[lttng-tools.git] / src / common / pipe.c

/*
 * Copyright (C) 2013 - David Goulet <dgoulet@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 _LGPL_SOURCE
#include <assert.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>

#include <common/common.h>

#include "pipe.h"

/*
 * Lock read side of a pipe.
 */
static void lock_read_side(struct lttng_pipe *pipe)
{
	pthread_mutex_lock(&pipe->read_mutex);
}

/*
 * Unlock read side of a pipe.
 */
static void unlock_read_side(struct lttng_pipe *pipe)
{
	pthread_mutex_unlock(&pipe->read_mutex);
}

/*
 * Lock write side of a pipe.
 */
static void lock_write_side(struct lttng_pipe *pipe)
{
	pthread_mutex_lock(&pipe->write_mutex);
}

/*
 * Unlock write side of a pipe.
 */
static void unlock_write_side(struct lttng_pipe *pipe)
{
	pthread_mutex_unlock(&pipe->write_mutex);
}

/*
 * Internal function. Close read side of pipe WITHOUT locking the mutex.
 *
 * Return 0 on success else a negative errno from close(2).
 */
static int _pipe_read_close(struct lttng_pipe *pipe)
{
	int ret, ret_val = 0;

	assert(pipe);

	if (!lttng_pipe_is_read_open(pipe)) {
		goto end;
	}

	do {
		ret = close(pipe->fd[0]);
	} while (ret < 0 && errno == EINTR);
	if (ret < 0) {
		PERROR("close lttng read pipe");
		ret_val = -errno;
	}
	pipe->r_state = LTTNG_PIPE_STATE_CLOSED;

end:
	return ret_val;
}

/*
 * Internal function. Close write side of pipe WITHOUT locking the mutex.
 *
 * Return 0 on success else a negative errno from close(2).
 */
static int _pipe_write_close(struct lttng_pipe *pipe)
{
	int ret, ret_val = 0;

	assert(pipe);

	if (!lttng_pipe_is_write_open(pipe)) {
		goto end;
	}

	do {
		ret = close(pipe->fd[1]);
	} while (ret < 0 && errno == EINTR);
	if (ret < 0) {
		PERROR("close lttng write pipe");
		ret_val = -errno;
	}
	pipe->w_state = LTTNG_PIPE_STATE_CLOSED;

end:
	return ret_val;
}

static struct lttng_pipe *_pipe_create(void)
{
	int ret;
	struct lttng_pipe *p;

	p = zmalloc(sizeof(*p));
	if (!p) {
		PERROR("zmalloc pipe create");
		goto end;
	}
	p->fd[0] = p->fd[1] = -1;

	ret = pthread_mutex_init(&p->read_mutex, NULL);
	if (ret) {
		PERROR("pthread_mutex_init read lock pipe create");
		goto error_destroy;
	}
	ret = pthread_mutex_init(&p->write_mutex, NULL);
	if (ret) {
		PERROR("pthread_mutex_init write lock pipe create");
		goto error_destroy_rmutex;
	}
end:
	return p;
error_destroy_rmutex:
	(void) pthread_mutex_destroy(&p->read_mutex);
error_destroy:
	free(p);
	return NULL;
}

static int _pipe_set_flags(struct lttng_pipe *pipe, int flags)
{
	int i, ret = 0;

	if (!flags) {
		goto end;
	}

	for (i = 0; i < 2; i++) {
		ret = fcntl(pipe->fd[i], F_SETFD, flags);
		if (ret < 0) {
			PERROR("fcntl lttng pipe %d", flags);
			goto end;
		}
	}
end:
	return ret;
}

/*
 * Open a new lttng pipe and set flags using fcntl().
 *
 * Return a newly allocated lttng pipe on success or else NULL.
 */
LTTNG_HIDDEN
struct lttng_pipe *lttng_pipe_open(int flags)
{
	int ret;
	struct lttng_pipe *p;

	p = _pipe_create();
	if (!p) {
		goto error;
	}

	ret = pipe(p->fd);
	if (ret < 0) {
		PERROR("lttng pipe");
		goto error;
	}
	p->r_state = LTTNG_PIPE_STATE_OPENED;
	p->w_state = LTTNG_PIPE_STATE_OPENED;

	ret = _pipe_set_flags(p, flags);
	if (ret) {
		goto error;
	}

	p->flags = flags;

