RENAME))
Fkqueue_rm_watch (descriptor);
}
return;
}
DEFUN ("kqueue-add-watch", Fkqueue_add_watch, Skqueue_add_watch, 3, 3, 0,
doc: /* Add a watch for filesystem events pertaining to FILE.
This arranges for filesystem events pertaining to FILE to be reported
to Emacs. Use `kqueue-rm-watch' to cancel the watch.
Returned value is a descriptor for the added watch. If the file cannot be
watched for some reason, this function signals a `file-notify-error' error.
FLAGS is a list of events to be watched for. It can include the
following symbols:
`create' -- FILE was created
`delete' -- FILE was deleted
`write' -- FILE has changed
`extend' -- FILE was extended
`attrib' -- a FILE attribute was changed
`link' -- a FILE's link count was changed
`rename' -- FILE was moved to FILE1
When any event happens, Emacs will call the CALLBACK function passing
it a single argument EVENT, which is of the form
(DESCRIPTOR ACTIONS FILE [FILE1])
DESCRIPTOR is the same object as the one returned by this function.
ACTIONS is a list of events.
FILE is the name of the file whose event is being reported. FILE1
will be reported only in case of the `rename' event. This is possible
only when the upper directory of the renamed file is watched. */)
(Lisp_Object file, Lisp_Object flags, Lisp_Object callback)
{
Lisp_Object watch_object, dir_list;
int fd, oflags;
u_short fflags = 0;
struct kevent kev;
/* Check parameters. */
CHECK_STRING (file);
file = Fdirectory_file_name (Fexpand_file_name (file, Qnil));
if (NILP (Ffile_exists_p (file)))
report_file_error ("File does not exist", file);
CHECK_LIST (flags);
if (! FUNCTIONP (callback))
wrong_type_argument (Qinvalid_function, callback);
if (kqueuefd < 0)
{
/* Create kqueue descriptor. */
kqueuefd = kqueue ();
if (kqueuefd < 0)
report_file_notify_error ("File watching is not available", Qnil);
/* Start monitoring for possible I/O. */
add_read_fd (kqueuefd, kqueue_callback, NULL);
watch_list = Qnil;
}
/* Open file. */
file = ENCODE_FILE (file);
oflags = O_NONBLOCK;
#if O_EVTONLY
oflags |= O_EVTONLY;
#else
oflags |= O_RDONLY;
#endif
#if O_SYMLINK
oflags |= O_SYMLINK;
#else
oflags |= O_NOFOLLOW;
#endif
fd = emacs_open (SSDATA (file), oflags, 0);
if (fd == -1)
report_file_error ("File cannot be opened", file);
/* Assemble filter flags */
if (! NILP (Fmember (Qdelete, flags))) fflags |= NOTE_DELETE;
if (! NILP (Fmember (Qwrite, flags))) fflags |= NOTE_WRITE;
if (! NILP (Fmember (Qextend, flags))) fflags |= NOTE_EXTEND;
if (! NILP (Fmember (Qattrib, flags))) fflags |= NOTE_ATTRIB;
if (! NILP (Fmember (Qlink, flags))) fflags |= NOTE_LINK;
if (! NILP (Fmember (Qrename, flags))) fflags |= NOTE_RENAME;
/* Register event. */
EV_SET (&kev, fd, EVFILT_VNODE, EV_ADD | EV_ENABLE | EV_CLEAR,
fflags, 0, NULL);
if (kevent (kqueuefd, &kev, 1, NULL, 0, NULL) < 0) {
emacs_close (fd);
report_file_error ("Cannot watch file", file);
}
/* Store watch object in watch list. */
Lisp_Object watch_descriptor = make_number (fd);
if (NILP (Ffile_directory_p (file)))
watch_object = list4 (watch_descriptor, file, flags, callback);
else {
dir_list = directory_files_internal (file, Qnil, Qnil, Qnil, 1, Qnil);
watch_object = list5 (watch_descriptor, file, flags, callback, dir_list);
}
watch_list = Fcons (watch_object, watch_list);
return watch_descriptor;
}
DEFUN ("kqueue-rm-watch", Fkqueue_rm_watch, Skqueue_rm_watch, 1, 1, 0,
doc: /* Remove an existing WATCH-DESCRIPTOR.
WATCH-DESCRIPTOR should be an object returned by `kqueue-add-watch'. */)
(Lisp_Object watch_descriptor)
{
Lisp_Object watch_object = assq_no_quit (watch_descriptor, watch_list);
if (! CONSP (watch_object))
xsignal2 (Qfile_notify_error, build_string ("Not a watch descriptor"),
watch_descriptor);
eassert (INTEGERP (watch_descriptor));
int fd = XINT (watch_descriptor);
if ( fd >= 0)
emacs_close (fd);
/* Remove watch descriptor from watch list. */
watch_list = Fdelq (watch_object, watch_list);
if (NILP (watch_list) && (kqueuefd >= 0)) {
delete_read_fd (kqueuefd);
emacs_close (kqueuefd);
kqueuefd = -1;
}
return Qt;
}
DEFUN ("kqueue-valid-p", Fkqueue_valid_p, Skqueue_valid_p, 1, 1, 0,
doc: /* "Check a watch specified by its WATCH-DESCRIPTOR.
WATCH-DESCRIPTOR should be an object returned by `kqueue-add-watch'.
A watch can become invalid if the file or directory it watches is
deleted, or if the watcher thread exits abnormally for any other
reason. Removing the watch by calling `kqueue-rm-watch' also makes it
invalid. */)
(Lisp_Object watch_descriptor)
{
return NILP (assq_no_quit (watch_descriptor, watch_list)) ? Qnil : Qt;
}
void
globals_of_kqueue (void)
{
watch_list = Qnil;
}
void
syms_of_kqueue (void)
{
defsubr (&Skqueue_add_watch);
defsubr (&Skqueue_rm_watch);
defsubr (&Skqueue_valid_p);
/* Event types. */
DEFSYM (Qcreate, "create");
DEFSYM (Qdelete, "delete"); /* NOTE_DELETE */
DEFSYM (Qwrite, "write"); /* NOTE_WRITE */
DEFSYM (Qextend, "extend"); /* NOTE_EXTEND */
DEFSYM (Qattrib, "attrib"); /* NOTE_ATTRIB */
DEFSYM (Qlink, "link"); /* NOTE_LINK */
DEFSYM (Qrename, "rename"); /* NOTE_RENAME */
staticpro (&watch_list);
Fprovide (intern_c_string ("kqueue"), Qnil);
}
#endif /* HAVE_KQUEUE */
/* PROBLEMS
* https://bugs.launchpad.net/ubuntu/+source/libkqueue/+bug/1514837
prevents tests on Ubuntu. */