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

/*
 * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 */

#define _LGPL_SOURCE
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>

#include <common/common.hpp>

#include "pipe.hpp"

/*
 * 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;

	LTTNG_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;

	LTTNG_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<lttng_pipe>();
	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++) {
		if (flags & O_NONBLOCK) {
			ret = fcntl(pipe->fd[i], F_SETFL, O_NONBLOCK);
			if (ret < 0) {
				PERROR("fcntl lttng pipe %d", flags);
				goto end;
			}
		}
		if (flags & FD_CLOEXEC) {
			ret = fcntl(pipe->fd[i], F_SETFD, FD_CLOEXEC);
			if (ret < 0) {
				PERROR("fcntl lttng pipe %d", flags);
				goto end;
			}
		}
		/*
		 * We only check for O_NONBLOCK or FD_CLOEXEC, if another flag is
		 * needed, we can add it, but for now just make sure we don't make
		 * mistakes with the parameters we pass.
		 */
		if (!(flags & O_NONBLOCK) && !(flags & FD_CLOEXEC)) {
			fprintf(stderr, "Unsupported flag\n");
			ret = -1;
			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.
 */
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.
 */
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");
		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");
		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.
 */
int lttng_pipe_read_close(struct lttng_pipe *pipe)
{
	int ret;

	LTTNG_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.
 */
int lttng_pipe_write_close(struct lttng_pipe *pipe)
{
	int ret;

	LTTNG_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.
 */
int lttng_pipe_close(struct lttng_pipe *pipe)
{
	int ret, ret_val = 0;

	LTTNG_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.
 */
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);
	LTTNG_ASSERT(!ret);
	ret = pthread_mutex_trylock(&pipe->write_mutex);
	LTTNG_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.
 */
ssize_t lttng_pipe_read(struct lttng_pipe *pipe, void *buf, size_t count)
{
	ssize_t ret;

	LTTNG_ASSERT(pipe);
	LTTNG_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.
 */
ssize_t lttng_pipe_write(struct lttng_pipe *pipe, const void *buf,
		size_t count)
{
	ssize_t ret;

