Linux Message Queue Demo

Client:

 

#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <mqueue.h>
#include <unistd.h>
#include <stdio.h>

#define MSG_SERVER "/msgqueue"
#define BUF_LEN 20000

int main(int argc,char** argv)
{
    mqd_t   qd;
    int     len;
    ssize_t rec_len;
    char    rec_buf[BUF_LEN];
    char    *p = NULL;

    memset(rec_buf, 1, sizeof(rec_buf));

    /*
     * Opn message queue
     */
    if ( (qd = mq_open(MSG_SERVER, O_RDONLY, 0, NULL)) < 0)
    {
        printf("open msg queue error.\n");
        exit(-1);
    }

    /*
     * Read msg
     */
    while (1)
    {
        if ( (rec_len = mq_receive(qd, rec_buf, sizeof(rec_buf), 0)) < 0)
        {
            printf("Receive msg error.\n");
            exit(-1);
        }
        else
        {
            printf("Receive msg successfully.\n");
            for (p = rec_buf; *p != '\0' && p != (rec_buf + rec_len); ++p)
            {
                printf("%c", *p);
            }
        }

        sleep(2);
    }

    mq_close(qd);
    mq_unlink(MSG_SERVER);
    exit(0);
}

Server:

 

#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <mqueue.h>
#include <stdio.h>
#include <unistd.h>

#define MSG_SERVER "/msgqueue"
#define BUF_LEN 100

int main(int argc, char** argv)
{
    mqd_t   qd;
    struct mq_attr *attr;
    mode_t  access;
    char    send_buf[BUF_LEN];

    access = S_IRUSR | S_IWUSR | S_IROTH;

    if ( (attr = (struct mq_attr *)malloc(sizeof(struct mq_attr))) == NULL)
    {
        printf("Alloc memory error!\n");
        exit(-1);
    }
    memset(attr, 0, sizeof(struct mq_attr));

    memset(send_buf, 1, sizeof(send_buf));
    send_buf[BUF_LEN - 1] = '\0';

    /*
     * Create message queue
     */

    if ( (qd = mq_open(MSG_SERVER, O_RDWR | O_CREAT | O_EXCL, access, NULL)) < 0)
    {
        printf("open msg queue error.\n");
        exit(-1);
    }

    /*
     * Get default attr
     */
    printf("Get message queue default attr:\n");
    if (mq_getattr(qd, attr) < 0)
    {
       printf("Get attr error.\n");
    }
    else if (attr != NULL)
    {
       printf("Default msg count:%ld, msgsize:%ld \n", attr->mq_maxmsg, attr->mq_msgsize);
    }
    free(attr);

    /*
     * Send msg
     */
    while (1)
    {
        if (mq_send(qd, send_buf, sizeof(send_buf), 0) < 0)
        {
            printf("Send msg error.\n");
            exit(-1);
        }
        else
        {
            printf("Send msg successfully.\n");
        }

        sleep(2);
    }

    mq_close(qd);
    mq_unlink(MSG_SERVER);
    exit(0);
}