[glib: 1/4] kqueue: Make it possible to pass file monitor tests

[Philip Withnall <pwithnall src gnome org>]

commit 09c019a4f03c7a57aa8048479824104e8d3b3870
Author: Ting-Wei Lan <lantw src gnome org>
Date:   Sun Jun 3 19:35:48 2018 +0800

    kqueue: Make it possible to pass file monitor tests
    
    Previously, kqueue file monitor only add event sources for directories
    regardless of the type of the file being monitored. Doing so may be
    possible on inotify, but it is not sufficient on kqueue. Watching a
    directory on kqueue doesn't report changes made to files under it, and
    we must watch files themselves to get notified. This problem is fixed
    by adding a second watch for non-directory file monitors, and the result
    is that we are now able to receive 'CHANGED' and 'ATTRIBUTE_CHANGED'
    events for non-directory files.
    
    Since having two watches on one file monitor requires many code changes
    to work properly, this commit also changes the following things:
    
     - NOTE_ALL macro is now replaced by note_all inline function. Since the
       kqueue backend is shared by all BSD operating systems, there are a
       few difference between these systems. It is easier to do '#ifdef'
       check in a function than in a macro.
    
     - Both g_kqueue_file_monitor_callback and g_kqueue_file_monitor_cancel
       now holds a lock before accessing kqueue_sub structs. This fixes a
       crash when these two functions are called from different threads,
       causing g_kqueue_file_monitor_callback to access freed memory.
    
     - 'mask' variable in g_kqueue_file_monitor_callback is now removed.
       The usage of 'mask' was wrong because of the 'mask > 0' check.
       'CHANGED' event has value 0 so the 'mask > 0' check made it
       impossible to emit 'CHANGED' events.
    
     - kqueue-missing scans can now be triggered from the kqueue event
       callback instead of always waiting for 4 seconds.
    
     - Don't remove a file from kqueue on unlink unless its hard link count
       has dropped to zero.
    
     - Don't use 'else if' in the check of 'fflags'. It is possible for a
       kevent to have multiple flags set.
    
     - Don't use g_file_monitor_emit_event directly. Always use
       g_file_monitor_source_handle_event to report events.
       Events submitted to g_file_monitor_emit_event are delivered
       immediately, but events sent to g_file_monitor_source_handle_event
       are scheduled by GLocalFileMonitor. If we mix the two, the order of
       events will be wrong and tests will fail.
    
     - Report 'CHANGES_DONE_HINT' immediately after 'CREATED' if the file
       created is not a regular file. This is copied from ih_event_callback.

 gio/kqueue/gkqueuefilemonitor.c | 286 ++++++++++++++++++++++++++++++++--------
 gio/kqueue/kqueue-helper.c      |  21 ++-
 gio/kqueue/kqueue-helper.h      |  13 +-
 gio/kqueue/kqueue-missing.c     |  39 +++---
 4 files changed, 284 insertions(+), 75 deletions(-)
---
diff --git a/gio/kqueue/gkqueuefilemonitor.c b/gio/kqueue/gkqueuefilemonitor.c
index d6fea41cf..816647512 100644
--- a/gio/kqueue/gkqueuefilemonitor.c
+++ b/gio/kqueue/gkqueuefilemonitor.c
@@ -33,6 +33,7 @@
 #include <string.h>
 
 #include <glib-object.h>
+#include <glib/gfileutils.h>
 #include <gio/gfilemonitor.h>
 #include <gio/glocalfilemonitor.h>
 #include <gio/giomodule.h>
@@ -52,19 +53,44 @@ static int        kq_queue = -1;
 #define G_KQUEUE_FILE_MONITOR(inst)    (G_TYPE_CHECK_INSTANCE_CAST ((inst), \
                                        G_TYPE_KQUEUE_FILE_MONITOR, GKqueueFileMonitor))
 
+/* C11 allows type redefinition, but GLib is configured to use C89, which causes
+ * clang to show warnings when we use a C11 feature. Since the C89 requirement
+ * is mostly used to support MSVC, we simply ignore the warning here because
+ * this file is never going to be useful on Windows. */
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wtypedef-redefinition"
+#endif
+
 typedef GLocalFileMonitorClass GKqueueFileMonitorClass;
 
