[lttng-tools.git] / liblttng-ustconsumer / lttng-ustconsumer.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 <fcntl.h>
#include <poll.h>
#include <pthread.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>

#include <lttng-sessiond-comm.h>
#include <lttng/lttng-ustconsumer.h>
#include <lttng/ust-ctl.h>
#include <lttngerr.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
 */
int 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) {
		ret = -errno;
		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) {
			ret = -errno;
			perror("Error in file write");
			goto end;
		}
		/* This won't block, but will start writeout asynchronously */
		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.
 */
int 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) {
		ret = errno;
		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) {
		ret = errno;
		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;
	}
	/*
	 * The channel fds are passed to ustctl, we only keep a copy.
	 */
	chan->shm_fd_is_copy = 1;
	chan->wait_fd_is_copy = 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;
	stream->mmap_base = ustctl_get_mmap_base(stream->chan->handle, stream->buf);
	if (!stream->mmap_base) {
		return -EINVAL;
	}
	/*
	 * The stream fds are passed to ustctl, we only keep a copy.
	 */
	stream->shm_fd_is_copy = 1;
	stream->wait_fd_is_copy = 1;

	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 = open(stream->path_name,
				O_WRONLY|O_CREAT|O_TRUNC, S_IRWXU|S_IRWXG|S_IRWXO);
		if (ret < 0) {
			ERR("Opening %s", stream->path_name);
			perror("open");
			goto error;
		}
		stream->out_fd = ret;
		ret = chown(stream->path_name, stream->uid, stream->gid);
		if (ret < 0) {
			ERR("Changing ownership of %s", stream->path_name);
			perror("chown");
		}
	}

	/* 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>
	22	#include <fcntl.h>
	23	#include <poll.h>
	24	#include <pthread.h>
	25	#include <stdlib.h>
	26	#include <string.h>
	27	#include <sys/mman.h>
	28	#include <sys/socket.h>
	29	#include <sys/types.h>
	30	#include <unistd.h>
	31
3bd1e081 MD	32	#include <lttng-sessiond-comm.h>
3bd1e081 MD	33	#include <lttng/lttng-ustconsumer.h>
9df8df5e	34	#include <lttng/ust-ctl.h>
3bd1e081 MD	35	#include <lttngerr.h>
	36
	37	extern struct lttng_consumer_global_data consumer_data;
	38	extern int consumer_poll_timeout;
	39	extern volatile int consumer_quit;
	40
	41	/*
	42	* Mmap the ring buffer, read it and write the data to the tracefile.
	43	*
	44	* Returns the number of bytes written
	45	*/
	46	int lttng_ustconsumer_on_read_subbuffer_mmap(
	47	struct lttng_consumer_local_data *ctx,
	48	struct lttng_consumer_stream *stream, unsigned long len)
	49	{
	50	unsigned long mmap_offset;
	51	long ret = 0;
	52	off_t orig_offset = stream->out_fd_offset;
	53	int outfd = stream->out_fd;
	54
	55	/* get the offset inside the fd to mmap */
	56	ret = ustctl_get_mmap_read_offset(stream->chan->handle,
	57	stream->buf, &mmap_offset);
	58	if (ret != 0) {
	59	ret = -errno;
	60	perror("ustctl_get_mmap_read_offset");
	61	goto end;
	62	}
	63	while (len > 0) {
	64	ret = write(outfd, stream->mmap_base + mmap_offset, len);
	65	if (ret >= len) {
	66	len = 0;
	67	} else if (ret < 0) {
	68	ret = -errno;
	69	perror("Error in file write");
	70	goto end;
	71	}
	72	/* This won't block, but will start writeout asynchronously */
	73	sync_file_range(outfd, stream->out_fd_offset, ret,
	74	SYNC_FILE_RANGE_WRITE);
	75	stream->out_fd_offset += ret;
	76	}
	77
	78	lttng_consumer_sync_trace_file(stream, orig_offset);
	79
	80	goto end;
	81
	82	end:
	83	return ret;
	84	}
	85
	86	/*
	87	* Splice the data from the ring buffer to the tracefile.
