Fix bug that munged selection info

On some optimizing C compilers, copying a structure did not
copy the padding bytes between elements, and the type punning
between struct input_data and struct selection_input_data did
not work.  Change the C code to use a proper union type instead.
Problem reported by YAMAMOTO Mitsuharu (Bug#20756).
* src/keyboard.c (kbd_buffer, kbd_fetch_ptr, kbd_store_ptr)
(readable_events, discard_mouse_events, kbd_buffer_events_waiting)
(kbd_buffer_get_event, process_special_events, stuff_buffered_input)
(mark_kboards):
Use union buffered_input_event, not struct input_event.
(clear_event, deliver_input_available_signal, process_special_events):
Remove unnecessary forward decls.
(kbd_buffer_store_buffered_event): New function, mostly just the
old kbd_buffer_store_event_hold, except its argument is of type
union buffered_input_event, not struct input_event.
(kbd_buffer_unget_event): Define only if HAVE_X11, since it's
not needed otherwise.  Argument is now of type
struct selection_input_event *, not struct input_event *.
All callers changed.
(clear_event): Arg is now of type union buffered_input_event *,
not struct input_event *.  All callers changed.
* src/keyboard.h [HAVE_X11]: Include "xterm.h".
(union buffered_input_event): New type.
(kbd_buffer_store_event_hold): Now an inline function,
defined here.
* src/termhooks.h (EVENT_KIND_WIDTH): New constant.
(struct input_event): Use it.
* src/xselect.c (struct selection_event_queue):
Make elements be of type struct selection_input_event,
not struct input_event.
(selection_input_event_equal): New static function.
(x_queue_event): Use it.
(x_queue_event, x_decline_selection_request)
(x_selection_current_request, x_reply_selection_request)
(x_handle_selection_request, x_handle_selection_clear)
(x_handle_selection_event): Use struct selection_input_event,
not struct input_event.  All callers changed.
(x_convert_selection): Omit unused first arg.  All callers changed.
(Fx_disown_selection_internal): Omit unnecessary union.
* src/xterm.c (handle_one_xevent): Use new union buffered_input_event
rather than rolling our own equivalent.  Prefer sie.kind when
setting up that kind of structure.
Call kbd_buffer_store_buffered_event, not kbd_buffer_store_event_hold.
* src/xterm.h (struct selection_input_event: Use EVENT_KIND_WIDTH.
(SELECTION_EVENT_DISPLAY, SELECTION_EVENT_DPYINFO)
(SELECTION_EVENT_REQUESTOR, SELECTION_EVENT_SELECTION)
(SELECTION_EVENT_TARGET, SELECTION_EVENT_PROPERTY)
(SELECTION_EVENT_TIME, x_handle_selection_event):
Arg is now of type struct selection_input_event *)
not struct input_event *.  All callers changed.

1 files changed, 27 insertions, 3 deletions

diff --git a/src/keyboard.h b/src/keyboard.h
index bcdeaf62165..52780516340 100644
--- a/src/keyboard.h
+++ b/src/keyboard.h
@@ -21,6 +21,10 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "coding.h"             /* for ENCODE_UTF_8 and ENCODE_SYSTEM */
 #include "termhooks.h"
 
+#ifdef HAVE_X11
+# include "xterm.h"		/* for struct selection_input_event */
+#endif
+
 INLINE_HEADER_BEGIN
 
 /* Most code should use this macro to access Lisp fields in struct kboard.  */
@@ -217,6 +221,15 @@ kset_window_system (struct kboard *kb, Lisp_Object val)
   kb->Vwindow_system_ = val;
 }
 
+union buffered_input_event
+{
+  ENUM_BF (event_kind) kind : EVENT_KIND_WIDTH;
+  struct input_event ie;
+#ifdef HAVE_X11
+  struct selection_input_event sie;
+#endif
+};
+
 /* Temporarily used before a frame has been opened. */
 extern KBOARD *initial_kboard;
 
@@ -438,9 +451,20 @@ extern void clear_waiting_for_input (void);
 extern void swallow_events (bool);
 extern bool lucid_event_type_list_p (Lisp_Object);
 extern void kbd_buffer_store_event (struct input_event *);
-extern void kbd_buffer_store_event_hold (struct input_event *,
-                                         struct input_event *);
-extern void kbd_buffer_unget_event (struct input_event *);
+extern void kbd_buffer_store_buffered_event (union buffered_input_event *,
+					     struct input_event *);
+INLINE void
+kbd_buffer_store_event_hold (struct input_event *event,
+			     struct input_event *hold_quit)
+{
+  union buffered_input_event *ev = (union buffered_input_event *) event;
+  verify (sizeof *event == sizeof *ev && alignof (*event) == alignof (*ev));
+  return kbd_buffer_store_buffered_event ((union buffered_input_event *) event,
+					  hold_quit);
+}
+#ifdef HAVE_X11
+extern void kbd_buffer_unget_event (struct selection_input_event *);
+#endif
 extern void poll_for_input_1 (void);
 extern void show_help_echo (Lisp_Object, Lisp_Object, Lisp_Object,
                             Lisp_Object);