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16.5.3 Example of Local-Namespace Sockets

Here is an example showing how to create and name a socket in the local namespace.

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

make_named_socket (const char *filename)
  struct sockaddr_un name;
  int sock;
  size_t size;

  /* Create the socket. */
  sock = socket (PF_LOCAL, SOCK_DGRAM, 0);
  if (sock < 0)
      perror ("socket");
      exit (EXIT_FAILURE);

  /* Bind a name to the socket. */
  name.sun_family = AF_LOCAL;
  strncpy (name.sun_path, filename, sizeof (name.sun_path));
  name.sun_path[sizeof (name.sun_path) - 1] = '\0';

  /* The size of the address is
     the offset of the start of the filename,
     plus its length (not including the terminating null byte).
     Alternatively you can just do:
     size = SUN_LEN (&name);
  size = (offsetof (struct sockaddr_un, sun_path)
          + strlen (name.sun_path));

  if (bind (sock, (struct sockaddr *) &name, size) < 0)
      perror ("bind");
      exit (EXIT_FAILURE);

  return sock;