	return p;
error:
	lttng_pipe_destroy(p);
	return NULL;
}

/*
 * Open a new lttng pipe at path and set flags using fcntl().
 *
 * Return a newly allocated lttng pipe on success or else NULL.
 */
LTTNG_HIDDEN
struct lttng_pipe *lttng_pipe_named_open(const char *path, mode_t mode,
		int flags)
{
	int ret, fd_r, fd_w;
	struct lttng_pipe *pipe;

	pipe = _pipe_create();
	if (!pipe) {
		goto error;
	}

	ret = mkfifo(path, mode);
	if (ret) {
		PERROR("mkfifo");
		goto error;
	}

	fd_r = open(path, O_RDONLY | O_NONBLOCK);
	if (fd_r < 0) {
		PERROR("open fifo");
		ret = fd_r;
		goto error;
	}
	pipe->fd[0] = fd_r;
	pipe->r_state = LTTNG_PIPE_STATE_OPENED;

	fd_w = open(path, O_WRONLY | O_NONBLOCK);
	if (fd_w < 0) {
		PERROR("open fifo");
		ret = fd_w;
		goto error;
	}
	pipe->fd[1] = fd_w;
	pipe->w_state = LTTNG_PIPE_STATE_OPENED;

	ret = _pipe_set_flags(pipe, flags);
	if (ret) {
		goto error;
	}
	pipe->flags = flags;

	return pipe;
error:
	lttng_pipe_destroy(pipe);
	return NULL;
}

/*
 * Close read side of a lttng pipe.
 *
 * Return 0 on success else a negative value.
 */
LTTNG_HIDDEN
int lttng_pipe_read_close(struct lttng_pipe *pipe)
{
	int ret;

	assert(pipe);

	/* Handle read side first. */
	lock_read_side(pipe);
	ret = _pipe_read_close(pipe);
	unlock_read_side(pipe);

	return ret;
}

/*
 * Close write side of a lttng pipe.
 *
 * Return 0 on success else a negative value.
 */
LTTNG_HIDDEN
int lttng_pipe_write_close(struct lttng_pipe *pipe)
{
	int ret;

	assert(pipe);

	lock_write_side(pipe);
	ret = _pipe_write_close(pipe);
	unlock_write_side(pipe);

	return ret;
}

/*
 * Close both read and write side of a lttng pipe.
 *
 * Return 0 on success else a negative value.
 */
LTTNG_HIDDEN
int lttng_pipe_close(struct lttng_pipe *pipe)
{
	int ret, ret_val = 0;

	assert(pipe);

	ret = lttng_pipe_read_close(pipe);
	if (ret < 0) {
		ret_val = ret;
	}

	ret = lttng_pipe_write_close(pipe);
	if (ret < 0) {
		ret_val = ret;
	}

	return ret_val;
}

/*
 * Close and destroy a lttng pipe object. Finally, pipe is freed.
 */
LTTNG_HIDDEN
void lttng_pipe_destroy(struct lttng_pipe *pipe)
{
	int ret;

	if (!pipe) {
		return;
	}

	/*
	 * Destroy should *never* be called with a locked mutex. These must always
	 * succeed so we unlock them after the close pipe below.
	 */
	ret = pthread_mutex_trylock(&pipe->read_mutex);
	assert(!ret);
	ret = pthread_mutex_trylock(&pipe->write_mutex);
	assert(!ret);

	/* Close pipes WITHOUT trying to lock the pipes. */
	(void) _pipe_read_close(pipe);
	(void) _pipe_write_close(pipe);

	unlock_read_side(pipe);
	unlock_write_side(pipe);

	(void) pthread_mutex_destroy(&pipe->read_mutex);
	(void) pthread_mutex_destroy(&pipe->write_mutex);

	free(pipe);
}

/*
 * Read on a lttng pipe and put the data in buf of at least size count.
 *
 * Return "count" on success. Return < count on error. errno can be used
 * to check the actual error.
 */
LTTNG_HIDDEN
ssize_t lttng_pipe_read(struct lttng_pipe *pipe, void *buf, size_t count)
{
	ssize_t ret;

	assert(pipe);
	assert(buf);

	lock_read_side(pipe);
	if (!lttng_pipe_is_read_open(pipe)) {
		ret = -1;
		errno = EBADF;
		goto error;
	}
	ret = lttng_read(pipe->fd[0], buf, count);
error:
	unlock_read_side(pipe);
	return ret;
}

