Originální popis anglicky:
listen - listen for socket connections and limit the queue of incoming
connections
Návod, kniha: POSIX Programmer's Manual
#include <sys/socket.h>
int listen(int
socket, int
backlog );
The
listen() function shall mark a connection-mode socket, specified by
the
socket argument, as accepting connections.
The
backlog argument provides a hint to the implementation which the
implementation shall use to limit the number of outstanding connections in the
socket's listen queue. Implementations may impose a limit on
backlog
and silently reduce the specified value. Normally, a larger
backlog
argument value shall result in a larger or equal length of the listen queue.
Implementations shall support values of
backlog up to SOMAXCONN,
defined in
<sys/socket.h>.
The implementation may include incomplete connections in its listen queue. The
limits on the number of incomplete connections and completed connections
queued may be different.
The implementation may have an upper limit on the length of the listen
queue-either global or per accepting socket. If
backlog exceeds this
limit, the length of the listen queue is set to the limit.
If
listen() is called with a
backlog argument value that is less
than 0, the function behaves as if it had been called with a
backlog
argument value of 0.
A
backlog argument of 0 may allow the socket to accept connections, in
which case the length of the listen queue may be set to an
implementation-defined minimum value.
The socket in use may require the process to have appropriate privileges to use
the
listen() function.
Upon successful completions,
listen() shall return 0; otherwise, -1 shall
be returned and
errno set to indicate the error.
The
listen() function shall fail if:
- EBADF
- The socket argument is not a valid file
descriptor.
- EDESTADDRREQ
-
The socket is not bound to a local address, and the protocol does not
support listening on an unbound socket.
- EINVAL
- The socket is already connected.
- ENOTSOCK
- The socket argument does not refer to a socket.
- EOPNOTSUPP
- The socket protocol does not support listen().
The
listen() function may fail if:
- EACCES
- The calling process does not have the appropriate
privileges.
- EINVAL
- The socket has been shut down.
- ENOBUFS
- Insufficient resources are available in the system to
complete the call.
The following sections are informative.
None.
None.
None.
None.
accept() ,
connect() ,
socket() , the Base Definitions
volume of IEEE Std 1003.1-2001,
<sys/socket.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html
.