-typedef struct
+/* When the file we are monitoring is a directory, sub_dir is subscribed to the
+ * directory itself and sub_file is NULL.
+ *
+ * When the file we are monitoring is a regular file, sub_dir is subscribed to
+ * the directory containing the file and sub_file is subscribed to the file
+ * being monitored. We have to monitor both because it is possible that the
+ * file chosen for monitoring doesn't exist when the file monitor is started.
+ * We monitor on its parent in order to get notification when it is created.
+ *
+ * To distinguish between a directory monitor and a regular file monitor, check
+ * whether sub_file is NULL. */
+typedef struct _GKqueueFileMonitor
 {
   GLocalFileMonitor parent_instance;
 
-  kqueue_sub *sub;
+  kqueue_sub *sub_dir;
+  kqueue_sub *sub_file;
 #ifndef O_EVTONLY
   GFileMonitor *fallback;
   GFile *fbfile;
 #endif
 } GKqueueFileMonitor;
 
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
+
 GType g_kqueue_file_monitor_get_type (void);
 G_DEFINE_TYPE_WITH_CODE (GKqueueFileMonitor, g_kqueue_file_monitor, G_TYPE_LOCAL_FILE_MONITOR,
        g_io_extension_point_implement (G_LOCAL_FILE_MONITOR_EXTENSION_POINT_NAME,
@@ -78,12 +104,23 @@ G_DEFINE_TYPE_WITH_CODE (GKqueueFileMonitor, g_kqueue_file_monitor, G_TYPE_LOCAL
 #define O_KQFLAG O_EVTONLY
 #endif
 
-#define NOTE_ALL (NOTE_DELETE|NOTE_WRITE|NOTE_EXTEND|NOTE_ATTRIB|NOTE_RENAME)
+static inline unsigned int
+note_all (void)
+{
+  unsigned int notes = NOTE_DELETE | NOTE_WRITE | NOTE_EXTEND | NOTE_ATTRIB | NOTE_RENAME;
+#ifdef NOTE_TRUNCATE
+  notes |= NOTE_TRUNCATE;
+#endif
+#ifdef NOTE_CLOSE_WRITE
+  notes |= NOTE_CLOSE_WRITE;
+#endif
+  return notes;
+}
 
 static gboolean g_kqueue_file_monitor_cancel (GFileMonitor* monitor);
 static gboolean g_kqueue_file_monitor_is_supported (void);
 
-static kqueue_sub      *_kqsub_new (const gchar *, GLocalFileMonitor *, GFileMonitorSource *);
+static kqueue_sub      *_kqsub_new (gchar *, gchar *, GKqueueFileMonitor *, GFileMonitorSource *);
 static void             _kqsub_free (kqueue_sub *);
 static gboolean                 _kqsub_cancel (kqueue_sub *);
 
@@ -138,11 +175,18 @@ g_kqueue_file_monitor_finalize (GObject *object)
 {
   GKqueueFileMonitor *kqueue_monitor = G_KQUEUE_FILE_MONITOR (object);
 
-  if (kqueue_monitor->sub)
+  if (kqueue_monitor->sub_dir)
+    {
+      _kqsub_cancel (kqueue_monitor->sub_dir);
+      _kqsub_free (kqueue_monitor->sub_dir);
+      kqueue_monitor->sub_dir = NULL;
+    }
+
+  if (kqueue_monitor->sub_file)
     {
-      _kqsub_cancel (kqueue_monitor->sub);
-      _kqsub_free (kqueue_monitor->sub);
-      kqueue_monitor->sub = NULL;
+      _kqsub_cancel (kqueue_monitor->sub_file);
+      _kqsub_free (kqueue_monitor->sub_file);
+      kqueue_monitor->sub_file = NULL;
     }
 
 #ifndef O_EVTONLY
@@ -165,17 +209,51 @@ g_kqueue_file_monitor_start (GLocalFileMonitor *local_monitor,
                              GFileMonitorSource *source)
 {
   GKqueueFileMonitor *kqueue_monitor = G_KQUEUE_FILE_MONITOR (local_monitor);
-  kqueue_sub *sub;
-  const gchar *path;
-
-  path = filename;
-  if (path == NULL)
-    path = dirname;
+  kqueue_sub *sub_dir = NULL, *sub_file = NULL;
+  gchar *path_dir, *path_file, *file_basename;
+
+  /* There are three possible cases here:
+   *
+   *  1. Directory: dirname != NULL, basename == NULL, filename == NULL
+   *  2. Regular file: dirname != NULL, basename != NULL, filename == NULL
+   *  3. Hard links: dirname == NULL, basename == NULL, filename != NULL
+   *
+   *  Note that we don't distinguish between case 2 and 3. Kqueue monitors
+   *  files based on file descriptors, so we always receive events come from
+   *  hard links.
+   */
+  if (filename != NULL)
+    {
+      path_dir = g_path_get_dirname (filename);
+      path_file = g_strdup (filename);
+      file_basename = g_path_get_basename (filename);
+    }
+  else
+    {
+      path_dir = g_strdup (dirname);
+      if (basename != NULL)
+        {
+          path_file = g_build_filename (dirname, basename, NULL);
+          file_basename = g_strdup (basename);
+        }
+      else
+        {
+          path_file = NULL;
+          file_basename = NULL;
+        }
+    }
 
