[lttng-tools.git] / src / common / ust-consumer / ust-consumer.c

/*
 * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
 *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * 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; only version 2
 * of the License.
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#define _GNU_SOURCE
#include <assert.h>
#include <poll.h>
#include <pthread.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <lttng/ust-ctl.h>

#include <common/common.h>
#include <common/sessiond-comm/sessiond-comm.h>
#include <common/compat/fcntl.h>

#include "ust-consumer.h"

extern struct lttng_consumer_global_data consumer_data;
extern int consumer_poll_timeout;
extern volatile int consumer_quit;

/*
 * Mmap the ring buffer, read it and write the data to the tracefile.
 *
 * Returns the number of bytes written, else negative value on error.
 */
ssize_t lttng_ustconsumer_on_read_subbuffer_mmap(
		struct lttng_consumer_local_data *ctx,
		struct lttng_consumer_stream *stream, unsigned long len)
{
	unsigned long mmap_offset;
	long ret = 0;
	off_t orig_offset = stream->out_fd_offset;
	int outfd = stream->out_fd;

	/* get the offset inside the fd to mmap */
	ret = ustctl_get_mmap_read_offset(stream->chan->handle,
		stream->buf, &mmap_offset);
	if (ret != 0) {
		errno = -ret;
		PERROR("ustctl_get_mmap_read_offset");
		goto end;
	}
	while (len > 0) {
		ret = write(outfd, stream->mmap_base + mmap_offset, len);
		if (ret >= len) {
			len = 0;
		} else if (ret < 0) {
			errno = -ret;
			PERROR("Error in file write");
			goto end;
		}
		/* This won't block, but will start writeout asynchronously */
		lttng_sync_file_range(outfd, stream->out_fd_offset, ret,
				SYNC_FILE_RANGE_WRITE);
		stream->out_fd_offset += ret;
	}

	lttng_consumer_sync_trace_file(stream, orig_offset);

	goto end;

end:
	return ret;
}

/*
 * Splice the data from the ring buffer to the tracefile.
 *
 * Returns the number of bytes spliced.
 */
ssize_t lttng_ustconsumer_on_read_subbuffer_splice(
		struct lttng_consumer_local_data *ctx,
		struct lttng_consumer_stream *stream, unsigned long len)
{
	return -ENOSYS;
}

/*
 * Take a snapshot for a specific fd
 *
 * Returns 0 on success, < 0 on error
 */
int lttng_ustconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
		struct lttng_consumer_stream *stream)
{
	int ret = 0;

	ret = ustctl_snapshot(stream->chan->handle, stream->buf);
	if (ret != 0) {
		errno = -ret;
		PERROR("Getting sub-buffer snapshot.");
	}

	return ret;
}

/*
 * Get the produced position
 *
 * Returns 0 on success, < 0 on error
 */
int lttng_ustconsumer_get_produced_snapshot(
		struct lttng_consumer_local_data *ctx,
		struct lttng_consumer_stream *stream,
		unsigned long *pos)
{
	int ret;

	ret = ustctl_snapshot_get_produced(stream->chan->handle,
			stream->buf, pos);
	if (ret != 0) {
		errno = -ret;
		PERROR("kernctl_snapshot_get_produced");
	}

	return ret;
}

int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
		int sock, struct pollfd *consumer_sockpoll)
{
	ssize_t ret;
	struct lttcomm_consumer_msg msg;

	ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
	if (ret != sizeof(msg)) {
		lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
		return ret;
	}
	if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
		return -ENOENT;
	}

	switch (msg.cmd_type) {
	case LTTNG_CONSUMER_ADD_CHANNEL:
	{
		struct lttng_consumer_channel *new_channel;
		int fds[1];
		size_t nb_fd = 1;

		/* block */
		if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
			return -EINTR;
		}
		ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
		if (ret != sizeof(fds)) {
			lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
			return ret;
		}

		DBG("consumer_add_channel %d", msg.u.channel.channel_key);

		new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
				fds[0], -1,
				msg.u.channel.mmap_len,
				msg.u.channel.max_sb_size);
		if (new_channel == NULL) {
			lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
			goto end_nosignal;
		}
		if (ctx->on_recv_channel != NULL) {
			ret = ctx->on_recv_channel(new_channel);
			if (ret == 0) {
				consumer_add_channel(new_channel);
			} else if (ret < 0) {
				goto end_nosignal;
			}
		} else {
			consumer_add_channel(new_channel);
		}
		goto end_nosignal;
	}
	case LTTNG_CONSUMER_ADD_STREAM:
	{
		struct lttng_consumer_stream *new_stream;
		int fds[2];
		size_t nb_fd = 2;

