msgqueue.c

Go to the documentation of this file.

#include "config.h"
#include "msgqueue.h"

#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <libintl.h>

#include "len.h"
#include "output.h"

#define MSGMAX 8192

typedef struct
{
        long mtype;
        char mtext[MSGMAX];
} mymsgbuf_t;

int send_message(int qid, int type, char *msg, int len, short flag)
{
        int res, n = 0;
        mymsgbuf_t mqbuf;
        struct msqid_ds mqinfo;
        short f;

        mqbuf.mtype = type;

        if(len == 0)
                len = str_len(msg);

        for(n = 0; n < len; n++)
                mqbuf.mtext[n] = msg[n]; // Copy 'len' characters from 'msg' to message struct

        while(n < MSGMAX)
                mqbuf.mtext[n++] = '\0'; // Fill with '\0' 's

        if((flag & MSG_PRIORITY) == MSG_PRIORITY)
                f = 100;
        else
                f = 90;

        if((flag & MSG_NOBLOCK) != MSG_NOBLOCK)
        {
                /* check if there is enough space in the message queue */
                while(((res = msgctl(qid, IPC_STAT, &mqinfo)) == 0) && ((mqinfo.__msg_cbytes + len + 1) > (mqinfo.msg_qbytes * f / 100)))
                        sleep(5); // Message queue is full, wait 5 seconds and try again
                if(res != 0)
                {
                        error(_("error in message control: %s"), strerror(errno));
                        return -4;
                }
        }
        else
        {
                res = msgctl(qid, IPC_STAT, &mqinfo);
                if(res != 0)
                {
                        error(_("error in message control: %s"), strerror(errno));
                        return -4;
                }
                /* check if there is enough space in the message queue */
                if((mqinfo.__msg_cbytes + len + 1) > (mqinfo.msg_qbytes * f / 100))
                {
                        errno = EAGAIN;
                        return -3;
                }
        }

        /* send the message */
        if((res = msgsnd(qid, &mqbuf, len + 1, ((flag & MSG_NOBLOCK) == MSG_NOBLOCK) ? IPC_NOWAIT : 0)) == -1)
        {
                if(errno == EAGAIN)
                        return -3;
                error(_("cannot put message in queue: %s"), strerror(errno));
                return -4;
        }

        return 0;
}

int receive_message(int qid, int type, char **msg)
{
        int res = 0, n = 0;
        char *ptr = NULL;
        mymsgbuf_t mqbuf;

        if((res = msgrcv(qid, &mqbuf, MSGMAX, type, 0)) == -1)
        {
                        error(_("cannot receive message: %s"), strerror(errno));
                        return -1;
        }

        ptr = *msg = (char *)malloc(res);

        while(n < res)
                *ptr++ = mqbuf.mtext[n++];

        return res;
}

int remove_queue(int qid)
{
        if(msgctl(qid, IPC_RMID, 0) == -1)
        {
                error(_("error in message control: %s"), strerror(errno));
                return -1;
        }
        return 0;
}

int create_queue(void)
{
        return msgget(IPC_PRIVATE, 0660);
}