 #ifndef O_EVTONLY
-  if (_ke_is_excluded (path))
+  if (_ke_is_excluded (path_dir))
     {
-      GFile *file = g_file_new_for_path (path);
+      GFile *file;
+      if (path_file != NULL)
+        file = g_file_new_for_path (path_file);
+      else
+        file = g_file_new_for_path (path_dir);
+      g_free (path_dir);
+      g_free (path_file);
+      g_free (file_basename);
       kqueue_monitor->fbfile = file;
       kqueue_monitor->fallback = _g_poll_file_monitor_new (file);
       g_signal_connect (kqueue_monitor->fallback, "changed",
@@ -191,13 +269,30 @@ g_kqueue_file_monitor_start (GLocalFileMonitor *local_monitor,
    * file, GIO uses a GKqueueFileMonitor object for that. If a directory
    * will be created under that path, GKqueueFileMonitor will have to
    * handle the directory notifications. */
-  sub = _kqsub_new (path, local_monitor, source);
-  if (sub == NULL)
-    return;
+  sub_dir = _kqsub_new (g_steal_pointer (&path_dir), NULL,
+                        kqueue_monitor, source);
+  if (!_kqsub_start_watching (sub_dir))
+    _km_add_missing (sub_dir);
+
+  /* Unlike GInotifyFileMonitor, which always uses a directory monitor
+   * regardless of the type of the file being monitored, kqueue doesn't
+   * give us events generated by files under it when we are monitoring
+   * a directory. We have to monitor the file itself to know changes which
+   * was made to the file itself. */
+  if (path_file != NULL)
+    {
+      sub_file = _kqsub_new (g_steal_pointer (&path_file),
+                             g_steal_pointer (&file_basename),
+                             kqueue_monitor, source);
+      if (!_kqsub_start_watching (sub_file))
+        _km_add_missing (sub_file);
+    }
 
-  kqueue_monitor->sub = sub;
-  if (!_kqsub_start_watching (sub))
-    _km_add_missing (sub);
+  kqueue_monitor->sub_dir = sub_dir;
+  kqueue_monitor->sub_file = sub_file;
+  g_clear_pointer (&path_dir, g_free);
+  g_clear_pointer (&path_file, g_free);
+  g_clear_pointer (&file_basename, g_free);
 }
 
 static void
@@ -230,59 +325,127 @@ g_kqueue_file_monitor_callback (gint fd, GIOCondition condition, gpointer user_d
   struct timespec ts;
 
   memset (&ts, 0, sizeof(ts));
+
+  /* We must hold the global lock before accessing any kqueue_sub because it is
+   * possible for other threads to call g_kqueue_file_monitor_cancel, which may
+   * free the kqueue_sub struct we are accessing. */
+  G_LOCK (kq_lock);
+
   while (kevent(fd, NULL, 0, &ev, 1, &ts) > 0)
     {
-        GFileMonitorEvent mask = 0;
-
         if (ev.filter != EVFILT_VNODE || ev.udata == NULL)
           continue;
 
-       sub = ev.udata;
+        sub = ev.udata;
         source = sub->source;
 
+        /* When we are monitoring a regular file which already exists, ignore
+         * events generated by its parent directory. This has to be the first
+         * check to prevent the following code to emit useless events */
+        if (sub->is_dir && sub->mon->sub_file != NULL && sub->mon->sub_file->fd != -1)
+          continue;
+
         if (ev.flags & EV_ERROR)
           ev.fflags = NOTE_REVOKE;
 
