examples/PIPS/opencmessagequeuelibraryex/engine/src/msgqrecv.c

#include <errno.h>
#include <sys/msg.h>
#include <sys/sem.h>
#include <unistd.h>
#include <string.h>
#include "MsgQInternal.h"



/*******************************************************************************
* MsgQReceive (qName, msg, maxNBytes, timeout, err)
* Description: Function for receiving a message with internal copy
********************************************************************************/

EXPORT_C int MsgQReceive(ULONG qName, char* msg, ULONG maxNBytes, int timeout, int* err) {
        MSGQ_INFO* pMsgQInfo = NULL;
        ssize_t rxBytes;
        int toTicks;

        struct {
                long  mtype;
                char mtext[MAX_MSG_LEN];
        } message;

        /* check parameters */
        if ((pMsgQInfo = MsgQTableLookup(qName)) != NULL) {
                if(timeout != NO_WAIT && timeout != WAIT_FOREVER)
                        toTicks = timeout < 10 ? 1: (ULONG)((timeout * sysconf(_SC_CLK_TCK)) / 1000);
                else
                        toTicks = timeout;      

                message.mtype = 1;
                /* receive message */
                if((rxBytes = msgrcv(pMsgQInfo->qId, &message, (size_t)maxNBytes, 1, toTicks)) != -1) {
                        message.mtext[rxBytes-4] = '\0';
                        bcopy(message.mtext, msg, rxBytes);
                        pMsgQInfo->numMsgs--;
                        *err = OK;
                        return ((ULONG)rxBytes);
                }
                else
                        *err = errno;
        }
        else
                *err = KMsgQLibQIdErr;

        return(ERROR);
}

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