	LTTNG_ASSERT(pipe);
	LTTNG_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.
 */
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.
 */
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	1	/*
ab5be9fa	2	* Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
9fd92637	3	*
ab5be9fa	4	* SPDX-License-Identifier: GPL-2.0-only
9fd92637	5	*
9fd92637 DG	6	*/
9fd92637 DG	7
6c1c0768	8	#define _LGPL_SOURCE
9fd92637 DG	9	#include <fcntl.h>
9fd92637 DG	10	#include <unistd.h>
9c2bd8db JG	11	#include <sys/types.h>
9c2bd8db JG	12	#include <sys/stat.h>
9fd92637	13
c9e313bc	14	#include <common/common.hpp>
9fd92637	15
c9e313bc	16	#include "pipe.hpp"
9fd92637 DG	17
	18	/*
	19	* Lock read side of a pipe.
	20	*/
	21	static void lock_read_side(struct lttng_pipe *pipe)
	22	{
	23	pthread_mutex_lock(&pipe->read_mutex);
	24	}
	25
	26	/*
	27	* Unlock read side of a pipe.
	28	*/
	29	static void unlock_read_side(struct lttng_pipe *pipe)
	30	{
	31	pthread_mutex_unlock(&pipe->read_mutex);
	32	}
	33
	34	/*
	35	* Lock write side of a pipe.
	36	*/
	37	static void lock_write_side(struct lttng_pipe *pipe)
	38	{
	39	pthread_mutex_lock(&pipe->write_mutex);
	40	}
	41
	42	/*
	43	* Unlock write side of a pipe.
	44	*/
	45	static void unlock_write_side(struct lttng_pipe *pipe)
	46	{
	47	pthread_mutex_unlock(&pipe->write_mutex);
	48	}
	49
	50	/*
	51	* Internal function. Close read side of pipe WITHOUT locking the mutex.
	52	*
	53	* Return 0 on success else a negative errno from close(2).
	54	*/
	55	static int _pipe_read_close(struct lttng_pipe *pipe)
	56	{
	57	int ret, ret_val = 0;
	58
a0377dfe	59	LTTNG_ASSERT(pipe);
9fd92637 DG	60
	61	if (!lttng_pipe_is_read_open(pipe)) {
	62	goto end;
	63	}
	64
	65	do {
	66	ret = close(pipe->fd[0]);
	67	} while (ret < 0 && errno == EINTR);
	68	if (ret < 0) {
	69	PERROR("close lttng read pipe");
	70	ret_val = -errno;
	71	}
	72	pipe->r_state = LTTNG_PIPE_STATE_CLOSED;
	73
	74	end:
	75	return ret_val;
	76	}
	77
	78	/*
	79	* Internal function. Close write side of pipe WITHOUT locking the mutex.
	80	*
	81	* Return 0 on success else a negative errno from close(2).
	82	*/
	83	static int _pipe_write_close(struct lttng_pipe *pipe)
	84	{
	85	int ret, ret_val = 0;
	86
a0377dfe	87	LTTNG_ASSERT(pipe);
9fd92637 DG	88
	89	if (!lttng_pipe_is_write_open(pipe)) {
	90	goto end;
	91	}
	92
	93	do {
	94	ret = close(pipe->fd[1]);
	95	} while (ret < 0 && errno == EINTR);
	96	if (ret < 0) {
	97	PERROR("close lttng write pipe");
	98	ret_val = -errno;
	99	}
	100	pipe->w_state = LTTNG_PIPE_STATE_CLOSED;
	101
	102	end:
	103	return ret_val;
	104	}
	105
9c2bd8db JG	106	static struct lttng_pipe *_pipe_create(void)
	107	{
	108	int ret;
	109	struct lttng_pipe *p;
	110
64803277	111	p = zmalloc<lttng_pipe>();
9c2bd8db JG	112	if (!p) {
	113	PERROR("zmalloc pipe create");
	114	goto end;
	115	}
	116	p->fd[0] = p->fd[1] = -1;
	117
	118	ret = pthread_mutex_init(&p->read_mutex, NULL);
	119	if (ret) {
	120	PERROR("pthread_mutex_init read lock pipe create");
	121	goto error_destroy;
	122	}
	123	ret = pthread_mutex_init(&p->write_mutex, NULL);
	124	if (ret) {
	125	PERROR("pthread_mutex_init write lock pipe create");
	126	goto error_destroy_rmutex;
	127	}
	128	end:
	129	return p;
	130	error_destroy_rmutex:
	131	(void) pthread_mutex_destroy(&p->read_mutex);
	132	error_destroy:
	133	free(p);
	134	return NULL;
	135	}
	136
	137	static int _pipe_set_flags(struct lttng_pipe *pipe, int flags)
	138	{
	139	int i, ret = 0;
	140
	141	if (!flags) {
	142	goto end;
	143	}
	144
	145	for (i = 0; i < 2; i++) {
699f8738 JD	146	if (flags & O_NONBLOCK) {
