client.c

#define _GNU_SOURCE
#include <unistd.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <mqueue.h>
#include <stdint.h>
#include <errno.h>
#include <signal.h>
#include <string.h>

#include "mqcommon.h"
#include "common.h"

#define MSG_LIMIT 20
#define MAX_MSG 10
#define ERR(source) (perror(source),\
    fprintf(stderr,"%s:%d\n",__FILE__,__LINE__),\
    exit(EXIT_FAILURE))

void sethandler( void (*f)(int), int sigNo) {
        struct sigaction act;
        memset(&act, 0, sizeof(struct sigaction));
        act.sa_handler = f;
        if (-1==sigaction(sigNo, &act, NULL)) ERR("sigaction");
}

void client(mqd_t _c, char *arg)
{
    int ret;
    mqd_t s_sv;
	if((s_sv=TEMP_FAILURE_RETRY(mq_open(arg, O_WRONLY, FILE_MODE, NULL)))==(mqd_t)-1) ERR("mq open in");
    struct msg to_sv;
    to_sv.pid = getpid();
    scanf("%f %f", &to_sv.a, &to_sv.b);
    ret = Mq_send(s_sv, (char *) &to_sv, sizeof(to_sv), 0);
    float res;
    ret = Mq_receive(_c, (char *) &res, sizeof(res), NULL);
    printf("%f\n", res);
}

int main(int argc, char *argv[])
{
    int ret;
    pid_t pid = getpid();
    char pid_c[20];
    ret = sprintf(pid_c, "/%d_c", pid);
    if (ret < 0) ERR("sprintf");
	mqd_t _c;
	struct mq_attr attr;
	attr.mq_maxmsg=MAX_MSG;
	attr.mq_msgsize=sizeof(float);
	if((_c=TEMP_FAILURE_RETRY(mq_open(pid_c, O_RDONLY| O_CREAT, FILE_MODE, &attr)))==(mqd_t)-1) ERR("mq open in");
    printf("open: %s\n", pid_c);
    client(_c, argv[1]);
    Mq_close(_c);
    Mq_unlink(pid_c);
    return 0;
}