	88	*
	89	* Returns the number of bytes spliced.
	90	*/
	91	int lttng_ustconsumer_on_read_subbuffer_splice(
	92	struct lttng_consumer_local_data *ctx,
	93	struct lttng_consumer_stream *stream, unsigned long len)
	94	{
	95	return -ENOSYS;
	96	}
	97
	98	/*
99	* Take a snapshot for a specific fd
100	*
101	* Returns 0 on success, < 0 on error
102	*/
103	int lttng_ustconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
104	struct lttng_consumer_stream *stream)
105	{
106	int ret = 0;
107
108	ret = ustctl_snapshot(stream->chan->handle, stream->buf);
109	if (ret != 0) {
110	ret = errno;
111	perror("Getting sub-buffer snapshot.");
112	}
113
114	return ret;
115	}
116
117	/*
118	* Get the produced position
119	*
120	* Returns 0 on success, < 0 on error
121	*/
122	int lttng_ustconsumer_get_produced_snapshot(
123	struct lttng_consumer_local_data *ctx,
124	struct lttng_consumer_stream *stream,
125	unsigned long *pos)
126	{
127	int ret;
128
129	ret = ustctl_snapshot_get_produced(stream->chan->handle,
130	stream->buf, pos);
131	if (ret != 0) {
132	ret = errno;
133	perror("kernctl_snapshot_get_produced");
134	}
135
136	return ret;
137	}
138
139	int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
140	int sock, struct pollfd *consumer_sockpoll)
141	{
142	ssize_t ret;
143	struct lttcomm_consumer_msg msg;
144
145	ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
146	if (ret != sizeof(msg)) {
147	lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
148	return ret;
149	}
150	if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
151	return -ENOENT;
152	}
153
154	switch (msg.cmd_type) {
155	case LTTNG_CONSUMER_ADD_CHANNEL:
156	{
157	struct lttng_consumer_channel *new_channel;
158	int fds[1];
159	size_t nb_fd = 1;
160
161	/* block */
162	if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
163	return -EINTR;
164	}
165	ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
166	if (ret != sizeof(fds)) {
167	lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
168	return ret;
169	}
170
171	DBG("consumer_add_channel %d", msg.u.channel.channel_key);
172
173	new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
174	fds[0], -1,
175	msg.u.channel.mmap_len,
176	msg.u.channel.max_sb_size);
177	if (new_channel == NULL) {
178	lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
179	goto end_nosignal;
180	}
181	if (ctx->on_recv_channel != NULL) {
182	ret = ctx->on_recv_channel(new_channel);
183	if (ret == 0) {
184	consumer_add_channel(new_channel);
185	} else if (ret < 0) {
186	goto end_nosignal;
187	}
188	} else {
189	consumer_add_channel(new_channel);
190	}
191	goto end_nosignal;
192	}
193	case LTTNG_CONSUMER_ADD_STREAM:
194	{
195	struct lttng_consumer_stream *new_stream;
196	int fds[2];
197	size_t nb_fd = 2;
198
199	/* block */
200	if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
201	return -EINTR;
202	}
203	ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
204	if (ret != sizeof(fds)) {
205	lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
206	return ret;
207	}
208
209	DBG("consumer_add_stream %s (%d,%d)", msg.u.stream.path_name,
210	fds[0], fds[1]);
d41f73b7	211	assert(msg.u.stream.output == LTTNG_EVENT_MMAP);