	147	ret = fcntl(pipe->fd[i], F_SETFL, O_NONBLOCK);
	148	if (ret < 0) {
	149	PERROR("fcntl lttng pipe %d", flags);
	150	goto end;
	151	}
	152	}
	153	if (flags & FD_CLOEXEC) {
	154	ret = fcntl(pipe->fd[i], F_SETFD, FD_CLOEXEC);
	155	if (ret < 0) {
	156	PERROR("fcntl lttng pipe %d", flags);
	157	goto end;
	158	}
	159	}
	160	/*
	161	* We only check for O_NONBLOCK or FD_CLOEXEC, if another flag is
	162	* needed, we can add it, but for now just make sure we don't make
	163	* mistakes with the parameters we pass.
	164	*/
	165	if (!(flags & O_NONBLOCK) && !(flags & FD_CLOEXEC)) {
	166	fprintf(stderr, "Unsupported flag\n");
	167	ret = -1;
9c2bd8db JG	168	goto end;
	169	}
	170	}
	171	end:
	172	return ret;
	173	}
9fd92637 DG	174
	175	/*
	176	* Open a new lttng pipe and set flags using fcntl().
	177	*
	178	* Return a newly allocated lttng pipe on success or else NULL.
	179	*/
	180	struct lttng_pipe *lttng_pipe_open(int flags)
	181	{
	182	int ret;
	183	struct lttng_pipe *p;
	184
9c2bd8db	185	p = _pipe_create();
9fd92637	186	if (!p) {
9fd92637 DG	187	goto error;
	188	}
	189
	190	ret = pipe(p->fd);
	191	if (ret < 0) {
	192	PERROR("lttng pipe");
	193	goto error;
	194	}
9c2bd8db JG	195	p->r_state = LTTNG_PIPE_STATE_OPENED;
9c2bd8db JG	196	p->w_state = LTTNG_PIPE_STATE_OPENED;
9fd92637	197
9c2bd8db JG	198	ret = _pipe_set_flags(p, flags);
	199	if (ret) {
	200	goto error;
9fd92637 DG	201	}
9fd92637 DG	202
9fd92637 DG	203	p->flags = flags;
	204
	205	return p;
9fd92637 DG	206	error:
	207	lttng_pipe_destroy(p);
	208	return NULL;
	209	}
	210
9c2bd8db JG	211	/*
	212	* Open a new lttng pipe at path and set flags using fcntl().
	213	*
	214	* Return a newly allocated lttng pipe on success or else NULL.
	215	*/
9c2bd8db JG	216	struct lttng_pipe lttng_pipe_named_open(const char path, mode_t mode,
	217	int flags)
	218	{
	219	int ret, fd_r, fd_w;
	220	struct lttng_pipe *pipe;
	221
	222	pipe = _pipe_create();
	223	if (!pipe) {
	224	goto error;
	225	}
	226
	227	ret = mkfifo(path, mode);
	228	if (ret) {
	229	PERROR("mkfifo");
	230	goto error;
	231	}
	232
	233	fd_r = open(path, O_RDONLY \| O_NONBLOCK);
	234	if (fd_r < 0) {
	235	PERROR("open fifo");
9c2bd8db JG	236	goto error;
	237	}
	238	pipe->fd[0] = fd_r;
	239	pipe->r_state = LTTNG_PIPE_STATE_OPENED;
	240
	241	fd_w = open(path, O_WRONLY \| O_NONBLOCK);
	242	if (fd_w < 0) {
	243	PERROR("open fifo");
9c2bd8db JG	244	goto error;
	245	}
	246	pipe->fd[1] = fd_w;
	247	pipe->w_state = LTTNG_PIPE_STATE_OPENED;
	248
	249	ret = _pipe_set_flags(pipe, flags);
	250	if (ret) {
	251	goto error;
	252	}
	253	pipe->flags = flags;
	254
	255	return pipe;
	256	error:
	257	lttng_pipe_destroy(pipe);
	258	return NULL;
	259	}
	260
9fd92637 DG	261	/*
	262	* Close read side of a lttng pipe.
	263	*
	264	* Return 0 on success else a negative value.
	265	*/
	266	int lttng_pipe_read_close(struct lttng_pipe *pipe)
	267	{
	268	int ret;
	269
a0377dfe	270	LTTNG_ASSERT(pipe);
9fd92637 DG	271
	272	/* Handle read side first. */
	273	lock_read_side(pipe);
	274	ret = _pipe_read_close(pipe);
	275	unlock_read_side(pipe);
	276
	277	return ret;
	278	}
	279
	280	/*
	281	* Close write side of a lttng pipe.
	282	*
	283	* Return 0 on success else a negative value.
	284	*/
	285	int lttng_pipe_write_close(struct lttng_pipe *pipe)
	286	{
	287	int ret;
	288
a0377dfe	289	LTTNG_ASSERT(pipe);
9fd92637 DG	290
	291	lock_write_side(pipe);
	292	ret = _pipe_write_close(pipe);
	293	unlock_write_side(pipe);
	294
	295	return ret;
	296	}
	297
	298	/*
	299	* Close both read and write side of a lttng pipe.
	300	*
	301	* Return 0 on success else a negative value.
