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master 3d846efb85: Fix race conditions in handling of unsupported drops
From: |
Po Lu |
Subject: |
master 3d846efb85: Fix race conditions in handling of unsupported drops on X |
Date: |
Sun, 8 May 2022 21:17:45 -0400 (EDT) |
branch: master
commit 3d846efb857c0ace95d6fe026522fcdbffe04dc3
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>
Fix race conditions in handling of unsupported drops on X
* lisp/x-dnd.el (x-dnd-handle-unsupported-drop): Adjust for new
parameters.
* src/keyboard.c (kbd_buffer, kbd_fetch_ptr, kbd_store_ptr):
Export variables.
(kbd_buffer_get_event): Ignore already handled unsupported
drops.
* src/keyboard.h: Update prototypes.
* src/termhooks.h (enum event_kind): Document meaning of
`modifiers' in UNSUPPORTED_DROP_EVENTs.
* src/xterm.c (x_dnd_send_unsupported_drop): Set event modifiers
to current level.
(x_toggle_visible_pointer): Fix fixes fallback.
(x_dnd_begin_drag_and_drop): Handle UNSUPPORTED_DROP_EVENTs
already in the keyboard buffer before starting DND.
(syms_of_xterm): Give timestamp to unsupported drop function.
* src/xterm.h: Update prototypes.
---
lisp/x-dnd.el | 2 +-
src/keyboard.c | 18 ++++++----
src/keyboard.h | 9 +++++
src/termhooks.h | 5 +++
src/xterm.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++----------
src/xterm.h | 1 +
6 files changed, 110 insertions(+), 25 deletions(-)
diff --git a/lisp/x-dnd.el b/lisp/x-dnd.el
index 47d8ae14cf..c2498a57a1 100644
--- a/lisp/x-dnd.el
+++ b/lisp/x-dnd.el
@@ -783,7 +783,7 @@ FORMAT is 32 (not used). MESSAGE is the data part of an
XClientMessageEvent."
;;; Handling drops.
-(defun x-dnd-handle-unsupported-drop (targets _x _y action _window-id _frame)
+(defun x-dnd-handle-unsupported-drop (targets _x _y action _window-id _frame
_time)
"Return non-nil if the drop described by TARGETS and ACTION should not
proceeed."
(not (and (or (eq action 'XdndActionCopy)
(eq action 'XdndActionMove))
diff --git a/src/keyboard.c b/src/keyboard.c
index 70908120cb..e8f51f8a6f 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -95,8 +95,6 @@ volatile int interrupt_input_blocked;
The maybe_quit function checks this. */
volatile bool pending_signals;
-enum { KBD_BUFFER_SIZE = 4096 };
-
KBOARD *initial_kboard;
KBOARD *current_kboard;
static KBOARD *all_kboards;
@@ -290,14 +288,14 @@ bool input_was_pending;
/* Circular buffer for pre-read keyboard input. */
-static union buffered_input_event kbd_buffer[KBD_BUFFER_SIZE];
+union buffered_input_event kbd_buffer[KBD_BUFFER_SIZE];
/* Pointer to next available character in kbd_buffer.
