evclient.c

#include <stdio.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <poll.h>
#include <sys/eventfd.h>
#include <errno.h>

#include "ancillary.h"


// X will be replaced by '\0' post-snprintf
char *name = "Xeventfd_socket";

int main(void)
{
    struct sockaddr_un address;
    int  socket_fd;
    int evfd;

    socket_fd = socket(PF_UNIX, SOCK_STREAM, 0);
    if (socket_fd < 0)	{
	fprintf(stderr,"socket() failed: %s\n", strerror(errno));
	return 1;
    }

    memset(&address, 0, sizeof(struct sockaddr_un));

    address.sun_family = AF_UNIX;
    snprintf(address.sun_path,sizeof(address.sun_path), name);
    address.sun_path[0] = '\0';

    if (connect(socket_fd, (struct sockaddr *) &address, 
		sizeof(struct sockaddr_un)) != 0) {
	fprintf(stderr,"connect() failed: %s\n", strerror(errno));
	return 1;
    }

    if (ancil_recv_fd(socket_fd, &evfd)) {
	perror("ancil_recv_fd");
	exit(1);
    } else {
	printf("Received eventfd on: %d\n", evfd);
    }

    if (evfd < 0) {
	printf("bad event fd\n");
	exit(1);
    }
    struct pollfd   fds[1];
    int             rc;
    fds[0].fd = evfd;
    fds[0].events = POLLERR | POLLIN ;

    printf("starting poll\n");

    while (1) {
	rc = poll((struct pollfd *) &fds, 1, -1);
	if (rc < 0)
	    perror("poll");
	else {
	    uint64_t u;
	    ssize_t s;
	    if (fds[0].revents & POLLIN) {
		printf("about to read\n");
		s = read(evfd, &u, sizeof(uint64_t));
		if (s != sizeof(uint64_t))
		    perror("read");
		printf("read %llu (0x%llx) from efd %d\n",
		       (unsigned long long) u, (unsigned long long) u, evfd);
	    }
	    if (fds[0].revents & POLLERR) {
		printf("POLLERR \n");
		break;
	    }
	}
    }
    close(socket_fd);

    return 0;
}