-        if (ev.fflags & (NOTE_DELETE | NOTE_REVOKE))
-          {
-            _kqsub_cancel (sub);
-            _km_add_missing (sub);
-          }
-
         if (sub->is_dir && ev.fflags & (NOTE_WRITE | NOTE_EXTEND))
           {
-            _kh_dir_diff (sub);
+            /* If we are monitoring on a non-existent regular file, trigger the
+             * rescan of missing files immediately so we don't have to wait for
+             * 4 seconds for discovering missing files. We pass the sub_file
+             * corresponding to the GKqueueFileMonitor to 'check_this_sub_only'
+             * argument to prevent _km_scan_missing from emiting 'CREATED'
+             * events because _kh_dir_diff will do it for us. */
+            if (sub->mon->sub_file != NULL && sub->mon->sub_file->fd == -1)
+              _km_scan_missing (sub->mon->sub_file);
+
+            /* If we are monitoring a regular file, don't emit 'DELETED' events
+             * from the directory monitor because it will be emitted from the
+             * file itself when a NOTE_DELETE is reported on sub_file. */
+            _kh_dir_diff (sub, sub->mon->sub_file == NULL);
+
+#ifdef NOTE_TRUNCATE
+            ev.fflags &= ~(NOTE_WRITE | NOTE_EXTEND | NOTE_TRUNCATE);
+#else
             ev.fflags &= ~(NOTE_WRITE | NOTE_EXTEND);
+#endif
           }
 
+        /* Here starts the long section of mapping kqueue events to
+         * GFileMonitorEvent. Since kqueue can return multiple events in a
+         * single kevent struct, we must use 'if' instead of 'else if'. */
         if (ev.fflags & NOTE_DELETE)
           {
-            mask = G_FILE_MONITOR_EVENT_DELETED;
+            struct stat st;
+            if (fstat (sub->fd, &st) < 0)
+              st.st_nlink = 0;
+
+            g_file_monitor_source_handle_event (source,
+                                                G_FILE_MONITOR_EVENT_DELETED,
+                                                sub->basename, NULL, NULL, now);
+
+            /* If the last reference to the file was removed, delete the
+             * subscription from kqueue and add it to the missing list.
+             * If you are monitoring a file which has hard link count higher
+             * than 1, it is possible for the same file to emit 'DELETED'
+             * events multiple times. */
+            if (st.st_nlink == 0)
+              {
+                _kqsub_cancel (sub);
+                _km_add_missing (sub);
+              }
           }
-        else if (ev.fflags & NOTE_ATTRIB)
+         if (ev.fflags & NOTE_REVOKE)
+           {
+             g_file_monitor_source_handle_event (source,
+                                                 G_FILE_MONITOR_EVENT_UNMOUNTED,
+                                                 sub->basename, NULL, NULL, now);
+             _kqsub_cancel (sub);
+             _km_add_missing (sub);
+           }
+        if (ev.fflags & NOTE_ATTRIB)
           {
-            mask = G_FILE_MONITOR_EVENT_ATTRIBUTE_CHANGED;
+            g_file_monitor_source_handle_event (source,
+                                                G_FILE_MONITOR_EVENT_ATTRIBUTE_CHANGED,
+                                                sub->basename, NULL, NULL, now);
           }
-        else if (ev.fflags & (NOTE_WRITE | NOTE_EXTEND))
+#ifdef NOTE_TRUNCATE
+        if (ev.fflags & (NOTE_WRITE | NOTE_EXTEND | NOTE_TRUNCATE))
+#else
+        if (ev.fflags & (NOTE_WRITE | NOTE_EXTEND))
+#endif
           {
-            mask = G_FILE_MONITOR_EVENT_CHANGED;
+            g_file_monitor_source_handle_event (source,
+                                                G_FILE_MONITOR_EVENT_CHANGED,
+                                                sub->basename, NULL, NULL, now);
           }
-        else if (ev.fflags & NOTE_RENAME)
+        if (ev.fflags & NOTE_RENAME)
           {
             /* Since there’s apparently no way to get the new name of the
              * file out of kqueue(), all we can do is say that this one has
              * been deleted. */
-            mask = G_FILE_MONITOR_EVENT_DELETED;
+            g_file_monitor_source_handle_event (source,
+                                                G_FILE_MONITOR_EVENT_DELETED,
+                                                sub->basename, NULL, NULL, now);
           }
-        else if (ev.fflags & NOTE_REVOKE)
+#ifdef NOTE_CLOSE_WRITE
+        if (ev.fflags & NOTE_CLOSE_WRITE)
           {
-            mask = G_FILE_MONITOR_EVENT_UNMOUNTED;
+            g_file_monitor_source_handle_event (source,
+                                                G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT,
+                                                sub->basename, NULL, NULL, now);
           }
+#endif
 
