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Add comments for all functions in components/libc/posix/ipc/mqueue.c

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Troy 2024-04-30 12:16:57 +08:00 committed by Meco Man
parent f190cba0ab
commit 1d2fde8d73
1 changed files with 161 additions and 1 deletions
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162
components/libc/posix/ipc/mqueue.c
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@ -4,13 +4,29 @@
* SPDX-License-Identifier: Apache-2.0
*
* Change Logs:
* Date Author Notes
* Date Author Notes
* 2023-07-20 zmq810150896 first version
* 2024-04-30 TroyMitchell Add comments for all functions
*/
#include <dfs_file.h>
#include <unistd.h>
#include "mqueue.h"
/**
* @brief Sets the attributes of a message queue.
* @param id Identifier of the message queue.
* @param mqstat Pointer to a struct mq_attr containing the new attributes (ignored).
* @param omqstat Pointer to a struct mq_attr where the old attributes will be stored.
* @return Upon successful completion, returns 0; otherwise, returns -1 and sets errno to indicate the error.
*
* @note This function sets the attributes of the message queue specified by id.
* The new attributes are provided in the mqstat parameter, but this implementation ignores it.
* Instead, the function calls mq_getattr() to retrieve the current attributes of the message queue
* and stores them in the struct mq_attr pointed to by omqstat.
* If mqstat is RT_NULL, the function behaves as a query and retrieves the attributes without setting new values.
* If an error occurs during the operation, errno is set to indicate the error, and the function returns -1.
*/
int mq_setattr(mqd_t id,
const struct mq_attr *mqstat,
struct mq_attr *omqstat)
@ -24,6 +40,21 @@ int mq_setattr(mqd_t id,
}
RTM_EXPORT(mq_setattr);
/**
* @brief Gets the attributes of a message queue.
* @param id Identifier of the message queue.
* @param mqstat Pointer to a struct mq_attr where the attributes will be stored.
* @return Upon successful completion, returns 0; otherwise, returns -1 and sets errno to indicate the error.
*
* @note This function retrieves the attributes of the message queue specified by id.
* The attributes include the maximum number of messages that can be queued (mq_maxmsg),
* the maximum size of each message (mq_msgsize), the number of messages currently in the queue (mq_curmsgs),
* and the flags associated with the queue (mq_flags).
* The attributes are stored in the struct mq_attr pointed to by mqstat.
* If the message queue identified by id does not exist or if mqstat is a null pointer, errno is set to EBADF,
* indicating a bad file descriptor, and the function returns -1.
* Otherwise, the function retrieves the attributes from the message queue and stores them in mqstat, returning 0 to indicate success.
*/
int mq_getattr(mqd_t id, struct mq_attr *mqstat)
{
rt_mq_t mq;
@ -45,6 +76,30 @@ int mq_getattr(mqd_t id, struct mq_attr *mqstat)
}
RTM_EXPORT(mq_getattr);
/**
* @brief Opens or creates a message queue.
* @param name Name of the message queue.
* @param oflag Flags indicating the access mode and creation options (O_CREAT, O_EXCL, etc.).
* @param ... Additional arguments for creation options (mode, attr) (ignored).
* @return Upon successful completion, returns a message queue descriptor (mqd_t);
* otherwise, returns (mqd_t)(-1) and sets errno to indicate the error.
*
* @note This function opens or creates a message queue specified by name with the specified flags.
* If the name starts with '/', the leading '/' is ignored.
* The function then checks the length of the name and verifies if it exceeds the maximum allowed length.
* If the name is too long, errno is set to ENAMETOOLONG, indicating a name too long error.
* Next, the function attempts to find the message queue file corresponding to the name.
* If the file exists and O_CREAT and O_EXCL flags are both set, indicating exclusive creation,
* errno is set to EEXIST, indicating that the file already exists.
* If the file does not exist and O_CREAT flag is set, the function checks the message queue attributes.