/*
 * Write on a lttng pipe using the data in buf and size of count.
 *
 * Return "count" on success. Return < count on error. errno can be used
 * to check the actual error.
 */
LTTNG_HIDDEN
ssize_t lttng_pipe_write(struct lttng_pipe *pipe, const void *buf,
		size_t count)
{
	ssize_t ret;

	assert(pipe);
	assert(buf);

	lock_write_side(pipe);
	if (!lttng_pipe_is_write_open(pipe)) {
		ret = -1;
		errno = EBADF;
		goto error;
	}
	ret = lttng_write(pipe->fd[1], buf, count);
error:
	unlock_write_side(pipe);
	return ret;
}

/*
 * Return and release the read end of the pipe.
 *
 * This call transfers the ownership of the read fd of the underlying pipe
 * to the caller if it is still open.
 *
 * Returns the fd of the read end of the pipe, or -1 if it was already closed or
 * released.
 */
LTTNG_HIDDEN
int lttng_pipe_release_readfd(struct lttng_pipe *pipe)
{
	int ret;

	if (!pipe) {
		ret = -1;
		goto end;
	}

	lock_read_side(pipe);
	if (!lttng_pipe_is_read_open(pipe)) {
		ret = -1;
		goto end_unlock;
	}
	ret = pipe->fd[0];
	pipe->fd[0] = -1;
	pipe->r_state = LTTNG_PIPE_STATE_CLOSED;
end_unlock:
	unlock_read_side(pipe);
end:
	return ret;
}

/*
 * Return and release the write end of the pipe.
 *
 * This call transfers the ownership of the write fd of the underlying pipe
 * to the caller if it is still open.
 *
 * Returns the fd of the write end of the pipe, or -1 if it was alwritey closed
 * or released.
 */
LTTNG_HIDDEN
int lttng_pipe_release_writefd(struct lttng_pipe *pipe)
{
	int ret;

