Fix package: don't distribute generated headers

[lttng-ust.git] / liblttng-ust / lttng-ust-abi.c

/*
 * lttng-ust-abi.c
 *
 * LTTng UST ABI
 *
 * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; only
 * version 2.1 of the License.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 *
 * Mimic system calls for:
 * - session creation, returns an object descriptor or failure.
 *   - channel creation, returns an object descriptor or failure.
 *     - Operates on a session object descriptor
 *     - Takes all channel options as parameters.
 *   - stream get, returns an object descriptor or failure.
 *     - Operates on a channel object descriptor.
 *   - stream notifier get, returns an object descriptor or failure.
 *     - Operates on a channel object descriptor.
 *   - event creation, returns an object descriptor or failure.
 *     - Operates on a channel object descriptor
 *     - Takes an event name as parameter
 *     - Takes an instrumentation source as parameter
 *       - e.g. tracepoints, dynamic_probes...
 *     - Takes instrumentation source specific arguments.
 */

#include <lttng/ust-abi.h>
#include <lttng/ust-error.h>
#include <urcu/compiler.h>
#include <urcu/list.h>
#include <lttng/ust-events.h>
#include <lttng/ust-version.h>
#include <lttng/tracepoint.h>
#include "tracepoint-internal.h"
#include <usterr-signal-safe.h>
#include <helper.h>
#include "lttng-tracer.h"

#define OBJ_NAME_LEN	16

static int lttng_ust_abi_close_in_progress;

static
int lttng_abi_tracepoint_list(void *owner);
static
int lttng_abi_tracepoint_field_list(void *owner);

/*
 * Object descriptor table. Should be protected from concurrent access
 * by the caller.
 */

struct lttng_ust_obj {
	union {
		struct {
			void *private_data;
			const struct lttng_ust_objd_ops *ops;
			int f_count;
			void *owner;
			char name[OBJ_NAME_LEN];
		} s;
		int freelist_next;	/* offset freelist. end is -1. */
	} u;
};

struct lttng_ust_objd_table {
	struct lttng_ust_obj *array;
	unsigned int len, allocated_len;
	int freelist_head;		/* offset freelist head. end is -1 */
};

static struct lttng_ust_objd_table objd_table = {
	.freelist_head = -1,
};

static
int objd_alloc(void *private_data, const struct lttng_ust_objd_ops *ops,
		void *owner, const char *name)
{
	struct lttng_ust_obj *obj;

	if (objd_table.freelist_head != -1) {
		obj = &objd_table.array[objd_table.freelist_head];
		objd_table.freelist_head = obj->u.freelist_next;
		goto end;
	}

	if (objd_table.len >= objd_table.allocated_len) {
		unsigned int new_allocated_len, old_allocated_len;
		struct lttng_ust_obj *new_table, *old_table;

		old_allocated_len = objd_table.allocated_len;
		old_table = objd_table.array;
		if (!old_allocated_len)
			new_allocated_len = 1;
		else
			new_allocated_len = old_allocated_len << 1;
		new_table = zmalloc(sizeof(struct lttng_ust_obj) * new_allocated_len);
		if (!new_table)
			return -ENOMEM;
		memcpy(new_table, old_table,
		       sizeof(struct lttng_ust_obj) * old_allocated_len);
		free(old_table);
		objd_table.array = new_table;
		objd_table.allocated_len = new_allocated_len;
	}
	obj = &objd_table.array[objd_table.len];
	objd_table.len++;
end:
	obj->u.s.private_data = private_data;
	obj->u.s.ops = ops;
	obj->u.s.f_count = 2;	/* count == 1 : object is allocated */
				/* count == 2 : allocated + hold ref */
	obj->u.s.owner = owner;
	strncpy(obj->u.s.name, name, OBJ_NAME_LEN);
	obj->u.s.name[OBJ_NAME_LEN - 1] = '\0';
	return obj - objd_table.array;
}

static
struct lttng_ust_obj *_objd_get(int id)
{
	if (id >= objd_table.len)
		return NULL;
	if (!objd_table.array[id].u.s.f_count)
		return NULL;
	return &objd_table.array[id];
}

static
void *objd_private(int id)
{
	struct lttng_ust_obj *obj = _objd_get(id);
	assert(obj);
	return obj->u.s.private_data;
}

static
void objd_set_private(int id, void *private_data)
{
	struct lttng_ust_obj *obj = _objd_get(id);
	assert(obj);
	obj->u.s.private_data = private_data;
}