7ad0a0cb	212	new_stream = consumer_allocate_stream(msg.u.channel.channel_key,
3bd1e081 MD	213	msg.u.stream.stream_key,
	214	fds[0], fds[1],
	215	msg.u.stream.state,
	216	msg.u.stream.mmap_len,
	217	msg.u.stream.output,
6df2e2c9 MD	218	msg.u.stream.path_name,
	219	msg.u.stream.uid,
	220	msg.u.stream.gid);
3bd1e081 MD	221	if (new_stream == NULL) {
	222	lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
	223	goto end;
	224	}
	225	if (ctx->on_recv_stream != NULL) {
	226	ret = ctx->on_recv_stream(new_stream);
	227	if (ret == 0) {
	228	consumer_add_stream(new_stream);
	229	} else if (ret < 0) {
	230	goto end;
	231	}
	232	} else {
	233	consumer_add_stream(new_stream);
	234	}
	235	break;
	236	}
	237	case LTTNG_CONSUMER_UPDATE_STREAM:
	238	{
7ad0a0cb MD	239	return -ENOSYS;
7ad0a0cb MD	240	#if 0
3bd1e081 MD	241	if (ctx->on_update_stream != NULL) {
	242	ret = ctx->on_update_stream(msg.u.stream.stream_key, msg.u.stream.state);
	243	if (ret == 0) {
	244	consumer_change_stream_state(msg.u.stream.stream_key, msg.u.stream.state);
	245	} else if (ret < 0) {
	246	goto end;
	247	}
	248	} else {
	249	consumer_change_stream_state(msg.u.stream.stream_key,
	250	msg.u.stream.state);
	251	}
7ad0a0cb	252	#endif
3bd1e081 MD	253	break;
	254	}
	255	default:
	256	break;
	257	}
	258	end:
	259	/* signal the poll thread */
	260	ret = write(ctx->consumer_poll_pipe[1], "4", 1);
	261	if (ret < 0) {
	262	perror("write consumer poll");
	263	}
	264	end_nosignal:
	265	return 0;
	266	}
	267
	268	int lttng_ustconsumer_allocate_channel(struct lttng_consumer_channel *chan)
	269	{
13161846	270	struct lttng_ust_object_data obj;
3bd1e081 MD	271
	272	obj.handle = -1;
	273	obj.shm_fd = chan->shm_fd;
	274	obj.wait_fd = chan->wait_fd;
	275	obj.memory_map_size = chan->mmap_len;
	276	chan->handle = ustctl_map_channel(&obj);
	277	if (!chan->handle) {
	278	return -ENOMEM;
	279	}
ee77a7b0	280	/*
b5c5fc29	281	* The channel fds are passed to ustctl, we only keep a copy.
ee77a7b0	282	*/
b5c5fc29 MD	283	chan->shm_fd_is_copy = 1;
	284	chan->wait_fd_is_copy = 1;
	285
3bd1e081 MD	286	return 0;
	287	}
	288
d056b477 MD	289	void lttng_ustconsumer_on_stream_hangup(struct lttng_consumer_stream *stream)
	290	{
	291	ustctl_flush_buffer(stream->chan->handle, stream->buf, 0);
effcf122	292	stream->hangup_flush_done = 1;
d056b477 MD	293	}
d056b477 MD	294
3bd1e081 MD	295	void lttng_ustconsumer_del_channel(struct lttng_consumer_channel *chan)
	296	{
	297	ustctl_unmap_channel(chan->handle);
	298	}
	299
	300	int lttng_ustconsumer_allocate_stream(struct lttng_consumer_stream *stream)
	301	{
13161846	302	struct lttng_ust_object_data obj;
3bd1e081 MD	303	int ret;
	304
	305	obj.handle = -1;
	306	obj.shm_fd = stream->shm_fd;
	307	obj.wait_fd = stream->wait_fd;
	308	obj.memory_map_size = stream->mmap_len;
	309	ret = ustctl_add_stream(stream->chan->handle, &obj);
	310	if (ret)
	311	return ret;
	312	stream->buf = ustctl_open_stream_read(stream->chan->handle, stream->cpu);
	313	if (!stream->buf)
	314	return -EBUSY;
	315	stream->mmap_base = ustctl_get_mmap_base(stream->chan->handle, stream->buf);
	316	if (!stream->mmap_base) {
	317	return -EINVAL;
	318	}
ee77a7b0	319	/*
b5c5fc29	320	* The stream fds are passed to ustctl, we only keep a copy.