	302	*/
	303	int lttng_pipe_close(struct lttng_pipe *pipe)
	304	{
	305	int ret, ret_val = 0;
	306
a0377dfe	307	LTTNG_ASSERT(pipe);
9fd92637 DG	308
	309	ret = lttng_pipe_read_close(pipe);
	310	if (ret < 0) {
	311	ret_val = ret;
	312	}
	313
	314	ret = lttng_pipe_write_close(pipe);
	315	if (ret < 0) {
	316	ret_val = ret;
	317	}
	318
	319	return ret_val;
	320	}
	321
	322	/*
	323	* Close and destroy a lttng pipe object. Finally, pipe is freed.
	324	*/
	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);
a0377dfe	338	LTTNG_ASSERT(!ret);
9fd92637	339	ret = pthread_mutex_trylock(&pipe->write_mutex);
a0377dfe	340	LTTNG_ASSERT(!ret);
9fd92637 DG	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 DG	360	*/
	361	ssize_t lttng_pipe_read(struct lttng_pipe pipe, void buf, size_t count)
	362	{
6cd525e8	363	ssize_t ret;
9fd92637	364
a0377dfe FD	365	LTTNG_ASSERT(pipe);
a0377dfe FD	366	LTTNG_ASSERT(buf);
9fd92637 DG	367
9fd92637 DG	368	lock_read_side(pipe);
9fd92637	369	if (!lttng_pipe_is_read_open(pipe)) {
6cd525e8 MD	370	ret = -1;
6cd525e8 MD	371	errno = EBADF;
9fd92637 DG	372	goto error;
9fd92637 DG	373	}
6cd525e8	374	ret = lttng_read(pipe->fd[0], buf, count);
9fd92637 DG	375	error:
	376	unlock_read_side(pipe);
	377	return ret;
	378	}
	379
	380	/*
	381	* Write on a lttng pipe using the data in buf and size of count.
	382	*
6cd525e8 MD	383	* Return "count" on success. Return < count on error. errno can be used
6cd525e8 MD	384	* to check the actual error.
9fd92637 DG	385	*/
	386	ssize_t lttng_pipe_write(struct lttng_pipe pipe, const void buf,
	387	size_t count)
	388	{
6cd525e8	389	ssize_t ret;
9fd92637	390
a0377dfe FD	391	LTTNG_ASSERT(pipe);
a0377dfe FD	392	LTTNG_ASSERT(buf);
9fd92637 DG	393
9fd92637 DG	394	lock_write_side(pipe);
9fd92637	395	if (!lttng_pipe_is_write_open(pipe)) {
6cd525e8 MD	396	ret = -1;
6cd525e8 MD	397	errno = EBADF;
9fd92637 DG	398	goto error;
9fd92637 DG	399	}
6cd525e8	400	ret = lttng_write(pipe->fd[1], buf, count);
9fd92637 DG	401	error:
	402	unlock_write_side(pipe);
	403	return ret;
	404	}
55dfb029 JG	405
	406	/*
	407	* Return and release the read end of the pipe.
	408	*
	409	* This call transfers the ownership of the read fd of the underlying pipe
	410	* to the caller if it is still open.
	411	*
	412	* Returns the fd of the read end of the pipe, or -1 if it was already closed or
	413	* released.
	414	*/
55dfb029 JG	415	int lttng_pipe_release_readfd(struct lttng_pipe *pipe)
	416	{
	417	int ret;
	418
	419	if (!pipe) {
	420	ret = -1;
	421	goto end;
	422	}
	423
	424	lock_read_side(pipe);
	425	if (!lttng_pipe_is_read_open(pipe)) {
	426	ret = -1;
	427	goto end_unlock;
	428	}
	429	ret = pipe->fd[0];
	430	pipe->fd[0] = -1;
	431	pipe->r_state = LTTNG_PIPE_STATE_CLOSED;
	432	end_unlock:
	433	unlock_read_side(pipe);
	434	end:
	435	return ret;
	436	}
	437
	438	/*
	439	* Return and release the write end of the pipe.
	440	*
	441	* This call transfers the ownership of the write fd of the underlying pipe
	442	* to the caller if it is still open.
	443	*
	444	* Returns the fd of the write end of the pipe, or -1 if it was alwritey closed
	445	* or released.
	446	*/
55dfb029 JG	447	int lttng_pipe_release_writefd(struct lttng_pipe *pipe)
	448	{
	449	int ret;
	450
	451	if (!pipe) {
	452	ret = -1;
	453	goto end;
	454	}
	455
	456	lock_write_side(pipe);
	457	if (!lttng_pipe_is_write_open(pipe)) {
	458	ret = -1;
	459	goto end_unlock;
	460	}
	461	ret = pipe->fd[1];
	462	pipe->fd[1] = -1;
	463	pipe->w_state = LTTNG_PIPE_STATE_CLOSED;
	464	end_unlock:
	465	unlock_write_side(pipe);
	466	end:
	467	return ret;
	468	}