const struct lttng_ust_objd_ops *objd_ops(int id)
{
	struct lttng_ust_obj *obj = _objd_get(id);

	if (!obj)
		return NULL;
	return obj->u.s.ops;
}

static
void objd_free(int id)
{
	struct lttng_ust_obj *obj = _objd_get(id);

	assert(obj);
	obj->u.freelist_next = objd_table.freelist_head;
	objd_table.freelist_head = obj - objd_table.array;
	assert(obj->u.s.f_count == 1);
	obj->u.s.f_count = 0;	/* deallocated */
}

static
void objd_ref(int id)
{
	struct lttng_ust_obj *obj = _objd_get(id);
	obj->u.s.f_count++;
}

int lttng_ust_objd_unref(int id)
{
	struct lttng_ust_obj *obj = _objd_get(id);

	if (!obj)
		return -EINVAL;
	if (obj->u.s.f_count == 1) {
		ERR("Reference counting error\n");
		return -EINVAL;
	}
	if ((--obj->u.s.f_count) == 1) {
		const struct lttng_ust_objd_ops *ops = objd_ops(id);
		
		if (ops->release)
			ops->release(id);
		objd_free(id);
	}
	return 0;
}

static
void objd_table_destroy(void)
{
	int i;

	for (i = 0; i < objd_table.allocated_len; i++)
		(void) lttng_ust_objd_unref(i);
	free(objd_table.array);
	objd_table.array = NULL;
	objd_table.len = 0;
	objd_table.allocated_len = 0;
	objd_table.freelist_head = -1;
}

void lttng_ust_objd_table_owner_cleanup(void *owner)
{
	int i;

	for (i = 0; i < objd_table.allocated_len; i++) {
		struct lttng_ust_obj *obj;

		obj = _objd_get(i);
		if (!obj)
			continue;
		if (!obj->u.s.owner)
			continue;	/* skip root handles */
		if (obj->u.s.owner == owner)
			(void) lttng_ust_objd_unref(i);
	}
}

/*
 * This is LTTng's own personal way to create an ABI for sessiond.
 * We send commands over a socket.
 */

static const struct lttng_ust_objd_ops lttng_ops;
static const struct lttng_ust_objd_ops lttng_session_ops;
static const struct lttng_ust_objd_ops lttng_channel_ops;
static const struct lttng_ust_objd_ops lttng_metadata_ops;
static const struct lttng_ust_objd_ops lttng_enabler_ops;
static const struct lttng_ust_objd_ops lib_ring_buffer_objd_ops;
static const struct lttng_ust_objd_ops lttng_tracepoint_list_ops;
static const struct lttng_ust_objd_ops lttng_tracepoint_field_list_ops;

enum channel_type {
	PER_CPU_CHANNEL,
	METADATA_CHANNEL,
};

int lttng_abi_create_root_handle(void)
{
	int root_handle;

	/* root handles have NULL owners */
	root_handle = objd_alloc(NULL, &lttng_ops, NULL, "root");
	return root_handle;
}

static
int lttng_abi_create_session(void *owner)
{
	struct lttng_session *session;
	int session_objd, ret;

	session = lttng_session_create();
	if (!session)
		return -ENOMEM;
	session_objd = objd_alloc(session, &lttng_session_ops, owner, "session");
	if (session_objd < 0) {
		ret = session_objd;
		goto objd_error;
	}
	session->objd = session_objd;
	return session_objd;

objd_error:
	lttng_session_destroy(session);
	return ret;
}

static
long lttng_abi_tracer_version(int objd,
	struct lttng_ust_tracer_version *v)
{
	v->major = LTTNG_UST_INTERNAL_MAJOR_VERSION;
	v->minor = LTTNG_UST_INTERNAL_MINOR_VERSION;
	v->patchlevel = LTTNG_UST_INTERNAL_PATCHLEVEL_VERSION;
	return 0;
}

static
long lttng_abi_add_context(int objd,
	struct lttng_ust_context *context_param,
	struct lttng_ctx **ctx, struct lttng_session *session)
{
	return lttng_attach_context(context_param, ctx, session);
}

