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accept(2)
NAME
  accept - Accept a new connection on a socket

SYNOPSIS
  #include <sys/socket.h>

  int accept(
	  int socket,
	  struct sockaddr *address,
	  socklen_t *address_len );

  [XNS4.0]  The definition of the accept() function in XNS4.0 uses a size_t
  data type instead of socklen_t data type as specified in XNS5.0 (the
  previous definition).

  [Tru64 UNIX]	The following definition of the accept() function does not
  conform to current standards and is supported only for compatibility (see
  standards(5)):

  int accept(
	  int socket,
	  struct sockaddr *address,
	  int *address_len );

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  accept(): XNS4.0, XNS5.0

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  socket
      Specifies a file descriptor for the socket that was created with the
      socket() function, has been bound to an address with the bind()
      function, and has issued a successful call to the listen() function.

  address
      Points to a sockaddr structure, the format of which is determined by
      the domain and by the behavior requested for the socket. The sockaddr
      structure is an overlay for a sockaddr_in, sockaddr_un, sockaddr_in6,
      or sockaddr_storage structure, depending on which of the supported
      address families is active.

      [Tru64 UNIX]   If the compile-time option _SOCKADDR_LEN is defined
      before the sys/socket.h header file is included, the sockaddr structure
      takes 4.4BSD behavior, with a field for specifying the length of the
      socket address. Otherwise, the default 4.3BSD sockaddr structure is
      used, with the length of the socket address assumed to be 14 bytes or
      less.

      You can specify NULL to indicate that the address of the peer is not
      required.

      If _SOCKADDR_LEN is defined, the 4.3BSD sockaddr structure is defined
      with the name osockaddr.

  address_len
      Specifies the length of the sockaddr structure pointed to by the
      address parameter. If the address parameter is NULL then this parameter
      is ignored.

DESCRIPTION
  The accept() function extracts the first connection on the queue of pending
  connections, creates a new socket with the same properties as the specified
  socket, and allocates a new file descriptor for that socket.

  If the listen() queue is empty of connection requests, the accept()
  function blocks a calling socket of the blocking type until a connection is
  present, or returns an [EWOULDBLOCK] for sockets marked nonblocking.

  The accepted socket cannot itself accept more connections. The original
  socket remains open and can accept more connections.

NOTES
  [Tru64 UNIX]	When compiled in the X/Open UNIX environment or the POSIX.1g
  socket environment, calls to the accept() function are internally renamed
  by prepending _E to the function name. When you are debugging a module that
  includes the accept() function and for which _XOPEN_SOURCE_EXTENDED or
  _POSIX_PII_SOCKET has been defined, use _Eaccept to refer to the accept()
  call. See standards(5) for further information.

RETURN VALUES
  Upon successful completion, the accept() function returns the nonnegative
  socket descriptor of the accepted socket. Additionally, if the address
  parameter was specified then it places the address of the peer in the
  sockaddr structure pointed to by the address, and sets the address_len
  parameter to the length of address.  If the accept() function fails, a
  value of -1 is returned and errno is set to indicate the error.

ERRORS
  If the accept() function fails, errno may be set to one of the following
  values:

  [EBADF]
      The socket parameter is not valid.

  [ECONNABORTED]
      A connection has been aborted.

  [EFAULT]
      The address parameter or address_len parameter is inaccessible or
      cannot be written.

  [EINTR]
      The accept() function was interrupted by a signal that was caught
      before a valid connection arrived.

  [EINVAL]
      The socket is not accepting connections.

  [EMFILE]
      There are too many open file descriptors.

  [ENFILE]
      The maximum number of file descriptors in the system are already open.

  [ENOBUFS]
      Insufficient resources are available in the system to complete the
      call.

  [ENOMEM]
      The system was unable to allocate kernel memory to increase the process
      descriptor table.

  [ENOSR]
      The available STREAMS resources were insufficient for the operation to
      complete.

  [ENOTSOCK]
      The socket parameter refers to a file, not a socket.

  [EOPNOTSUPP]
      The referenced socket cannot accept connections.

  [EPROTO]
      A protocol error occurred.

  [EWOULDBLOCK]
      The socket is marked nonblocking, and no connections are present to be
      accepted.

SEE ALSO
  Functions: bind(2), connect(2), listen(2), socket(2).

  Standards: standards(5).

  Network Programmer's Guide

Index for Section 2

Alphabetical listing for A

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