x11: Add X11 selection management

This code takes care of both setting up X11 selection sources whenever
X11 clients claim selection ownership, and claiming selection ownership
on a mutter X11 window whenever other selection sources claim ownership.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/320

src/meson.build

@@ -385,6 +385,8 @@ mutter_sources = [
   'x11/meta-x11-display.c',
   'x11/meta-x11-display-private.h',
   'x11/meta-x11-errors.c',
+  'x11/meta-x11-selection.c',
+  'x11/meta-x11-selection-private.h',
   'x11/meta-x11-selection-input-stream.c',
   'x11/meta-x11-selection-input-stream-private.h',
   'x11/meta-x11-selection-output-stream.c',

src/x11/events.c

@@ -40,6 +40,7 @@
 #include "meta/meta-x11-errors.h"
 #include "x11/meta-startup-notification-x11.h"
 #include "x11/meta-x11-display-private.h"
+#include "x11/meta-x11-selection-private.h"
 #include "x11/meta-x11-selection-input-stream-private.h"
 #include "x11/meta-x11-selection-output-stream-private.h"
 #include "x11/window-x11.h"
@@ -1726,6 +1727,8 @@ process_selection_event (MetaX11Display *x11_display,
   gboolean handled = FALSE;
   GList *l;
 
+  handled |= meta_x11_selection_handle_event (x11_display, event);
+
   for (l = x11_display->selection.input_streams; l && !handled; l = l->next)
     handled |= meta_x11_selection_input_stream_xevent (l->data, event);
 

src/x11/meta-x11-display-private.h

@@ -30,6 +30,7 @@
 
 #include "backends/meta-monitor-manager-private.h"
 #include "core/display-private.h"
+#include "core/meta-selection-source.h"
 #include "meta/common.h"
 #include "meta/types.h"
 #include "meta/meta-x11-display.h"
@@ -125,6 +126,9 @@ struct _MetaX11Display
 
   struct {
     Window xwindow;
+    MetaSelectionSource *owners[META_N_SELECTION_TYPES];
+    GCancellable *cancellables[META_N_SELECTION_TYPES];
+
     GList *input_streams;
     GList *output_streams;
   } selection;

src/x11/meta-x11-display.c

@@ -61,6 +61,7 @@
 
 #include "x11/events.h"
 #include "x11/group-props.h"
+#include "x11/meta-x11-selection-private.h"
 #include "x11/window-props.h"
 #include "x11/xprops.h"
 
@@ -105,6 +106,8 @@ meta_x11_display_dispose (GObject *object)
 
   meta_x11_display_ungrab_keys (x11_display);
 
+  meta_x11_selection_shutdown (x11_display);
+
   if (x11_display->ui)
     {
       meta_ui_free (x11_display->ui);
@@ -1327,6 +1330,7 @@ meta_x11_display_new (MetaDisplay *display, GError **error)
   set_x11_bell_is_audible (x11_display, meta_prefs_bell_is_audible ());
 
   meta_x11_startup_notification_init (x11_display);
+  meta_x11_selection_init (x11_display);
 
   return x11_display;
 }

src/x11/meta-x11-selection-private.h

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2018 Red Hat
+ *
+ * This program 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 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * Author: Carlos Garnacho <carlosg@gnome.org>
+ */
+
+#ifndef META_X11_SELECTION_H
+#define META_X11_SELECTION_H
+
+#include "core/meta-selection.h"
+#include "x11/meta-x11-display-private.h"
+
+gboolean meta_x11_selection_handle_event (MetaX11Display *display,
+                                          XEvent         *event);
+
+void     meta_x11_selection_init     (MetaX11Display *x11_display);
+void     meta_x11_selection_shutdown (MetaX11Display *x11_display);
+
+#endif /* META_X11_SELECTION_H */

