Handle selection transfer errors earlier

* src/xselect.c (x_decline_selection_request, struct transfer)
(struct x_selection_request, x_cancel_selection_transfer)
(x_start_selection_transfer, x_continue_selection_transfer):
Give the right serial to x_ignore_errors_for_next_request.
(x_handle_selection_error): New function.
(x_reply_selection_request): Give the right serial to
x_ignore_errors_for_next_request.
* src/xterm.c (x_ignore_errors_for_next_request): New arg
`selection_serial'.  All callers changed.
(x_error_handler): Call selection error handler.
* src/xterm.h (struct x_failable_request): New field
`selection_serial'.

1 files changed, 65 insertions, 9 deletions

diff --git a/src/xselect.c b/src/xselect.c
index 191f0770337..05548be311f 100644
--- a/src/xselect.c
+++ b/src/xselect.c
@@ -460,7 +460,7 @@ x_decline_selection_request (struct selection_input_event *event)
   /* The reason for the error may be that the receiver has
      died in the meantime.  Handle that case.  */
   block_input ();
-  x_ignore_errors_for_next_request (dpyinfo);
+  x_ignore_errors_for_next_request (dpyinfo, 0);
   XSendEvent (dpyinfo->display, reply->requestor,
 	      False, 0, &reply_base);
   x_stop_ignoring_errors (dpyinfo);
@@ -523,6 +523,9 @@ struct transfer
   /* The atimer for the timeout.  */
   struct atimer *timeout;
 
+  /* The selection serial.  */
+  unsigned int serial;
+
   /* Flags.  */
   int flags;
 };
@@ -543,6 +546,9 @@ struct x_selection_request
   /* Linked list of the above (in support of MULTIPLE targets).  */
   struct selection_data *converted_selections;
 
+  /* The serial used to handle X errors.  */
+  unsigned int serial;
+
   /* Whether or not conversion was successful.  */
   bool converted;
 };
@@ -557,6 +563,10 @@ struct x_selection_request *selection_request_stack;
 
 struct transfer outstanding_transfers;
 
+/* A counter for selection serials.  */
+
+static unsigned int selection_serial;
+
 
 
 struct prop_location
@@ -793,7 +803,7 @@ x_cancel_selection_transfer (struct transfer *transfer)
       /* Ignore errors generated by the change window request in case
 	 the window has gone away.  */
       block_input ();
-      x_ignore_errors_for_next_request (transfer->dpyinfo);
+      x_ignore_errors_for_next_request (transfer->dpyinfo, 0);
       XSelectInput (transfer->dpyinfo->display,
 		    transfer->requestor, NoEventMask);
       x_stop_ignoring_errors (transfer->dpyinfo);
@@ -885,12 +895,23 @@ x_start_selection_transfer (struct x_display_info *dpyinfo, Window requestor,
       transfer->next->last = transfer;
       transfer->last->next = transfer;
 
+      /* Find a valid (non-zero) serial for the selection transfer.
+	 Any asynchronously trapped errors will then cause the
+	 selection transfer to be cancelled.  */
+      transfer->serial = (++selection_serial
+			  ? selection_serial
+			  : ++selection_serial);
+
       /* Now, write the INCR property to begin incremental selection
 	 transfer.  offset is currently 0.  */
 
       data_size = selection_data_size (&transfer->data);
 
-      x_ignore_errors_for_next_request (dpyinfo);
+      /* Set SELECTED_EVENTS before the actual XSelectInput
+	 request.  */
+      transfer->flags |= SELECTED_EVENTS;
+
+      x_ignore_errors_for_next_request (dpyinfo, transfer->serial);
       XChangeProperty (dpyinfo->display, requestor,
 		       transfer->data.property,
 		       dpyinfo->Xatom_INCR, 32, PropModeReplace,
@@ -903,7 +924,6 @@ x_start_selection_transfer (struct x_display_info *dpyinfo, Window requestor,
          manager) asks Emacs for selection data, things will subtly go
          wrong.  */
       XSelectInput (dpyinfo->display, requestor, PropertyChangeMask);
-      transfer->flags |= SELECTED_EVENTS;
       x_stop_ignoring_errors (dpyinfo);
     }
   else
@@ -917,7 +937,7 @@ x_start_selection_transfer (struct x_display_info *dpyinfo, Window requestor,
 	      " %zu elements directly to requestor window",
 	      remaining);
 