/**
 *	lttng_cmd - lttng control through socket commands
 *
 *	@objd: the object descriptor
 *	@cmd: the command
 *	@arg: command arg
 *	@uargs: UST arguments (internal)
 *	@owner: objd owner
 *
 *	This descriptor implements lttng commands:
 *	LTTNG_UST_SESSION
 *		Returns a LTTng trace session object descriptor
 *	LTTNG_UST_TRACER_VERSION
 *		Returns the LTTng kernel tracer version
 *	LTTNG_UST_TRACEPOINT_LIST
 *		Returns a file descriptor listing available tracepoints
 *	LTTNG_UST_TRACEPOINT_FIELD_LIST
 *		Returns a file descriptor listing available tracepoint fields
 *	LTTNG_UST_WAIT_QUIESCENT
 *		Returns after all previously running probes have completed
 *
 * The returned session will be deleted when its file descriptor is closed.
 */
static
long lttng_cmd(int objd, unsigned int cmd, unsigned long arg,
	union ust_args *uargs, void *owner)
{
	switch (cmd) {
	case LTTNG_UST_SESSION:
		return lttng_abi_create_session(owner);
	case LTTNG_UST_TRACER_VERSION:
		return lttng_abi_tracer_version(objd,
				(struct lttng_ust_tracer_version *) arg);
	case LTTNG_UST_TRACEPOINT_LIST:
		return lttng_abi_tracepoint_list(owner);
	case LTTNG_UST_TRACEPOINT_FIELD_LIST:
		return lttng_abi_tracepoint_field_list(owner);
	case LTTNG_UST_WAIT_QUIESCENT:
		synchronize_trace();
		return 0;
	default:
		return -EINVAL;
	}
}

static const struct lttng_ust_objd_ops lttng_ops = {
	.cmd = lttng_cmd,
};

/*
 * We tolerate no failure in this function (if one happens, we print a dmesg
 * error, but cannot return any error, because the channel information is
 * invariant.
 */
static
void lttng_metadata_create_events(int channel_objd)
{
	struct lttng_channel *chan = objd_private(channel_objd);
	struct lttng_enabler *enabler;
	static struct lttng_ust_event metadata_params = {
		.instrumentation = LTTNG_UST_TRACEPOINT,
		.name = "lttng_ust:metadata",
		.loglevel_type = LTTNG_UST_LOGLEVEL_ALL,
		.loglevel = TRACE_DEFAULT,
	};

	/*
	 * We tolerate no failure path after event creation. It will stay
	 * invariant for the rest of the session.
	 */
	enabler = lttng_enabler_create(LTTNG_ENABLER_EVENT,
				&metadata_params, chan);
	if (!enabler) {
		goto create_error;
	}
	return;

create_error:
	WARN_ON(1);
	return;		/* not allowed to return error */
}

int lttng_abi_create_channel(int session_objd,
			     struct lttng_ust_channel *chan_param,
			     enum channel_type channel_type,
			     union ust_args *uargs,
			     void *owner)
{
	struct lttng_session *session = objd_private(session_objd);
	const struct lttng_ust_objd_ops *ops;
	const char *transport_name;
	struct lttng_channel *chan;
	int chan_objd;
	int ret = 0;
	struct lttng_channel chan_priv_init;

	switch (channel_type) {
	case PER_CPU_CHANNEL:
		if (chan_param->output == LTTNG_UST_MMAP) {
			transport_name = chan_param->overwrite ?
				"relay-overwrite-mmap" : "relay-discard-mmap";
		} else {
			return -EINVAL;
		}
		ops = &lttng_channel_ops;
		break;
	case METADATA_CHANNEL:
		if (chan_param->output == LTTNG_UST_MMAP)
			transport_name = "relay-metadata-mmap";
		else
			return -EINVAL;
		ops = &lttng_metadata_ops;
		break;
	default:
		transport_name = "<unknown>";
		return -EINVAL;
	}
	chan_objd = objd_alloc(NULL, ops, owner, "channel");
	if (chan_objd < 0) {
		ret = chan_objd;
		goto objd_error;
	}
	memset(&chan_priv_init, 0, sizeof(chan_priv_init));
	/* Copy of session UUID for consumer (availability through shm) */
	memcpy(chan_priv_init.uuid, session->uuid, sizeof(session->uuid));
	
