[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, version 2 only,
 * as published by the Free Software Foundation.
 *
 * 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 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, written = 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");
		written = ret;
		goto end;
	}
	while (len > 0) {
		ret = write(outfd, stream->mmap_base + mmap_offset, len);
		if (ret < 0) {
			if (errno == EINTR) {
				/* restart the interrupted system call */
				continue;
			} else {
				PERROR("Error in file write");
				if (written == 0) {
					written = ret;
				}
				goto end;
			}
		} else if (ret > len) {
			PERROR("Error in file write");
			written += ret;
			goto end;
		} else {
			len -= ret;
			mmap_offset += ret;
		}
		/* 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;
		written += ret;
	}
	lttng_consumer_sync_trace_file(stream, orig_offset);
end:
	return written;
}

/*
 * 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:
	/*
	 * Wake-up the other end by writing a null byte in the pipe
	 * (non-blocking). Important note: Because writing into the
	 * pipe is non-blocking (and therefore we allow dropping wakeup
	 * data, as long as there is wakeup data present in the pipe
	 * buffer to wake up the other end), the other end should
	 * perform the following sequence for waiting:
	 * 1) empty the pipe (reads).
	 * 2) perform update operation.
	 * 3) wait on the pipe (poll).
	 */
	do {
		ret = write(ctx->consumer_poll_pipe[1], "", 1);
	} while (ret == -1UL && errno == EINTR);
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 != len) {
		/*
		 * 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	*
d14d33bf AM	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License, version 2 only,
	7	* as published by the Free Software Foundation.
3bd1e081 MD	8	*
	9	* This program is distributed in the hope that it will be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
	13	*
d14d33bf AM	14	* You should have received a copy of the GNU General Public License along
	15	* with this program; if not, write to the Free Software Foundation, Inc.,
	16	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
3bd1e081 MD	17	*/
	18
	19	#define _GNU_SOURCE
	20	#include <assert.h>
3bd1e081 MD	21	#include <poll.h>
	22	#include <pthread.h>
	23	#include <stdlib.h>
	24	#include <string.h>
	25	#include <sys/mman.h>
	26	#include <sys/socket.h>
dbb5dfe6	27	#include <sys/stat.h>
3bd1e081 MD	28	#include <sys/types.h>
3bd1e081 MD	29	#include <unistd.h>
9df8df5e	30	#include <lttng/ust-ctl.h>
0857097f	31
990570ed	32	#include <common/common.h>
10a8a223	33	#include <common/sessiond-comm/sessiond-comm.h>
dbb5dfe6	34	#include <common/compat/fcntl.h>
10a8a223 DG	35
10a8a223 DG	36	#include "ust-consumer.h"
3bd1e081 MD	37
	38	extern struct lttng_consumer_global_data consumer_data;
	39	extern int consumer_poll_timeout;
	40	extern volatile int consumer_quit;
	41
	42	/*
	43	* Mmap the ring buffer, read it and write the data to the tracefile.
	44	*
4078b776	45	* Returns the number of bytes written, else negative value on error.
3bd1e081	46	*/
4078b776	47	ssize_t lttng_ustconsumer_on_read_subbuffer_mmap(
3bd1e081 MD	48	struct lttng_consumer_local_data *ctx,
	49	struct lttng_consumer_stream *stream, unsigned long len)
	50	{
	51	unsigned long mmap_offset;
47e81c02	52	long ret = 0, written = 0;
3bd1e081 MD	53	off_t orig_offset = stream->out_fd_offset;
	54	int outfd = stream->out_fd;
	55
	56	/* get the offset inside the fd to mmap */
	57	ret = ustctl_get_mmap_read_offset(stream->chan->handle,
	58	stream->buf, &mmap_offset);
	59	if (ret != 0) {
87dc6a9c	60	errno = -ret;
4c462e79	61	PERROR("ustctl_get_mmap_read_offset");
47e81c02	62	written = ret;
3bd1e081 MD	63	goto end;
	64	}
	65	while (len > 0) {
	66	ret = write(outfd, stream->mmap_base + mmap_offset, len);
47e81c02 MD	67	if (ret < 0) {
	68	if (errno == EINTR) {
	69	/* restart the interrupted system call */
	70	continue;
	71	} else {
	72	PERROR("Error in file write");
	73	if (written == 0) {
	74	written = ret;
	75	}
	76	goto end;
	77	}
	78	} else if (ret > len) {
4c462e79	79	PERROR("Error in file write");
47e81c02	80	written += ret;
3bd1e081	81	goto end;
47e81c02 MD	82	} else {
	83	len -= ret;
	84	mmap_offset += ret;
3bd1e081 MD	85	}
3bd1e081 MD	86	/* This won't block, but will start writeout asynchronously */
dbb5dfe6	87	lttng_sync_file_range(outfd, stream->out_fd_offset, ret,
3bd1e081 MD	88	SYNC_FILE_RANGE_WRITE);
3bd1e081 MD	89	stream->out_fd_offset += ret;
47e81c02	90	written += ret;
3bd1e081	91	}
3bd1e081	92	lttng_consumer_sync_trace_file(stream, orig_offset);
3bd1e081	93	end:
47e81c02	94	return written;
3bd1e081 MD	95	}
	96
	97	/*
	98	* Splice the data from the ring buffer to the tracefile.