* If the maximum number of messages (mq_maxmsg) in the attributes is less than or equal to 0,
* errno is set to EINVAL, indicating an invalid argument for the maximum number of messages.
* If the file does not exist and O_CREAT flag is not set, errno is set to ENOENT, indicating no such file or directory.
* If the message queue needs to be created (O_CREAT flag set), a new mqueue_file structure is allocated and initialized
* with the specified message queue attributes, and it is inserted into the message queue filesystem.
* Finally, the function constructs the path to the message queue device file, opens it with the specified flags,
* and returns the file descriptor as a message queue descriptor (mqd_t).
*/
mqd_t mq_open(const char *name, int oflag, ...)
{
int mq_fd;
@ -115,6 +170,26 @@ mqd_t mq_open(const char *name, int oflag, ...)
}
RTM_EXPORT(mq_open);
/**
* @brief Receives a message from a message queue.
* @param id Message queue descriptor.
* @param msg_ptr Pointer to the buffer where the received message will be stored.
* @param msg_len Maximum size of the message buffer.
* @param msg_prio Pointer to an unsigned integer where the priority of the received message will be stored (ignored).
* @return Upon successful completion, returns the number of bytes received;
* otherwise, returns -1 and sets errno to indicate the error.
*
* @note This function receives a message from the message queue identified by id.
* The received message is stored in the buffer pointed to by msg_ptr, with a maximum size of msg_len bytes.
* The priority of the received message is stored in the unsigned integer pointed to by msg_prio (ignored in this implementation).
* If either the message queue identified by id or the msg_ptr buffer is a null pointer, errno is set to EINVAL,
* indicating an invalid argument, and the function returns -1.
* The function then attempts to receive a message from the message queue using the rt_mq_recv_prio() function
* with an infinite timeout and uninterruptible mode.
* If a message is successfully received, the function returns the number of bytes received.
* If an error occurs during the receive operation, errno is set to EBADF, indicating a bad file descriptor,
* and the function returns -1.
*/
ssize_t mq_receive(mqd_t id, char *msg_ptr, size_t msg_len, unsigned *msg_prio)
{
rt_mq_t mq;
@ -137,6 +212,26 @@ ssize_t mq_receive(mqd_t id, char *msg_ptr, size_t msg_len, unsigned *msg_prio)
}
RTM_EXPORT(mq_receive);
/**
* @brief Sends a message to a message queue.
* @param id Message queue descriptor.
* @param msg_ptr Pointer to the buffer containing the message to be sent.
* @param msg_len Size of the message to be sent.
* @param msg_prio Priority of the message to be sent.
* @return Upon successful completion, returns 0;
* otherwise, returns -1 and sets errno to indicate the error.
*
* @note This function sends a message to the message queue identified by id.
* The message to be sent is contained in the buffer pointed to by msg_ptr, with a size of msg_len bytes.
* The priority of the message is specified by the msg_prio parameter.
* If either the message queue identified by id or the msg_ptr buffer is a null pointer, errno is set to EINVAL,
* indicating an invalid argument, and the function returns -1.
* The function then attempts to send the message to the message queue using the rt_mq_send_wait_prio() function
* with zero timeout and uninterruptible mode.
* If the message is successfully sent, the function returns 0.
* If an error occurs during the send operation, errno is set to EBADF, indicating a bad file descriptor,
* and the function returns -1.
*/
int mq_send(mqd_t id, const char *msg_ptr, size_t msg_len, unsigned msg_prio)
{
rt_mq_t mq;
@ -160,6 +255,31 @@ int mq_send(mqd_t id, const char *msg_ptr, size_t msg_len, unsigned msg_prio)
}
RTM_EXPORT(mq_send);
/**
* @brief Receives a message from a message queue with a timeout.
* @param id Message queue descriptor.
* @param msg_ptr Pointer to the buffer where the received message will be stored.
* @param msg_len Maximum size of the message buffer.
* @param msg_prio Pointer to an unsigned integer where the priority of the received message will be stored.