	/*
	 * We tolerate no failure path after channel creation. It will stay
	 * invariant for the rest of the session.
	 */
	chan = lttng_channel_create(session, transport_name, NULL,
				  chan_param->subbuf_size,
				  chan_param->num_subbuf,
				  chan_param->switch_timer_interval,
				  chan_param->read_timer_interval,
				  &uargs->channel.shm_fd,
				  &uargs->channel.wait_fd,
				  &uargs->channel.memory_map_size,
				  &chan_priv_init);
	if (!chan) {
		ret = -EINVAL;
		goto chan_error;
	}
	objd_set_private(chan_objd, chan);
	chan->objd = chan_objd;
	if (channel_type == METADATA_CHANNEL) {
		session->metadata = chan;
		lttng_metadata_create_events(chan_objd);
	}
	/* The channel created holds a reference on the session */
	objd_ref(session_objd);

	return chan_objd;

chan_error:
	{
		int err;

		err = lttng_ust_objd_unref(chan_objd);
		assert(!err);
	}
objd_error:
	return ret;
}

/**
 *	lttng_session_cmd - lttng session object command
 *
 *	@obj: the object
 *	@cmd: the command
 *	@arg: command arg
 *	@uargs: UST arguments (internal)
 *	@owner: objd owner
 *
 *	This descriptor implements lttng commands:
 *	LTTNG_UST_CHANNEL
 *		Returns a LTTng channel object descriptor
 *	LTTNG_UST_ENABLE
 *		Enables tracing for a session (weak enable)
 *	LTTNG_UST_DISABLE
 *		Disables tracing for a session (strong disable)
 *	LTTNG_UST_METADATA
 *		Returns a LTTng metadata object descriptor
 *
 * The returned channel will be deleted when its file descriptor is closed.
 */
static
long lttng_session_cmd(int objd, unsigned int cmd, unsigned long arg,
	union ust_args *uargs, void *owner)
{
	struct lttng_session *session = objd_private(objd);

	switch (cmd) {
	case LTTNG_UST_CHANNEL:
		return lttng_abi_create_channel(objd,
				(struct lttng_ust_channel *) arg,
				PER_CPU_CHANNEL, uargs, owner);
	case LTTNG_UST_SESSION_START:
	case LTTNG_UST_ENABLE:
		return lttng_session_enable(session);
	case LTTNG_UST_SESSION_STOP:
	case LTTNG_UST_DISABLE:
		return lttng_session_disable(session);
	case LTTNG_UST_METADATA:
		return lttng_abi_create_channel(objd,
				(struct lttng_ust_channel *) arg,
				METADATA_CHANNEL, uargs, owner);
	default:
		return -EINVAL;
	}
}

/*
 * Called when the last file reference is dropped.
 *
 * Big fat note: channels and events are invariant for the whole session after
 * their creation. So this session destruction also destroys all channel and
 * event structures specific to this session (they are not destroyed when their
 * individual file is released).
 */
static
int lttng_release_session(int objd)
{
	struct lttng_session *session = objd_private(objd);

	if (session) {
		lttng_session_destroy(session);
		return 0;
	} else {
		return -EINVAL;
	}
}

static const struct lttng_ust_objd_ops lttng_session_ops = {
	.release = lttng_release_session,
	.cmd = lttng_session_cmd,
};

static
long lttng_tracepoint_list_cmd(int objd, unsigned int cmd, unsigned long arg,
	union ust_args *uargs, void *owner)
{
	struct lttng_ust_tracepoint_list *list = objd_private(objd);
	struct lttng_ust_tracepoint_iter *tp =
		(struct lttng_ust_tracepoint_iter *) arg;
	struct lttng_ust_tracepoint_iter *iter;

	switch (cmd) {
	case LTTNG_UST_TRACEPOINT_LIST_GET:
	{
	retry:
		iter = lttng_ust_tracepoint_list_get_iter_next(list);
		if (!iter)
			return -LTTNG_UST_ERR_NOENT;
		if (!strcmp(iter->name, "lttng_ust:metadata"))
			goto retry;
		memcpy(tp, iter, sizeof(*tp));
		return 0;
	}
	default:
		return -EINVAL;
	}
}

static
int lttng_abi_tracepoint_list(void *owner)
{
	int list_objd, ret;
	struct lttng_ust_tracepoint_list *list;

	list_objd = objd_alloc(NULL, &lttng_tracepoint_list_ops, owner, "tp_list");
	if (list_objd < 0) {
		ret = list_objd;
		goto objd_error;
	}
	list = zmalloc(sizeof(*list));
	if (!list) {
		ret = -ENOMEM;
		goto alloc_error;
	}
	objd_set_private(list_objd, list);

