6 files changed, 556 insertions, 20 deletions

diff --git a/src/Makefile.in b/src/Makefile.in
index d667c55ee33..d7ad3954579 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -160,12 +160,13 @@ SETTINGS_LIBS = @SETTINGS_LIBS@
 ## gtkutil.o if USE_GTK, else empty.
 GTK_OBJ=@GTK_OBJ@
 
-## gfilenotify.o if HAVE_GFILENOTIFY.
 ## inotify.o if HAVE_INOTIFY.
+## kqueue.o if HAVE_KQUEUE.
+## gfilenotify.o if HAVE_GFILENOTIFY.
 ## w32notify.o if HAVE_W32NOTIFY.
 NOTIFY_OBJ = @NOTIFY_OBJ@
-GFILENOTIFY_CFLAGS = @GFILENOTIFY_CFLAGS@
-GFILENOTIFY_LIBS = @GFILENOTIFY_LIBS@
+NOTIFY_CFLAGS = @NOTIFY_CFLAGS@
+NOTIFY_LIBS = @NOTIFY_LIBS@
 
 ## -ltermcap, or -lncurses, or -lcurses, or "".
 LIBS_TERMCAP=@LIBS_TERMCAP@
@@ -355,7 +356,7 @@ ALL_CFLAGS=-Demacs $(MYCPPFLAGS) -I. -I$(srcdir) \
   $(XRANDR_CFLAGS) $(XINERAMA_CFLAGS) $(XFIXES_CFLAGS) \
   $(SETTINGS_CFLAGS) $(FREETYPE_CFLAGS) $(FONTCONFIG_CFLAGS) \
   $(LIBOTF_CFLAGS) $(M17N_FLT_CFLAGS) $(DEPFLAGS) \
-  $(LIBGNUTLS_CFLAGS) $(GFILENOTIFY_CFLAGS) $(CAIRO_CFLAGS) \
+  $(LIBGNUTLS_CFLAGS) $(NOTIFY_CFLAGS) $(CAIRO_CFLAGS) \
   $(WARN_CFLAGS) $(WERROR_CFLAGS) $(CFLAGS)
 ALL_OBJC_CFLAGS=$(ALL_CFLAGS) $(GNU_OBJC_CFLAGS)
 
@@ -468,7 +469,7 @@ LIBES = $(LIBS) $(W32_LIBS) $(LIBS_GNUSTEP) $(LIBX_BASE) $(LIBIMAGE) \
    $(LIBS_TERMCAP) $(GETLOADAVG_LIBS) $(SETTINGS_LIBS) $(LIBSELINUX_LIBS) \
    $(FREETYPE_LIBS) $(FONTCONFIG_LIBS) $(LIBOTF_LIBS) $(M17N_FLT_LIBS) \
    $(LIBGNUTLS_LIBS) $(LIB_PTHREAD) \
-   $(GFILENOTIFY_LIBS) $(LIB_MATH) $(LIBZ)
+   $(NOTIFY_LIBS) $(LIB_MATH) $(LIBZ)
 
 $(leimdir)/leim-list.el: bootstrap-emacs$(EXEEXT)
         $(MAKE) -C ../leim leim-list.el EMACS="$(bootstrap_exe)"
diff --git a/src/emacs.c b/src/emacs.c
index b4052b851d7..2e9f950851a 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -1350,6 +1350,10 @@ Using an Emacs configured with --with-x-toolkit=lucid does not have this problem
     tzset ();
 #endif /* MSDOS */
 
+#ifdef HAVE_KQUEUE
+  globals_of_kqueue ();
+#endif
+
 #ifdef HAVE_GFILENOTIFY
   globals_of_gfilenotify ();
 #endif
@@ -1520,14 +1524,18 @@ Using an Emacs configured with --with-x-toolkit=lucid does not have this problem
 
       syms_of_gnutls ();
 
-#ifdef HAVE_GFILENOTIFY
-      syms_of_gfilenotify ();
-#endif /* HAVE_GFILENOTIFY */
-
 #ifdef HAVE_INOTIFY
       syms_of_inotify ();
 #endif /* HAVE_INOTIFY */
 