		/* block */
		if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
			return -EINTR;
		}
		ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
		if (ret != sizeof(fds)) {
			lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
			return ret;
		}

		DBG("consumer_add_stream %s (%d,%d)", msg.u.stream.path_name,
			fds[0], fds[1]);
		assert(msg.u.stream.output == LTTNG_EVENT_MMAP);
		new_stream = consumer_allocate_stream(msg.u.channel.channel_key,
				msg.u.stream.stream_key,
				fds[0], fds[1],
				msg.u.stream.state,
				msg.u.stream.mmap_len,
				msg.u.stream.output,
				msg.u.stream.path_name,
				msg.u.stream.uid,
				msg.u.stream.gid);
		if (new_stream == NULL) {
			lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
			goto end;
		}
		if (ctx->on_recv_stream != NULL) {
			ret = ctx->on_recv_stream(new_stream);
			if (ret == 0) {
				consumer_add_stream(new_stream);
			} else if (ret < 0) {
				goto end;
			}
		} else {
			consumer_add_stream(new_stream);
		}
		break;
	}
	case LTTNG_CONSUMER_UPDATE_STREAM:
	{
		return -ENOSYS;
#if 0
		if (ctx->on_update_stream != NULL) {
			ret = ctx->on_update_stream(msg.u.stream.stream_key, msg.u.stream.state);
			if (ret == 0) {
				consumer_change_stream_state(msg.u.stream.stream_key, msg.u.stream.state);
			} else if (ret < 0) {
				goto end;
			}
		} else {
			consumer_change_stream_state(msg.u.stream.stream_key,
				msg.u.stream.state);
		}
#endif
		break;
	}
	default:
		break;
	}
end:
	/* signal the poll thread */
	ret = write(ctx->consumer_poll_pipe[1], "4", 1);
	if (ret < 0) {
		PERROR("write consumer poll");
	}
end_nosignal:
	return 0;
}

int lttng_ustconsumer_allocate_channel(struct lttng_consumer_channel *chan)
{
	struct lttng_ust_object_data obj;

	obj.handle = -1;
	obj.shm_fd = chan->shm_fd;
	obj.wait_fd = chan->wait_fd;
	obj.memory_map_size = chan->mmap_len;
	chan->handle = ustctl_map_channel(&obj);
	if (!chan->handle) {
		return -ENOMEM;
	}
	chan->wait_fd_is_copy = 1;
	chan->shm_fd = -1;

	return 0;
}

void lttng_ustconsumer_on_stream_hangup(struct lttng_consumer_stream *stream)
{
	ustctl_flush_buffer(stream->chan->handle, stream->buf, 0);
	stream->hangup_flush_done = 1;
}

void lttng_ustconsumer_del_channel(struct lttng_consumer_channel *chan)
{
	ustctl_unmap_channel(chan->handle);
}

int lttng_ustconsumer_allocate_stream(struct lttng_consumer_stream *stream)
{
	struct lttng_ust_object_data obj;
	int ret;

	obj.handle = -1;
	obj.shm_fd = stream->shm_fd;
	obj.wait_fd = stream->wait_fd;
	obj.memory_map_size = stream->mmap_len;
	ret = ustctl_add_stream(stream->chan->handle, &obj);
	if (ret)
		return ret;
	stream->buf = ustctl_open_stream_read(stream->chan->handle, stream->cpu);
	if (!stream->buf)
		return -EBUSY;
	/* ustctl_open_stream_read has closed the shm fd. */
	stream->wait_fd_is_copy = 1;
	stream->shm_fd = -1;

	stream->mmap_base = ustctl_get_mmap_base(stream->chan->handle, stream->buf);
	if (!stream->mmap_base) {
		return -EINVAL;
	}

	return 0;
}

void lttng_ustconsumer_del_stream(struct lttng_consumer_stream *stream)
{
	ustctl_close_stream_read(stream->chan->handle, stream->buf);
}


int lttng_ustconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
		struct lttng_consumer_local_data *ctx)
{
	unsigned long len;
	int err;
	long ret = 0;
	struct lttng_ust_shm_handle *handle;
	struct lttng_ust_lib_ring_buffer *buf;
	char dummy;
	ssize_t readlen;