	if (!pipe) {
		ret = -1;
		goto end;
	}

	lock_write_side(pipe);
	if (!lttng_pipe_is_write_open(pipe)) {
		ret = -1;
		goto end_unlock;
	}
	ret = pipe->fd[1];
	pipe->fd[1] = -1;
	pipe->w_state = LTTNG_PIPE_STATE_CLOSED;
end_unlock:
	unlock_write_side(pipe);
end:
	return ret;
}
Commit	Line	Data
9fd92637 DG	1	/*
	2	* Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
	3	*
	4	* This program is free software; you can redistribute it and/or modify it
	5	* under the terms of the GNU General Public License, version 2 only, as
	6	* published by the Free Software Foundation.
	7	*
	8	* This program is distributed in the hope that it will be useful, but WITHOUT
	9	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	10	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	11	* more details.
	12	*
	13	* You should have received a copy of the GNU General Public License along with
	14	* this program; if not, write to the Free Software Foundation, Inc., 51
	15	* Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
	16	*/
	17
6c1c0768	18	#define _LGPL_SOURCE
9fd92637 DG	19	#include <assert.h>
	20	#include <fcntl.h>
	21	#include <unistd.h>
9c2bd8db JG	22	#include <sys/types.h>
9c2bd8db JG	23	#include <sys/stat.h>
9fd92637 DG	24
	25	#include <common/common.h>
	26
	27	#include "pipe.h"
	28
	29	/*
	30	* Lock read side of a pipe.
	31	*/
	32	static void lock_read_side(struct lttng_pipe *pipe)
	33	{
	34	pthread_mutex_lock(&pipe->read_mutex);
	35	}
	36
	37	/*
	38	* Unlock read side of a pipe.
	39	*/
	40	static void unlock_read_side(struct lttng_pipe *pipe)
	41	{
	42	pthread_mutex_unlock(&pipe->read_mutex);
	43	}
	44
	45	/*
	46	* Lock write side of a pipe.
	47	*/
	48	static void lock_write_side(struct lttng_pipe *pipe)
	49	{
	50	pthread_mutex_lock(&pipe->write_mutex);
	51	}
	52
	53	/*
	54	* Unlock write side of a pipe.
	55	*/
	56	static void unlock_write_side(struct lttng_pipe *pipe)
	57	{
	58	pthread_mutex_unlock(&pipe->write_mutex);
	59	}
	60
	61	/*
	62	* Internal function. Close read side of pipe WITHOUT locking the mutex.
	63	*
	64	* Return 0 on success else a negative errno from close(2).
	65	*/
	66	static int _pipe_read_close(struct lttng_pipe *pipe)
	67	{
	68	int ret, ret_val = 0;
	69
	70	assert(pipe);
	71
	72	if (!lttng_pipe_is_read_open(pipe)) {
	73	goto end;
	74	}
	75
	76	do {
	77	ret = close(pipe->fd[0]);
	78	} while (ret < 0 && errno == EINTR);
	79	if (ret < 0) {
	80	PERROR("close lttng read pipe");
	81	ret_val = -errno;
	82	}
	83	pipe->r_state = LTTNG_PIPE_STATE_CLOSED;
	84
	85	end:
	86	return ret_val;
	87	}
88
89	/*
90	* Internal function. Close write side of pipe WITHOUT locking the mutex.
91	*
92	* Return 0 on success else a negative errno from close(2).
93	*/
94	static int _pipe_write_close(struct lttng_pipe *pipe)
95	{
96	int ret, ret_val = 0;
97
98	assert(pipe);
99
100	if (!lttng_pipe_is_write_open(pipe)) {
101	goto end;
102	}
103
104	do {
105	ret = close(pipe->fd[1]);
106	} while (ret < 0 && errno == EINTR);
107	if (ret < 0) {
108	PERROR("close lttng write pipe");
109	ret_val = -errno;
110	}
111	pipe->w_state = LTTNG_PIPE_STATE_CLOSED;
112
113	end:
114	return ret_val;
115	}
116
9c2bd8db JG	117	static struct lttng_pipe *_pipe_create(void)
	118	{
	119	int ret;
	120	struct lttng_pipe *p;
	121
	122	p = zmalloc(sizeof(*p));
	123	if (!p) {
	124	PERROR("zmalloc pipe create");
	125	goto end;
	126	}
	127	p->fd[0] = p->fd[1] = -1;
	128
	129	ret = pthread_mutex_init(&p->read_mutex, NULL);
	130	if (ret) {
	131	PERROR("pthread_mutex_init read lock pipe create");
	132	goto error_destroy;
	133	}
	134	ret = pthread_mutex_init(&p->write_mutex, NULL);
	135	if (ret) {
	136	PERROR("pthread_mutex_init write lock pipe create");
	137	goto error_destroy_rmutex;
	138	}
	139	end:
	140	return p;
	141	error_destroy_rmutex:
	142	(void) pthread_mutex_destroy(&p->read_mutex);
	143	error_destroy:
	144	free(p);