	99	*
	100	* Returns the number of bytes spliced.
	101	*/
4078b776	102	ssize_t lttng_ustconsumer_on_read_subbuffer_splice(
3bd1e081 MD	103	struct lttng_consumer_local_data *ctx,
	104	struct lttng_consumer_stream *stream, unsigned long len)
	105	{
	106	return -ENOSYS;
	107	}
	108
	109	/*
	110	* Take a snapshot for a specific fd
	111	*
	112	* Returns 0 on success, < 0 on error
	113	*/
	114	int lttng_ustconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
	115	struct lttng_consumer_stream *stream)
	116	{
	117	int ret = 0;
	118
	119	ret = ustctl_snapshot(stream->chan->handle, stream->buf);
	120	if (ret != 0) {
87dc6a9c	121	errno = -ret;
4c462e79	122	PERROR("Getting sub-buffer snapshot.");
3bd1e081 MD	123	}
	124
	125	return ret;
	126	}
	127
	128	/*
	129	* Get the produced position
	130	*
	131	* Returns 0 on success, < 0 on error
	132	*/
	133	int lttng_ustconsumer_get_produced_snapshot(
	134	struct lttng_consumer_local_data *ctx,
	135	struct lttng_consumer_stream *stream,
	136	unsigned long *pos)
	137	{
	138	int ret;
	139
	140	ret = ustctl_snapshot_get_produced(stream->chan->handle,
	141	stream->buf, pos);
	142	if (ret != 0) {
87dc6a9c	143	errno = -ret;
4c462e79	144	PERROR("kernctl_snapshot_get_produced");
3bd1e081 MD	145	}
	146
	147	return ret;
	148	}
	149
	150	int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
	151	int sock, struct pollfd *consumer_sockpoll)
	152	{
	153	ssize_t ret;
	154	struct lttcomm_consumer_msg msg;
	155
	156	ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
	157	if (ret != sizeof(msg)) {
	158	lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
	159	return ret;
	160	}
	161	if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
	162	return -ENOENT;
	163	}
	164
	165	switch (msg.cmd_type) {
	166	case LTTNG_CONSUMER_ADD_CHANNEL:
	167	{
	168	struct lttng_consumer_channel *new_channel;
	169	int fds[1];
	170	size_t nb_fd = 1;
	171
	172	/* block */
	173	if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
	174	return -EINTR;
	175	}
	176	ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
	177	if (ret != sizeof(fds)) {
	178	lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
	179	return ret;
	180	}
	181
	182	DBG("consumer_add_channel %d", msg.u.channel.channel_key);
	183
	184	new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
	185	fds[0], -1,
	186	msg.u.channel.mmap_len,
	187	msg.u.channel.max_sb_size);
	188	if (new_channel == NULL) {
	189	lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
	190	goto end_nosignal;
	191	}
	192	if (ctx->on_recv_channel != NULL) {
	193	ret = ctx->on_recv_channel(new_channel);
	194	if (ret == 0) {
	195	consumer_add_channel(new_channel);
	196	} else if (ret < 0) {
	197	goto end_nosignal;
	198	}
	199	} else {
	200	consumer_add_channel(new_channel);
	201	}
	202	goto end_nosignal;
	203	}
	204	case LTTNG_CONSUMER_ADD_STREAM:
	205	{
	206	struct lttng_consumer_stream *new_stream;
	207	int fds[2];
	208	size_t nb_fd = 2;
209
210	/* block */
211	if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
212	return -EINTR;
213	}
214	ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
215	if (ret != sizeof(fds)) {
216	lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
217	return ret;
218	}
219
220	DBG("consumer_add_stream %s (%d,%d)", msg.u.stream.path_name,
221	fds[0], fds[1]);