	DBG("In read_subbuffer (wait_fd: %d, stream key: %d)",
		stream->wait_fd, stream->key);

	/* We can consume the 1 byte written into the wait_fd by UST */
	if (!stream->hangup_flush_done) {
		do {
			readlen = read(stream->wait_fd, &dummy, 1);
		} while (readlen == -1 && errno == EINTR);
		if (readlen == -1) {
			ret = readlen;
			goto end;
		}
	}

	buf = stream->buf;
	handle = stream->chan->handle;
	/* Get the next subbuffer */
	err = ustctl_get_next_subbuf(handle, buf);
	if (err != 0) {
		ret = -ret;	/* ustctl_get_next_subbuf returns negative, caller expect positive. */
		/*
		 * This is a debug message even for single-threaded consumer,
		 * because poll() have more relaxed criterions than get subbuf,
		 * so get_subbuf may fail for short race windows where poll()
		 * would issue wakeups.
		 */
		DBG("Reserving sub buffer failed (everything is normal, "
				"it is due to concurrency)");
		goto end;
	}
	assert(stream->output == LTTNG_EVENT_MMAP);
	/* read the used subbuffer size */
	err = ustctl_get_padded_subbuf_size(handle, buf, &len);
	assert(err == 0);
	/* write the subbuffer to the tracefile */
	ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
	if (ret < 0) {
		/*
		 * display the error but continue processing to try
		 * to release the subbuffer
		 */
		ERR("Error writing to tracefile");
	}
	err = ustctl_put_next_subbuf(handle, buf);
	assert(err == 0);
end:
	return ret;
}

int lttng_ustconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
{
	int ret;

	/* Opening the tracefile in write mode */
	if (stream->path_name != NULL) {
		ret = run_as_open(stream->path_name,
				O_WRONLY|O_CREAT|O_TRUNC,
				S_IRWXU|S_IRWXG|S_IRWXO,
				stream->uid, stream->gid);
		if (ret < 0) {
			ERR("Opening %s", stream->path_name);
			PERROR("open");
			goto error;
		}
		stream->out_fd = ret;
	}

	/* we return 0 to let the library handle the FD internally */
	return 0;