* @param abs_timeout Pointer to a struct timespec specifying the absolute timeout value (ignored if null).
* @return Upon successful completion, returns the number of bytes received;
* otherwise, returns -1 and sets errno to indicate the error.
*
* @note This function receives a message from the message queue identified by id with a specified timeout.
* The received message is stored in the buffer pointed to by msg_ptr, with a maximum size of msg_len bytes.
* The priority of the received message is stored in the unsigned integer pointed to by msg_prio.
* If either the message queue identified by id or the msg_ptr buffer is a null pointer, errno is set to EINVAL,
* indicating an invalid argument, and the function returns -1.
* The function then converts the absolute timeout value specified by abs_timeout to system ticks,
* or sets the timeout to RT_WAITING_FOREVER if abs_timeout is null.
* It attempts to receive a message from the message queue using the rt_mq_recv_prio() function
* with the specified timeout and uninterruptible mode.
* If a message is successfully received, the function returns the number of bytes received.
* If the receive operation times out, errno is set to ETIMEDOUT, indicating a timeout error.
* If the received message is too large for the specified buffer, errno is set to EMSGSIZE, indicating a message too large error.
* If an unknown error occurs during the receive operation, errno is set to EBADMSG, indicating a bad message error,
* and the function returns -1.
*/
ssize_t mq_timedreceive(mqd_t id,
char *msg_ptr,
size_t msg_len,
@ -199,6 +319,23 @@ ssize_t mq_timedreceive(mqd_t id,
}
RTM_EXPORT(mq_timedreceive);
/**
* @brief Sends a message to a message queue with a timeout (not supported).
* @param id Message queue descriptor.
* @param msg_ptr Pointer to the buffer containing the message to be sent.
* @param msg_len Size of the message to be sent.
* @param msg_prio Priority of the message to be sent.
* @param abs_timeout Pointer to a struct timespec specifying the absolute timeout value (ignored).
* @return Upon successful completion, returns 0;
* otherwise, returns -1 and sets errno to indicate the error.
*
* @note This function attempts to send a message to the message queue identified by id with a specified timeout,
* but timed send is not supported in the RT-Thread environment.
* Therefore, the function simply delegates the message sending operation to the mq_send() function,
* which does not involve a timeout.
* The abs_timeout parameter is ignored, and the message is sent without waiting for a timeout to occur.
* The function returns the result of the mq_send() function, which indicates whether the message was successfully sent.
*/
int mq_timedsend(mqd_t id,
const char *msg_ptr,
size_t msg_len,
@ -210,6 +347,18 @@ int mq_timedsend(mqd_t id,
}
RTM_EXPORT(mq_timedsend);
/**
* @brief Registers for notification when a message is available in a message queue (not supported).
* @param id Message queue descriptor.
* @param notification Pointer to a struct sigevent specifying the notification settings (ignored).
* @return Upon successful completion, returns 0;
* otherwise, returns -1 and sets errno to indicate the error.
*
* @note This function attempts to register for notification when a message is available in the message queue identified by id.
* However, message queue notification is not supported in the RT-Thread environment.
* Therefore, this function simply sets errno to EBADF, indicating a bad file descriptor,
* and returns -1 to indicate that the operation is not supported.
*/
int mq_notify(mqd_t id, const struct sigevent *notification)
{
rt_mq_t mq;
@ -227,6 +376,17 @@ int mq_notify(mqd_t id, const struct sigevent *notification)
}
RTM_EXPORT(mq_notify);
/**
* @brief Closes a message queue descriptor.
* @param id Message queue descriptor to be closed.
* @return Upon successful completion, returns 0;
* otherwise, returns -1 and sets errno to indicate the error.
*
* @note This function closes the message queue descriptor specified by id.
* It delegates the closing operation to the close() function, which closes the file descriptor associated with the message queue.
* If the close operation is successful, the function returns 0.
* If an error occurs during the close operation, errno is set to indicate the error, and the function returns -1.
*/
int mq_close(mqd_t id)
{
return close(id);