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521/****************************************************************************
* fs/mqueue/mq_open.c
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/stat.h>
#include <stdbool.h>
#include <stdarg.h>
#include <stdio.h>
#include <sched.h>
#include <mqueue.h>
#include <fcntl.h>
#include <assert.h>
#include <errno.h>
#include <nuttx/mqueue.h>
#include <nuttx/fs/fs.h>
#include "inode/inode.h"
#include "mqueue/mqueue.h"
#include "vfs/vfs.h"
/****************************************************************************
* Private Functions Prototypes
****************************************************************************/
static int nxmq_file_close(FAR struct file *filep);
static int nxmq_file_poll(FAR struct file *filep,
FAR struct pollfd *fds, bool setup);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_nxmq_fileops =
{
NULL, /* open */
nxmq_file_close, /* close */
NULL, /* read */
NULL, /* write */
NULL, /* seek */
NULL, /* ioctl */
NULL, /* mmap */
NULL, /* truncate */
nxmq_file_poll /* poll */
};
/****************************************************************************
* Private Functions
****************************************************************************/
static int nxmq_file_close(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
if (atomic_read(&inode->i_crefs) <= 1)
{
FAR struct mqueue_inode_s *msgq = inode->i_private;
if (msgq)
{
nxmq_free_msgq(msgq);
inode->i_private = NULL;
}
}
return 0;
}
static int nxmq_file_poll(FAR struct file *filep,
FAR struct pollfd *fds, bool setup)
{
FAR struct inode *inode = filep->f_inode;
FAR struct mqueue_inode_s *msgq = inode->i_private;
pollevent_t eventset = 0;
irqstate_t flags;
int ret = 0;
int i;
flags = enter_critical_section();
if (setup)
{
for (i = 0; i < CONFIG_FS_MQUEUE_NPOLLWAITERS; i++)
{
/* Find an available slot */
if (msgq->fds[i] == NULL)
{
/* Bind the poll structure and this slot */
msgq->fds[i] = fds;
fds->priv = &msgq->fds[i];
break;
}
}
if (i >= CONFIG_FS_MQUEUE_NPOLLWAITERS)
{
fds->priv = NULL;
ret = -EBUSY;
goto errout;
}
/* Immediately notify on any of the requested events */
if (msgq->nmsgs < msgq->maxmsgs)
{
eventset |= POLLOUT;
}
if (msgq->nmsgs > 0)
{
eventset |= POLLIN;
}
poll_notify(&fds, 1, eventset);
}
else if (fds->priv != NULL)
{
for (i = 0; i < CONFIG_FS_MQUEUE_NPOLLWAITERS; i++)
{
if (fds == msgq->fds[i])
{
msgq->fds[i] = NULL;
fds->priv = NULL;
break;
}
}
}
errout:
leave_critical_section(flags);
return ret;
}
static int file_mq_vopen(FAR struct file *mq, FAR const char *mq_name,
int oflags, mode_t umask, va_list ap,
FAR int *created)
{
FAR struct inode *inode;
FAR struct mqueue_inode_s *msgq;
FAR struct mq_attr *attr = NULL;
struct inode_search_s desc;
char fullpath[MAX_MQUEUE_PATH];
irqstate_t flags;
mode_t mode = 0;
int ret;
/* Make sure that a non-NULL name is supplied */
if (!mq || !mq_name || *mq_name == '\0')
{
ret = -EINVAL;
goto errout;
}
if (sizeof(CONFIG_FS_MQUEUE_VFS_PATH) + 1 + strlen(mq_name)
>= MAX_MQUEUE_PATH)
{
ret = -ENAMETOOLONG;
goto errout;
}
/* Were we asked to create it? */
if ((oflags & O_CREAT) != 0)
{
/* We have to extract the additional
* parameters from the variable argument list.
*/
mode = va_arg(ap, mode_t);
attr = va_arg(ap, FAR struct mq_attr *);
if (attr != NULL)
{
if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
{
ret = -EINVAL;
goto errout;
}
}
}
mode &= ~umask;
/* Skip over any leading '/'. All message queue paths are relative to
* CONFIG_FS_MQUEUE_VFS_PATH.
*/
while (*mq_name == '/')
{
mq_name++;
}
/* Get the full path to the message queue */
snprintf(fullpath, MAX_MQUEUE_PATH,
CONFIG_FS_MQUEUE_VFS_PATH "/%s", mq_name);
/* Make sure that the check for the existence of the message queue
* and the creation of the message queue are atomic with respect to
* other processes executing mq_open(). A simple sched_lock() would
* be sufficient for non-SMP case but critical section is needed for
* SMP case.
*/
flags = enter_critical_section();
/* Get the inode for this mqueue. This should succeed if the message
* queue has already been created. In this case, inode_find() will
* have incremented the reference count on the inode.
*/
SETUP_SEARCH(&desc, fullpath, false);
ret = inode_find(&desc);
if (ret >= 0)
{
/* Something exists at this path. Get the search results */
inode = desc.node;
/* Verify that the inode is a message queue */
if (!INODE_IS_MQUEUE(inode))
{
ret = -ENXIO;
goto errout_with_inode;
}
/* It exists and is a message queue. Check if the caller wanted to
* create a new mqueue with this name.