error:
	return ret;
}
Commit	Line	Data
3bd1e081 MD	1	/*
	2	* Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
	3	* Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	4	*
	5	* This program is free software; you can redistribute it and/or
	6	* modify it under the terms of the GNU General Public License
	7	* as published by the Free Software Foundation; only version 2
	8	* of the License.
	9	*
	10	* This program is distributed in the hope that it will be useful,
	11	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	13	* GNU General Public License for more details.
	14	*
	15	* You should have received a copy of the GNU General Public License
	16	* along with this program; if not, write to the Free Software
	17	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	18	*/
	19
	20	#define _GNU_SOURCE
	21	#include <assert.h>
3bd1e081 MD	22	#include <poll.h>
	23	#include <pthread.h>
	24	#include <stdlib.h>
	25	#include <string.h>
	26	#include <sys/mman.h>
	27	#include <sys/socket.h>
dbb5dfe6	28	#include <sys/stat.h>
3bd1e081 MD	29	#include <sys/types.h>
3bd1e081 MD	30	#include <unistd.h>
9df8df5e	31	#include <lttng/ust-ctl.h>
0857097f	32
990570ed	33	#include <common/common.h>
10a8a223	34	#include <common/sessiond-comm/sessiond-comm.h>
dbb5dfe6	35	#include <common/compat/fcntl.h>
10a8a223 DG	36
10a8a223 DG	37	#include "ust-consumer.h"
3bd1e081 MD	38
	39	extern struct lttng_consumer_global_data consumer_data;
	40	extern int consumer_poll_timeout;
	41	extern volatile int consumer_quit;
	42
	43	/*
	44	* Mmap the ring buffer, read it and write the data to the tracefile.
	45	*
4078b776	46	* Returns the number of bytes written, else negative value on error.
3bd1e081	47	*/
4078b776	48	ssize_t lttng_ustconsumer_on_read_subbuffer_mmap(
3bd1e081 MD	49	struct lttng_consumer_local_data *ctx,
	50	struct lttng_consumer_stream *stream, unsigned long len)
	51	{
	52	unsigned long mmap_offset;
	53	long ret = 0;
	54	off_t orig_offset = stream->out_fd_offset;
	55	int outfd = stream->out_fd;
	56
	57	/* get the offset inside the fd to mmap */
	58	ret = ustctl_get_mmap_read_offset(stream->chan->handle,
	59	stream->buf, &mmap_offset);
	60	if (ret != 0) {
87dc6a9c	61	errno = -ret;
4c462e79	62	PERROR("ustctl_get_mmap_read_offset");
3bd1e081 MD	63	goto end;
	64	}
	65	while (len > 0) {
	66	ret = write(outfd, stream->mmap_base + mmap_offset, len);
	67	if (ret >= len) {
	68	len = 0;
	69	} else if (ret < 0) {
87dc6a9c	70	errno = -ret;
4c462e79	71	PERROR("Error in file write");
3bd1e081 MD	72	goto end;
	73	}
	74	/* This won't block, but will start writeout asynchronously */
dbb5dfe6	75	lttng_sync_file_range(outfd, stream->out_fd_offset, ret,
3bd1e081 MD	76	SYNC_FILE_RANGE_WRITE);
	77	stream->out_fd_offset += ret;
	78	}
	79
	80	lttng_consumer_sync_trace_file(stream, orig_offset);
	81
	82	goto end;
	83
	84	end:
	85	return ret;
	86	}
	87
	88	/*
	89	* Splice the data from the ring buffer to the tracefile.
	90	*
	91	* Returns the number of bytes spliced.
	92	*/
4078b776	93	ssize_t lttng_ustconsumer_on_read_subbuffer_splice(
3bd1e081 MD	94	struct lttng_consumer_local_data *ctx,
	95	struct lttng_consumer_stream *stream, unsigned long len)
	96	{
	97	return -ENOSYS;
	98	}
	99
	100	/*
	101	* Take a snapshot for a specific fd
	102	*
	103	* Returns 0 on success, < 0 on error
	104	*/
	105	int lttng_ustconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
	106	struct lttng_consumer_stream *stream)
	107	{
	108	int ret = 0;
	109
	110	ret = ustctl_snapshot(stream->chan->handle, stream->buf);
	111	if (ret != 0) {
87dc6a9c	112	errno = -ret;
4c462e79	113	PERROR("Getting sub-buffer snapshot.");
3bd1e081 MD	114	}
	115
	116	return ret;
	117	}
	118
	119	/*
	120	* Get the produced position
	121	*
	122	* Returns 0 on success, < 0 on error
	123	*/
	124	int lttng_ustconsumer_get_produced_snapshot(
	125	struct lttng_consumer_local_data *ctx,
	126	struct lttng_consumer_stream *stream,
	127	unsigned long *pos)
	128	{
	129	int ret;
	130
	131	ret = ustctl_snapshot_get_produced(stream->chan->handle,
	132	stream->buf, pos);
	133	if (ret != 0) {
87dc6a9c	134	errno = -ret;
4c462e79	135	PERROR("kernctl_snapshot_get_produced");