-        if (mask)
-          g_file_monitor_source_handle_event (source, mask, NULL, NULL, NULL, now);
+        /* Handle the case when a file is created again shortly after it was
+         * deleted. It has to be the last check because 'DELETED' must happen
+         * before 'CREATED'. */
+        if (ev.fflags & (NOTE_DELETE | NOTE_REVOKE))
+          _km_scan_missing (NULL);
     }
 
+  G_UNLOCK (kq_lock);
+
   return TRUE;
 }
 
@@ -320,14 +483,28 @@ g_kqueue_file_monitor_cancel (GFileMonitor *monitor)
 {
   GKqueueFileMonitor *kqueue_monitor = G_KQUEUE_FILE_MONITOR (monitor);
 
-  if (kqueue_monitor->sub)
+  /* We must hold the global lock before calling _kqsub_cancel. However, we
+   * cannot call G_LOCK in _kqsub_cancel because it is also used by
+   * g_kqueue_file_monitor_callback, which already holds the lock itself. */
+  G_LOCK (kq_lock);
+
+  if (kqueue_monitor->sub_dir)
     {
-      _kqsub_cancel (kqueue_monitor->sub);
-      _kqsub_free (kqueue_monitor->sub);
-      kqueue_monitor->sub = NULL;
+      _kqsub_cancel (kqueue_monitor->sub_dir);
+      _kqsub_free (kqueue_monitor->sub_dir);
+      kqueue_monitor->sub_dir = NULL;
     }
+  if (kqueue_monitor->sub_file)
+    {
+      _kqsub_cancel (kqueue_monitor->sub_file);
+      _kqsub_free (kqueue_monitor->sub_file);
+      kqueue_monitor->sub_file = NULL;
+    }
+
+  G_UNLOCK (kq_lock);
+
 #ifndef O_EVTONLY
-  else if (kqueue_monitor->fallback)
+  if (kqueue_monitor->fallback)
     {
       g_signal_handlers_disconnect_by_func (kqueue_monitor->fallback, _fallback_callback, kqueue_monitor);
       g_file_monitor_cancel (kqueue_monitor->fallback);
@@ -341,12 +518,13 @@ g_kqueue_file_monitor_cancel (GFileMonitor *monitor)
 }
 
 static kqueue_sub *
-_kqsub_new (const gchar *filename, GLocalFileMonitor *mon, GFileMonitorSource *source)
+_kqsub_new (gchar *filename, gchar *basename, GKqueueFileMonitor *mon, GFileMonitorSource *source)
 {
   kqueue_sub *sub;
 
   sub = g_slice_new (kqueue_sub);
-  sub->filename = g_strdup (filename);
+  sub->filename = filename;
+  sub->basename = basename;
   sub->mon = mon;
   g_source_ref ((GSource *) source);
   sub->source = source;
@@ -365,19 +543,23 @@ _kqsub_free (kqueue_sub *sub)
 
   g_source_unref ((GSource *) sub->source);
   g_free (sub->filename);
+  g_free (sub->basename);
   g_slice_free (kqueue_sub, sub);
 }
 
 static gboolean
 _kqsub_cancel (kqueue_sub *sub)
 {
+  /* WARNING: Before calling this function, you must hold a lock on kq_lock
+   * or you will cause use-after-free in g_kqueue_file_monitor_callback. */
+
   struct kevent ev;
 
   /* Remove the event and close the file descriptor to automatically
    * delete pending events. */
   if (sub->fd != -1)
     {
-      EV_SET (&ev, sub->fd, EVFILT_VNODE, EV_DELETE, NOTE_ALL, 0, sub);
+      EV_SET (&ev, sub->fd, EVFILT_VNODE, EV_DELETE, note_all (), 0, sub);
       if (kevent (kq_queue, &ev, 1, NULL, 0, NULL) == -1)
         {
           g_warning ("Unable to remove event for %s: %s", sub->filename, g_strerror (errno));
@@ -425,7 +607,7 @@ _kqsub_start_watching (kqueue_sub *sub)
       sub->deps = dl_listing (sub->filename);
     }
 