-      x_ignore_errors_for_next_request (dpyinfo);
+      x_ignore_errors_for_next_request (dpyinfo, 0);
       XChangeProperty (dpyinfo->display, requestor,
 		       transfer->data.property,
 		       transfer->data.type,
@@ -951,7 +971,7 @@ x_continue_selection_transfer (struct transfer *transfer)
 	 signal EOF and remove the transfer.  */
       TRACE0 (" x_continue_selection_transfer: writing 0 items to"
 	      " indicate EOF");
-      x_ignore_errors_for_next_request (transfer->dpyinfo);
+      x_ignore_errors_for_next_request (transfer->dpyinfo, 0);
       XChangeProperty (transfer->dpyinfo->display,
 		       transfer->requestor,
 		       transfer->data.property,
@@ -970,7 +990,10 @@ x_continue_selection_transfer (struct transfer *transfer)
 	      "; current offset is %zu", remaining, transfer->offset);
       eassert (remaining <= INT_MAX);
 
-      x_ignore_errors_for_next_request (transfer->dpyinfo);
+      transfer->offset += remaining;
+
+      x_ignore_errors_for_next_request (transfer->dpyinfo,
+					transfer->serial);
       XChangeProperty (transfer->dpyinfo->display,
 		       transfer->requestor,
 		       transfer->data.property,
@@ -979,7 +1002,6 @@ x_continue_selection_transfer (struct transfer *transfer)
 		       PropModeReplace, xdata,
 		       remaining);
       x_stop_ignoring_errors (transfer->dpyinfo);
-      transfer->offset += remaining;
     }
 }
 
@@ -999,6 +1021,40 @@ x_remove_selection_transfers (struct x_display_info *dpyinfo)
     }
 }
 
+/* Handle an X error generated trying to write to a window.  SERIAL
+   identifies the outstanding incremental selection transfer, which is
+   immediately removed.  */
+
+void
+x_handle_selection_error (unsigned int serial, XErrorEvent *error)
+{
+  struct transfer *next, *last;
+
+  if (error->error_code != BadWindow)
+    /* The error was not caused by the window going away.  As such,
+       Emacs must deselect for PropertyChangeMask from the requestor
+       window, which isn't safe here.  Return and wait for the timeout
+       to run.  */
+    return;
+
+  next = outstanding_transfers.next;
+  while (next != &outstanding_transfers)
+    {
+      last = next;
+      next = next->next;
+
+      if (last->serial == serial)
+	{
+	  /* Clear SELECTED_EVENTS, so x_cancel_selection_transfer
+	     will not make X requests.  That is unsafe inside an error
+	     handler, and unnecessary because the window has already
+	     gone.  */
+	  last->flags &= ~SELECTED_EVENTS;
+	  x_cancel_selection_transfer (last);
+	}
+    }
+}
+
 /* Send the reply to a selection request event EVENT.  */
 
 static void
@@ -1033,7 +1089,7 @@ x_reply_selection_request (struct selection_input_event *event,
 
   /* Send the SelectionNotify event to the requestor, telling it that
      the property data has arrived.  */
-  x_ignore_errors_for_next_request (dpyinfo);
+  x_ignore_errors_for_next_request (dpyinfo, 0);
   XSendEvent (dpyinfo->display, SELECTION_EVENT_REQUESTOR (event),
 	      False, NoEventMask, &message);
   x_stop_ignoring_errors (dpyinfo);