accept(2) — DG/UX R4.11MU05



accept(2)                      DG/UX R4.11MU05                     accept(2)


NAME
       accept - accept a connection on a socket

SYNOPSIS
       #include <sys/socket.h>

       int    accept (s, addr, addrlen)
       int    s;
       struct sockaddr * addr;
       int *  addrlen;
       int    ns;

   where:
       s         File descriptor of socket listening for connection requests

       addr      Structure to receive the address of newly connected peer

       addrlen   On input contains the number of bytes available for the
                 peer address; updated to indicate the number of bytes
                 returned

       ns        Value returned by accept.

DESCRIPTION
       The argument s is the file descriptor of a socket that has been:

       ·      Created with the socket system call.
       ·      Bound to an address with bind(2).
       ·      Made to listen for connections with listen(2).

       Accept extracts the first connection on the queue of pending
       connections, creates a new socket of the same type (e.g.
       SOCK_STREAM) as s, and allocates a new file descriptor, ns, for the
       socket.  If no pending connections are present on the queue and the
       socket is not marked as non-blocking, accept blocks the caller until
       a connection is present.  If the socket is marked non-blocking and no
       pending connections are present on the queue, accept returns an error
       as described below.  The accepted socket, ns, will be in the
       connected state.  The original socket s remains open listening for
       more connections.

       The argument addr is a result parameter that is filled in with the
       address of the connecting entity, as known to the communications
       layer.  The exact format of the addr parameter is determined by the
       domain in which the communication is occurring. See related
       documentation for a description of address formats for each domain.
       addrlen is a value/result parameter; it should initially contain the
       amount of space pointed to by addr; on return it will contain the
       actual length (in bytes) of the address returned.  If addrlen is
       zero, the pointer will be ignored.  If the address buffer is too
       small to hold all of the address, the address will be truncated.

       This call is used with connection-based socket types, currently with
       SOCK_STREAM.

       A select system call can be issued on a listening socket for
       notification of connection requests.

ACCESS CONTROL
       None.

RETURN VALUE
       ns     The call was successful.  ns is a non-negative integer that is
              a descriptor for the accepted socket.

       -1     An error occurred.  errno is set to indicate the error.

DIAGNOSTICS
       Errno may be set to one of the following error codes:

       EBADF          The argument s is not an active, valid descriptor.

       ENOTSOCK       The descriptor references a file, not a socket.

       EMFILE         No more user file descriptors available, the per-
                      process limit has been reached.

       ENFILE         No more system file descriptors available, the system
                      limit has been reached.

       EINVAL         The socket s is not in the listen state.

       EOPNOTSUPP     The referenced socket is not of type SOCK_STREAM.

       EFAULT         The addr parameter is not in a writable part of the
                      user address space.

       ECONNABORTED   Listen operation aborted by system.

       EAGAIN         The socket is marked non-blocking and no connections
                      are present to be accepted.

       EINTR          The call was interrupted by a signal.

SEE ALSO
       bind(2), connect(2), listen(2), select(2), socket(2), inet(3N),
       inet(6F), unixipc(6F).


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