d41f73b7	222	assert(msg.u.stream.output == LTTNG_EVENT_MMAP);
7ad0a0cb	223	new_stream = consumer_allocate_stream(msg.u.channel.channel_key,
3bd1e081 MD	224	msg.u.stream.stream_key,
	225	fds[0], fds[1],
	226	msg.u.stream.state,
	227	msg.u.stream.mmap_len,
	228	msg.u.stream.output,
6df2e2c9 MD	229	msg.u.stream.path_name,
	230	msg.u.stream.uid,
	231	msg.u.stream.gid);
3bd1e081 MD	232	if (new_stream == NULL) {
	233	lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
	234	goto end;
	235	}
	236	if (ctx->on_recv_stream != NULL) {
	237	ret = ctx->on_recv_stream(new_stream);
	238	if (ret == 0) {
	239	consumer_add_stream(new_stream);
	240	} else if (ret < 0) {
	241	goto end;
	242	}
	243	} else {
	244	consumer_add_stream(new_stream);
	245	}
	246	break;
	247	}
	248	case LTTNG_CONSUMER_UPDATE_STREAM:
	249	{
7ad0a0cb MD	250	return -ENOSYS;
7ad0a0cb MD	251	#if 0
3bd1e081 MD	252	if (ctx->on_update_stream != NULL) {
	253	ret = ctx->on_update_stream(msg.u.stream.stream_key, msg.u.stream.state);
	254	if (ret == 0) {
	255	consumer_change_stream_state(msg.u.stream.stream_key, msg.u.stream.state);
	256	} else if (ret < 0) {
	257	goto end;
	258	}
	259	} else {
	260	consumer_change_stream_state(msg.u.stream.stream_key,
	261	msg.u.stream.state);
	262	}
7ad0a0cb	263	#endif
3bd1e081 MD	264	break;
	265	}
	266	default:
	267	break;
	268	}
	269	end:
04fdd819 MD	270	/*
	271	* Wake-up the other end by writing a null byte in the pipe
	272	* (non-blocking). Important note: Because writing into the
	273	* pipe is non-blocking (and therefore we allow dropping wakeup
	274	* data, as long as there is wakeup data present in the pipe
	275	* buffer to wake up the other end), the other end should
	276	* perform the following sequence for waiting:
	277	* 1) empty the pipe (reads).
	278	* 2) perform update operation.
	279	* 3) wait on the pipe (poll).
	280	*/
	281	do {
	282	ret = write(ctx->consumer_poll_pipe[1], "", 1);
	283	} while (ret == -1UL && errno == EINTR);
3bd1e081 MD	284	end_nosignal:
	285	return 0;
	286	}
	287
	288	int lttng_ustconsumer_allocate_channel(struct lttng_consumer_channel *chan)
	289	{
13161846	290	struct lttng_ust_object_data obj;
3bd1e081 MD	291
	292	obj.handle = -1;
	293	obj.shm_fd = chan->shm_fd;
	294	obj.wait_fd = chan->wait_fd;
	295	obj.memory_map_size = chan->mmap_len;
	296	chan->handle = ustctl_map_channel(&obj);
	297	if (!chan->handle) {
	298	return -ENOMEM;
	299	}
b5c5fc29	300	chan->wait_fd_is_copy = 1;
2c1dd183	301	chan->shm_fd = -1;
b5c5fc29	302
3bd1e081 MD	303	return 0;
	304	}
	305
d056b477 MD	306	void lttng_ustconsumer_on_stream_hangup(struct lttng_consumer_stream *stream)
	307	{
	308	ustctl_flush_buffer(stream->chan->handle, stream->buf, 0);
effcf122	309	stream->hangup_flush_done = 1;
d056b477 MD	310	}
d056b477 MD	311
3bd1e081 MD	312	void lttng_ustconsumer_del_channel(struct lttng_consumer_channel *chan)
	313	{
	314	ustctl_unmap_channel(chan->handle);
	315	}
	316
	317	int lttng_ustconsumer_allocate_stream(struct lttng_consumer_stream *stream)
	318	{
13161846	319	struct lttng_ust_object_data obj;
3bd1e081 MD	320	int ret;
	321
	322	obj.handle = -1;
	323	obj.shm_fd = stream->shm_fd;
	324	obj.wait_fd = stream->wait_fd;
	325	obj.memory_map_size = stream->mmap_len;
	326	ret = ustctl_add_stream(stream->chan->handle, &obj);
	327	if (ret)
	328	return ret;