-  EV_SET (&ev, sub->fd, EVFILT_VNODE, EV_ADD | EV_CLEAR, NOTE_ALL, 0, sub);
+  EV_SET (&ev, sub->fd, EVFILT_VNODE, EV_ADD | EV_CLEAR, note_all (), 0, sub);
   if (kevent (kq_queue, &ev, 1, NULL, 0, NULL) == -1)
     {
       g_warning ("Unable to add event for %s: %s", sub->filename, g_strerror (errno));
diff --git a/gio/kqueue/kqueue-helper.c b/gio/kqueue/kqueue-helper.c
index 497c30b15..36a5b58a7 100644
--- a/gio/kqueue/kqueue-helper.c
+++ b/gio/kqueue/kqueue-helper.c
@@ -25,6 +25,7 @@
 #include <sys/event.h>
 #include <sys/time.h>
 #include <sys/socket.h>
+#include <sys/stat.h>
 #include <gio/glocalfile.h>
 #include <gio/glocalfilemonitor.h>
 #include <gio/gfile.h>
@@ -38,6 +39,7 @@
 typedef struct {
   kqueue_sub *sub;
   GFileMonitorSource *source;
+  gboolean handle_deleted;
 } handle_ctx;
 
 /**
@@ -53,6 +55,9 @@ static void
 handle_created (void *udata, const char *path, ino_t inode)
 {
   handle_ctx *ctx = NULL;
+  gint64 now;
+  gchar *fullname;
+  struct stat st;
 
   (void) inode;
   ctx = (handle_ctx *) udata;
@@ -60,8 +65,16 @@ handle_created (void *udata, const char *path, ino_t inode)
   g_assert (ctx->sub != NULL);
   g_assert (ctx->source != NULL);
 
+  now = g_get_monotonic_time ();
   g_file_monitor_source_handle_event (ctx->source, G_FILE_MONITOR_EVENT_CREATED, path,
-                                      NULL, NULL, g_get_monotonic_time ());
+                                      NULL, NULL, now);
+
+  /* Copied from ih_event_callback to report 'CHANGES_DONE_HINT' earlier. */
+  fullname = g_build_filename (ctx->sub->filename, path, NULL);
+  if (stat (fullname, &st) != 0 || !S_ISREG (st.st_mode) || st.st_nlink != 1)
+    g_file_monitor_source_handle_event (ctx->source, G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT, path,
+                                        NULL, NULL, now);
+  g_free (fullname);
 }
 
 /**
@@ -84,6 +97,9 @@ handle_deleted (void *udata, const char *path, ino_t inode)
   g_assert (ctx->sub != NULL);
   g_assert (ctx->source != NULL);
 
+  if (!ctx->handle_deleted)
+    return;
+
   g_file_monitor_source_handle_event (ctx->source, G_FILE_MONITOR_EVENT_DELETED, path,
                                       NULL, NULL, g_get_monotonic_time ());
 }
@@ -161,7 +177,7 @@ static const traverse_cbs cbs = {
 
 
 void
-_kh_dir_diff (kqueue_sub *sub)
+_kh_dir_diff (kqueue_sub *sub, gboolean handle_deleted)
 {
   dep_list *was;
   handle_ctx ctx;
@@ -169,6 +185,7 @@ _kh_dir_diff (kqueue_sub *sub)
   memset (&ctx, 0, sizeof (handle_ctx));
   ctx.sub = sub;
   ctx.source = sub->source;
+  ctx.handle_deleted = handle_deleted;
 
   was = sub->deps;
   sub->deps = dl_listing (sub->filename);
diff --git a/gio/kqueue/kqueue-helper.h b/gio/kqueue/kqueue-helper.h
index 38a32a2f9..418b38c08 100644
--- a/gio/kqueue/kqueue-helper.h
+++ b/gio/kqueue/kqueue-helper.h
@@ -28,26 +28,33 @@
 
 #include "dep-list.h"
 
