[lttng-tools.git] / src / common / actions / snapshot-session.c

/*
 * Copyright (C) 2019 Simon Marchi <simon.marchi@efficios.com>
 *
 * SPDX-License-Identifier: LGPL-2.1-only
 *
 */

#include <assert.h>
#include <common/error.h>
#include <common/macros.h>
#include <common/snapshot.h>
#include <common/payload.h>
#include <common/payload-view.h>
#include <lttng/action/action-internal.h>
#include <lttng/action/snapshot-session-internal.h>
#include <lttng/action/snapshot-session.h>
#include <lttng/snapshot.h>
#include <lttng/snapshot-internal.h>
#include <inttypes.h>

#define IS_SNAPSHOT_SESSION_ACTION(action) \
	(lttng_action_get_type(action) == LTTNG_ACTION_TYPE_SNAPSHOT_SESSION)

struct lttng_action_snapshot_session {
	struct lttng_action parent;

	/* Owned by this. */
	char *session_name;

	/*
	 * When non-NULL, use this custom output when taking the snapshot,
	 * rather than the session's registered snapshot output.
	 *
	 * Owned by this.
	 */
	struct lttng_snapshot_output *output;
};

struct lttng_action_snapshot_session_comm {
	/* All string lengths include the trailing \0. */
	uint32_t session_name_len;
	uint32_t snapshot_output_len;

	/*
	 * Variable data (all strings are null-terminated):
	 *
	 *  - session name string
	 *  - snapshot output object
	 *
	 */
	char data[];
} LTTNG_PACKED;

static struct lttng_action_snapshot_session *
action_snapshot_session_from_action(struct lttng_action *action)
{
	assert(action);

	return container_of(
			action, struct lttng_action_snapshot_session, parent);
}

static const struct lttng_action_snapshot_session *
action_snapshot_session_from_action_const(const struct lttng_action *action)
{
	assert(action);

	return container_of(
			action, struct lttng_action_snapshot_session, parent);
}

static bool lttng_action_snapshot_session_validate(struct lttng_action *action)
{
	bool valid = false;
	struct lttng_action_snapshot_session *action_snapshot_session;

	if (!action) {
		goto end;
	}

	action_snapshot_session = action_snapshot_session_from_action(action);

	/* A non-empty session name is mandatory. */
	if (!action_snapshot_session->session_name ||
			strlen(action_snapshot_session->session_name) == 0) {
		goto end;
	}

	if (action_snapshot_session->output &&
			!lttng_snapshot_output_validate(action_snapshot_session->output)) {
		goto end;
	}

	valid = true;
end:
	return valid;
}

static bool lttng_action_snapshot_session_is_equal(
		const struct lttng_action *_a, const struct lttng_action *_b)
{
	bool is_equal = false;
	const struct lttng_action_snapshot_session *a, *b;

	a = action_snapshot_session_from_action_const(_a);
	b = action_snapshot_session_from_action_const(_b);

	/* Action is not valid if this is not true. */
	assert(a->session_name);
	assert(b->session_name);
	if (strcmp(a->session_name, b->session_name)) {
		goto end;
	}

	if (a->output && b->output &&
			!lttng_snapshot_output_is_equal(a->output, b->output)) {
		goto end;
	} else if (!!a->output != !!b->output) {
		goto end;
	}

	is_equal = true;
end:
	return is_equal;
}

static size_t serialize_strlen(const char *str)
{
	return str ? strlen(str) + 1 : 0;
}

static int lttng_action_snapshot_session_serialize(
		struct lttng_action *action, struct lttng_payload *payload)
{
	struct lttng_action_snapshot_session *action_snapshot_session;
	struct lttng_action_snapshot_session_comm comm = {};
	int ret;
	size_t size_before_comm;

	assert(action);
	assert(payload);

	size_before_comm = payload->buffer.size;

	action_snapshot_session = action_snapshot_session_from_action(action);
	comm.session_name_len =
		serialize_strlen(action_snapshot_session->session_name);

	/* Add header. */
	ret = lttng_dynamic_buffer_append(
			&payload->buffer, &comm, sizeof(comm));
	if (ret) {
		goto end;
	}

	assert(action_snapshot_session->session_name);
	DBG("Serializing snapshot session action: session-name: %s",
			action_snapshot_session->session_name);

	/* Add session name. */
	ret = lttng_dynamic_buffer_append(&payload->buffer,
			action_snapshot_session->session_name,
			comm.session_name_len);
	if (ret) {
		goto end;
	}