	329	stream->buf = ustctl_open_stream_read(stream->chan->handle, stream->cpu);
	330	if (!stream->buf)
	331	return -EBUSY;
2c1dd183 MD	332	/* ustctl_open_stream_read has closed the shm fd. */
	333	stream->wait_fd_is_copy = 1;
	334	stream->shm_fd = -1;
	335
3bd1e081 MD	336	stream->mmap_base = ustctl_get_mmap_base(stream->chan->handle, stream->buf);
	337	if (!stream->mmap_base) {
	338	return -EINVAL;
	339	}
ee77a7b0	340
3bd1e081 MD	341	return 0;
	342	}
	343
	344	void lttng_ustconsumer_del_stream(struct lttng_consumer_stream *stream)
	345	{
	346	ustctl_close_stream_read(stream->chan->handle, stream->buf);
	347	}
d41f73b7 MD	348
	349
	350	int lttng_ustconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
	351	struct lttng_consumer_local_data *ctx)
	352	{
	353	unsigned long len;
	354	int err;
	355	long ret = 0;
	356	struct lttng_ust_shm_handle *handle;
	357	struct lttng_ust_lib_ring_buffer *buf;
	358	char dummy;
	359	ssize_t readlen;
	360
	361	DBG("In read_subbuffer (wait_fd: %d, stream key: %d)",
	362	stream->wait_fd, stream->key);
	363
	364	/* We can consume the 1 byte written into the wait_fd by UST */
effcf122 MD	365	if (!stream->hangup_flush_done) {
	366	do {
	367	readlen = read(stream->wait_fd, &dummy, 1);
87dc6a9c	368	} while (readlen == -1 && errno == EINTR);
effcf122 MD	369	if (readlen == -1) {
	370	ret = readlen;
	371	goto end;
	372	}
d41f73b7 MD	373	}
	374
	375	buf = stream->buf;
	376	handle = stream->chan->handle;
	377	/* Get the next subbuffer */
	378	err = ustctl_get_next_subbuf(handle, buf);
	379	if (err != 0) {
effcf122	380	ret = -ret; /* ustctl_get_next_subbuf returns negative, caller expect positive. */
d41f73b7 MD	381	/*
	382	* This is a debug message even for single-threaded consumer,
	383	* because poll() have more relaxed criterions than get subbuf,
	384	* so get_subbuf may fail for short race windows where poll()
	385	* would issue wakeups.
	386	*/
	387	DBG("Reserving sub buffer failed (everything is normal, "
	388	"it is due to concurrency)");
	389	goto end;
	390	}
	391	assert(stream->output == LTTNG_EVENT_MMAP);
	392	/* read the used subbuffer size */
	393	err = ustctl_get_padded_subbuf_size(handle, buf, &len);
effcf122	394	assert(err == 0);
d41f73b7 MD	395	/* write the subbuffer to the tracefile */
d41f73b7 MD	396	ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
47e81c02	397	if (ret != len) {
d41f73b7 MD	398	/*
	399	* display the error but continue processing to try
	400	* to release the subbuffer
	401	*/
	402	ERR("Error writing to tracefile");
	403	}
	404	err = ustctl_put_next_subbuf(handle, buf);
effcf122	405	assert(err == 0);
d41f73b7 MD	406	end:
	407	return ret;
	408	}
	409
	410	int lttng_ustconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
	411	{
	412	int ret;
	413
	414	/* Opening the tracefile in write mode */
	415	if (stream->path_name != NULL) {
e11d277b	416	ret = run_as_open(stream->path_name,
60b6c79c MD	417	O_WRONLY\|O_CREAT\|O_TRUNC,
	418	S_IRWXU\|S_IRWXG\|S_IRWXO,
	419	stream->uid, stream->gid);
d41f73b7 MD	420	if (ret < 0) {
d41f73b7 MD	421	ERR("Opening %s", stream->path_name);
4c462e79	422	PERROR("open");
d41f73b7 MD	423	goto error;
	424	}
	425	stream->out_fd = ret;
	426	}
	427
	428	/* we return 0 to let the library handle the FD internally */
	429	return 0;
	430
	431	error:
	432	return ret;
	433	}