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[libc/posix] Fix mq_send() to block when queue is full per POSIX standard #11197

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[libc/posix] Fix mq_send() to block when queue is full per POSIX standard #11197

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65 changes: 50 additions & 15 deletions components/libc/posix/ipc/mqueue.c
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Original file line number Diff line number Diff line change
Expand Up @@ -226,10 +226,10 @@ RTM_EXPORT(mq_receive);
* 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 queue is full, the function blocks until space becomes available,
* following POSIX standard behavior.
* 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,
* If an error occurs during the send operation, errno is set appropriately,
* and the function returns -1.
*/
int mq_send(mqd_t id, const char *msg_ptr, size_t msg_len, unsigned msg_prio)
Expand All @@ -245,11 +245,18 @@ int mq_send(mqd_t id, const char *msg_ptr, size_t msg_len, unsigned msg_prio)
rt_set_errno(EINVAL);
return -1;
}
result = rt_mq_send_wait_prio(mq, (void *)msg_ptr, msg_len, msg_prio, 0, RT_UNINTERRUPTIBLE);
result = rt_mq_send_wait_prio(mq, (void *)msg_ptr, msg_len, msg_prio, RT_WAITING_FOREVER, RT_UNINTERRUPTIBLE);
if (result == RT_EOK)
return 0;

rt_set_errno(EBADF);
if (result == -RT_EINTR)
rt_set_errno(EINTR);
else if (result == -RT_ERROR)
rt_set_errno(EMSGSIZE);
else if (result == -RT_EINVAL)
rt_set_errno(EINVAL);
else
rt_set_errno(EBADF);

return -1;
}
Expand Down Expand Up @@ -320,30 +327,58 @@ ssize_t mq_timedreceive(mqd_t id,
RTM_EXPORT(mq_timedreceive);

/**
* @brief Sends a message to a message queue with a timeout (not supported).
* @brief Sends a message to a message queue with a timeout.
* @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).
* @param abs_timeout Pointer to a struct timespec specifying the absolute timeout value (ignored if null).
* @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.
* @note This function sends a message to the message queue identified by id with a specified timeout.
* If the message queue is full and the timeout has not expired, the function blocks.
* If abs_timeout is NULL, the function waits indefinitely (same as mq_send).
* If the timeout expires before space becomes available, errno is set to ETIMEDOUT.
*/
int mq_timedsend(mqd_t id,
const char *msg_ptr,
size_t msg_len,
unsigned msg_prio,
const struct timespec *abs_timeout)
{
/* RT-Thread does not support timed send */
return mq_send(id, msg_ptr, msg_len, msg_prio);
rt_mq_t mq;
rt_err_t result;
int tick = 0;
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Code style: Variable initialization / 代码风格：变量初始化

English: The variable tick is initialized to 0 on line 352, but this initialization is unnecessary since tick is always assigned a value before use (either from rt_timespec_to_tick() on line 364 or RT_WAITING_FOREVER on line 366). This follows the same pattern as mq_timedreceive() on line 298.

中文：变量 tick 在第 352 行初始化为 0，但这个初始化是不必要的，因为 tick 在使用前总是会被赋值（要么是第 364 行的 rt_timespec_to_tick()，要么是第 366 行的 RT_WAITING_FOREVER）。这与 mq_timedreceive() 第 298 行的模式相同。

Note: This is a minor style issue and the code is functionally correct. The initialization to 0 does not cause any problems.

Suggested change
int tick = 0;
int tick;

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struct mqueue_file *mq_file;
mq_file = fd_get(id)->vnode->data;
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Missing null pointer check for fd_get() return value / 缺少 fd_get() 返回值的空指针检查

English: The code directly dereferences fd_get(id)->vnode->data without checking if fd_get() returns NULL. If fd_get() returns NULL (e.g., invalid file descriptor), this will cause a segmentation fault. Other code in the codebase (e.g., components/libc/posix/io/poll/poll.c:216-219) shows that fd_get() can return NULL and should be checked before dereferencing.

中文：代码直接解引用 fd_get(id)->vnode->data 而没有检查 fd_get() 是否返回 NULL。如果 fd_get() 返回 NULL（例如无效的文件描述符），这将导致段错误。代码库中的其他代码（例如 components/libc/posix/io/poll/poll.c:216-219）显示 fd_get() 可能返回 NULL，应在解引用前进行检查。

Suggested fix: Add null pointer check after line 354:

struct dfs_file *df = fd_get(id);
if (!df || !df->vnode) {
    rt_set_errno(EBADF);
    return -1;
}
mq_file = df->vnode->data;
Suggested change
mq_file = fd_get(id)->vnode->data;
struct dfs_file *df;
df = fd_get(id);
if (!df || !df->vnode)
{
rt_set_errno(EBADF);
return -1;
}
mq_file = (struct mqueue_file *)df->vnode->data;
if (!mq_file)
{
rt_set_errno(EBADF);
return -1;
}

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mq = (rt_mq_t)mq_file->data;

if ((mq == RT_NULL) || (msg_ptr == RT_NULL))
{
rt_set_errno(EINVAL);
return -1;
}

if (abs_timeout != RT_NULL)
tick = rt_timespec_to_tick(abs_timeout);
else
tick = RT_WAITING_FOREVER;

result = rt_mq_send_wait_prio(mq, (void *)msg_ptr, msg_len, msg_prio, tick, RT_UNINTERRUPTIBLE);
if (result == RT_EOK)
return 0;

if (result == -RT_ETIMEOUT)
rt_set_errno(ETIMEDOUT);
else if (result == -RT_EINTR)
rt_set_errno(EINTR);
else if (result == -RT_ERROR)
rt_set_errno(EMSGSIZE);
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Inconsistent error handling for -RT_EINVAL / -RT_EINVAL 错误处理不一致

English: The error handling in mq_timedsend() (line 378) does not include a case for -RT_EINVAL, while mq_send() includes it (line 256-257). According to src/ipc.c, _rt_mq_send_wait() returns -RT_EINVAL when invalid parameters are passed through RT_ASSERT checks. This inconsistency means -RT_EINVAL in mq_timedsend() will be mapped to EBADF instead of EINVAL, which is incorrect.

中文：mq_timedsend() 中的错误处理（第 378 行）不包含 -RT_EINVAL 的情况，而 mq_send() 包含它（第 256-257 行）。根据 src/ipc.c，当通过 RT_ASSERT 检查传递无效参数时，_rt_mq_send_wait() 返回 -RT_EINVAL。这种不一致意味着 mq_timedsend() 中的 -RT_EINVAL 将被映射到 EBADF 而不是 EINVAL，这是不正确的。

Suggested fix: Add the same case in mq_timedsend() error handling (after line 377):

else if (result == -RT_EINVAL)
    rt_set_errno(EINVAL);
Suggested change
rt_set_errno(EMSGSIZE);
rt_set_errno(EMSGSIZE);
else if (result == -RT_EINVAL)
rt_set_errno(EINVAL);

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else
rt_set_errno(EBADF);

return -1;
}
RTM_EXPORT(mq_timedsend);

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