[deliverable/binutils-gdb.git] / gdb / remote-notif.c

/* Remote notification in GDB protocol

   Copyright (C) 1988-2017 Free Software Foundation, Inc.

   This file is part of GDB.

   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 3 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, see <http://www.gnu.org/licenses/>.  */

/* Remote async notification is sent from remote target over RSP.
   Each type of notification is represented by an object of
   'struct notif', which has a field 'pending_reply'.  It is not
   NULL when GDB receives a notification from GDBserver, but hasn't
   acknowledge yet.  Before GDB acknowledges the notification,
   GDBserver shouldn't send notification again (see the header comments
   in gdbserver/notif.c).

   Notifications are processed in an almost-unified approach for both
   all-stop mode and non-stop mode, except the timing to process them.
   In non-stop mode, notifications are processed in
   remote_async_get_pending_events_handler, while in all-stop mode,
   they are processed in remote_resume.  */

#include "defs.h"
#include "remote.h"
#include "remote-notif.h"
#include "observer.h"
#include "event-loop.h"
#include "target.h"
#include "inferior.h"
#include "infrun.h"
#include "gdbcmd.h"

int notif_debug = 0;

/* Supported clients of notifications.  */

static struct notif_client *notifs[] =
{
  &notif_client_stop,
};

gdb_static_assert (ARRAY_SIZE (notifs) == REMOTE_NOTIF_LAST);

static void do_notif_event_xfree (void *arg);

/* Parse the BUF for the expected notification NC, and send packet to
   acknowledge.  */

void
remote_notif_ack (struct notif_client *nc, char *buf)
{
  struct notif_event *event = nc->alloc_event ();
  struct cleanup *old_chain
    = make_cleanup (do_notif_event_xfree, event);

  if (notif_debug)
    fprintf_unfiltered (gdb_stdlog, "notif: ack '%s'\n",
			nc->ack_command);

  nc->parse (nc, buf, event);
  nc->ack (nc, buf, event);

  discard_cleanups (old_chain);
}

/* Parse the BUF for the expected notification NC.  */

struct notif_event *
remote_notif_parse (struct notif_client *nc, char *buf)
{
  struct notif_event *event = nc->alloc_event ();
  struct cleanup *old_chain
    = make_cleanup (do_notif_event_xfree, event);

  if (notif_debug)
    fprintf_unfiltered (gdb_stdlog, "notif: parse '%s'\n", nc->name);

  nc->parse (nc, buf, event);

  discard_cleanups (old_chain);
  return event;
}

DEFINE_QUEUE_P (notif_client_p);

/* Process notifications in STATE's notification queue one by one.
   EXCEPT is not expected in the queue.  */

void
remote_notif_process (struct remote_notif_state *state,
		      struct notif_client *except)
{
  while (!QUEUE_is_empty (notif_client_p, state->notif_queue))
    {
      struct notif_client *nc = QUEUE_deque (notif_client_p,
					     state->notif_queue);

      gdb_assert (nc != except);

      if (nc->can_get_pending_events (nc))
	remote_notif_get_pending_events (nc);
    }
}

static void
remote_async_get_pending_events_handler (gdb_client_data data)
{
  gdb_assert (target_is_non_stop_p ());
  remote_notif_process ((struct remote_notif_state *) data, NULL);
}

/* Remote notification handler.  Parse BUF, queue notification and
   update STATE.  */

void
handle_notification (struct remote_notif_state *state, char *buf)
{
  struct notif_client *nc;
  size_t i;

  for (i = 0; i < ARRAY_SIZE (notifs); i++)
    {
      const char *name = notifs[i]->name;

      if (startswith (buf, name)
	  && buf[strlen (name)] == ':')
	break;
    }

  /* We ignore notifications we don't recognize, for compatibility
     with newer stubs.  */
  if (i == ARRAY_SIZE (notifs))
    return;

  nc =  notifs[i];

  if (state->pending_event[nc->id] != NULL)
    {
      /* We've already parsed the in-flight reply, but the stub for some
	 reason thought we didn't, possibly due to timeout on its side.
	 Just ignore it.  */
      if (notif_debug)
	fprintf_unfiltered (gdb_stdlog,
			    "notif: ignoring resent notification\n");
    }
  else
    {
      struct notif_event *event
	= remote_notif_parse (nc, buf + strlen (nc->name) + 1);

      /* Be careful to only set it after parsing, since an error
	 may be thrown then.  */
      state->pending_event[nc->id] = event;

      /* Notify the event loop there's a stop reply to acknowledge
	 and that there may be more events to fetch.  */
      QUEUE_enque (notif_client_p, state->notif_queue, nc);
      if (target_is_non_stop_p ())
	{
	  /* In non-stop, We mark REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN
	     in order to go on what we were doing and postpone
	     querying notification events to some point safe to do so.
	     See details in the function comment of
	     remote.c:remote_notif_get_pending_events.