src/x11/meta-x11-selection.c

@@ -0,0 +1,411 @@
+/*
+ * Copyright (C) 2018 Red Hat
+ *
+ * This program 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 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * Author: Carlos Garnacho <carlosg@gnome.org>
+ */
+
+#include "config.h"
+
+#include <gdk/gdkx.h>
+
+#include "x11/meta-selection-source-x11-private.h"
+#include "x11/meta-x11-selection-output-stream-private.h"
+#include "x11/meta-x11-selection-private.h"
+
+static gboolean
+atom_to_selection_type (Display           *xdisplay,
+                        Atom               selection,
+                        MetaSelectionType *selection_type)
+{
+  if (selection == XInternAtom (xdisplay, "PRIMARY", False))
+    *selection_type = META_SELECTION_PRIMARY;
+  else if (selection == XInternAtom (xdisplay, "CLIPBOARD", False))
+    *selection_type = META_SELECTION_CLIPBOARD;
+  else if (selection == XInternAtom (xdisplay, "XdndSelection", False))
+    *selection_type = META_SELECTION_DND;
+  else
+    return FALSE;
+
+  return TRUE;
+}
+
+static Atom
+selection_to_atom (MetaSelectionType  type,
+                   Display           *xdisplay)
+{
+  Atom atom;
+
+  switch (type)
+    {
+    case META_SELECTION_PRIMARY:
+      atom = XInternAtom (xdisplay, "PRIMARY", False);
+      break;
+    case META_SELECTION_CLIPBOARD:
+      atom = XInternAtom (xdisplay, "CLIPBOARD", False);
+      break;
+    case META_SELECTION_DND:
+      atom = XInternAtom (xdisplay, "XdndSelection", False);
+      break;
+    default:
+      g_warn_if_reached ();
+      atom = None;
+      break;
+    }
+
+  return atom;
+}
+
+static GBytes *
+mimetypes_to_bytes (GList   *mimetypes,
+                    Display *xdisplay)
+{
+  gint i = 0, len = g_list_length (mimetypes) + 2;
+  Atom *atoms = g_new0 (Atom, len);
+  GList *l;
+
+  for (l = mimetypes; l; l = l->next)
+    atoms[i++] = XInternAtom (xdisplay, l->data, False);
+
+  atoms[i++] = XInternAtom (xdisplay, "TARGETS", False);
+  atoms[i++] = XInternAtom (xdisplay, "TIMESTAMP", False);
+  g_assert (i == len);
+
+  return g_bytes_new_take (atoms, len * sizeof (Atom));
+}
+
+static void
+send_selection_notify (XSelectionRequestEvent *request_event,
+                       gboolean                accepted)
+{
+  Display *xdisplay = GDK_DISPLAY_XDISPLAY (gdk_display_get_default ());
+  XSelectionEvent event;
+
+  memset(&event, 0, sizeof (XSelectionEvent));
+  event.type = SelectionNotify;
+  event.time = request_event->time;
+  event.requestor = request_event->requestor;
+  event.selection = request_event->selection;
+  event.target = request_event->target;
+  event.property = accepted ? request_event->property : None;
+
+  XSendEvent (xdisplay, request_event->requestor,
+              False, NoEventMask, (XEvent *) &event);
+}
+
+static void
+write_mimetypes_cb (GOutputStream *stream,
+                    GAsyncResult  *res,
+                    gpointer       user_data)
+{
+  GError *error = NULL;
+
+  g_output_stream_write_bytes_finish (stream, res, &error);
+  g_output_stream_close (stream, NULL, NULL);
+
+  if (error)
+    {
+      g_warning ("Could not fetch selection mimetypes: %s\n", error->message);
+      g_error_free (error);
+    }
+}
+
+static void
+transfer_cb (MetaSelection *selection,
+             GAsyncResult  *res,
+             GOutputStream *output)
+{
+  GError *error = NULL;
+
+  if (!meta_selection_transfer_finish (selection, res, &error))
+    {
+      g_warning ("Error writing data to X11 selection: %s", error->message);
+      g_error_free (error);
+    }
+
+  g_output_stream_close (output, NULL, NULL);
+  g_object_unref (output);
+}
+
+static gboolean
+meta_x11_selection_handle_selection_request (MetaX11Display *x11_display,
+                                             XEvent         *xevent)
+{
+  XSelectionRequestEvent *event = (XSelectionRequestEvent *) xevent;
+  MetaSelectionType selection_type;
+  MetaSelection *selection;
+  GOutputStream *output;
+  GList *mimetypes;
+
+  if (!atom_to_selection_type (x11_display->xdisplay, event->selection, &selection_type))
+    return FALSE;
+  if (x11_display->selection.xwindow != event->owner)
+    return FALSE;
+
+  selection = meta_display_get_selection (meta_get_display ());
+
+  if (event->target == gdk_x11_get_xatom_by_name ("TARGETS"))
+    {
+      GBytes *bytes;
+
+      mimetypes = meta_selection_get_mimetypes (selection, selection_type);
+
+      if (!mimetypes)
+        {
+          send_selection_notify (event, FALSE);
