Implementation of message queue functions in mqueue.h. More...

#include <string.h>
#include "FreeRTOS_POSIX.h"
#include "FreeRTOS_POSIX/errno.h"
#include "FreeRTOS_POSIX/fcntl.h"
#include "FreeRTOS_POSIX/mqueue.h"
#include "FreeRTOS_POSIX/utils.h"

Data Structures
struct	QueueElement_t
	Element of the FreeRTOS queues that store mq data. More...

struct	QueueListElement_t
	Data structure of an mq. More...

Functions
static int	prvCalculateTickTimeout (long lMessageQueueFlags, const struct timespec const pxAbsoluteTimeout, TickType_t pxTimeoutTicks)
	Convert an absolute timespec into a tick timeout, taking into account queue flags. More...

static BaseType_t	prvCreateNewMessageQueue (QueueListElement_t *ppxMessageQueue, const struct mq_attr const pxAttr, const char *const pcName, size_t xNameLength)
	Add a new queue to the queue list. More...

static void	prvDeleteMessageQueue (const QueueListElement_t *const pxMessageQueue)
	Free all the resources used by a message queue. More...

static BaseType_t	prvFindQueueInList (QueueListElement_t *const ppxQueueListElement, const char const pcName, mqd_t xMessageQueueDescriptor)
	Attempt to find the queue identified by pcName or xMqId in the queue list. More...

static void	prvInitializeQueueList (void)
	Initialize the queue list. More...

static BaseType_t	prvValidateQueueName (const char const pcName, size_t pxNameLength)
	Checks that pcName is a valid name for a message queue. More...

int	mq_close (mqd_t mqdes)
	Close a message queue. More...

int	mq_getattr (mqd_t mqdes, struct mq_attr *mqstat)
	Get message queue attributes. More...

mqd_t	mq_open (const char name, int oflag, mode_t mode, struct mq_attr attr)
	Open a message queue. More...

ssize_t	mq_receive (mqd_t mqdes, char msg_ptr, size_t msg_len, unsigned int msg_prio)
	Receive a message from a message queue. More...

int	mq_send (mqd_t mqdes, const char *msg_ptr, size_t msg_len, unsigned msg_prio)
	Send a message to a message queue. More...

ssize_t	mq_timedreceive (mqd_t mqdes, char msg_ptr, size_t msg_len, unsigned msg_prio, const struct timespec *abstime)
	Receive a message from a message queue with timeout. More...

int	mq_timedsend (mqd_t mqdes, const char msg_ptr, size_t msg_len, unsigned int msg_prio, const struct timespec abstime)

int	mq_unlink (const char *name)
	Remove a message queue. More...

Variables
static StaticSemaphore_t	xQueueListMutex = { { 0 }, .u = { 0 } }
	Guards access to the list of message queues.

static Link_t	xQueueListHead = { 0 }
	Head of the linked list of queues.

Detailed Description

Implementation of message queue functions in mqueue.h.

Function Documentation

◆ prvCalculateTickTimeout()

static int prvCalculateTickTimeout	(	long	lMessageQueueFlags,
		const struct timespec *const	pxAbsoluteTimeout,
		TickType_t *	pxTimeoutTicks
	)

static

Convert an absolute timespec into a tick timeout, taking into account queue flags.

Parameters

[in]	lMessageQueueFlags	Message queue flags to consider.
[in]	pxAbsoluteTimeout	The absolute timespec to convert.
[out]	pxTimeoutTicks	Output parameter of the timeout in ticks.

Returns: 0 if successful; EINVAL if pxAbsoluteTimeout is invalid, or ETIMEDOUT if pxAbsoluteTimeout is in the past.

◆ prvCreateNewMessageQueue()

static BaseType_t prvCreateNewMessageQueue	(	QueueListElement_t **	ppxMessageQueue,
		const struct mq_attr *const	pxAttr,
		const char *const	pcName,
		size_t	xNameLength
	)

static

Add a new queue to the queue list.

Parameters

[out]	ppxMessageQueue	Pointer to new queue.
[in]	pxAttr	mq_attr of the new queue.
[in]	pcName	Name of new queue.
[in]	xNameLength	Length of pcName.

Returns: pdTRUE if the queue is found; pdFALSE otherwise.

◆ prvDeleteMessageQueue()

static void prvDeleteMessageQueue ( const QueueListElement_t *const pxMessageQueue )

static

Free all the resources used by a message queue.

Parameters

[out] pxMessageQueue Pointer to queue to free.

Returns: nothing

◆ prvFindQueueInList()

static BaseType_t prvFindQueueInList	(	QueueListElement_t **const	ppxQueueListElement,
		const char *const	pcName,
		mqd_t	xMessageQueueDescriptor
	)

static

Attempt to find the queue identified by pcName or xMqId in the queue list.

Matches queues by pcName first; if pcName is NULL, matches by xMqId.

Parameters

[out]	ppxQueueListElement	Output parameter set when queue is found.
[in]	pcName	A queue name to match.
[in]	xMessageQueueDescriptor	A queue descriptor to match.

Returns: pdTRUE if the queue is found; pdFALSE otherwise.

◆ prvInitializeQueueList()

static void prvInitializeQueueList ( void )

static

Initialize the queue list.

Performs initialization of the queue list mutex and queue list head.

Returns: nothing

◆ prvValidateQueueName()

static BaseType_t prvValidateQueueName	(	const char *const	pcName,
		size_t *	pxNameLength
	)

static

Checks that pcName is a valid name for a message queue.

Also outputs the length of pcName.

Parameters

[in]	pcName	The name to check.
[out]	pxNameLength	Output parameter for name length.

