BIND(3)                    POSIX Programmer's Manual                   BIND(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NAME
       bind -- bind a name to a socket

SYNOPSIS
       #include <sys/socket.h>

       int bind(int socket, const struct sockaddr *address,
           socklen_t address__len);

DESCRIPTION
       The bind() function shall assign a local socket address address to a
       socket identified by descriptor socket that has no local socket address
       assigned. Sockets created with the socket() function are initially
       unnamed; they are identified only by their address family.

       The bind() function takes the following arguments:

       socket      Specifies the file descriptor of the socket to be bound.

       address     Points to a sockaddr structure containing the address to be
                   bound to the socket. The length and format of the address
                   depend on the address family of the socket.

       address__len Specifies the length of the sockaddr structure pointed to
                   by the address argument.

       The socket specified by socket may require the process to have
       appropriate privileges to use the bind() function.

       If the address family of the socket is AF_UNIX and the pathname in
       address names a symbolic link, bind() shall fail and set errno to
       [EADDRINUSE].

       If the socket address cannot be assigned immediately and O_NONBLOCK is
       set for the file descriptor for the socket, bind() shall fail and set
       errno to [EINPROGRESS], but the assignment request shall not be
       aborted, and the assignment shall be completed asynchronously.
       Subsequent calls to bind() for the same socket, before the assignment
       is completed, shall fail and set errno to [EALREADY].

       When the assignment has been performed asynchronously, pselect(),
       select(), and poll() shall indicate that the file descriptor for the
       socket is ready for reading and writing.

RETURN VALUE
       Upon successful completion, bind() shall return 0; otherwise, -1 shall
       be returned and errno set to indicate the error.

ERRORS
       The bind() function shall fail if:

       EADDRINUSE
              The specified address is already in use.

       EADDRNOTAVAIL
              The specified address is not available from the local machine.

       EAFNOSUPPORT
              The specified address is not a valid address for the address
              family of the specified socket.

       EALREADY
              An assignment request is already in progress for the specified
              socket.

       EBADF  The socket argument is not a valid file descriptor.

       EINPROGRESS
              O_NONBLOCK is set for the file descriptor for the socket and the
              assignment cannot be immediately performed; the assignment shall
              be performed asynchronously.

       EINVAL The socket is already bound to an address, and the protocol does
              not support binding to a new address; or the socket has been
              shut down.

       ENOBUFS
              Insufficient resources were available to complete the call.

       ENOTSOCK
              The socket argument does not refer to a socket.

       EOPNOTSUPP
              The socket type of the specified socket does not support binding
              to an address.

       If the address family of the socket is AF_UNIX, then bind() shall fail
       if:

       EACCES A component of the path prefix denies search permission, or the
              requested name requires writing in a directory with a mode that
              denies write permission.

       EDESTADDRREQ or EISDIR
              The address argument is a null pointer.

       EIO    An I/O error occurred.

       ELOOP  A loop exists in symbolic links encountered during resolution of
              the pathname in address.

       ENAMETOOLONG
              The length of a component of a pathname is longer than
              {NAME_MAX}.

       ENOENT A component of the path prefix of the pathname in address does
              not name an existing file or the pathname is an empty string.

       ENOENT or ENOTDIR
              The pathname in address contains at least one non-<slash>
              character and ends with one or more trailing <slash> characters.
              If the pathname without the trailing <slash> characters would
              name an existing file, an [ENOENT] error shall not occur.

       ENOTDIR
              A component of the path prefix of the pathname in address names
              an existing file that is neither a directory nor a symbolic link
              to a directory, or the pathname in address contains at least one
              non-<slash> character and ends with one or more trailing <slash>
              characters and the last pathname component names an existing
              file that is neither a directory nor a symbolic link to a
              directory.

       EROFS  The name would reside on a read-only file system.

       The bind() function may fail if:

       EACCES The specified address is protected and the current user does not
              have permission to bind to it.

       EINVAL The address__len argument is not a valid length for the address
              family.

       EISCONN
              The socket is already connected.

       ELOOP  More than {SYMLOOP_MAX} symbolic links were encountered during
              resolution of the pathname in address.

       ENAMETOOLONG
              The length of a pathname exceeds {PATH_MAX}, or pathname
              resolution of a symbolic link produced an intermediate result
              with a length that exceeds {PATH_MAX}.

       The following sections are informative.

EXAMPLES
       The following code segment shows how to create a socket and bind it to
       a name in the AF_UNIX domain.


           #define MY_SOCK_PATH "/somepath"

           int sfd;
           struct sockaddr_un my_addr;

           sfd = socket(AF_UNIX, SOCK_STREAM, 0);
           if (sfd == -1)
               /* Handle error */;

           memset(&my_addr, '\0', sizeof(struct sockaddr_un));
                                /* Clear structure */
           my_addr.sun_family = AF_UNIX;
           strncpy(my_addr.sun_path, MY_SOCK_PATH, sizeof(my_addr.sun_path) -1);

           if (bind(sfd, (struct sockaddr *) &my_addr,
               sizeof(struct sockaddr_un)) == -1)
               /* Handle error */;

APPLICATION USAGE
       An application program can retrieve the assigned socket name with the
       getsockname() function.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       connect(), getsockname(), listen(), socket()

       The Base Definitions volume of POSIX.1-2017, <sys_socket.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  In the event of any discrepancy between this version and the
       original IEEE and The Open Group Standard, the original IEEE and The
       Open Group Standard is the referee document. The original Standard can
       be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                              BIND(3)