+          return FALSE;
+        }
+
+      output = meta_x11_selection_output_stream_new (x11_display, event->requestor,
+                                                     gdk_x11_get_xatom_name (event->selection),
+                                                     gdk_x11_get_xatom_name (event->target),
+                                                     gdk_x11_get_xatom_name (event->property),
+                                                     "ATOM", 32, event->time);
+
+      bytes = mimetypes_to_bytes (mimetypes, x11_display->xdisplay);
+      g_list_free_full (mimetypes, g_free);
+
+      g_output_stream_write_bytes_async (output,
+                                         bytes,
+                                         G_PRIORITY_DEFAULT,
+                                         NULL,
+                                         (GAsyncReadyCallback) write_mimetypes_cb,
+                                         output);
+      g_bytes_unref (bytes);
+      return TRUE;
+    }
+  else if (event->target == gdk_x11_get_xatom_by_name ("DELETE"))
+    {
+      /* DnD only, this is just handled through other means on our non-x11
+       * sources, so just go with it.
+       */
+      send_selection_notify (event, TRUE);
+    }
+  else
+    {
+      gboolean has_target;
+
+      mimetypes = meta_selection_get_mimetypes (selection, selection_type);
+      has_target = g_list_find_custom (mimetypes,
+                                       gdk_x11_get_xatom_name (event->target),
+                                       (GCompareFunc) g_strcmp0) != NULL;
+      g_list_free_full (mimetypes, g_free);
+
+      if (has_target)
+        {
+          output = meta_x11_selection_output_stream_new (x11_display,
+                                                         event->requestor,
+                                                         gdk_x11_get_xatom_name (event->selection),
+                                                         gdk_x11_get_xatom_name (event->target),
+                                                         gdk_x11_get_xatom_name (event->property),
+                                                         gdk_x11_get_xatom_name (event->target),
+                                                         8, event->time);
+
+          meta_selection_transfer_async (selection,
+                                         selection_type,
+                                         gdk_x11_get_xatom_name (event->target),
+                                         -1,
+                                         output,
+                                         NULL,
+                                         (GAsyncReadyCallback) transfer_cb,
+                                         output);
+          return TRUE;
+        }
+      else
+        send_selection_notify (event, FALSE);
+    }
+
+  return FALSE;
+}
+
+typedef struct
+{
+  MetaX11Display *x11_display;
+  MetaSelection *selection;
+  MetaSelectionType selection_type;
+} SourceNewData;
+
+static void
+source_new_cb (GObject      *object,
+               GAsyncResult *res,
+               gpointer      user_data)
+{
+  MetaSelectionSource *source;
+  SourceNewData *data = user_data;
+  MetaSelection *selection = data->selection;
+  MetaSelectionType selection_type = data->selection_type;
+  MetaX11Display *x11_display = data->x11_display;
+  GError *error = NULL;
+
+  source = meta_selection_source_x11_new_finish (res, &error);
+  if (source)
+    {
+      meta_selection_set_owner (selection, selection_type, source);
+      g_set_object (&x11_display->selection.owners[selection_type], source);
+    }
+  else
+    {
+      g_warning ("Could not create selection source for X11: %s",
+                 error->message);
+    }
+
+  g_free (data);
+}
+
+static gboolean
+meta_x11_selection_handle_xfixes_selection_notify (MetaX11Display *x11_display,
+                                                   XEvent         *xevent)
+{
+  XFixesSelectionNotifyEvent *event = (XFixesSelectionNotifyEvent *) xevent;
+  Display *xdisplay = x11_display->xdisplay;
+  MetaSelectionType selection_type;
+  MetaSelection *selection;
+
+  if (!atom_to_selection_type (xdisplay, event->selection, &selection_type))
+    return FALSE;
+
+  selection = meta_display_get_selection (meta_get_display ());
+
+  if (x11_display->selection.cancellables[selection_type])
+    {
+      g_cancellable_cancel (x11_display->selection.cancellables[selection_type]);