+typedef struct _GKqueueFileMonitor GKqueueFileMonitor;
+
 /**
  * kqueue_sub:
+ * @mon: a pointer to the GKqueueFileMonitor which holds this subscription
  * @filename: a name of the file to monitor
  * @fd: the associated file descriptor (used by kqueue)
  *
- * Represents a subscription on a file or directory.
+ * Represents a subscription on a file or directory. To check whether a
+ * subscription is active, check the fd field. If fd is not -1, it is an
+ * active subscription which can emit events from kqueue.
  */
 typedef struct
 {
-  GLocalFileMonitor   *mon;
+  GKqueueFileMonitor  *mon;
   GFileMonitorSource  *source;
   gchar*    filename;
+  gchar*    basename;
   int       fd;
   dep_list* deps;
   int       is_dir;
 } kqueue_sub;
 
 gboolean _kqsub_start_watching (kqueue_sub *sub);
-void _kh_dir_diff    (kqueue_sub *sub);
+void _kh_dir_diff    (kqueue_sub *sub, gboolean handle_deleted);
 void _km_add_missing (kqueue_sub *sub);
+gboolean _km_scan_missing (kqueue_sub *check_this_sub_only);
 void _km_remove      (kqueue_sub *sub);
 
 #endif /* __KQUEUE_HELPER_H */
diff --git a/gio/kqueue/kqueue-missing.c b/gio/kqueue/kqueue-missing.c
index 93135b962..a08f3a736 100644
--- a/gio/kqueue/kqueue-missing.c
+++ b/gio/kqueue/kqueue-missing.c
@@ -21,16 +21,13 @@
 *******************************************************************************/
 
 #include <glib.h>
+#include "glib-private.h"
 
 #include "kqueue-helper.h"
 
 
 #define SCAN_MISSING_TIME 4 /* 1/4 Hz */
 
-void _kh_file_appeared_cb (kqueue_sub *sub);
-
-static gboolean km_scan_missing (gpointer user_data);
-
 static gboolean km_debug_enabled = FALSE;
 #define KM_W if (km_debug_enabled) g_warning
 
@@ -40,6 +37,12 @@ G_LOCK_DEFINE_STATIC (missing_lock);
 static volatile gboolean scan_missing_running = FALSE;
 
 
+static gboolean
+_km_scan_missing_cb (gpointer user_data)
+{
+  return _km_scan_missing (NULL);
+}
+
 /**
  * _km_add_missing:
  * @sub: a #kqueue_sub
@@ -77,10 +80,10 @@ _km_add_missing (kqueue_sub *sub)
  * Signals that a missing file has finally appeared in the filesystem.
  * Emits %G_FILE_MONITOR_EVENT_CREATED.
  **/
-void
+static void
 _kh_file_appeared_cb (kqueue_sub *sub)
 {
-  GFile *child;
+  gint64 now = g_get_monotonic_time ();
 
   g_assert (sub != NULL);
   g_assert (sub->filename);
@@ -88,18 +91,14 @@ _kh_file_appeared_cb (kqueue_sub *sub)
   if (!g_file_test (sub->filename, G_FILE_TEST_EXISTS))
     return;
 
-  child = g_file_new_for_path (sub->filename);
-
-  g_file_monitor_emit_event (G_FILE_MONITOR (sub->mon),
-                             child,
-                             NULL,
-                             G_FILE_MONITOR_EVENT_CREATED);
-
-  g_object_unref (child);
+  g_file_monitor_source_handle_event (sub->source, G_FILE_MONITOR_EVENT_CREATED,
+                                      sub->basename, NULL, NULL, now);
+  g_file_monitor_source_handle_event (sub->source, G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT,
+                                      sub->basename, NULL, NULL, now);
 }
 
 /**
- * km_scan_missing:
+ * _km_scan_missing:
  * @user_data: unused
  *
  * The core missing files watching routine.
@@ -110,8 +109,8 @@ _kh_file_appeared_cb (kqueue_sub *sub)
  *
  * Returns: %FALSE if no missing files left, %TRUE otherwise.
  **/
-static gboolean
-km_scan_missing (gpointer user_data)
+gboolean
+_km_scan_missing (kqueue_sub *check_this_sub_only)
 {
   GSList *head;
   GSList *not_missing = NULL;
@@ -128,10 +127,14 @@ km_scan_missing (gpointer user_data)
       g_assert (sub != NULL);
       g_assert (sub->filename != NULL);
 
+      if (check_this_sub_only != NULL && sub != check_this_sub_only)
+        continue;
+
       if (_kqsub_start_watching (sub))
         {
           KM_W ("file %s now exists, starting watching", sub->filename);
-          _kh_file_appeared_cb (sub);
+          if (check_this_sub_only == NULL)
+            _kh_file_appeared_cb (sub);
           not_missing = g_slist_prepend (not_missing, head);
         }
     }