If kbd_fetch_ptr == kbd_store_ptr, the buffer is empty. */
-static union buffered_input_event *kbd_fetch_ptr;
+union buffered_input_event *kbd_fetch_ptr;
/* Pointer to next place to store character in kbd_buffer. */
-static union buffered_input_event *kbd_store_ptr;
+union buffered_input_event *kbd_store_ptr;
/* The above pair of variables forms a "queue empty" flag. When we
enqueue a non-hook event, we increment kbd_store_ptr. When we
@@ -4022,6 +4020,11 @@ kbd_buffer_get_event (KBOARD **kbp,
kbd_fetch_ptr = next_kbd_event (event);
input_pending = readable_events (0);
+ /* This means this event was already handled in
+ `x_dnd_begin_drag_and_drop'. */
+ if (event->ie.modifiers < x_dnd_unsupported_event_level)
+ break;
+
f = XFRAME (event->ie.frame_or_window);
if (!FRAME_LIVE_P (f))
@@ -4029,11 +4032,12 @@ kbd_buffer_get_event (KBOARD **kbp,
if (!NILP (Vx_dnd_unsupported_drop_function))
{
- if (!NILP (call6 (Vx_dnd_unsupported_drop_function,
+ if (!NILP (call7 (Vx_dnd_unsupported_drop_function,
XCAR (XCDR (event->ie.arg)), event->ie.x,
event->ie.y, XCAR (XCDR (XCDR (event->ie.arg))),
make_uint (event->ie.code),
- event->ie.frame_or_window)))
+ event->ie.frame_or_window,
+ make_int (event->ie.timestamp))))
break;
}
diff --git a/src/keyboard.h b/src/keyboard.h
index cd5f677b96..a0b7204fa2 100644
--- a/src/keyboard.h
+++ b/src/keyboard.h
@@ -358,6 +358,11 @@ enum menu_item_idx
MENU_ITEMS_ITEM_LENGTH
};
+enum
+ {
+ KBD_BUFFER_SIZE = 4096
+ };
+
extern void unuse_menu_items (void);
/* This is how to deal with multibyte text if HAVE_MULTILINGUAL_MENU
@@ -419,6 +424,10 @@ extern void unuse_menu_items (void);
happens. */
extern struct timespec *input_available_clear_time;
+extern union buffered_input_event kbd_buffer[KBD_BUFFER_SIZE];
+extern union buffered_input_event *kbd_fetch_ptr;
+extern union buffered_input_event *kbd_store_ptr;
+
extern bool ignore_mouse_drag_p;
extern Lisp_Object parse_modifiers (Lisp_Object);
diff --git a/src/termhooks.h b/src/termhooks.h
index 8c193914ba..08bde0aec0 100644
--- a/src/termhooks.h
+++ b/src/termhooks.h
@@ -223,6 +223,11 @@ enum event_kind
gives the timestamp where the drop
happened.
+ .modifiers gives a number that
+ determines if an event was already
+ handled by
+ `x_dnd_begin_drag_and_drop'.
+
.x and .y give the coordinates of
the drop originating from the root
window. */
diff --git a/src/xterm.c b/src/xterm.c
index d32bdea843..2bbc9f3d0c 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -868,6 +868,10 @@ static int x_filter_event (struct x_display_info *, XEvent
*);
/* Flag that indicates if a drag-and-drop operation is in progress. */
bool x_dnd_in_progress;
+/* Number that indicates the last "generation" of
+ UNSUPPORTED_DROP_EVENTs handled. */
+unsigned x_dnd_unsupported_event_level;
+
/* The frame where the drag-and-drop operation originated. */
struct frame *x_dnd_frame;
@@ -3070,6 +3074,7 @@ x_dnd_send_unsupported_drop (struct x_display_info
*dpyinfo, Window target_windo
ie.kind = UNSUPPORTED_DROP_EVENT;
ie.code = (unsigned) target_window;
+ ie.modifiers = x_dnd_unsupported_event_level;
ie.arg = list3 (assq_no_quit (QXdndSelection,
dpyinfo->terminal->Vselection_alist),
targets, arg);
@@ -9479,15 +9484,18 @@ x_toggle_visible_pointer (struct frame *f, bool
invisible)
invisible = false;
#else
/* But if Xfixes is available, try using it instead. */
- if (x_probe_xfixes_extension (dpyinfo))
+ if (dpyinfo->invisible_cursor == None)
{
- dpyinfo->fixes_pointer_blanking = true;
- xfixes_toggle_visible_pointer (f, invisible);
+ if (x_probe_xfixes_extension (dpyinfo))
+ {
+ dpyinfo->fixes_pointer_blanking = true;
+ xfixes_toggle_visible_pointer (f, invisible);
- return;
+ return;
+ }
+ else
+ invisible = false;
}
- else
- invisible = false;
#endif
if (invisible)
