289 lines
8.0 KiB
C
289 lines
8.0 KiB
C
/* Remote notification in GDB protocol
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Copyright (C) 1988-2015 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* Remote async notification is sent from remote target over RSP.
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Each type of notification is represented by an object of
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'struct notif', which has a field 'pending_reply'. It is not
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NULL when GDB receives a notification from GDBserver, but hasn't
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acknowledge yet. Before GDB acknowledges the notification,
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GDBserver shouldn't send notification again (see the header comments
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in gdbserver/notif.c).
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Notifications are processed in an almost-unified approach for both
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all-stop mode and non-stop mode, except the timing to process them.
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In non-stop mode, notifications are processed in
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remote_async_get_pending_events_handler, while in all-stop mode,
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they are processed in remote_resume. */
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#include "defs.h"
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#include "remote.h"
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#include "remote-notif.h"
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#include "observer.h"
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#include "event-loop.h"
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#include "target.h"
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#include "inferior.h"
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#include "infrun.h"
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#include "gdbcmd.h"
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int notif_debug = 0;
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/* Supported clients of notifications. */
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static struct notif_client *notifs[] =
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{
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¬if_client_stop,
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};
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gdb_static_assert (ARRAY_SIZE (notifs) == REMOTE_NOTIF_LAST);
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static void do_notif_event_xfree (void *arg);
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/* Parse the BUF for the expected notification NC, and send packet to
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acknowledge. */
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void
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remote_notif_ack (struct notif_client *nc, char *buf)
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{
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struct notif_event *event = nc->alloc_event ();
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struct cleanup *old_chain
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= make_cleanup (do_notif_event_xfree, event);
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if (notif_debug)
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fprintf_unfiltered (gdb_stdlog, "notif: ack '%s'\n",
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nc->ack_command);
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nc->parse (nc, buf, event);
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nc->ack (nc, buf, event);
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discard_cleanups (old_chain);
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}
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/* Parse the BUF for the expected notification NC. */
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struct notif_event *
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remote_notif_parse (struct notif_client *nc, char *buf)
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{
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struct notif_event *event = nc->alloc_event ();
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struct cleanup *old_chain
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= make_cleanup (do_notif_event_xfree, event);
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if (notif_debug)
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fprintf_unfiltered (gdb_stdlog, "notif: parse '%s'\n", nc->name);
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nc->parse (nc, buf, event);
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discard_cleanups (old_chain);
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return event;
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}
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DEFINE_QUEUE_P (notif_client_p);
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/* Process notifications in STATE's notification queue one by one.
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EXCEPT is not expected in the queue. */
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void
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remote_notif_process (struct remote_notif_state *state,
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struct notif_client *except)
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{
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while (!QUEUE_is_empty (notif_client_p, state->notif_queue))
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{
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struct notif_client *nc = QUEUE_deque (notif_client_p,
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state->notif_queue);
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gdb_assert (nc != except);
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if (nc->can_get_pending_events (nc))
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remote_notif_get_pending_events (nc);
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}
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}
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static void
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remote_async_get_pending_events_handler (gdb_client_data data)
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{
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gdb_assert (target_is_non_stop_p ());
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remote_notif_process ((struct remote_notif_state *) data, NULL);
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}
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/* Remote notification handler. Parse BUF, queue notification and
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update STATE. */
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void
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handle_notification (struct remote_notif_state *state, char *buf)
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{
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struct notif_client *nc;
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size_t i;
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for (i = 0; i < ARRAY_SIZE (notifs); i++)
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{
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const char *name = notifs[i]->name;
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if (startswith (buf, name)
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&& buf[strlen (name)] == ':')
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break;
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}
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/* We ignore notifications we don't recognize, for compatibility
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with newer stubs. */
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if (i == ARRAY_SIZE (notifs))
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return;
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nc = notifs[i];
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if (state->pending_event[nc->id] != NULL)
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{
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/* We've already parsed the in-flight reply, but the stub for some
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reason thought we didn't, possibly due to timeout on its side.