	/* populate list by walking on all registered probes. */
	ret = lttng_probes_get_event_list(list);
	if (ret) {
		goto list_error;
	}
	return list_objd;

list_error:
	free(list);
alloc_error:
	{
		int err;

		err = lttng_ust_objd_unref(list_objd);
		assert(!err);
	}
objd_error:
	return ret;
}

static
int lttng_release_tracepoint_list(int objd)
{
	struct lttng_ust_tracepoint_list *list = objd_private(objd);

	if (list) {
		lttng_probes_prune_event_list(list);
		free(list);
		return 0;
	} else {
		return -EINVAL;
	}
}

static const struct lttng_ust_objd_ops lttng_tracepoint_list_ops = {
	.release = lttng_release_tracepoint_list,
	.cmd = lttng_tracepoint_list_cmd,
};

static
long lttng_tracepoint_field_list_cmd(int objd, unsigned int cmd,
	unsigned long arg, union ust_args *uargs, void *owner)
{
	struct lttng_ust_field_list *list = objd_private(objd);
	struct lttng_ust_field_iter *tp = &uargs->field_list.entry;
	struct lttng_ust_field_iter *iter;

	switch (cmd) {
	case LTTNG_UST_TRACEPOINT_FIELD_LIST_GET:
	{
	retry:
		iter = lttng_ust_field_list_get_iter_next(list);
		if (!iter)
			return -LTTNG_UST_ERR_NOENT;
		if (!strcmp(iter->event_name, "lttng_ust:metadata"))
			goto retry;
		memcpy(tp, iter, sizeof(*tp));
		return 0;
	}
	default:
		return -EINVAL;
	}
}

static
int lttng_abi_tracepoint_field_list(void *owner)
{
	int list_objd, ret;
	struct lttng_ust_field_list *list;

	list_objd = objd_alloc(NULL, &lttng_tracepoint_field_list_ops, owner,
			"tp_field_list");
	if (list_objd < 0) {
		ret = list_objd;
		goto objd_error;
	}
	list = zmalloc(sizeof(*list));
	if (!list) {
		ret = -ENOMEM;
		goto alloc_error;
	}
	objd_set_private(list_objd, list);

	/* populate list by walking on all registered probes. */
	ret = lttng_probes_get_field_list(list);
	if (ret) {
		goto list_error;
	}
	return list_objd;

list_error:
	free(list);
alloc_error:
	{
		int err;

		err = lttng_ust_objd_unref(list_objd);
		assert(!err);
	}
objd_error:
	return ret;
}

static
int lttng_release_tracepoint_field_list(int objd)
{
	struct lttng_ust_field_list *list = objd_private(objd);

	if (list) {
		lttng_probes_prune_field_list(list);
		free(list);
		return 0;
	} else {
		return -EINVAL;
	}
}

static const struct lttng_ust_objd_ops lttng_tracepoint_field_list_ops = {
	.release = lttng_release_tracepoint_field_list,
	.cmd = lttng_tracepoint_field_list_cmd,
};

struct stream_priv_data {
	struct lttng_ust_lib_ring_buffer *buf;
	struct lttng_channel *lttng_chan;
};

static
int lttng_abi_open_stream(int channel_objd, struct lttng_ust_stream *info,
		union ust_args *uargs, void *owner)
{
	struct lttng_channel *channel = objd_private(channel_objd);
	struct lttng_ust_lib_ring_buffer *buf;
	struct stream_priv_data *priv;
	int stream_objd, ret;

	buf = channel->ops->buffer_read_open(channel->chan, channel->handle,
			&uargs->stream.shm_fd,
			&uargs->stream.wait_fd,
			&uargs->stream.memory_map_size);
	if (!buf)
		return -ENOENT;

	priv = zmalloc(sizeof(*priv));
	if (!priv) {
		ret = -ENOMEM;
		goto alloc_error;
	}
	priv->buf = buf;
	priv->lttng_chan = channel;
	stream_objd = objd_alloc(priv, &lib_ring_buffer_objd_ops, owner, "open_stream");
	if (stream_objd < 0) {
		ret = stream_objd;
		goto objd_error;
	}
	/* Hold a reference on the channel object descriptor */
	objd_ref(channel_objd);
	return stream_objd;

objd_error:
	free(priv);
alloc_error:
	channel->ops->buffer_read_close(buf, channel->handle);
	return ret;
}