	     In all-stop, GDB may be blocked to wait for the reply, we
	     shouldn't return to event loop until the expected reply
	     arrives.  For example:

	     1.1) --> vCont;c
	       GDB expects getting stop reply 'T05 thread:2'.
	     1.2) <-- %Notif
	       <GDB marks the REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN>

	     After step #1.2, we return to the event loop, which
	     notices there is a new event on the
	     REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN and calls the
	     handler, which will send 'vNotif' packet.
	     1.3) --> vNotif
	     It is not safe to start a new sequence, because target
	     is still running and GDB is expecting the stop reply
	     from stub.

	     To solve this, whenever we parse a notification
	     successfully, we don't mark the
	     REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN and let GDB blocked
	     there as before to get the sequence done.

	     2.1) --> vCont;c
	       GDB expects getting stop reply 'T05 thread:2'
	     2.2) <-- %Notif
	       <Don't mark the REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN>
	     2.3) <-- T05 thread:2

	     These pending notifications can be processed later.  */
	  mark_async_event_handler (state->get_pending_events_token);
	}

      if (notif_debug)
	fprintf_unfiltered (gdb_stdlog,
			    "notif: Notification '%s' captured\n",
			    nc->name);
    }
}

/* Invoke destructor of EVENT and xfree it.  */

void
notif_event_xfree (struct notif_event *event)
{
  if (event != NULL && event->dtr != NULL)
    event->dtr (event);

  xfree (event);
}

/* Cleanup wrapper.  */

static void
do_notif_event_xfree (void *arg)
{
  notif_event_xfree ((struct notif_event *) arg);
}

/* Return an allocated remote_notif_state.  */

struct remote_notif_state *
remote_notif_state_allocate (void)
{
  struct remote_notif_state *notif_state = XCNEW (struct remote_notif_state);

  notif_state->notif_queue = QUEUE_alloc (notif_client_p, NULL);

  /* Register async_event_handler for notification.  */

  notif_state->get_pending_events_token
    = create_async_event_handler (remote_async_get_pending_events_handler,
				  notif_state);

  return notif_state;
}

/* Free STATE and its fields.  */

void
remote_notif_state_xfree (struct remote_notif_state *state)
{
  int i;

  QUEUE_free (notif_client_p, state->notif_queue);

  /* Unregister async_event_handler for notification.  */
  if (state->get_pending_events_token != NULL)
    delete_async_event_handler (&state->get_pending_events_token);

  for (i = 0; i < REMOTE_NOTIF_LAST; i++)
    notif_event_xfree (state->pending_event[i]);

  xfree (state);
}

/* -Wmissing-prototypes */
extern initialize_file_ftype _initialize_notif;