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Just ignore it. */
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if (notif_debug)
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fprintf_unfiltered (gdb_stdlog,
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"notif: ignoring resent notification\n");
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}
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else
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{
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struct notif_event *event
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= remote_notif_parse (nc, buf + strlen (nc->name) + 1);
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/* Be careful to only set it after parsing, since an error
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may be thrown then. */
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state->pending_event[nc->id] = event;
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/* Notify the event loop there's a stop reply to acknowledge
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and that there may be more events to fetch. */
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QUEUE_enque (notif_client_p, state->notif_queue, nc);
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if (target_is_non_stop_p ())
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{
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/* In non-stop, We mark REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN
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in order to go on what we were doing and postpone
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querying notification events to some point safe to do so.
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See details in the function comment of
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remote.c:remote_notif_get_pending_events.
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In all-stop, GDB may be blocked to wait for the reply, we
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shouldn't return to event loop until the expected reply
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arrives. For example:
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1.1) --> vCont;c
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GDB expects getting stop reply 'T05 thread:2'.
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1.2) <-- %Notif
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<GDB marks the REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN>
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After step #1.2, we return to the event loop, which
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notices there is a new event on the
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REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN and calls the
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handler, which will send 'vNotif' packet.
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1.3) --> vNotif
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It is not safe to start a new sequence, because target
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is still running and GDB is expecting the stop reply
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from stub.
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To solve this, whenever we parse a notification
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successfully, we don't mark the
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REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN and let GDB blocked
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there as before to get the sequence done.
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2.1) --> vCont;c
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GDB expects getting stop reply 'T05 thread:2'
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2.2) <-- %Notif
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<Don't mark the REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN>
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2.3) <-- T05 thread:2
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These pending notifications can be processed later. */
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mark_async_event_handler (state->get_pending_events_token);
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}
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if (notif_debug)
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fprintf_unfiltered (gdb_stdlog,
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"notif: Notification '%s' captured\n",
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nc->name);
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}
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}
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/* Invoke destructor of EVENT and xfree it. */
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void
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notif_event_xfree (struct notif_event *event)
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{
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if (event != NULL && event->dtr != NULL)
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event->dtr (event);
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xfree (event);
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}
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/* Cleanup wrapper. */
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static void
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do_notif_event_xfree (void *arg)
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{
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notif_event_xfree ((struct notif_event *) arg);
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}
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/* Return an allocated remote_notif_state. */
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struct remote_notif_state *
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remote_notif_state_allocate (void)
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{
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struct remote_notif_state *notif_state = XCNEW (struct remote_notif_state);
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notif_state->notif_queue = QUEUE_alloc (notif_client_p, NULL);
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/* Register async_event_handler for notification. */
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notif_state->get_pending_events_token
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= create_async_event_handler (remote_async_get_pending_events_handler,
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notif_state);
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return notif_state;
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}
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/* Free STATE and its fields. */
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void
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remote_notif_state_xfree (struct remote_notif_state *state)
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{
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int i;
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QUEUE_free (notif_client_p, state->notif_queue);
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/* Unregister async_event_handler for notification. */
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if (state->get_pending_events_token != NULL)
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delete_async_event_handler (&state->get_pending_events_token);
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for (i = 0; i < REMOTE_NOTIF_LAST; i++)
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notif_event_xfree (state->pending_event[i]);
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xfree (state);
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}
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/* -Wmissing-prototypes */
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extern initialize_file_ftype _initialize_notif;
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void
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_initialize_notif (void)
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{
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add_setshow_boolean_cmd ("notification", no_class, ¬if_debug,
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_("\
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Set debugging of async remote notification."), _("\
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Show debugging of async remote notification."), _("\
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When non-zero, debugging output about async remote notifications"
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" is enabled."),
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NULL,
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NULL,
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&setdebuglist, &showdebuglist);
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}
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