3bd1e081 MD	136	}
	137
	138	return ret;
	139	}
	140
	141	int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
	142	int sock, struct pollfd *consumer_sockpoll)
	143	{
	144	ssize_t ret;
	145	struct lttcomm_consumer_msg msg;
	146
	147	ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
	148	if (ret != sizeof(msg)) {
	149	lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
	150	return ret;
	151	}
	152	if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
	153	return -ENOENT;
	154	}
	155
	156	switch (msg.cmd_type) {
	157	case LTTNG_CONSUMER_ADD_CHANNEL:
	158	{
	159	struct lttng_consumer_channel *new_channel;
	160	int fds[1];
	161	size_t nb_fd = 1;
	162
	163	/* block */
	164	if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
	165	return -EINTR;
	166	}
	167	ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
	168	if (ret != sizeof(fds)) {
	169	lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
	170	return ret;
	171	}
	172
	173	DBG("consumer_add_channel %d", msg.u.channel.channel_key);
	174
	175	new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
	176	fds[0], -1,
	177	msg.u.channel.mmap_len,
	178	msg.u.channel.max_sb_size);
	179	if (new_channel == NULL) {
	180	lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
	181	goto end_nosignal;
	182	}
	183	if (ctx->on_recv_channel != NULL) {
	184	ret = ctx->on_recv_channel(new_channel);
	185	if (ret == 0) {
	186	consumer_add_channel(new_channel);
	187	} else if (ret < 0) {
	188	goto end_nosignal;
	189	}
	190	} else {
	191	consumer_add_channel(new_channel);
	192	}
	193	goto end_nosignal;
	194	}
	195	case LTTNG_CONSUMER_ADD_STREAM:
	196	{
	197	struct lttng_consumer_stream *new_stream;
	198	int fds[2];
	199	size_t nb_fd = 2;
200
201	/* block */
202	if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
203	return -EINTR;
204	}
205	ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
206	if (ret != sizeof(fds)) {
207	lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
208	return ret;
209	}
210
211	DBG("consumer_add_stream %s (%d,%d)", msg.u.stream.path_name,
212	fds[0], fds[1]);
d41f73b7	213	assert(msg.u.stream.output == LTTNG_EVENT_MMAP);
7ad0a0cb	214	new_stream = consumer_allocate_stream(msg.u.channel.channel_key,
3bd1e081 MD	215	msg.u.stream.stream_key,
	216	fds[0], fds[1],
	217	msg.u.stream.state,
	218	msg.u.stream.mmap_len,
	219	msg.u.stream.output,
6df2e2c9 MD	220	msg.u.stream.path_name,
	221	msg.u.stream.uid,
	222	msg.u.stream.gid);
3bd1e081 MD	223	if (new_stream == NULL) {
	224	lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
	225	goto end;
	226	}
	227	if (ctx->on_recv_stream != NULL) {
	228	ret = ctx->on_recv_stream(new_stream);
	229	if (ret == 0) {
	230	consumer_add_stream(new_stream);
	231	} else if (ret < 0) {
	232	goto end;
	233	}
	234	} else {
	235	consumer_add_stream(new_stream);
	236	}
	237	break;
	238	}
	239	case LTTNG_CONSUMER_UPDATE_STREAM:
	240	{
7ad0a0cb MD	241	return -ENOSYS;
7ad0a0cb MD	242	#if 0
3bd1e081 MD	243	if (ctx->on_update_stream != NULL) {
	244	ret = ctx->on_update_stream(msg.u.stream.stream_key, msg.u.stream.state);
	245	if (ret == 0) {
	246	consumer_change_stream_state(msg.u.stream.stream_key, msg.u.stream.state);
	247	} else if (ret < 0) {
	248	goto end;
	249	}
	250	} else {
	251	consumer_change_stream_state(msg.u.stream.stream_key,
	252	msg.u.stream.state);
	253	}
7ad0a0cb	254	#endif
3bd1e081 MD	255	break;
	256	}
	257	default:
	258	break;
	259	}
	260	end:
	261	/* signal the poll thread */
	262	ret = write(ctx->consumer_poll_pipe[1], "4", 1);
	263	if (ret < 0) {
4c462e79	264	PERROR("write consumer poll");
3bd1e081 MD	265	}
	266	end_nosignal:
	267	return 0;
	268	}
	269
	270	int lttng_ustconsumer_allocate_channel(struct lttng_consumer_channel *chan)
	271	{
13161846	272	struct lttng_ust_object_data obj;
3bd1e081 MD	273
	274	obj.handle = -1;
	275	obj.shm_fd = chan->shm_fd;
	276	obj.wait_fd = chan->wait_fd;
	277	obj.memory_map_size = chan->mmap_len;
	278	chan->handle = ustctl_map_channel(&obj);
	279	if (!chan->handle) {
	280	return -ENOMEM;
	281	}
b5c5fc29	282	chan->wait_fd_is_copy = 1;
2c1dd183	283	chan->shm_fd = -1;
