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accept(2) [mojave man page]

ACCEPT(2)						      BSD System Calls Manual							 ACCEPT(2)

NAME
accept -- accept a connection on a socket SYNOPSIS
#include <sys/socket.h> int accept(int socket, struct sockaddr *restrict address, socklen_t *restrict address_len); DESCRIPTION
The argument socket is a socket that has been created with socket(2), bound to an address with bind(2), and is listening for connections after a listen(2). accept() extracts the first connection request on the queue of pending connections, creates a new socket with the same properties of socket, and allocates a new file descriptor 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 may not be used to accept more con- nections. The original socket socket, remains open. The argument address 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 address parameter is determined by the domain in which the communication is occurring. The address_len is a value- result parameter; it should initially contain the amount of space pointed to by address; on return it will contain the actual length (in bytes) of the address returned. This call is used with connection-based socket types, currently with SOCK_STREAM. It is possible to select(2) a socket for the purposes of doing an accept() by selecting it for read. For certain protocols which require an explicit confirmation, such as ISO or DATAKIT, accept() can be thought of as merely dequeuing the next connection request and not implying confirmation. Confirmation can be implied by a normal read or write on the new file descriptor, and rejection can be implied by closing the new socket. One can obtain user connection request data without confirming the connection by issuing a recvmsg(2) call with an msg_iovlen of 0 and a non- zero msg_controllen, or by issuing a getsockopt(2) request. Similarly, one can provide user connection rejection information by issuing a sendmsg(2) call with providing only the control information, or by calling setsockopt(2). RETURN VALUES
The call returns -1 on error and the global variable errno is set to indicate the error. If it succeeds, it returns a non-negative integer that is a descriptor for the accepted socket. ERRORS
The accept() system call will fail if: [EBADF] socket is not a valid file descriptor. [ECONNABORTED] The connection to socket has been aborted. [EFAULT] The address parameter is not in a writable part of the user address space. [EINTR] The accept() system call was terminated by a signal. [EINVAL] socket is unwilling to accept connections. [EMFILE] The per-process descriptor table is full. [ENFILE] The system file table is full. [ENOMEM] Insufficient memory was available to complete the operation. [ENOTSOCK] socket references a file type other than a socket. [EOPNOTSUPP] socket is not of type SOCK_STREAM and thus does not accept connections. [EWOULDBLOCK] socket is marked as non-blocking and no connections are present to be accepted. LEGACY SYNOPSIS
#include <sys/types.h> #include <sys/socket.h> The include file <sys/types.h> is necessary. SEE ALSO
bind(2), connect(2), connectx(2), listen(2), select(2), socket(2), compat(5) HISTORY
The accept() function appeared in 4.2BSD. 4.2 Berkeley Distribution March 18, 2015 4.2 Berkeley Distribution

Check Out this Related Man Page

accept(3SOCKET) 					     Sockets Library Functions						   accept(3SOCKET)

NAME
accept - accept a connection on a socket SYNOPSIS
cc [ flag ... ] file ... -lsocket -lnsl [ library ... ] #include <sys/types.h> #include <sys/socket.h> int accept(int s, struct sockaddr *addr, socklen_t *addrlen); DESCRIPTION
The argument s is a socket that has been created with socket(3SOCKET) and bound to an address with bind(3SOCKET), and that is listening for connections after a call to listen(3SOCKET). The accept() function extracts the first connection on the queue of pending connections, cre- ates a new socket with the properties of 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 as non-blocking and no pending connections are present on the queue, accept() returns an error as described below. The accept() function uses the netconfig(4) file to determine the STREAMS device file name associated with s. This is the device on which the connect indication will be accepted. The accepted socket, ns, is used to read and write data to and from the socket that connected to ns. It is not used to accept more connections. The original socket (s) remains open for accepting further connections. The argument addr is a result parameter that is filled in with the address of the connecting entity as it is known to the communications layer. The exact format of the addr parameter is determined by the domain in which the communication occurs. The argument addrlen is a value-result parameter. Initially, it contains the amount of space pointed to by addr; on return it contains the length in bytes of the address returned. The accept() function is used with connection-based socket types, currently with SOCK_STREAM. It is possible to select(3C) or poll(2) a socket for the purpose of an accept() by selecting or polling it for a read. However, this will only indicate when a connect indication is pending; it is still necessary to call accept(). RETURN VALUES
The accept() function returns -1 on error. If it succeeds, it returns a non-negative integer that is a descriptor for the accepted socket. ERRORS
accept() will fail if: EBADF The descriptor is invalid. ECONNABORTED The remote side aborted the connection before the accept() operation completed. EFAULT The addr parameter or the addrlen parameter is invalid. EINTR The accept() attempt was interrupted by the delivery of a signal. EMFILE The per-process descriptor table is full. ENODEV The protocol family and type corresponding to s could not be found in the netconfig file. ENOMEM There was insufficient user memory available to complete the operation. ENOSR There were insufficient STREAMS resources available to complete the operation. ENOTSOCK The descriptor does not reference a socket. EOPNOTSUPP The referenced socket is not of type SOCK_STREAM. EPROTO A protocol error has occurred; for example, the STREAMS protocol stack has not been initialized or the connection has already been released. EWOULDBLOCK The socket is marked as non-blocking and no connections are present to be accepted. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |MT-Level |Safe | +-----------------------------+-----------------------------+ SEE ALSO
poll(2), bind(3SOCKET), connect(3SOCKET), listen(3SOCKET), select(3C), socket.h(3HEAD), socket(3SOCKET), netconfig(4), attributes(5) SunOS 5.11 24 Jan 2002 accept(3SOCKET)

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