void
_initialize_notif (void)
{
  add_setshow_boolean_cmd ("notification", no_class, &notif_debug,
			   _("\
Set debugging of async remote notification."), _("\
Show debugging of async remote notification."), _("\
When non-zero, debugging output about async remote notifications"
" is enabled."),
			   NULL,
			   NULL,
			   &setdebuglist, &showdebuglist);
}
Commit	Line	Data
722247f1 YQ	1	/* Remote notification in GDB protocol
722247f1 YQ	2
61baf725	3	Copyright (C) 1988-2017 Free Software Foundation, Inc.
722247f1 YQ	4
	5	This file is part of GDB.
	6
	7	This program is free software; you can redistribute it and/or modify
	8	it under the terms of the GNU General Public License as published by
	9	the Free Software Foundation; either version 3 of the License, or
	10	(at your option) any later version.
	11
	12	This program is distributed in the hope that it will be useful,
	13	but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	GNU General Public License for more details.
	16
	17	You should have received a copy of the GNU General Public License
	18	along with this program. If not, see <http://www.gnu.org/licenses/>. */
	19
	20	/* Remote async notification is sent from remote target over RSP.
	21	Each type of notification is represented by an object of
	22	'struct notif', which has a field 'pending_reply'. It is not
	23	NULL when GDB receives a notification from GDBserver, but hasn't
	24	acknowledge yet. Before GDB acknowledges the notification,
	25	GDBserver shouldn't send notification again (see the header comments
	26	in gdbserver/notif.c).
	27
	28	Notifications are processed in an almost-unified approach for both
	29	all-stop mode and non-stop mode, except the timing to process them.
	30	In non-stop mode, notifications are processed in
	31	remote_async_get_pending_events_handler, while in all-stop mode,
	32	they are processed in remote_resume. */
	33
	34	#include "defs.h"
	35	#include "remote.h"
	36	#include "remote-notif.h"
	37	#include "observer.h"
	38	#include "event-loop.h"
	39	#include "target.h"
	40	#include "inferior.h"
45741a9c	41	#include "infrun.h"
c9b6281a	42	#include "gdbcmd.h"
722247f1	43
99f0a309	44	int notif_debug = 0;
722247f1 YQ	45
	46	/* Supported clients of notifications. */
	47
	48	static struct notif_client *notifs[] =
	49	{
	50	&notif_client_stop,
	51	};
	52
f48ff2a7 YQ	53	gdb_static_assert (ARRAY_SIZE (notifs) == REMOTE_NOTIF_LAST);
f48ff2a7 YQ	54
722247f1 YQ	55	static void do_notif_event_xfree (void *arg);
	56
	57	/* Parse the BUF for the expected notification NC, and send packet to
	58	acknowledge. */
	59
	60	void
	61	remote_notif_ack (struct notif_client nc, char buf)
	62	{
	63	struct notif_event *event = nc->alloc_event ();
	64	struct cleanup *old_chain
	65	= make_cleanup (do_notif_event_xfree, event);
	66
	67	if (notif_debug)
	68	fprintf_unfiltered (gdb_stdlog, "notif: ack '%s'\n",
	69	nc->ack_command);
	70
	71	nc->parse (nc, buf, event);
	72	nc->ack (nc, buf, event);
	73
	74	discard_cleanups (old_chain);
	75	}
	76
	77	/* Parse the BUF for the expected notification NC. */
	78
	79	struct notif_event *
	80	remote_notif_parse (struct notif_client nc, char buf)
	81	{
	82	struct notif_event *event = nc->alloc_event ();
	83	struct cleanup *old_chain
	84	= make_cleanup (do_notif_event_xfree, event);
	85
	86	if (notif_debug)
	87	fprintf_unfiltered (gdb_stdlog, "notif: parse '%s'\n", nc->name);
	88
	89	nc->parse (nc, buf, event);
	90
	91	discard_cleanups (old_chain);
	92	return event;
	93	}
	94
722247f1 YQ	95	DEFINE_QUEUE_P (notif_client_p);
722247f1 YQ	96
5965e028 YQ	97	/* Process notifications in STATE's notification queue one by one.
5965e028 YQ	98	EXCEPT is not expected in the queue. */
722247f1 YQ	99
722247f1 YQ	100	void
5965e028 YQ	101	remote_notif_process (struct remote_notif_state *state,
5965e028 YQ	102	struct notif_client *except)
722247f1	103	{
5965e028	104	while (!QUEUE_is_empty (notif_client_p, state->notif_queue))
722247f1 YQ	105	{
722247f1 YQ	106	struct notif_client *nc = QUEUE_deque (notif_client_p,
5965e028	107	state->notif_queue);
722247f1 YQ	108
	109	gdb_assert (nc != except);
	110
	111	if (nc->can_get_pending_events (nc))
	112	remote_notif_get_pending_events (nc);
	113	}
	114	}
	115
	116	static void
	117	remote_async_get_pending_events_handler (gdb_client_data data)
	118	{
6efcd9a8	119	gdb_assert (target_is_non_stop_p ());
19ba03f4	120	remote_notif_process ((struct remote_notif_state *) data, NULL);
722247f1 YQ	121	}
722247f1 YQ	122
5965e028 YQ	123	/* Remote notification handler. Parse BUF, queue notification and
5965e028 YQ	124	update STATE. */
722247f1 YQ	125
722247f1 YQ	126	void
5965e028	127	handle_notification (struct remote_notif_state state, char buf)
722247f1	128	{
62972e0b YQ	129	struct notif_client *nc;
62972e0b YQ	130	size_t i;
722247f1 YQ	131
	132	for (i = 0; i < ARRAY_SIZE (notifs); i++)
	133	{
62972e0b YQ	134	const char *name = notifs[i]->name;
62972e0b YQ	135
61012eef	136	if (startswith (buf, name)
62972e0b	137	&& buf[strlen (name)] == ':')
722247f1 YQ	138	break;