	/* Serialize the snapshot output object, if any. */
	if (action_snapshot_session->output) {
		const size_t size_before_output = payload->buffer.size;
		struct lttng_action_snapshot_session_comm *comm_in_payload;

		ret = lttng_snapshot_output_serialize(
				action_snapshot_session->output,
				payload);
		if (ret) {
			goto end;
		}

		/* Adjust action length in header. */
		comm_in_payload = (typeof(comm_in_payload))(
				payload->buffer.data + size_before_comm);
		comm_in_payload->snapshot_output_len =
				payload->buffer.size - size_before_output;
	}

end:
	return ret;
}

static void lttng_action_snapshot_session_destroy(struct lttng_action *action)
{
	struct lttng_action_snapshot_session *action_snapshot_session;

	if (!action) {
		goto end;
	}

	action_snapshot_session = action_snapshot_session_from_action(action);

	free(action_snapshot_session->session_name);
	lttng_snapshot_output_destroy(action_snapshot_session->output);
	free(action_snapshot_session);

end:
	return;
}

ssize_t lttng_action_snapshot_session_create_from_payload(
		struct lttng_payload_view *view,
		struct lttng_action **p_action)
{
	ssize_t consumed_len;
	const char *variable_data;
	struct lttng_action *action;
	enum lttng_action_status status;
	struct lttng_snapshot_output *snapshot_output = NULL;
	const struct lttng_action_snapshot_session_comm *comm;
	const struct lttng_payload_view snapshot_session_comm_view =
			lttng_payload_view_from_view(
				view, 0, sizeof(*comm));

	action = lttng_action_snapshot_session_create();
	if (!action) {
		goto error;
	}

	if (!lttng_payload_view_is_valid(&snapshot_session_comm_view)) {
		/* Payload not large enough to contain the header. */
		goto error;
	}

	comm = (typeof(comm)) snapshot_session_comm_view.buffer.data;
	variable_data = (const char *) &comm->data;

	consumed_len = sizeof(struct lttng_action_snapshot_session_comm);

	if (!lttng_buffer_view_contains_string(
			&view->buffer, variable_data, comm->session_name_len)) {
		goto error;
	}

	status = lttng_action_snapshot_session_set_session_name(
			action, variable_data);
	if (status != LTTNG_ACTION_STATUS_OK) {
		goto error;
	}

	variable_data += comm->session_name_len;
	consumed_len += comm->session_name_len;

	/* If there is a snapshot output object, deserialize it. */
	if (comm->snapshot_output_len > 0) {
		ssize_t snapshot_output_consumed_len;
		enum lttng_action_status action_status;
		struct lttng_payload_view snapshot_output_buffer_view =
			lttng_payload_view_from_view(view, consumed_len,
				comm->snapshot_output_len);

		if (!lttng_payload_view_is_valid(&snapshot_output_buffer_view)) {
			ERR("Failed to create buffer view for snapshot output.");
			goto error;
		}

		snapshot_output_consumed_len =
				lttng_snapshot_output_create_from_payload(
						&snapshot_output_buffer_view,
						&snapshot_output);
		if (snapshot_output_consumed_len != comm->snapshot_output_len) {
			ERR("Failed to deserialize snapshot output object: "
					"consumed-len: %zd, expected-len: %" PRIu32,
					snapshot_output_consumed_len,
					comm->snapshot_output_len);
			goto error;
		}

		action_status = lttng_action_snapshot_session_set_output(
			action, snapshot_output);
		if (action_status != LTTNG_ACTION_STATUS_OK) {
			goto error;
		}

		/* Ownership has been transferred to the action. */
		snapshot_output = NULL;
	}

	variable_data += comm->snapshot_output_len;
	consumed_len += comm->snapshot_output_len;
	*p_action = action;
	action = NULL;

	goto end;

error:
	consumed_len = -1;

end:
	lttng_action_snapshot_session_destroy(action);
	lttng_snapshot_output_destroy(snapshot_output);

	return consumed_len;
}

struct lttng_action *lttng_action_snapshot_session_create(void)
{
	struct lttng_action *action;

	action = zmalloc(sizeof(struct lttng_action_snapshot_session));
	if (!action) {
		goto end;
	}

	lttng_action_init(action, LTTNG_ACTION_TYPE_SNAPSHOT_SESSION,
			lttng_action_snapshot_session_validate,
			lttng_action_snapshot_session_serialize,
			lttng_action_snapshot_session_is_equal,
			lttng_action_snapshot_session_destroy);