static
int lttng_abi_create_enabler(int channel_objd,
			   struct lttng_ust_event *event_param,
			   void *owner,
			   enum lttng_enabler_type type)
{
	struct lttng_channel *channel = objd_private(channel_objd);
	struct lttng_enabler *enabler;
	int event_objd, ret;

	event_param->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
	event_objd = objd_alloc(NULL, &lttng_enabler_ops, owner, "enabler");
	if (event_objd < 0) {
		ret = event_objd;
		goto objd_error;
	}
	/*
	 * We tolerate no failure path after event creation. It will stay
	 * invariant for the rest of the session.
	 */
	enabler = lttng_enabler_create(type, event_param, channel);
	if (!enabler) {
		ret = -ENOMEM;
		goto event_error;
	}
	objd_set_private(event_objd, enabler);
	/* The event holds a reference on the channel */
	objd_ref(channel_objd);
	return event_objd;

event_error:
	{
		int err;

		err = lttng_ust_objd_unref(event_objd);
		assert(!err);
	}
objd_error:
	return ret;
}

/**
 *	lttng_channel_cmd - lttng control through object descriptors
 *
 *	@objd: the object descriptor
 *	@cmd: the command
 *	@arg: command arg
 *	@uargs: UST arguments (internal)
 *	@owner: objd owner
 *
 *	This object descriptor implements lttng commands:
 *      LTTNG_UST_STREAM
 *              Returns an event stream object descriptor or failure.
 *              (typically, one event stream records events from one CPU)
 *	LTTNG_UST_EVENT
 *		Returns an event object descriptor or failure.
 *	LTTNG_UST_CONTEXT
 *		Prepend a context field to each event in the channel
 *	LTTNG_UST_ENABLE
 *		Enable recording for events in this channel (weak enable)
 *	LTTNG_UST_DISABLE
 *		Disable recording for events in this channel (strong disable)
 *
 * Channel and event file descriptors also hold a reference on the session.
 */
static
long lttng_channel_cmd(int objd, unsigned int cmd, unsigned long arg,
	union ust_args *uargs, void *owner)
{
	struct lttng_channel *channel = objd_private(objd);

	switch (cmd) {
	case LTTNG_UST_STREAM:
	{
		struct lttng_ust_stream *stream;

		stream = (struct lttng_ust_stream *) arg;
		/* stream used as output */
		return lttng_abi_open_stream(objd, stream, uargs, owner);
	}
	case LTTNG_UST_EVENT:
	{
		struct lttng_ust_event *event_param =
			(struct lttng_ust_event *) arg;
		if (event_param->name[strlen(event_param->name) - 1] == '*') {
			/* If ends with wildcard, create wildcard. */
			return lttng_abi_create_enabler(objd, event_param,
					owner, LTTNG_ENABLER_WILDCARD);
		} else {
			return lttng_abi_create_enabler(objd, event_param,
					owner, LTTNG_ENABLER_EVENT);
		}
	}
	case LTTNG_UST_CONTEXT:
		return lttng_abi_add_context(objd,
				(struct lttng_ust_context *) arg,
				&channel->ctx, channel->session);
	case LTTNG_UST_ENABLE:
		return lttng_channel_enable(channel);
	case LTTNG_UST_DISABLE:
		return lttng_channel_disable(channel);
	case LTTNG_UST_FLUSH_BUFFER:
		return channel->ops->flush_buffer(channel->chan, channel->handle);
	default:
		return -EINVAL;
	}
}

/**
 *	lttng_metadata_cmd - lttng control through object descriptors
 *
 *	@objd: the object descriptor
 *	@cmd: the command
 *	@arg: command arg
 *	@uargs: UST arguments (internal)
 *	@owner: objd owner
 *
 *	This object descriptor implements lttng commands:
 *      LTTNG_UST_STREAM
 *              Returns an event stream file descriptor or failure.
 *
 * Channel and event file descriptors also hold a reference on the session.
 */
static
long lttng_metadata_cmd(int objd, unsigned int cmd, unsigned long arg,
	union ust_args *uargs, void *owner)
{
	struct lttng_channel *channel = objd_private(objd);

	switch (cmd) {
	case LTTNG_UST_STREAM:
	{
		struct lttng_ust_stream *stream;

		stream = (struct lttng_ust_stream *) arg;
		/* stream used as output */
		return lttng_abi_open_stream(objd, stream, uargs, owner);
	}
	case LTTNG_UST_FLUSH_BUFFER:
		return channel->ops->flush_buffer(channel->chan, channel->handle);
	default:
		return -EINVAL;
	}
}

static
int lttng_channel_release(int objd)
{
	struct lttng_channel *channel = objd_private(objd);

	if (channel)
		return lttng_ust_objd_unref(channel->session->objd);
	return 0;
}

static const struct lttng_ust_objd_ops lttng_channel_ops = {
	.release = lttng_channel_release,
	.cmd = lttng_channel_cmd,
};

static const struct lttng_ust_objd_ops lttng_metadata_ops = {
	.release = lttng_channel_release,
	.cmd = lttng_metadata_cmd,
};