Returns: pdTRUE if the name is valid; pdFALSE otherwise.

◆ mq_close()

int mq_close ( mqd_t mqdes )

Close a message queue.

http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_close.html

Return values

0	- Upon successful completion
-1	- A error occurred. errno is also set.

Side Effects Possible errno values: EBADF - The mqdes argument is not a valid message queue descriptor.

◆ mq_getattr()

int mq_getattr	(	mqd_t	mqdes,
		struct mq_attr *	mqstat
	)

Get message queue attributes.

http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_getattr.html

Return values

0	- Upon successful completion
-1	- A error occurred. errno is also set.

Side Effects Possible errno values: DBADF - The mqdes argument is not a valid message queue descriptor.

◆ mq_open()

mqd_t mq_open	(	const char *	name,
		int	oflag,
		mode_t	mode,
		struct mq_attr *	attr
	)

Open a message queue.

http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_open.html

Note: Supported name pattern: leading <slash> character in name is always required; the maximum length (excluding null-terminator) of the name argument can be NAME_MAX. The default value of NAME_MAX in FreeRTOS_POSIX_portable_default.h is 64, which can be overwritten by user.; mode argument is not supported.; Supported oflags: O_RDWR, O_CREAT, O_EXCL, and O_NONBLOCK.

Return values

Message	queue descriptor – Upon successful completion
(mqd_t)	- 1 – An error occurred. errno is also set.

Side Effects Possible errno values: EINVAL - name argument is invalid (not following name pattern), OR if O_CREAT is specified in oflag with attr argument not NULL and either mq_maxmsg or mq_msgsize is equal to or less than zero, OR either O_CREAT or O_EXCL is not set and a queue with the same name is unlinked but pending to be removed.
EEXIST - O_CREAT and O_EXCL are set and the named message queue already exists.
ENOSPC - There is insufficient space for the creation of the new message queue.
ENOENT - O_CREAT is not set and the named message queue does not exist.

◆ mq_receive()

ssize_t mq_receive	(	mqd_t	mqdes,
		char *	msg_ptr,
		size_t	msg_len,
		unsigned int *	msg_prio
	)

Receive a message from a message queue.

http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_receive.html

Note: msg_prio argument is not supported. Messages are not checked for corruption.

Return values

The	length of the selected message in bytes - Upon successful completion. The message is removed from the queue
-1	- An error occurred. errno is also set.

Side Effects Possible errno values: EBADF - The mqdes argument is not a valid message queue descriptor open for reading.
EMSGSIZE - The specified message buffer size, msg_len, is less than the message size attribute of the message queue.
ETIMEDOUT - The O_NONBLOCK flag was not set when the message queue was opened, but no message arrived on the queue before the specified timeout expired.
EAGAIN - O_NONBLOCK was set in the message description associated with mqdes, and the specified message queue is empty.

◆ mq_send()

int mq_send	(	mqd_t	mqdes,
		const char *	msg_ptr,
		size_t	msg_len,
		unsigned	msg_prio
	)

Send a message to a message queue.

http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_send.html

Note: msg_prio argument is not supported.

Return values

0	- Upon successful completion.
-1	- An error occurred. errno is also set.

Side Effects Possible errno values: EBADF - The mqdes argument is not a valid message queue descriptor open for writing.
EMSGSIZE - The specified message length, msg_len, exceeds the message size attribute of the message queue, OR insufficient memory for the message to be sent.
ETIMEDOUT - The O_NONBLOCK flag was not set when the message queue was opened, but the timeout expired before the message could be added to the queue.
EAGAIN - The O_NONBLOCK flag is set in the message queue description associated with mqdes, and the specified message queue is full.

◆ mq_timedreceive()

ssize_t mq_timedreceive	(	mqd_t	mqdes,
		char *	msg_ptr,
		size_t	msg_len,
		unsigned *	msg_prio,
		const struct timespec *	abstime
	)

Receive a message from a message queue with timeout.

http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_timedreceive.html

Note: msg_prio argument is not supported. Messages are not checked for corruption.

Return values

The	length of the selected message in bytes - Upon successful completion. The message is removed from the queue
-1	- An error occurred. errno is also set.

Side Effects Possible errno values: EBADF - The mqdes argument is not a valid message queue descriptor open for reading.
EMSGSIZE - The specified message buffer size, msg_len, is less than the message size attribute of the message queue.
EINVAL - The process or thread would have blocked, and the abstime parameter specified a nanoseconds field value less than zero or greater than or equal to 1000 million.
ETIMEDOUT - The O_NONBLOCK flag was not set when the message queue was opened, but no message arrived on the queue before the specified timeout expired.
EAGAIN - O_NONBLOCK was set in the message description associated with mqdes, and the specified message queue is empty.

◆ mq_unlink()

int mq_unlink ( const char * name )

Remove a message queue.

http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_unlink.html

Return values

0	- Upon successful completion.
-1	- An error occurred. errno is also set.

Side Effects Possible errno values: EINVAL - name argument is invalid. Refer to requirements on name argument in mq_open().
ENOENT - The named message queue does not exist.

Data Structures

Functions

Variables

Detailed Description

Function Documentation

◆ prvCalculateTickTimeout()

◆ prvCreateNewMessageQueue()

◆ prvDeleteMessageQueue()

◆ prvFindQueueInList()

◆ prvInitializeQueueList()

◆ prvValidateQueueName()

◆ mq_close()

◆ mq_getattr()

◆ mq_open()

◆ mq_receive()

◆ mq_send()

◆ mq_timedreceive()

◆ mq_unlink()