@@ -9864,6 +9872,64 @@ x_dnd_begin_drag_and_drop (struct frame *f, Time time,
Atom xaction,
#ifndef USE_GTK
struct x_display_info *event_display;
#endif
+ union buffered_input_event *events, *event;
+ int n_events;
+ struct frame *event_frame;
+
+ /* Before starting drag-and-drop, walk through the keyboard buffer
+ to see if there are any UNSUPPORTED_DROP_EVENTs, and run them now
+ if they exist, to prevent race conditions from happening due to
+ multiple unsupported drops running at once. */
+
+ block_input ();
+ events = alloca (sizeof *events * KBD_BUFFER_SIZE);
+ n_events = 0;
+ event = kbd_fetch_ptr;
+
+ while (event != kbd_store_ptr)
+ {
+ if (event->ie.kind == UNSUPPORTED_DROP_EVENT
+ && event->ie.modifiers < x_dnd_unsupported_event_level)
+ events[n_events++] = *event;
+
+ event = (event == kbd_buffer + KBD_BUFFER_SIZE - 1
+ ? kbd_buffer : event + 1);
+ }
+
+ x_dnd_unsupported_event_level += 1;
+ unblock_input ();
+
+ for (i = 0; i < n_events; ++i)
+ {
+ maybe_quit ();
+
+ event = &events[i];
+ event_frame = XFRAME (event->ie.frame_or_window);
+
+ if (!FRAME_LIVE_P (event_frame))
+ continue;
+
+ if (!NILP (Vx_dnd_unsupported_drop_function))
+ {
+ if (!NILP (call7 (Vx_dnd_unsupported_drop_function,
+ XCAR (XCDR (event->ie.arg)), event->ie.x,
+ event->ie.y, XCAR (XCDR (XCDR (event->ie.arg))),
+ make_uint (event->ie.code),
+ event->ie.frame_or_window,
+ make_int (event->ie.timestamp))))
+ continue;
+ }
+
+ x_dnd_do_unsupported_drop (FRAME_DISPLAY_INFO (event_frame),
+ event->ie.frame_or_window,
+ XCAR (event->ie.arg),
+ XCAR (XCDR (event->ie.arg)),
+ (Window) event->ie.code,
+ XFIXNUM (event->ie.x),
+ XFIXNUM (event->ie.y),
+ event->ie.timestamp);
+ break;
+ }
if (!FRAME_VISIBLE_P (f))
{
@@ -24849,16 +24915,16 @@ mouse position list. */);
DEFVAR_LISP ("x-dnd-unsupported-drop-function",
Vx_dnd_unsupported_drop_function,
doc: /* Function called when trying to drop on an unsupported window.
-This function is called whenever the user tries to drop
-something on a window that does not support either the XDND or
-Motif protocols for drag-and-drop. It should return a non-nil
-value if the drop was handled by the function, and nil if it was
-not. It should accept several arguments TARGETS, X, Y, ACTION,
-WINDOW-ID and FRAME, where TARGETS is the list of targets that
-was passed to `x-begin-drag', WINDOW-ID is the numeric XID of
-the window that is being dropped on, X and Y are the root
-window-relative coordinates where the drop happened, ACTION
-is the action that was passed to `x-begin-drag', and FRAME is
-the frame which initiated the drag-and-drop operation. */);
+This function is called whenever the user tries to drop something on a
+window that does not support either the XDND or Motif protocols for
+drag-and-drop. It should return a non-nil value if the drop was
+handled by the function, and nil if it was not. It should accept
+several arguments TARGETS, X, Y, ACTION, WINDOW-ID, FRAME and TIME,
+where TARGETS is the list of targets that was passed to
+`x-begin-drag', WINDOW-ID is the numeric XID of the window that is
+being dropped on, X and Y are the root window-relative coordinates
+where the drop happened, ACTION is the action that was passed to
+`x-begin-drag', FRAME is the frame which initiated the drag-and-drop
+operation, and TIME is the X server time when the drop happened. */);
Vx_dnd_unsupported_drop_function = Qnil;
}
diff --git a/src/xterm.h b/src/xterm.h
index 66c4b17823..16635053be 100644
--- a/src/xterm.h
+++ b/src/xterm.h
@@ -1586,6 +1586,7 @@ extern struct input_event xg_pending_quit_event;
extern bool x_dnd_in_progress;
extern struct frame *x_dnd_frame;
+extern unsigned x_dnd_unsupported_event_level;
#ifdef HAVE_XINPUT2
extern struct xi_device_t *xi_device_from_id (struct x_display_info *, int);
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