	145	return NULL;
	146	}
	147
	148	static int _pipe_set_flags(struct lttng_pipe *pipe, int flags)
	149	{
	150	int i, ret = 0;
	151
	152	if (!flags) {
	153	goto end;
	154	}
	155
	156	for (i = 0; i < 2; i++) {
	157	ret = fcntl(pipe->fd[i], F_SETFD, flags);
	158	if (ret < 0) {
	159	PERROR("fcntl lttng pipe %d", flags);
	160	goto end;
	161	}
	162	}
	163	end:
	164	return ret;
	165	}
9fd92637 DG	166
	167	/*
	168	* Open a new lttng pipe and set flags using fcntl().
	169	*
	170	* Return a newly allocated lttng pipe on success or else NULL.
	171	*/
a247c6e0	172	LTTNG_HIDDEN
9fd92637 DG	173	struct lttng_pipe *lttng_pipe_open(int flags)
	174	{
	175	int ret;
	176	struct lttng_pipe *p;
	177
9c2bd8db	178	p = _pipe_create();
9fd92637	179	if (!p) {
9fd92637 DG	180	goto error;
	181	}
	182
	183	ret = pipe(p->fd);
	184	if (ret < 0) {
	185	PERROR("lttng pipe");
	186	goto error;
	187	}
9c2bd8db JG	188	p->r_state = LTTNG_PIPE_STATE_OPENED;
9c2bd8db JG	189	p->w_state = LTTNG_PIPE_STATE_OPENED;
9fd92637	190
9c2bd8db JG	191	ret = _pipe_set_flags(p, flags);
	192	if (ret) {
	193	goto error;
9fd92637 DG	194	}
9fd92637 DG	195
9fd92637 DG	196	p->flags = flags;
	197
	198	return p;
9fd92637 DG	199	error:
	200	lttng_pipe_destroy(p);
	201	return NULL;
	202	}
	203
9c2bd8db JG	204	/*
	205	* Open a new lttng pipe at path and set flags using fcntl().
	206	*
	207	* Return a newly allocated lttng pipe on success or else NULL.
	208	*/
	209	LTTNG_HIDDEN
	210	struct lttng_pipe lttng_pipe_named_open(const char path, mode_t mode,
	211	int flags)
	212	{
	213	int ret, fd_r, fd_w;
	214	struct lttng_pipe *pipe;
	215
	216	pipe = _pipe_create();
	217	if (!pipe) {
	218	goto error;
	219	}
	220
	221	ret = mkfifo(path, mode);
	222	if (ret) {
	223	PERROR("mkfifo");
	224	goto error;
	225	}
	226
	227	fd_r = open(path, O_RDONLY \| O_NONBLOCK);
	228	if (fd_r < 0) {
	229	PERROR("open fifo");
	230	ret = fd_r;
	231	goto error;
	232	}
	233	pipe->fd[0] = fd_r;
	234	pipe->r_state = LTTNG_PIPE_STATE_OPENED;
	235
	236	fd_w = open(path, O_WRONLY \| O_NONBLOCK);
	237	if (fd_w < 0) {
	238	PERROR("open fifo");
	239	ret = fd_w;
	240	goto error;
	241	}
	242	pipe->fd[1] = fd_w;
	243	pipe->w_state = LTTNG_PIPE_STATE_OPENED;
	244
	245	ret = _pipe_set_flags(pipe, flags);
	246	if (ret) {
	247	goto error;
	248	}
	249	pipe->flags = flags;
	250
	251	return pipe;
	252	error:
	253	lttng_pipe_destroy(pipe);
	254	return NULL;
	255	}
	256
9fd92637 DG	257	/*
	258	* Close read side of a lttng pipe.
	259	*
	260	* Return 0 on success else a negative value.
	261	*/
a247c6e0	262	LTTNG_HIDDEN
9fd92637 DG	263	int lttng_pipe_read_close(struct lttng_pipe *pipe)
	264	{
	265	int ret;
	266
	267	assert(pipe);
	268
	269	/* Handle read side first. */
	270	lock_read_side(pipe);
	271	ret = _pipe_read_close(pipe);
	272	unlock_read_side(pipe);
	273
	274	return ret;
	275	}
	276
	277	/*
	278	* Close write side of a lttng pipe.
	279	*
	280	* Return 0 on success else a negative value.
	281	*/
a247c6e0	282	LTTNG_HIDDEN
9fd92637 DG	283	int lttng_pipe_write_close(struct lttng_pipe *pipe)
	284	{
	285	int ret;
	286
	287	assert(pipe);
	288
	289	lock_write_side(pipe);
	290	ret = _pipe_write_close(pipe);
	291	unlock_write_side(pipe);
	292
	293	return ret;
	294	}
	295
	296	/*
	297	* Close both read and write side of a lttng pipe.
	298	*
	299	* Return 0 on success else a negative value.
	300	*/
a247c6e0	301	LTTNG_HIDDEN
9fd92637 DG	302	int lttng_pipe_close(struct lttng_pipe *pipe)
	303	{
	304	int ret, ret_val = 0;
	305
	306	assert(pipe);
	307
	308	ret = lttng_pipe_read_close(pipe);
	309	if (ret < 0) {
	310	ret_val = ret;
	311	}
	312
	313	ret = lttng_pipe_write_close(pipe);
	314	if (ret < 0) {
	315	ret_val = ret;
	316	}
	317
	318	return ret_val;
	319	}
	320
	321	/*
	322	* Close and destroy a lttng pipe object. Finally, pipe is freed.
	323	*/
a247c6e0	324	LTTNG_HIDDEN
