85 lines
2.7 KiB
C
85 lines
2.7 KiB
C
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/****************************************************************************
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* sched/mqueue/msgget.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include "mqueue/msg.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: msgget
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*
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* Description:
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* Get a System V message queue identifier
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* The msgget() system call returns the System V message queue
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* identifier associated with the value of the key argument. It may
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* be used either to obtain the identifier of a previously created
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* message queue (when msgflg is zero and key does not have the
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* value IPC_PRIVATE), or to create a new set.
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*
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* Input Parameters:
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* key - Key associated with the message queue
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* msgflg - Operations and permissions flag
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*
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* Returned Value:
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* On success, msgget() returns the message queue identifier (a
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* nonnegative integer). On failure, -1 is returned, and errno is
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* set to indicate the error.
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*
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****************************************************************************/
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int msgget(key_t key, int msgflg)
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{
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FAR struct msgq_s *msgq;
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irqstate_t flags;
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int ret = OK;
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flags = enter_critical_section();
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msgq = nxmsg_lookup(key);
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if (msgq)
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{
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if ((msgflg & IPC_CREAT) && (msgflg & IPC_EXCL))
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{
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ret = -EEXIST;
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}
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}
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else
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{
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ret = (key != IPC_PRIVATE && !(msgflg & IPC_CREAT)) ?
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-ENOENT : nxmsg_alloc(&msgq);
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}
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leave_critical_section(flags);
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if (ret < 0)
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{
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set_errno(-ret);
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return ERROR;
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}
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return msgq->key;
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}
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