+#ifdef HAVE_KQUEUE
+      syms_of_kqueue ();
+#endif /* HAVE_KQUEUE */
+
+#ifdef HAVE_GFILENOTIFY
+      syms_of_gfilenotify ();
+#endif /* HAVE_GFILENOTIFY */
+
 #ifdef HAVE_DBUS
       syms_of_dbusbind ();
 #endif /* HAVE_DBUS */
diff --git a/src/inotify.c b/src/inotify.c
index d1a80bbad1b..6577ee28cd1 100644
--- a/src/inotify.c
+++ b/src/inotify.c
@@ -46,8 +46,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 static int inotifyfd = -1;
 
 /* Assoc list of files being watched.
-   Format:
-   (watch-descriptor . callback)
+   Format: (watch-descriptor name callback)
  */
 static Lisp_Object watch_list;
 
@@ -106,12 +105,14 @@ inotifyevent_to_event (Lisp_Object watch_object, struct inotify_event const *ev)
       name = make_unibyte_string (ev->name, min (len, ev->len));
       name = DECODE_FILE (name);
     }
+  else
+    name = XCAR (XCDR (watch_object));
 
   return list2 (list4 (make_watch_descriptor (ev->wd),
                        mask_to_aspects (ev->mask),
                        name,
                        make_number (ev->cookie)),
-                XCDR (watch_object));
+                Fnth (make_number (2), watch_object));
 }
 
 /* This callback is called when the FD is available for read.  The inotify
@@ -325,7 +326,7 @@ is managed internally and there is no corresponding inotify_init.  Use
       watch_list = Fdelete (watch_object, watch_list);
 
   /* Store watch object in watch list.  */
-  watch_object = Fcons (watch_descriptor, callback);
+  watch_object = list3 (watch_descriptor, encoded_file_name, callback);
   watch_list = Fcons (watch_object, watch_list);
 
   return watch_descriptor;
diff --git a/src/keyboard.c b/src/keyboard.c
index 2449abb7dfc..ab7cb34a030 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -5945,12 +5945,12 @@ make_lispy_event (struct input_event *event)
       }
 #endif /* HAVE_DBUS */
 
-#if defined HAVE_GFILENOTIFY || defined HAVE_INOTIFY
+#if defined HAVE_INOTIFY || defined HAVE_KQUEUE || defined HAVE_GFILENOTIFY
     case FILE_NOTIFY_EVENT:
       {
         return Fcons (Qfile_notify, event->arg);
       }
-#endif /* defined HAVE_GFILENOTIFY || defined HAVE_INOTIFY */
+#endif /* HAVE_INOTIFY || HAVE_KQUEUE || HAVE_GFILENOTIFY */
 
     case CONFIG_CHANGED_EVENT:
         return list3 (Qconfig_changed_event,
diff --git a/src/kqueue.c b/src/kqueue.c
new file mode 100644
index 00000000000..1830040637e
--- /dev/null
+++ b/src/kqueue.c
@@ -0,0 +1,520 @@
+/* Filesystem notifications support with kqueue API.
+   Copyright (C) 2015 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
+     nonexisting 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);
+  //  if (! NILP (deleted_dl))
+  //    report_file_error ("Deleted events list not empty", deleted_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.  */
diff --git a/src/lisp.h b/src/lisp.h
index 3efa492e0e8..426b6c949e9 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -4257,17 +4257,23 @@ extern void init_font (void);
 extern void syms_of_fontset (void);
 #endif
 
+/* Defined in inotify.c */
+#ifdef HAVE_INOTIFY
+extern void syms_of_inotify (void);
+#endif
+
+/* Defined in kqueue.c */
+#ifdef HAVE_KQUEUE
+extern void globals_of_kqueue (void);
+extern void syms_of_kqueue (void);
+#endif
+
 /* Defined in gfilenotify.c */
 #ifdef HAVE_GFILENOTIFY
 extern void globals_of_gfilenotify (void);
 extern void syms_of_gfilenotify (void);
 #endif
 
-/* Defined in inotify.c */
-#ifdef HAVE_INOTIFY
-extern void syms_of_inotify (void);
-#endif
-
 #ifdef HAVE_W32NOTIFY
 /* Defined on w32notify.c.  */
 extern void syms_of_w32notify (void);