accept

Accepts a connection on a socket.

Format 

#include  <socket.h>

int accept  (int s, struct sockaddr *addr, int
            *addrlen);
Routine Variants This socket routine has a variant named __bsd44_accept. Enabled by defining _SOCKADDR_LEN, this variant implements 4.4BSD-compatible semantics. See Section A.7 for more information.

Arguments

s
A socket descriptor that has been returned by socket, subsequently bound to an address with bind, and that is listening for connections after a listen.
addr
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 structure to which the address parameter points is determined by the domain in which the communication is occurring. This version of DEC C supports only the Internet domain (AF_INET).
addrlen
A value-result parameter; it should initially contain the size of the structure pointed to by addr. On return it will contain the actual length, in bytes, of the structure that has been filled in by the communication layer. See <socket.h> for a description of the sockaddr structure.

Description

This routine completes the first connection on the queue of pending connections, creates a new socket with the same properties as s, and allocates and returns a new descriptor for the socket. If no pending connections are present on the queue, and the socket is not marked as nonblocking, accept blocks the caller until a connection request is present. If the socket is marked nonblocking by using a setsockopt call and no pending connections are present on the queue, accept returns an error. The accepted socket may not be used to accept connections. The original socket s remains open (listening) for other connection requests. This call is used with connection-based socket types, currently with SOCK_STREAM.

It is possible to select a socket for the purposes of performing an accept by selecting it for read.

See also bind, connect, listen, select, and socket in this section.

Return Values
x  A nonnegative integer that is a descriptor for the accepted socket. 
- 1  Indicates an error; errno is set to one of the following:

  • EBADF - The socket descriptor is invalid.

  • ENOTSOCK - The socket descriptor references a file, not a socket.

  • EOPNOTSUPP - The reference socket is not of type SOCK_ STREAM.

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

  • EWOULDBLOCK - The socket is marked nonblocking and no connections are present to be accepted.
 

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