end:
	return action;
}

enum lttng_action_status lttng_action_snapshot_session_set_session_name(
		struct lttng_action *action, const char *session_name)
{
	struct lttng_action_snapshot_session *action_snapshot_session;
	enum lttng_action_status status;

	if (!action || !IS_SNAPSHOT_SESSION_ACTION(action) || !session_name ||
			strlen(session_name) == 0) {
		status = LTTNG_ACTION_STATUS_INVALID;
		goto end;
	}

	action_snapshot_session = action_snapshot_session_from_action(action);

	free(action_snapshot_session->session_name);

	action_snapshot_session->session_name = strdup(session_name);
	if (!action_snapshot_session->session_name) {
		status = LTTNG_ACTION_STATUS_ERROR;
		goto end;
	}

	status = LTTNG_ACTION_STATUS_OK;
end:
	return status;
}

enum lttng_action_status lttng_action_snapshot_session_get_session_name(
		const struct lttng_action *action, const char **session_name)
{
	const struct lttng_action_snapshot_session *action_snapshot_session;
	enum lttng_action_status status;

	if (!action || !IS_SNAPSHOT_SESSION_ACTION(action) || !session_name) {
		status = LTTNG_ACTION_STATUS_INVALID;
		goto end;
	}

	action_snapshot_session = action_snapshot_session_from_action_const(action);

	if (action_snapshot_session->session_name) {
		*session_name = action_snapshot_session->session_name;
		status = LTTNG_ACTION_STATUS_OK;
	} else {
		status = LTTNG_ACTION_STATUS_UNSET;
	}

end:

	return status;
}

enum lttng_action_status lttng_action_snapshot_session_set_output(
		struct lttng_action *action,
		struct lttng_snapshot_output *output)
{
	struct lttng_action_snapshot_session *action_snapshot_session;
	enum lttng_action_status status;

	if (!action || !IS_SNAPSHOT_SESSION_ACTION(action) || !output) {
		status = LTTNG_ACTION_STATUS_INVALID;
		goto end;
	}

	action_snapshot_session = action_snapshot_session_from_action(action);

	lttng_snapshot_output_destroy(action_snapshot_session->output);
	action_snapshot_session->output = output;

	status = LTTNG_ACTION_STATUS_OK;

end:
	return status;
}

enum lttng_action_status lttng_action_snapshot_session_get_output(
		const struct lttng_action *action,
		const struct lttng_snapshot_output **output)
{
	const struct lttng_action_snapshot_session *action_snapshot_session;
	enum lttng_action_status status;

	if (!action || !IS_SNAPSHOT_SESSION_ACTION(action)|| !output) {
		status = LTTNG_ACTION_STATUS_INVALID;
		goto end;
	}

	action_snapshot_session = action_snapshot_session_from_action_const(action);

	if (action_snapshot_session->output) {
		*output = action_snapshot_session->output;
		status = LTTNG_ACTION_STATUS_OK;
	} else {
		status = LTTNG_ACTION_STATUS_UNSET;
	}

