Here I have to send and receive dynamic data using a SysV message queue.

so in structure filed i have dynamic memory allocation char * because its size may be varies.

so how can i receive this type of message at receiver side.

Please let me know how can i send dynamic length of data with message queue.

I am getting problem in this i posted my code below.

send.c

/*filename   : send.c
 *To compile : gcc send.c -o send
 */
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>

struct my_msgbuf {
    long mtype;
    char *mtext;
};

int main(void)
{
    struct my_msgbuf buf;
    int msqid;
    key_t key;
    static int count = 0;
    char temp[5];
    int run = 1;
    if ((key = ftok("send.c", 'B')) == -1) {
        perror("ftok");
        exit(1);
    }

    printf("send.c Key is = %d\n",key);

    if ((msqid = msgget(key, 0644 | IPC_CREAT)) == -1) {
        perror("msgget");
        exit(1);
    }

    printf("Enter lines of text, ^D to quit:\n");

    buf.mtype = 1; /* we don't really care in this case */
    int ret = -1;
    while(run) {
        count++;
        buf.mtext = malloc(50);
        strcpy(buf.mtext,"Hi hello test message here");
        snprintf(temp, sizeof (temp), "%d",count);
        strcat(buf.mtext,temp);
        int len = strlen(buf.mtext);
        /* ditch newline at end, if it exists */
        if (buf.mtext[len-1] == '\n') buf.mtext[len-1] = '\0';
        if (msgsnd(msqid, &buf, len+1, IPC_NOWAIT) == -1) /* +1 for '\0' */
        perror("msgsnd");
        if(count == 100)
            run = 0;
        usleep(1000000);
    }

    if (msgctl(msqid, IPC_RMID, NULL) == -1) {
        perror("msgctl");
        exit(1);
    }

    return 0;
}

receive.c

/* filename   : receive.c
 * To compile : gcc receive.c -o receive
 */
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>

struct my_msgbuf {
    long mtype;
    char *mtext;
};

int main(void)
{
    struct my_msgbuf buf;
    int msqid;
    key_t key;

    if ((key = ftok("send.c", 'B')) == -1) {  /* same key as send.c */
        perror("ftok");
        exit(1);
    }

    if ((msqid = msgget(key, 0644)) == -1) { /* connect to the queue */
        perror("msgget");
        exit(1);
    }

    printf("test: ready to receive messages, captain.\n");

    for(;;) { /* receive never quits! */
        buf.mtext = malloc(50);
        if (msgrcv(msqid, &buf, 50, 0, 0) == -1) {
            perror("msgrcv");
            exit(1);
        }
        printf("test: \"%s\"\n", buf.mtext);
    }

    return 0;
}