/**
 *	lttng_rb_cmd - lttng ring buffer control through object descriptors
 *
 *	@objd: the object descriptor
 *	@cmd: the command
 *	@arg: command arg
 *	@uargs: UST arguments (internal)
 *	@owner: objd owner
 *
 *	This object descriptor implements lttng commands:
 *		(None for now. Access is done directly though shm.)
 */
static
long lttng_rb_cmd(int objd, unsigned int cmd, unsigned long arg,
	union ust_args *uargs, void *owner)
{
	switch (cmd) {
	default:
		return -EINVAL;
	}
}

static
int lttng_rb_release(int objd)
{
	struct stream_priv_data *priv = objd_private(objd);
	struct lttng_ust_lib_ring_buffer *buf;
	struct lttng_channel *channel;

	if (priv) {
		buf = priv->buf;
		channel = priv->lttng_chan;
		free(priv);
		/*
		 * If we are at ABI exit, we don't want to close the
		 * buffer opened for read: it is being shared between
		 * the parent and child (right after fork), and we don't
		 * want the child to close it for the parent. For a real
		 * exit, we don't care about marking it as closed, as
		 * the consumer daemon (if there is one) will do fine
		 * even if we don't mark it as "closed" for reading on
		 * our side.
		 * We only mark it as closed if it is being explicitely
		 * released by the session daemon with an explicit
		 * release command.
		 */
		if (!lttng_ust_abi_close_in_progress)
			channel->ops->buffer_read_close(buf, channel->handle);

		return lttng_ust_objd_unref(channel->objd);
	}
	return 0;
}

static const struct lttng_ust_objd_ops lib_ring_buffer_objd_ops = {
	.release = lttng_rb_release,
	.cmd = lttng_rb_cmd,
};

/**
 *	lttng_enabler_cmd - lttng control through object descriptors
 *
 *	@objd: the object descriptor
 *	@cmd: the command
 *	@arg: command arg
 *	@uargs: UST arguments (internal)
 *	@owner: objd owner
 *
 *	This object descriptor implements lttng commands:
 *	LTTNG_UST_CONTEXT
 *		Prepend a context field to each record of events of this
 *		enabler.
 *	LTTNG_UST_ENABLE
 *		Enable recording for this enabler
 *	LTTNG_UST_DISABLE
 *		Disable recording for this enabler
 *	LTTNG_UST_FILTER
 *		Attach a filter to an enabler.
 */
static
long lttng_enabler_cmd(int objd, unsigned int cmd, unsigned long arg,
	union ust_args *uargs, void *owner)
{
	struct lttng_enabler *enabler = objd_private(objd);

	switch (cmd) {
	case LTTNG_UST_CONTEXT:
		return lttng_enabler_attach_context(enabler,
				(struct lttng_ust_context *) arg);
	case LTTNG_UST_ENABLE:
		return lttng_enabler_enable(enabler);
	case LTTNG_UST_DISABLE:
		return lttng_enabler_disable(enabler);
	case LTTNG_UST_FILTER:
	{
		int ret;

		ret = lttng_enabler_attach_bytecode(enabler,
				(struct lttng_ust_filter_bytecode_node *) arg);
		if (ret)
			return ret;
		return 0;
	}
	default:
		return -EINVAL;
	}
}

static
int lttng_enabler_release(int objd)
{
	struct lttng_enabler *enabler = objd_private(objd);

	if (enabler)
		return lttng_ust_objd_unref(enabler->chan->objd);
	return 0;
}

static const struct lttng_ust_objd_ops lttng_enabler_ops = {
	.release = lttng_enabler_release,
	.cmd = lttng_enabler_cmd,
};

void lttng_ust_abi_exit(void)
{
	lttng_ust_abi_close_in_progress = 1;
	objd_table_destroy();
	lttng_ust_abi_close_in_progress = 0;
}