end:
	return status;
}
Commit	Line	Data
757c48a2 SM	1	/*
	2	* Copyright (C) 2019 Simon Marchi <simon.marchi@efficios.com>
	3	*
	4	* SPDX-License-Identifier: LGPL-2.1-only
	5	*
	6	*/
	7
	8	#include <assert.h>
	9	#include <common/error.h>
	10	#include <common/macros.h>
	11	#include <common/snapshot.h>
9e620ea7 JG	12	#include <common/payload.h>
9e620ea7 JG	13	#include <common/payload-view.h>
757c48a2 SM	14	#include <lttng/action/action-internal.h>
	15	#include <lttng/action/snapshot-session-internal.h>
	16	#include <lttng/action/snapshot-session.h>
	17	#include <lttng/snapshot.h>
	18	#include <lttng/snapshot-internal.h>
	19	#include <inttypes.h>
	20
	21	#define IS_SNAPSHOT_SESSION_ACTION(action) \
17182cfd	22	(lttng_action_get_type(action) == LTTNG_ACTION_TYPE_SNAPSHOT_SESSION)
757c48a2 SM	23
	24	struct lttng_action_snapshot_session {
	25	struct lttng_action parent;
	26
	27	/* Owned by this. */
	28	char *session_name;
	29
	30	/*
	31	* When non-NULL, use this custom output when taking the snapshot,
	32	* rather than the session's registered snapshot output.
	33	*
	34	* Owned by this.
	35	*/
	36	struct lttng_snapshot_output *output;
	37	};
	38
	39	struct lttng_action_snapshot_session_comm {
	40	/* All string lengths include the trailing \0. */
	41	uint32_t session_name_len;
	42	uint32_t snapshot_output_len;
	43
	44	/*
	45	* Variable data (all strings are null-terminated):
	46	*
	47	* - session name string
	48	* - snapshot output object
	49	*
	50	*/
	51	char data[];
	52	} LTTNG_PACKED;
	53
	54	static struct lttng_action_snapshot_session *
	55	action_snapshot_session_from_action(struct lttng_action *action)
	56	{
	57	assert(action);
	58
	59	return container_of(
	60	action, struct lttng_action_snapshot_session, parent);
	61	}
	62
	63	static const struct lttng_action_snapshot_session *
	64	action_snapshot_session_from_action_const(const struct lttng_action *action)
	65	{
	66	assert(action);
	67
	68	return container_of(
	69	action, struct lttng_action_snapshot_session, parent);
	70	}
	71
	72	static bool lttng_action_snapshot_session_validate(struct lttng_action *action)
	73	{
	74	bool valid = false;
	75	struct lttng_action_snapshot_session *action_snapshot_session;
	76
	77	if (!action) {
	78	goto end;
	79	}
	80
	81	action_snapshot_session = action_snapshot_session_from_action(action);
	82
	83	/* A non-empty session name is mandatory. */
	84	if (!action_snapshot_session->session_name \|\|
	85	strlen(action_snapshot_session->session_name) == 0) {
	86	goto end;
87	}
88
89	if (action_snapshot_session->output &&
90	!lttng_snapshot_output_validate(action_snapshot_session->output)) {
91	goto end;
92	}
93
94	valid = true;
95	end:
96	return valid;
97	}
98
99	static bool lttng_action_snapshot_session_is_equal(
100	const struct lttng_action _a, const struct lttng_action _b)
101	{
102	bool is_equal = false;
103	const struct lttng_action_snapshot_session a, b;
104
105	a = action_snapshot_session_from_action_const(_a);
106	b = action_snapshot_session_from_action_const(_b);
107
108	/* Action is not valid if this is not true. */
109	assert(a->session_name);
110	assert(b->session_name);
111	if (strcmp(a->session_name, b->session_name)) {
112	goto end;
113	}
114
115	if (a->output && b->output &&
116	!lttng_snapshot_output_is_equal(a->output, b->output)) {
117	goto end;
118	} else if (!!a->output != !!b->output) {
119	goto end;
120	}
121
122	is_equal = true;
123	end:
124	return is_equal;
125	}
126
0c51e8f3	127	static size_t serialize_strlen(const char *str)
757c48a2	128	{
0c51e8f3	129	return str ? strlen(str) + 1 : 0;
757c48a2 SM	130	}
	131
	132	static int lttng_action_snapshot_session_serialize(
	133	struct lttng_action action, struct lttng_payload payload)
	134	{
	135	struct lttng_action_snapshot_session *action_snapshot_session;
	136	struct lttng_action_snapshot_session_comm comm = {};
	137	int ret;
	138	size_t size_before_comm;
	139
	140	assert(action);
	141	assert(payload);
	142
	143	size_before_comm = payload->buffer.size;
757c48a2 SM	144
	145	action_snapshot_session = action_snapshot_session_from_action(action);
	146	comm.session_name_len =