*/
if ((oflags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
{
ret = -EEXIST;
goto errout_with_inode;
}
/* Associate the inode with a file structure */
mq->f_oflags = oflags;
mq->f_inode = inode;
if (created)
{
*created = 0;
}
}
else
{
/* The mqueue does not exists. Were we asked to create it? */
if ((oflags & O_CREAT) == 0)
{
/* The mqueue does not exist and O_CREAT is not set */
ret = -ENOENT;
goto errout_with_lock;
}
/* Create an inode in the pseudo-filesystem at this path */
inode_lock();
ret = inode_reserve(fullpath, mode, &inode);
inode_unlock();
if (ret < 0)
{
goto errout_with_lock;
}
/* Allocate memory for the new message queue. The new inode will
* be created with a reference count of zero.
*/
ret = nxmq_alloc_msgq(attr, &msgq);
if (ret < 0)
{
goto errout_with_inode;
}
/* Associate the inode with a file structure */
mq->f_oflags = oflags;
mq->f_inode = inode;
INODE_SET_MQUEUE(inode);
inode->u.i_ops = &g_nxmq_fileops;
inode->i_private = msgq;
msgq->inode = inode;
/* Set the initial reference count on this inode to one */
atomic_fetch_add(&inode->i_crefs, 1);
if (created)
{
*created = 1;
}
}
RELEASE_SEARCH(&desc);
leave_critical_section(flags);
#ifdef CONFIG_FS_NOTIFY
notify_open(fullpath, oflags);
#endif
return OK;
errout_with_inode:
inode_release(inode);
errout_with_lock:
RELEASE_SEARCH(&desc);
leave_critical_section(flags);
errout:
return ret;
}
static mqd_t nxmq_vopen(FAR const char *mq_name, int oflags, va_list ap)
{
FAR struct file *mq;
int created;
int ret;
int fd;
mq = file_allocate();
if (mq == NULL)
{
return -ENOMEM;
}
ret = file_mq_vopen(mq, mq_name, oflags, getumask(), ap, &created);
if (ret < 0)
{
file_deallocate(mq);
return ret;
}
fd = file_dup(mq, 0, oflags);
if (fd < 0)
{
file_close(mq);
file_deallocate(mq);
}
return fd;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: file_mq_open
*
* Description:
* This function establish a connection between a named message queue and
* the calling task. This is an internal OS interface. It is functionally
* equivalent to mq_open() except that:
*
* - It is not a cancellation point, and
* - It does not modify the errno value.
*
* See comments with mq_open() for a more complete description of the
* behavior of this function
*
* Input Parameters:
* mq - address of to-be-initialized struct file instance.
* mq_name - Name of the queue to open
* oflags - open flags
* Optional parameters. When the O_CREAT flag is specified, two optional
* parameters are expected:
*
* 1. mode_t mode, and
* 2. struct mq_attr *attr. The mq_maxmsg attribute
* is used at the time that the message queue is
* created to determine the maximum number of
* messages that may be placed in the message queue.
*
* Returned Value:
* This is an internal OS interface and should not be used by applications.
* It follows the NuttX internal error return policy: Zero (OK) is
* returned on success, instance pointed by mq is also initialized.
* A negated errno value is returned on failure.
*
****************************************************************************/
int file_mq_open(FAR struct file *mq,
FAR const char *mq_name, int oflags, ...)
{
va_list ap;
int ret;
memset(mq, 0, sizeof(*mq));
va_start(ap, oflags);
ret = file_mq_vopen(mq, mq_name, oflags, 0, ap, NULL);
va_end(ap);
return ret;
}
/****************************************************************************
* Name: nxmq_open
*
* Description:
* This function establish a connection between a named message queue and
* the calling task. This is an internal OS interface. It is functionally
* equivalent to mq_open() except that:
*
* - It is not a cancellation point, and
* - It does not modify the errno value.
*
* See comments with mq_open() for a more complete description of the
* behavior of this function
*
* Input Parameters:
* mq_name - Name of the queue to open
* oflags - open flags
* Optional parameters. When the O_CREAT flag is specified, two optional
* parameters are expected:
*
* 1. mode_t mode, and
* 2. struct mq_attr *attr. The mq_maxmsg attribute
* is used at the time that the message queue is
* created to determine the maximum number of
* messages that may be placed in the message queue.
*
* Returned Value:
* This is an internal OS interface and should not be used by applications.
* It follows the NuttX internal error return policy: Zero (OK) is
* returned on success, mqdes point to the new message queue descriptor.
* A negated errno value is returned on failure.
*
****************************************************************************/
mqd_t nxmq_open(FAR const char *mq_name, int oflags, ...)
{
va_list ap;
mqd_t ret;
va_start(ap, oflags);
ret = nxmq_vopen(mq_name, oflags, ap);
va_end(ap);
return ret;
}
/****************************************************************************
* Name: mq_open
*
* Description:
* This function establish a connection between a named message queue and
* the calling task. After a successful call of mq_open(), the task can
* reference the message queue using the address returned by the call. The
* message queue remains usable until it is closed by a successful call to
* mq_close().
*
* Input Parameters:
* mq_name - Name of the queue to open
* oflags - open flags
* Optional parameters. When the O_CREAT flag is specified, two optional
* parameters are expected:
*
* 1. mode_t mode, and
* 2. struct mq_attr *attr. The mq_maxmsg attribute
* is used at the time that the message queue is
* created to determine the maximum number of
* messages that may be placed in the message queue.
*
* Returned Value:
* A message queue descriptor or (mqd_t)-1 (ERROR)
*
* Assumptions:
*
****************************************************************************/
mqd_t mq_open(FAR const char *mq_name, int oflags, ...)
{
va_list ap;
mqd_t ret;
va_start(ap, oflags);
ret = nxmq_vopen(mq_name, oflags, ap);
va_end(ap);
if (ret < 0)
{
set_errno(-ret);
return ERROR;
}
return ret;
}