9fd92637 DG	325	void lttng_pipe_destroy(struct lttng_pipe *pipe)
	326	{
	327	int ret;
	328
	329	if (!pipe) {
	330	return;
	331	}
	332
	333	/*
	334	* Destroy should never be called with a locked mutex. These must always
	335	* succeed so we unlock them after the close pipe below.
	336	*/
	337	ret = pthread_mutex_trylock(&pipe->read_mutex);
	338	assert(!ret);
	339	ret = pthread_mutex_trylock(&pipe->write_mutex);
	340	assert(!ret);
	341
	342	/* Close pipes WITHOUT trying to lock the pipes. */
	343	(void) _pipe_read_close(pipe);
	344	(void) _pipe_write_close(pipe);
	345
	346	unlock_read_side(pipe);
	347	unlock_write_side(pipe);
	348
	349	(void) pthread_mutex_destroy(&pipe->read_mutex);
	350	(void) pthread_mutex_destroy(&pipe->write_mutex);
	351
	352	free(pipe);
	353	}
	354
	355	/*
	356	* Read on a lttng pipe and put the data in buf of at least size count.
	357	*
6cd525e8 MD	358	* Return "count" on success. Return < count on error. errno can be used
6cd525e8 MD	359	* to check the actual error.
9fd92637	360	*/
a247c6e0	361	LTTNG_HIDDEN
9fd92637 DG	362	ssize_t lttng_pipe_read(struct lttng_pipe pipe, void buf, size_t count)
9fd92637 DG	363	{
6cd525e8	364	ssize_t ret;
9fd92637 DG	365
	366	assert(pipe);
	367	assert(buf);
	368
	369	lock_read_side(pipe);
9fd92637	370	if (!lttng_pipe_is_read_open(pipe)) {
6cd525e8 MD	371	ret = -1;
6cd525e8 MD	372	errno = EBADF;
9fd92637 DG	373	goto error;
9fd92637 DG	374	}
6cd525e8	375	ret = lttng_read(pipe->fd[0], buf, count);
9fd92637 DG	376	error:
	377	unlock_read_side(pipe);
	378	return ret;
	379	}
	380
	381	/*
	382	* Write on a lttng pipe using the data in buf and size of count.
	383	*
6cd525e8 MD	384	* Return "count" on success. Return < count on error. errno can be used
6cd525e8 MD	385	* to check the actual error.
9fd92637	386	*/
a247c6e0	387	LTTNG_HIDDEN
9fd92637 DG	388	ssize_t lttng_pipe_write(struct lttng_pipe pipe, const void buf,
	389	size_t count)
	390	{
6cd525e8	391	ssize_t ret;
9fd92637 DG	392
	393	assert(pipe);
	394	assert(buf);
	395
	396	lock_write_side(pipe);
9fd92637	397	if (!lttng_pipe_is_write_open(pipe)) {
6cd525e8 MD	398	ret = -1;
6cd525e8 MD	399	errno = EBADF;
9fd92637 DG	400	goto error;
9fd92637 DG	401	}
6cd525e8	402	ret = lttng_write(pipe->fd[1], buf, count);
9fd92637 DG	403	error:
	404	unlock_write_side(pipe);
	405	return ret;
	406	}
55dfb029 JG	407
	408	/*
	409	* Return and release the read end of the pipe.
	410	*
	411	* This call transfers the ownership of the read fd of the underlying pipe
	412	* to the caller if it is still open.
	413	*
	414	* Returns the fd of the read end of the pipe, or -1 if it was already closed or
	415	* released.
	416	*/
	417	LTTNG_HIDDEN
	418	int lttng_pipe_release_readfd(struct lttng_pipe *pipe)
	419	{
	420	int ret;
	421
	422	if (!pipe) {
	423	ret = -1;
	424	goto end;
	425	}
	426
	427	lock_read_side(pipe);
	428	if (!lttng_pipe_is_read_open(pipe)) {
	429	ret = -1;
	430	goto end_unlock;
	431	}
	432	ret = pipe->fd[0];
	433	pipe->fd[0] = -1;
	434	pipe->r_state = LTTNG_PIPE_STATE_CLOSED;
	435	end_unlock:
	436	unlock_read_side(pipe);
	437	end:
	438	return ret;
	439	}
	440
	441	/*
	442	* Return and release the write end of the pipe.
	443	*
	444	* This call transfers the ownership of the write fd of the underlying pipe
	445	* to the caller if it is still open.
	446	*
	447	* Returns the fd of the write end of the pipe, or -1 if it was alwritey closed
	448	* or released.
	449	*/
	450	LTTNG_HIDDEN
	451	int lttng_pipe_release_writefd(struct lttng_pipe *pipe)
	452	{
	453	int ret;
	454
	455	if (!pipe) {
	456	ret = -1;
	457	goto end;
	458	}
	459
	460	lock_write_side(pipe);
	461	if (!lttng_pipe_is_write_open(pipe)) {
	462	ret = -1;
	463	goto end_unlock;
	464	}
	465	ret = pipe->fd[1];
	466	pipe->fd[1] = -1;
	467	pipe->w_state = LTTNG_PIPE_STATE_CLOSED;
	468	end_unlock:
	469	unlock_write_side(pipe);
	470	end:
471	return ret;
472	}