	147	serialize_strlen(action_snapshot_session->session_name);
	148
	149	/* Add header. */
	150	ret = lttng_dynamic_buffer_append(
	151	&payload->buffer, &comm, sizeof(comm));
	152	if (ret) {
	153	goto end;
	154	}
	155
	156	assert(action_snapshot_session->session_name);
	157	DBG("Serializing snapshot session action: session-name: %s",
	158	action_snapshot_session->session_name);
	159
	160	/* Add session name. */
	161	ret = lttng_dynamic_buffer_append(&payload->buffer,
	162	action_snapshot_session->session_name,
	163	comm.session_name_len);
	164	if (ret) {
	165	goto end;
	166	}
	167
	168	/* Serialize the snapshot output object, if any. */
	169	if (action_snapshot_session->output) {
	170	const size_t size_before_output = payload->buffer.size;
	171	struct lttng_action_snapshot_session_comm *comm_in_payload;
	172
	173	ret = lttng_snapshot_output_serialize(
	174	action_snapshot_session->output,
	175	payload);
	176	if (ret) {
	177	goto end;
	178	}
	179
	180	/* Adjust action length in header. */
	181	comm_in_payload = (typeof(comm_in_payload))(
	182	payload->buffer.data + size_before_comm);
	183	comm_in_payload->snapshot_output_len =
	184	payload->buffer.size - size_before_output;
	185	}
	186
	187	end:
	188	return ret;
	189	}
	190
	191	static void lttng_action_snapshot_session_destroy(struct lttng_action *action)
	192	{
	193	struct lttng_action_snapshot_session *action_snapshot_session;
	194
	195	if (!action) {
	196	goto end;
	197	}
	198
	199	action_snapshot_session = action_snapshot_session_from_action(action);
	200
	201	free(action_snapshot_session->session_name);
	202	lttng_snapshot_output_destroy(action_snapshot_session->output);
	203	free(action_snapshot_session);
	204
	205	end:
	206	return;
	207	}
208
209	ssize_t lttng_action_snapshot_session_create_from_payload(
210	struct lttng_payload_view *view,
211	struct lttng_action **p_action)
212	{
213	ssize_t consumed_len;
757c48a2 SM	214	const char *variable_data;
	215	struct lttng_action *action;
	216	enum lttng_action_status status;
	217	struct lttng_snapshot_output *snapshot_output = NULL;
3e6e0df2 JG	218	const struct lttng_action_snapshot_session_comm *comm;
	219	const struct lttng_payload_view snapshot_session_comm_view =
	220	lttng_payload_view_from_view(
	221	view, 0, sizeof(*comm));
757c48a2 SM	222
	223	action = lttng_action_snapshot_session_create();
	224	if (!action) {
	225	goto error;
	226	}
	227
3e6e0df2 JG	228	if (!lttng_payload_view_is_valid(&snapshot_session_comm_view)) {
	229	/* Payload not large enough to contain the header. */
	230	goto error;
	231	}
	232
	233	comm = (typeof(comm)) snapshot_session_comm_view.buffer.data;
757c48a2 SM	234	variable_data = (const char *) &comm->data;
	235
	236	consumed_len = sizeof(struct lttng_action_snapshot_session_comm);
	237
	238	if (!lttng_buffer_view_contains_string(
	239	&view->buffer, variable_data, comm->session_name_len)) {
	240	goto error;
	241	}
	242
	243	status = lttng_action_snapshot_session_set_session_name(
	244	action, variable_data);
	245	if (status != LTTNG_ACTION_STATUS_OK) {
	246	goto error;
	247	}
	248
	249	variable_data += comm->session_name_len;
	250	consumed_len += comm->session_name_len;
	251
	252	/* If there is a snapshot output object, deserialize it. */
	253	if (comm->snapshot_output_len > 0) {
	254	ssize_t snapshot_output_consumed_len;
	255	enum lttng_action_status action_status;
	256	struct lttng_payload_view snapshot_output_buffer_view =
	257	lttng_payload_view_from_view(view, consumed_len,
	258	comm->snapshot_output_len);
	259
3e6e0df2	260	if (!lttng_payload_view_is_valid(&snapshot_output_buffer_view)) {
0c51e8f3	261	ERR("Failed to create buffer view for snapshot output.");
757c48a2 SM	262	goto error;
	263	}
	264
	265	snapshot_output_consumed_len =
	266	lttng_snapshot_output_create_from_payload(
	267	&snapshot_output_buffer_view,
	268	&snapshot_output);
	269	if (snapshot_output_consumed_len != comm->snapshot_output_len) {
0c51e8f3	270	ERR("Failed to deserialize snapshot output object: "
757c48a2 SM	271	"consumed-len: %zd, expected-len: %" PRIu32,
	272	snapshot_output_consumed_len,
	273	comm->snapshot_output_len);
	274	goto error;
	275	}
	276
