--- /dev/null
+/*
+ * 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 _GNU_SOURCE
+#include <assert.h>
+#include <fcntl.h>
+#include <unistd.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;
+}
+
+
+/*
+ * 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 = zmalloc(sizeof(*p));
+ if (!p) {
+ PERROR("zmalloc pipe open");
+ goto error;
+ }
+
+ ret = pipe(p->fd);
+ if (ret < 0) {
+ PERROR("lttng pipe");
+ goto error;
+ }
+
+ if (flags) {
+ int i;
+
+ for (i = 0; i < 2; i++) {
+ ret = fcntl(p->fd[i], F_SETFD, flags);
+ if (ret < 0) {
+ PERROR("fcntl lttng pipe %d", flags);
+ goto error;
+ }
+ }
+ }
+
+ pthread_mutex_init(&p->read_mutex, NULL);
+ pthread_mutex_init(&p->write_mutex, NULL);
+ p->r_state = LTTNG_PIPE_STATE_OPENED;
+ p->w_state = LTTNG_PIPE_STATE_OPENED;
+ p->flags = flags;
+
+ return p;
+
+error:
+ lttng_pipe_destroy(p);
+ 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;
+
+ 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;
+
+ 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;
+
+ 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);
+ 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 0 on success or else a negative errno message from read(2).
+ */
+ssize_t lttng_pipe_read(struct lttng_pipe *pipe, void *buf, size_t count)
+{
+ ssize_t ret, read_len, read_left, index;
+
+ assert(pipe);
+ assert(buf);
+
+ lock_read_side(pipe);
+
+ if (!lttng_pipe_is_read_open(pipe)) {
+ ret = -EBADF;
+ goto error;
+ }
+
+ read_left = count;
+ index = 0;
+ do {
+ read_len = read(pipe->fd[0], buf + index, read_left);
+ if (read_len < 0) {
+ ret = -errno;
+ if (errno == EINTR) {
+ /* Read again. */
+ continue;
+ } else if (errno == EAGAIN || errno == EWOULDBLOCK) {
+ /*
+ * Return the number of bytes read up to this point if any.
+ */
+ if (index) {
+ ret = index;
+ }
+ goto error;
+ } else {
+ PERROR("lttng pipe read");
+ goto error;
+ }
+ }
+ read_left -= read_len;
+ index += read_len;
+ } while (read_left > 0);
+
+ /* Everything went fine. */
+ ret = index;
+
+error:
+ unlock_read_side(pipe);
+ return ret;
+}
+
+/*
+ * Write on a lttng pipe using the data in buf and size of count.
+ *
+ * Return 0 on success or else a negative errno message from write(2).
+ */
+ssize_t lttng_pipe_write(struct lttng_pipe *pipe, const void *buf,
+ size_t count)
+{
+ ssize_t ret, write_len, write_left, index;
+
+ assert(pipe);
+ assert(buf);
+
+ lock_write_side(pipe);
+
+ if (!lttng_pipe_is_write_open(pipe)) {
+ ret = -EBADF;
+ goto error;
+ }
+
+ write_left = count;
+ index = 0;
+ do {
+ write_len = write(pipe->fd[1], buf + index, write_left);
+ if (write_len < 0) {
+ ret = -errno;
+ if (errno == EINTR) {
+ /* Read again. */
+ continue;
+ } else if (errno == EAGAIN || errno == EWOULDBLOCK) {
+ /*
+ * Return the number of bytes read up to this point if any.
+ */
+ if (index) {
+ ret = index;
+ }
+ goto error;
+ } else {
+ PERROR("lttng pipe write");
+ goto error;
+ }
+ }
+ write_left -= write_len;
+ index += write_len;
+ } while (write_left > 0);
+
+ /* Everything went fine. */
+ ret = index;
+
+error:
+ unlock_write_side(pipe);
+ return ret;
+}
--- /dev/null
+/*
+ * 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.
+ */
+
+#ifndef LTTNG_PIPE_H
+#define LTTNG_PIPE_H
+
+#include <pthread.h>
+
+enum lttng_pipe_state {
+ LTTNG_PIPE_STATE_OPENED = 1,
+ LTTNG_PIPE_STATE_CLOSED = 2,
+};
+
+struct lttng_pipe {
+ /* Read: 0, Write: 1. */
+ int fd[2];
+ /*
+ * Flags of the pipe once opened. pipe(2) specifies either O_NONBLOCK or
+ * O_CLOEXEC can be used. Flags are set using fcntl(2) call.
+ */
+ int flags;
+
+ /*
+ * These states are protected by the operation mutex below.
+ */
+ enum lttng_pipe_state r_state;
+ enum lttng_pipe_state w_state;
+
+ /* Held for each read(2) operation. */
+ pthread_mutex_t read_mutex;
+ /* Held for each write(2) operation. */
+ pthread_mutex_t write_mutex;
+};
+
+/*
+ * Return 1 if read side is open else 0.
+ */
+static inline int lttng_pipe_is_read_open(struct lttng_pipe *pipe)
+{
+ return pipe->r_state == LTTNG_PIPE_STATE_OPENED ? 1 : 0;
+}
+
+/*
+ * Return 1 if write side is open else 0.
+ */
+static inline int lttng_pipe_is_write_open(struct lttng_pipe *pipe)
+{
+ return pipe->w_state == LTTNG_PIPE_STATE_OPENED ? 1 : 0;
+}
+
+static inline int lttng_pipe_get_readfd(struct lttng_pipe *pipe)
+{
+ return pipe->fd[0];
+}
+
+static inline int lttng_pipe_get_writefd(struct lttng_pipe *pipe)
+{
+ return pipe->fd[1];
+}
+
+struct lttng_pipe *lttng_pipe_open(int flags);
+int lttng_pipe_write_close(struct lttng_pipe *pipe);
+int lttng_pipe_read_close(struct lttng_pipe *pipe);
+/* Close both side of pipe. */
+int lttng_pipe_close(struct lttng_pipe *pipe);
+void lttng_pipe_destroy(struct lttng_pipe *pipe);
+
+ssize_t lttng_pipe_read(struct lttng_pipe *pipe, void *buf, size_t count);
+ssize_t lttng_pipe_write(struct lttng_pipe *pipe, const void *buf,
+ size_t count);
+
+#endif /* LTTNG_PIPE_H */
projects / lttng-tools.git / commitdiff