+      g_clear_object (&x11_display->selection.cancellables[selection_type]);
+    }
+
+  x11_display->selection.cancellables[selection_type] = g_cancellable_new ();
+
+  if (event->owner == None)
+    {
+      if (x11_display->selection.owners[selection_type])
+        {
+          /* An X client went away, clear the selection */
+          meta_selection_unset_owner (selection, selection_type,
+                                      x11_display->selection.owners[selection_type]);
+        }
+    }
+  else if (event->owner != x11_display->selection.xwindow)
+    {
+      SourceNewData *data;
+
+      data = g_new (SourceNewData, 1);
+      data->x11_display = x11_display;
+      data->selection = selection;
+      data->selection_type = selection_type;
+
+      meta_selection_source_x11_new_async (x11_display,
+                                           event->owner,
+                                           event->timestamp,
+                                           event->selection,
+                                           x11_display->selection.cancellables[selection_type],
+                                           source_new_cb,
+                                           data);
+    }
+
+  return TRUE;
+}
+
+gboolean
+meta_x11_selection_handle_event (MetaX11Display *x11_display,
+                                 XEvent         *xevent)
+{
+  if (xevent->type == SelectionRequest)
+    return meta_x11_selection_handle_selection_request (x11_display, xevent);
+  else if (xevent->type - x11_display->xfixes_event_base == XFixesSelectionNotify)
+    return meta_x11_selection_handle_xfixes_selection_notify (x11_display, xevent);
+
+  return FALSE;
+}
+
+static void
+owner_changed_cb (MetaSelection       *selection,
+                  MetaSelectionType    selection_type,
+                  MetaSelectionSource *new_owner,
+                  MetaX11Display      *x11_display)
+{
+  Display *xdisplay = x11_display->xdisplay;
+
+  if (new_owner && !META_IS_SELECTION_SOURCE_X11 (new_owner))
+    {
+      if (x11_display->selection.cancellables[selection_type])
+        {
+          g_cancellable_cancel (x11_display->selection.cancellables[selection_type]);
+          g_clear_object (&x11_display->selection.cancellables[selection_type]);
+        }
+
+      /* If the owner is non-X11, claim the selection on our selection
+       * window, so X11 apps can interface with it.
+       */
+      XSetSelectionOwner (xdisplay,
+                          selection_to_atom (selection_type, xdisplay),
+                          x11_display->selection.xwindow,
+                          META_CURRENT_TIME);
+    }
+}
+
+void
+meta_x11_selection_init (MetaX11Display *x11_display)
+{
+  XSetWindowAttributes attributes = { 0 };
+  MetaDisplay *display = meta_get_display ();
+  guint mask, i;
+
+  attributes.event_mask = PropertyChangeMask | SubstructureNotifyMask;
+  attributes.override_redirect = True;
+
+  x11_display->selection.xwindow =
+    XCreateWindow (x11_display->xdisplay,
+                   x11_display->xroot,
+                   -1, -1, 1, 1,
+                   0, /* border width */
+                   0, /* depth */
+                   InputOnly, /* class */
+                   CopyFromParent, /* visual */
+                   CWEventMask | CWOverrideRedirect,
+                   &attributes);
+
+  mask = XFixesSetSelectionOwnerNotifyMask |
+    XFixesSelectionWindowDestroyNotifyMask |
+    XFixesSelectionClientCloseNotifyMask;
+
+  for (i = 0; i < META_N_SELECTION_TYPES; i++)
+    {
+      XFixesSelectSelectionInput (x11_display->xdisplay,
+                                  x11_display->selection.xwindow,
+                                  selection_to_atom (i, x11_display->xdisplay),
+                                  mask);
+    }
+
+  g_signal_connect (meta_display_get_selection (display),
+                    "owner-changed",
+                    G_CALLBACK (owner_changed_cb),
+                    x11_display);
+}
+
+void
+meta_x11_selection_shutdown (MetaX11Display *x11_display)
+{
+  MetaDisplay *display = meta_get_display ();
+
+  g_signal_handlers_disconnect_by_func (meta_display_get_selection (display),
+                                        owner_changed_cb,
+                                        x11_display);
+  if (x11_display->selection.xwindow != None)
+    {
+      XDestroyWindow (x11_display->xdisplay, x11_display->selection.xwindow);
+      x11_display->selection.xwindow = None;
+    }
+}