	277	action_status = lttng_action_snapshot_session_set_output(
	278	action, snapshot_output);
	279	if (action_status != LTTNG_ACTION_STATUS_OK) {
	280	goto error;
	281	}
	282
	283	/* Ownership has been transferred to the action. */
	284	snapshot_output = NULL;
	285	}
	286
	287	variable_data += comm->snapshot_output_len;
	288	consumed_len += comm->snapshot_output_len;
	289	*p_action = action;
	290	action = NULL;
	291
	292	goto end;
	293
	294	error:
	295	consumed_len = -1;
	296
	297	end:
	298	lttng_action_snapshot_session_destroy(action);
	299	lttng_snapshot_output_destroy(snapshot_output);
	300
	301	return consumed_len;
	302	}
	303
	304	struct lttng_action *lttng_action_snapshot_session_create(void)
	305	{
	306	struct lttng_action *action;
	307
	308	action = zmalloc(sizeof(struct lttng_action_snapshot_session));
	309	if (!action) {
	310	goto end;
	311	}
	312
	313	lttng_action_init(action, LTTNG_ACTION_TYPE_SNAPSHOT_SESSION,
	314	lttng_action_snapshot_session_validate,
	315	lttng_action_snapshot_session_serialize,
	316	lttng_action_snapshot_session_is_equal,
	317	lttng_action_snapshot_session_destroy);
	318
	319	end:
	320	return action;
	321	}
	322
	323	enum lttng_action_status lttng_action_snapshot_session_set_session_name(
	324	struct lttng_action action, const char session_name)
	325	{
	326	struct lttng_action_snapshot_session *action_snapshot_session;
	327	enum lttng_action_status status;
	328
	329	if (!action \|\| !IS_SNAPSHOT_SESSION_ACTION(action) \|\| !session_name \|\|
	330	strlen(session_name) == 0) {
	331	status = LTTNG_ACTION_STATUS_INVALID;
	332	goto end;
	333	}
	334
335	action_snapshot_session = action_snapshot_session_from_action(action);
336
337	free(action_snapshot_session->session_name);
338
339	action_snapshot_session->session_name = strdup(session_name);
340	if (!action_snapshot_session->session_name) {
341	status = LTTNG_ACTION_STATUS_ERROR;
342	goto end;
343	}
344
345	status = LTTNG_ACTION_STATUS_OK;
346	end:
347	return status;
348	}
349
350	enum lttng_action_status lttng_action_snapshot_session_get_session_name(
351	const struct lttng_action action, const char *session_name)
352	{
353	const struct lttng_action_snapshot_session *action_snapshot_session;
354	enum lttng_action_status status;
355
356	if (!action \|\| !IS_SNAPSHOT_SESSION_ACTION(action) \|\| !session_name) {
357	status = LTTNG_ACTION_STATUS_INVALID;
358	goto end;
359	}
360
361	action_snapshot_session = action_snapshot_session_from_action_const(action);
362
363	if (action_snapshot_session->session_name) {
364	*session_name = action_snapshot_session->session_name;
365	status = LTTNG_ACTION_STATUS_OK;
366	} else {
367	status = LTTNG_ACTION_STATUS_UNSET;
368	}
369
370	end:
371
372	return status;
373	}
374
375	enum lttng_action_status lttng_action_snapshot_session_set_output(
376	struct lttng_action *action,
377	struct lttng_snapshot_output *output)
378	{
379	struct lttng_action_snapshot_session *action_snapshot_session;
380	enum lttng_action_status status;
381
382	if (!action \|\| !IS_SNAPSHOT_SESSION_ACTION(action) \|\| !output) {
383	status = LTTNG_ACTION_STATUS_INVALID;
384	goto end;
385	}
386
387	action_snapshot_session = action_snapshot_session_from_action(action);
388
389	lttng_snapshot_output_destroy(action_snapshot_session->output);
390	action_snapshot_session->output = output;
391
392	status = LTTNG_ACTION_STATUS_OK;
393
394	end:
395	return status;
396	}
397
398	enum lttng_action_status lttng_action_snapshot_session_get_output(
399	const struct lttng_action *action,
400	const struct lttng_snapshot_output **output)
401	{
402	const struct lttng_action_snapshot_session *action_snapshot_session;
403	enum lttng_action_status status;
404
405	if (!action \|\| !IS_SNAPSHOT_SESSION_ACTION(action)\|\| !output) {
406	status = LTTNG_ACTION_STATUS_INVALID;
407	goto end;
408	}
409
410	action_snapshot_session = action_snapshot_session_from_action_const(action);
411
412	if (action_snapshot_session->output) {
413	*output = action_snapshot_session->output;
414	status = LTTNG_ACTION_STATUS_OK;
415	} else {
416	status = LTTNG_ACTION_STATUS_UNSET;
417	}
418
419	end:
420	return status;
421	}