214 lines
8.1 KiB
C
214 lines
8.1 KiB
C
/****************************************************************************
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* include/sys/msg.h
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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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#ifndef __INCLUDE_SYS_MSG_H
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#define __INCLUDE_SYS_MSG_H
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/ipc.h>
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#include <time.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/* The MSG_NOERROR identifier value, the msqid_ds struct and the msg struct
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* are as defined by the SV API Intel 386 Processor Supplement.
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*/
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#define MSG_NOERROR 010000 /* No error if message is too big */
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#define MSG_EXCEPT 020000 /* Recv any msg except of specified type.*/
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#define MSG_COPY 040000 /* Copy (not remove) all queue messages */
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/****************************************************************************
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* Public Type Declarations
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****************************************************************************/
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typedef unsigned long msgqnum_t;
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typedef unsigned long msglen_t;
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struct msqid_ds
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{
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struct ipc_perm msg_perm; /* Ownership and permissions */
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time_t msg_stime; /* Time of last msgsnd(2) */
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time_t msg_rtime; /* Time of last msgrcv(2) */
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time_t msg_ctime; /* Time of last change */
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unsigned long msg_cbytes; /* Current number of bytes in
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* queue (nonstandard) */
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msgqnum_t msg_qnum; /* Current number of messages
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* in queue */
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msglen_t msg_qbytes; /* Maximum number of bytes
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* allowed in queue */
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pid_t msg_lspid; /* PID of last msgsnd(2) */
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pid_t msg_lrpid; /* PID of last msgrcv(2) */
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};
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/* Structure describing a message. The SVID doesn't suggest any
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* particular name for this structure. There is a reference in the
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* msgop man page that reads "The structure mymsg is an example of what
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* this user defined buffer might look like, and includes the following
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* members:". This sentence is followed by two lines equivalent
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* to the mtype and mtext field declarations below. It isn't clear
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* if "mymsg" refers to the name of the structure type or the name of an
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* instance of the structure...
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*/
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struct mymsg
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{
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long mtype; /* message type (+ve integer) */
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char mtext[1]; /* message body */
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};
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#ifdef __cplusplus
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#define EXTERN extern "C"
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extern "C"
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{
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#else
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#define EXTERN extern
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#endif
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/****************************************************************************
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* Public Function Prototypes
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****************************************************************************/
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/****************************************************************************
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* Name: msgctl
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*
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* Description:
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* System V message control operations.
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* msgctl() performs the control operation specified by cmd on the
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* System V message queue with identifier msqid.
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*
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* Input Parameters:
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* msqid - System V message queue identifier
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* cmd - Command operations
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* msqid_ds - Defines a message queue
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*
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* Returned Value:
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* On success, IPC_STAT, IPC_SET, and IPC_RMID return 0. A
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* successful IPC_INFO or MSG_INFO operation returns the index of
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* the highest used entry in the kernel's internal array recording
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* information about all message queues. (This information can be
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* used with repeated MSG_STAT or MSG_STAT_ANY operations to obtain
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* information about all queues on the system.) A successful
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* MSG_STAT or MSG_STAT_ANY operation returns the identifier of the
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* queue whose index was given in msqid.
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*
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* On failure, -1 is returned and errno is set to indicate the error.
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*
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****************************************************************************/
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int msgctl(int msqid, int cmd, FAR struct msqid_ds *buf);
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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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* Name: msgsnd
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*
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* Description:
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* The msgsnd() function is used to send a message to the queue
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* associated with the message queue identifier specified by msqid.
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* The msgp argument points to a user-defined buffer that must contain
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* first a field of type long int that will specify the type of the
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* message, and then a data portion that will hold the data bytes of
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* the message.
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*
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* Input Parameters:
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* msqid - Message queue identifier
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* msgp - Pointer to a buffer with the message to be sent
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* msgsz - Length of the data part of the message to be sent
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* msgflg - Operations flags
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*
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* Returned Value:
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* On success, mq_send() returns 0 (OK); on error, -1 (ERROR)
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* is returned, with errno set to indicate the error:
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*
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* EAGAIN The queue was full and the O_NONBLOCK flag was set for the
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* message queue description referred to by mqdes.
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* EINVAL Either msg or mqdes is NULL or the value of prio is invalid.
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* EPERM Message queue opened not opened for writing.
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* EMSGSIZE 'msglen' was greater than the maxmsgsize attribute of the
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* message queue.
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* EINTR The call was interrupted by a signal handler.
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*
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****************************************************************************/
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int msgsnd(int msqid, FAR const void *msgp, size_t msgsz, int msgflg);
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/****************************************************************************
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* Name: msgrcv
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*
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* Description:
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* The msgrcv() function reads a message from the message queue specified
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* by the msqid parameter and places it in the user-defined buffer
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* pointed to by the *msgp parameter.
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*
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* Input Parameters:
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* msqid - Message queue identifier
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* msgp - Pointer to a buffer in which the received message will be
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* stored
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* msgsz - Length of the data part of the buffer
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* msgtyp - Type of message to be received.
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* msgflg - Operations flags.
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*
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* Returned Value:
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* On success, msgrcv() returns the number of bytes actually copied
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* into the mtext array.
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* On failure, both functions return -1, and set errno to indicate
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* the error.
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*
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****************************************************************************/
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ssize_t msgrcv(int msqid, FAR void *msgp,
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size_t msgsz, long msgtyp, int msgflg);
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#undef EXTERN
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#ifdef __cplusplus
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}
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#endif
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#endif /* __INCLUDE_SYS_MSG_H */
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