ee77a7b0	321	*/
b5c5fc29 MD	322	stream->shm_fd_is_copy = 1;
b5c5fc29 MD	323	stream->wait_fd_is_copy = 1;
ee77a7b0	324
3bd1e081 MD	325	return 0;
	326	}
	327
	328	void lttng_ustconsumer_del_stream(struct lttng_consumer_stream *stream)
	329	{
	330	ustctl_close_stream_read(stream->chan->handle, stream->buf);
	331	}
d41f73b7 MD	332
	333
	334	int lttng_ustconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
	335	struct lttng_consumer_local_data *ctx)
	336	{
	337	unsigned long len;
	338	int err;
	339	long ret = 0;
	340	struct lttng_ust_shm_handle *handle;
	341	struct lttng_ust_lib_ring_buffer *buf;
	342	char dummy;
	343	ssize_t readlen;
	344
	345	DBG("In read_subbuffer (wait_fd: %d, stream key: %d)",
	346	stream->wait_fd, stream->key);
	347
	348	/* We can consume the 1 byte written into the wait_fd by UST */
effcf122 MD	349	if (!stream->hangup_flush_done) {
	350	do {
	351	readlen = read(stream->wait_fd, &dummy, 1);
	352	} while (readlen == -1 && errno == -EINTR);
	353	if (readlen == -1) {
	354	ret = readlen;
	355	goto end;
	356	}
d41f73b7 MD	357	}
	358
	359	buf = stream->buf;
	360	handle = stream->chan->handle;
	361	/* Get the next subbuffer */
	362	err = ustctl_get_next_subbuf(handle, buf);
	363	if (err != 0) {
effcf122	364	ret = -ret; /* ustctl_get_next_subbuf returns negative, caller expect positive. */
d41f73b7 MD	365	/*
	366	* This is a debug message even for single-threaded consumer,
	367	* because poll() have more relaxed criterions than get subbuf,
	368	* so get_subbuf may fail for short race windows where poll()
	369	* would issue wakeups.
	370	*/
	371	DBG("Reserving sub buffer failed (everything is normal, "
	372	"it is due to concurrency)");
	373	goto end;
	374	}
	375	assert(stream->output == LTTNG_EVENT_MMAP);
	376	/* read the used subbuffer size */
	377	err = ustctl_get_padded_subbuf_size(handle, buf, &len);
effcf122	378	assert(err == 0);
d41f73b7 MD	379	/* write the subbuffer to the tracefile */
	380	ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
	381	if (ret < 0) {
	382	/*
	383	* display the error but continue processing to try
	384	* to release the subbuffer
	385	*/
	386	ERR("Error writing to tracefile");
	387	}
	388	err = ustctl_put_next_subbuf(handle, buf);
effcf122	389	assert(err == 0);
d41f73b7 MD	390	end:
	391	return ret;
	392	}
	393
	394	int lttng_ustconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
	395	{
	396	int ret;
	397
	398	/* Opening the tracefile in write mode */
	399	if (stream->path_name != NULL) {
	400	ret = open(stream->path_name,
	401	O_WRONLY\|O_CREAT\|O_TRUNC, S_IRWXU\|S_IRWXG\|S_IRWXO);
	402	if (ret < 0) {
	403	ERR("Opening %s", stream->path_name);
	404	perror("open");
	405	goto error;
	406	}
	407	stream->out_fd = ret;
6df2e2c9 MD	408	ret = chown(stream->path_name, stream->uid, stream->gid);
	409	if (ret < 0) {
	410	ERR("Changing ownership of %s", stream->path_name);
	411	perror("chown");
	412	}
d41f73b7 MD	413	}
	414
	415	/* we return 0 to let the library handle the FD internally */
	416	return 0;
	417
	418	error:
	419	return ret;
	420	}