anchao commented on code in PR #7088: URL: https://github.com/apache/incubator-nuttx/pull/7088#discussion_r1001401312
########## sched/mqueue/msgrcv.c: ########## @@ -0,0 +1,261 @@ +/**************************************************************************** + * sched/mqueue/msgrcv.c + * + * 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 <assert.h> + +#include <nuttx/cancelpt.h> + +#include "sched/sched.h" +#include "mqueue/msg.h" + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: msgrcv_wait + ****************************************************************************/ + +static int msgrcv_wait(FAR struct msgq_s *msgq, FAR struct msgbuf_s **rcvmsg, + long msgtyp, int msgflg) +{ + FAR struct list_node *newmsg = NULL; + FAR struct list_node *node; + FAR struct tcb_s *rtcb; + +#ifdef CONFIG_CANCELLATION_POINTS + /* msgrcv_wait() is not a cancellation point, but it may be called + * from msgrcv() which are cancellation point. + */ + + if (check_cancellation_point()) + { + /* If there is a pending cancellation, then do not perform + * the wait. Exit now with ECANCELED. + */ + + return -ECANCELED; + } +#endif + + /* Get the message from the head of the queue */ + + while (1) + { + list_for_every(&msgq->msglist, node) + { + /* Unless MSG_COPY is specified in msgflg (see below), the msgtyp + * argument specifies the type of message requested, as follows: + * + * 1. If msgtyp is 0, then the first message in the queue is read. + * + * 2. If msgtyp is greater than 0, then the first message in the + * queue of type msgtyp is read, unless MSG_EXCEPT was + * specified in msgflg, in which case the first message in the + * queue of type not equal to msgtyp will be read. + * + * 3. If msgtyp is less than 0, then the first message in the + * queue with the lowest type less than or equal to the + * absolute value of msgtyp will be read. + */ + + if (msgtyp < 0) + { + if (newmsg == NULL || ((FAR struct msgbuf_s *)newmsg)->mtype > + ((FAR struct msgbuf_s *)node)->mtype) + { + newmsg = node; + } + } + else if (msgtyp == 0 || + (msgflg & MSG_EXCEPT) != 0 || + ((FAR struct msgbuf_s *)node)->mtype == msgtyp) + { + newmsg = node; + break; + } + } + + if (newmsg) + { + list_delete(newmsg); + goto found; + } + + if ((msgflg & IPC_NOWAIT) != 0) + { + return -EAGAIN; + } + + /* The queue is empty! Should we block until there the above condition + * has been satisfied? + */ + + rtcb = this_task(); + rtcb->waitobj = msgq; + msgq->cmn.nwaitnotempty++; + + /* Initialize the 'errcode" used to communication wake-up error + * conditions. + */ + + rtcb->errcode = OK; + + /* Make sure this is not the idle task, descheduling that + * isn't going to end well. + */ + + DEBUGASSERT(NULL != rtcb->flink); + up_block_task(rtcb, TSTATE_WAIT_MQNOTEMPTY); + + /* When we resume at this point, either (1) the message queue + * is no longer empty, or (2) the wait has been interrupted by + * a signal. We can detect the latter case be examining the + * errno value (should be either EINTR or ETIMEDOUT). + */ + + if (rtcb->errcode != OK) + { + return -rtcb->errcode; + } + } + +found: + *rcvmsg = (FAR struct msgbuf_s *)newmsg; + return OK; +} + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: msgrcv + * + * Description: + * The msgrcv() function reads a message from the message queue specified + * by the msqid parameter and places it in the user-defined buffer + * pointed to by the *msgp parameter. + * + * Input Parameters: + * msqid - Message queue identifier + * msgp - Pointer to a buffer in which the received message will be + * stored + * msgsz - Length of the data part of the buffer + * msgtyp - Type of message to be received. + * msgflg - Operations flags. + * + * Returned Value: + * On success, msgrcv() returns the number of bytes actually copied + * into the mtext array. + * On failure, both functions return -1, and set errno to indicate + * the error. + * + ****************************************************************************/ + +ssize_t msgrcv(int msqid, FAR void *msgp, size_t msgsz, long msgtyp, + int msgflg) +{ + FAR struct msgbuf_s *msg = NULL; + FAR struct mymsg *buf = msgp; + FAR struct msgq_s *msgq; + FAR struct tcb_s *btcb; + irqstate_t flags; + int ret; + + if (msgp == NULL) + { + ret = -EFAULT; + goto errout; + } + + flags = enter_critical_section(); + + msgq = nxmsg_lookup(msqid); + if (msgq == NULL) + { + ret = -EINVAL; + goto errout_with_critical; + } + + if (msgsz < msgq->maxmsgsize && + ((msgflg & MSG_NOERROR) == 0)) + { + ret = -EMSGSIZE; + goto errout_with_critical; + } + + ret = msgrcv_wait(msgq, &msg, msgtyp, msgflg); + if (ret < 0) + { + goto errout_with_critical; + } + + msgq->nmsgs--; Review Comment: Done ########## sched/mqueue/msgrcv.c: ########## @@ -0,0 +1,261 @@ +/**************************************************************************** + * sched/mqueue/msgrcv.c + * + * 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 <assert.h> + +#include <nuttx/cancelpt.h> + +#include "sched/sched.h" +#include "mqueue/msg.h" + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: msgrcv_wait + ****************************************************************************/ + +static int msgrcv_wait(FAR struct msgq_s *msgq, FAR struct msgbuf_s **rcvmsg, + long msgtyp, int msgflg) +{ + FAR struct list_node *newmsg = NULL; + FAR struct list_node *node; Review Comment: Done -- This is an automated message from the Apache Git Service. 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