	139	}
	140
	141	/* We ignore notifications we don't recognize, for compatibility
	142	with newer stubs. */
62972e0b	143	if (i == ARRAY_SIZE (notifs))
722247f1 YQ	144	return;
722247f1 YQ	145
62972e0b YQ	146	nc = notifs[i];
62972e0b YQ	147
f48ff2a7	148	if (state->pending_event[nc->id] != NULL)
722247f1 YQ	149	{
	150	/* We've already parsed the in-flight reply, but the stub for some
	151	reason thought we didn't, possibly due to timeout on its side.
	152	Just ignore it. */
	153	if (notif_debug)
	154	fprintf_unfiltered (gdb_stdlog,
	155	"notif: ignoring resent notification\n");
	156	}
	157	else
	158	{
	159	struct notif_event *event
	160	= remote_notif_parse (nc, buf + strlen (nc->name) + 1);
	161
	162	/* Be careful to only set it after parsing, since an error
	163	may be thrown then. */
f48ff2a7	164	state->pending_event[nc->id] = event;
722247f1 YQ	165
	166	/* Notify the event loop there's a stop reply to acknowledge
	167	and that there may be more events to fetch. */
5965e028	168	QUEUE_enque (notif_client_p, state->notif_queue, nc);
6efcd9a8	169	if (target_is_non_stop_p ())
722247f1 YQ	170	{
	171	/* In non-stop, We mark REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN
	172	in order to go on what we were doing and postpone
	173	querying notification events to some point safe to do so.
	174	See details in the function comment of
	175	remote.c:remote_notif_get_pending_events.
	176
	177	In all-stop, GDB may be blocked to wait for the reply, we
	178	shouldn't return to event loop until the expected reply
	179	arrives. For example:
	180
	181	1.1) --> vCont;c
	182	GDB expects getting stop reply 'T05 thread:2'.
	183	1.2) <-- %Notif
	184	<GDB marks the REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN>
	185
	186	After step #1.2, we return to the event loop, which
	187	notices there is a new event on the
	188	REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN and calls the
	189	handler, which will send 'vNotif' packet.
	190	1.3) --> vNotif
	191	It is not safe to start a new sequence, because target
	192	is still running and GDB is expecting the stop reply
	193	from stub.
	194
	195	To solve this, whenever we parse a notification
	196	successfully, we don't mark the
	197	REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN and let GDB blocked
	198	there as before to get the sequence done.
	199
	200	2.1) --> vCont;c
	201	GDB expects getting stop reply 'T05 thread:2'
	202	2.2) <-- %Notif
	203	<Don't mark the REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN>
	204	2.3) <-- T05 thread:2
	205
	206	These pending notifications can be processed later. */
5965e028	207	mark_async_event_handler (state->get_pending_events_token);
722247f1 YQ	208	}
	209
	210	if (notif_debug)
	211	fprintf_unfiltered (gdb_stdlog,
	212	"notif: Notification '%s' captured\n",
	213	nc->name);
	214	}
	215	}
	216
f48ff2a7	217	/* Invoke destructor of EVENT and xfree it. */
722247f1	218
f48ff2a7 YQ	219	void
f48ff2a7 YQ	220	notif_event_xfree (struct notif_event *event)
722247f1	221	{
f48ff2a7	222	if (event != NULL && event->dtr != NULL)
722247f1 YQ	223	event->dtr (event);
	224
	225	xfree (event);
	226	}
	227
f48ff2a7 YQ	228	/* Cleanup wrapper. */
	229
	230	static void
	231	do_notif_event_xfree (void *arg)
	232	{
19ba03f4	233	notif_event_xfree ((struct notif_event *) arg);
f48ff2a7 YQ	234	}
f48ff2a7 YQ	235
5965e028 YQ	236	/* Return an allocated remote_notif_state. */
	237
	238	struct remote_notif_state *
	239	remote_notif_state_allocate (void)
	240	{
8d749320	241	struct remote_notif_state *notif_state = XCNEW (struct remote_notif_state);
5965e028 YQ	242
	243	notif_state->notif_queue = QUEUE_alloc (notif_client_p, NULL);
	244
	245	/* Register async_event_handler for notification. */
	246
	247	notif_state->get_pending_events_token
	248	= create_async_event_handler (remote_async_get_pending_events_handler,
	249	notif_state);
	250
	251	return notif_state;
	252	}
	253
	254	/* Free STATE and its fields. */
	255
	256	void
	257	remote_notif_state_xfree (struct remote_notif_state *state)
722247f1	258	{
f48ff2a7 YQ	259	int i;
f48ff2a7 YQ	260
5965e028 YQ	261	QUEUE_free (notif_client_p, state->notif_queue);
	262
	263	/* Unregister async_event_handler for notification. */
	264	if (state->get_pending_events_token != NULL)
	265	delete_async_event_handler (&state->get_pending_events_token);
722247f1	266
f48ff2a7 YQ	267	for (i = 0; i < REMOTE_NOTIF_LAST; i++)
	268	notif_event_xfree (state->pending_event[i]);
	269
5965e028	270	xfree (state);
722247f1 YQ	271	}
	272
	273	/* -Wmissing-prototypes */
	274	extern initialize_file_ftype _initialize_notif;
	275
	276	void
	277	_initialize_notif (void)
	278	{
c9b6281a YQ	279	add_setshow_boolean_cmd ("notification", no_class, &notif_debug,
	280	_("\
	281	Set debugging of async remote notification."), _("\
	282	Show debugging of async remote notification."), _("\
	283	When non-zero, debugging output about async remote notifications"
	284	" is enabled."),
	285	NULL,
	286	NULL,
	287	&setdebuglist, &showdebuglist);
722247f1	288	}