b5c5fc29	284
3bd1e081 MD	285	return 0;
	286	}
	287
d056b477 MD	288	void lttng_ustconsumer_on_stream_hangup(struct lttng_consumer_stream *stream)
	289	{
	290	ustctl_flush_buffer(stream->chan->handle, stream->buf, 0);
effcf122	291	stream->hangup_flush_done = 1;
d056b477 MD	292	}
d056b477 MD	293
3bd1e081 MD	294	void lttng_ustconsumer_del_channel(struct lttng_consumer_channel *chan)
	295	{
	296	ustctl_unmap_channel(chan->handle);
	297	}
	298
	299	int lttng_ustconsumer_allocate_stream(struct lttng_consumer_stream *stream)
	300	{
13161846	301	struct lttng_ust_object_data obj;
3bd1e081 MD	302	int ret;
	303
	304	obj.handle = -1;
	305	obj.shm_fd = stream->shm_fd;
	306	obj.wait_fd = stream->wait_fd;
	307	obj.memory_map_size = stream->mmap_len;
	308	ret = ustctl_add_stream(stream->chan->handle, &obj);
	309	if (ret)
	310	return ret;
	311	stream->buf = ustctl_open_stream_read(stream->chan->handle, stream->cpu);
	312	if (!stream->buf)
	313	return -EBUSY;
2c1dd183 MD	314	/* ustctl_open_stream_read has closed the shm fd. */
	315	stream->wait_fd_is_copy = 1;
	316	stream->shm_fd = -1;
	317
3bd1e081 MD	318	stream->mmap_base = ustctl_get_mmap_base(stream->chan->handle, stream->buf);
	319	if (!stream->mmap_base) {
	320	return -EINVAL;
	321	}
ee77a7b0	322
3bd1e081 MD	323	return 0;
	324	}
	325
	326	void lttng_ustconsumer_del_stream(struct lttng_consumer_stream *stream)
	327	{
	328	ustctl_close_stream_read(stream->chan->handle, stream->buf);
	329	}
d41f73b7 MD	330
	331
	332	int lttng_ustconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
	333	struct lttng_consumer_local_data *ctx)
	334	{
	335	unsigned long len;
	336	int err;
	337	long ret = 0;
	338	struct lttng_ust_shm_handle *handle;
	339	struct lttng_ust_lib_ring_buffer *buf;
	340	char dummy;
	341	ssize_t readlen;
	342
	343	DBG("In read_subbuffer (wait_fd: %d, stream key: %d)",
	344	stream->wait_fd, stream->key);
	345
	346	/* We can consume the 1 byte written into the wait_fd by UST */
effcf122 MD	347	if (!stream->hangup_flush_done) {
	348	do {
	349	readlen = read(stream->wait_fd, &dummy, 1);
87dc6a9c	350	} while (readlen == -1 && errno == EINTR);
effcf122 MD	351	if (readlen == -1) {
	352	ret = readlen;
	353	goto end;
	354	}
d41f73b7 MD	355	}
	356
	357	buf = stream->buf;
	358	handle = stream->chan->handle;
	359	/* Get the next subbuffer */
	360	err = ustctl_get_next_subbuf(handle, buf);
	361	if (err != 0) {
effcf122	362	ret = -ret; /* ustctl_get_next_subbuf returns negative, caller expect positive. */
d41f73b7 MD	363	/*
	364	* This is a debug message even for single-threaded consumer,
	365	* because poll() have more relaxed criterions than get subbuf,
	366	* so get_subbuf may fail for short race windows where poll()
	367	* would issue wakeups.
	368	*/
	369	DBG("Reserving sub buffer failed (everything is normal, "
	370	"it is due to concurrency)");
	371	goto end;
	372	}
	373	assert(stream->output == LTTNG_EVENT_MMAP);
	374	/* read the used subbuffer size */
	375	err = ustctl_get_padded_subbuf_size(handle, buf, &len);
effcf122	376	assert(err == 0);
d41f73b7 MD	377	/* write the subbuffer to the tracefile */
	378	ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
	379	if (ret < 0) {
	380	/*
	381	* display the error but continue processing to try
	382	* to release the subbuffer
	383	*/
	384	ERR("Error writing to tracefile");
	385	}
	386	err = ustctl_put_next_subbuf(handle, buf);
effcf122	387	assert(err == 0);
d41f73b7 MD	388	end:
	389	return ret;
	390	}
	391
	392	int lttng_ustconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
	393	{
	394	int ret;
	395
	396	/* Opening the tracefile in write mode */
	397	if (stream->path_name != NULL) {
e11d277b	398	ret = run_as_open(stream->path_name,
60b6c79c MD	399	O_WRONLY\|O_CREAT\|O_TRUNC,
	400	S_IRWXU\|S_IRWXG\|S_IRWXO,
	401	stream->uid, stream->gid);
d41f73b7 MD	402	if (ret < 0) {
d41f73b7 MD	403	ERR("Opening %s", stream->path_name);
4c462e79	404	PERROR("open");
d41f73b7 MD	405	goto error;
	406	}
	407	stream->out_fd = ret;
	408	}
	409
	410	/* we return 0 to let the library handle the FD internally */
	411	return 0;
	412
	413	error:
	414	return ret;
	415	}