X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Fpipe.cpp;fp=src%2Fcommon%2Fpipe.cpp;h=2de91f5a06eaac1f87aec7e724d9a98c5ef25eb3;hp=0000000000000000000000000000000000000000;hb=a6bc4ca9d659caf016ef932fcd944029737ac57c;hpb=97535efaa975ca52bf02c2d5e76351bfd2e3defa

diff --git a/src/common/pipe.cpp b/src/common/pipe.cpp
new file mode 100644
index 000000000..2de91f5a0
--- /dev/null
+++ b/src/common/pipe.cpp
@@ -0,0 +1,468 @@
+/*
+ * 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.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;
+
+	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 = (lttng_pipe *) 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++) {
+		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;
+}