принять новое соединение с сокетом (accept a new connection on a socket)
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
accept — accept a new connection on a socket
Синопсис (Synopsis)
#include <sys/socket.h>
int accept(int socket, struct sockaddr *restrict address,
socklen_t *restrict address_len);
Описание (Description)
The accept() function shall extract the first connection on the
queue of pending connections, create a new socket with the same
socket type protocol and address family as the specified socket,
and allocate a new file descriptor for that socket. The file
descriptor shall be allocated as described in Section 2.14, File
Descriptor Allocation.
The accept() function takes the following arguments:
socket Specifies a socket that was created with socket(),
has been bound to an address with bind(), and has
issued a successful call to listen().
address Either a null pointer, or a pointer to a sockaddr
structure where the address of the connecting socket
shall be returned.
address_len Either a null pointer, if address is a null pointer,
or a pointer to a socklen_t object which on input
specifies the length of the supplied sockaddr
structure, and on output specifies the length of the
stored address.
If address is not a null pointer, the address of the peer for the
accepted connection shall be stored in the sockaddr structure
pointed to by address, and the length of this address shall be
stored in the object pointed to by address_len.
If the actual length of the address is greater than the length of
the supplied sockaddr structure, the stored address shall be
truncated.
If the protocol permits connections by unbound clients, and the
peer is not bound, then the value stored in the object pointed to
by address is unspecified.
If the listen queue is empty of connection requests and
O_NONBLOCK is not set on the file descriptor for the socket,
accept() shall block until a connection is present. If the
listen() queue is empty of connection requests and O_NONBLOCK is
set on the file descriptor for the socket, accept() shall fail
and set errno to [EAGAIN] or [EWOULDBLOCK].
The accepted socket cannot itself accept more connections. The
original socket remains open and can accept more connections.
Возвращаемое значение (Return value)
Upon successful completion, accept() shall return the non-
negative file descriptor of the accepted socket. Otherwise, -1
shall be returned, errno shall be set to indicate the error, and
any object pointed to by address_len shall remain unchanged.
Ошибки (Error)
The accept() function shall fail if:
EAGAIN or EWOULDBLOCK
O_NONBLOCK is set for the socket file descriptor and no
connections are present to be accepted.
EBADF The socket argument is not a valid file descriptor.
ECONNABORTED
A connection has been aborted.
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 All file descriptors available to the process are
currently open.
ENFILE The maximum number of file descriptors in the system are
already open.
ENOBUFS
No buffer space is available.
ENOMEM There was insufficient memory available to complete the
operation.
ENOTSOCK
The socket argument does not refer to a socket.
EOPNOTSUPP
The socket type of the specified socket does not support
accepting connections.
The accept() function may fail if:
EPROTO A protocol error has occurred; for example, the STREAMS
protocol stack has not been initialized.
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
When a connection is available, select() indicates that the file
descriptor for the socket is ready for reading.
Обоснование (Rationale)
None.
Будущие направления (Future directions)
None.
Смотри также (See also)
Section 2.14, File Descriptor Allocation, bind(3p), connect(3p),
listen(3p), socket(3p)
The Base Definitions volume of POSIX.1‐2017, sys_socket.h(0p)
