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

#define SOCK_PATH "/tmp/mysocket"

int sfd;

int
server ()
{
  struct sockaddr_un un;

  if (unlink (SOCK_PATH) < 0 && errno != ENOENT)
    {
      printf ("unlink: %d <%s>\n", errno, strerror (errno));
      return -1;
    }
  sfd = socket (AF_UNIX, SOCK_DGRAM | SOCK_NONBLOCK, 0);
  if (sfd < 0)
    {
      printf ("SRV socket: %d <%s>\n", errno, strerror (errno));
      return -1;
    }
  memset (&un, 0, sizeof un);
  un.sun_family = AF_UNIX;
  strcpy (un.sun_path, SOCK_PATH);
  if (bind (sfd, (const struct sockaddr *) &un, sizeof un) < 0)
    {
      printf ("SRV bind: %d <%s>\n", errno, strerror (errno));
      return -1;
    }
  return 0;
}

int
main ()
{
  int fd;
  struct sockaddr_un un;

  fd = socket (AF_UNIX, SOCK_DGRAM | SOCK_NONBLOCK, 0);
  if (fd < 0)
    {
      printf ("socket: %d <%s>\n", errno, strerror (errno));
      return 1;
    }

  if (server ())
    return 2;

  memset (&un, 0, sizeof un);
  un.sun_family = AF_UNIX;
  strcpy (un.sun_path, SOCK_PATH);

#define COUNT 64 * 1024
  for (int i = 0; i < COUNT; i++)
    {
      if (sendto (fd, &i, sizeof i, 0, (struct sockaddr *) &un, sizeof un)
	  != sizeof i)
	{
	  printf ("sendto: %d <%s>, i = %d\n", errno, strerror (errno), i);
	  return 3;
	}
    }
  for (int i = 0; i < COUNT; i++)
    {
      int j = -1;
      ssize_t nr = recv (sfd, &j, sizeof j, 0);

      if (nr < 0)
	{
	  printf ("recv: %d <%s>, i = %d\n", errno, strerror (errno), i);
	  return 4;
	}
      if (nr != sizeof j)
	{
	  printf ("partial read, i = %d\n", i);
	  return 5;
	}
      if (i != j)
	printf ("i = %d, j = %d\n", i, j);
    }
}