1ACCEPT(3P) POSIX Programmer's Manual ACCEPT(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 accept - accept a new connection on a socket
13
15 #include <sys/socket.h>
16 int accept(int socket, struct sockaddr *restrict address,
18 socklen_t *restrict address_len);
19
22 The accept() function shall extract the first connection on the queue
23 of pending connections, create a new socket with the same socket type
24 protocol and address family as the specified socket, and allocate a new
25 file descriptor for that socket.
26 The accept() function takes the following arguments:
28 socket Specifies a socket that was created with socket(), has been
30 bound to an address with bind(), and has issued a successful
31 call to listen().
32 address
34 Either a null pointer, or a pointer to a sockaddr structure
35 where the address of the connecting socket shall be returned.
36 address_len
38 Points to a socklen_t structure which on input specifies the
39 length of the supplied sockaddr structure, and on output speci‐
40 fies the length of the stored address.
41 If address is not a null pointer, the address of the peer for the
44 accepted connection shall be stored in the sockaddr structure pointed
45 to by address, and the length of this address shall be stored in the
46 object pointed to by address_len.
47 If the actual length of the address is greater than the length of the
49 supplied sockaddr structure, the stored address shall be truncated.
50 If the protocol permits connections by unbound clients, and the peer is
52 not bound, then the value stored in the object pointed to by address is
53 unspecified.
54 If the listen queue is empty of connection requests and O_NONBLOCK is
56 not set on the file descriptor for the socket, accept() shall block
57 until a connection is present. If the listen() queue is empty of con‐
58 nection requests and O_NONBLOCK is set on the file descriptor for the
59 socket, accept() shall fail and set errno to [EAGAIN] or [EWOULDBLOCK].
60 The accepted socket cannot itself accept more connections. The original
62 socket remains open and can accept more connections.
63
65 Upon successful completion, accept() shall return the non-negative file
66 descriptor of the accepted socket. Otherwise, -1 shall be returned and
67 errno set to indicate the error.
68
70 The accept() function shall fail if:
71 EAGAIN or EWOULDBLOCK
73 O_NONBLOCK is set for the socket file descriptor and no connec‐
75 tions are present to be accepted.
76 EBADF The socket argument is not a valid file descriptor.
78 ECONNABORTED
80 A connection has been aborted.
82 EINTR The accept() function was interrupted by a signal that was
84 caught before a valid connection arrived.
85 EINVAL The socket is not accepting connections.
87 EMFILE {OPEN_MAX} file descriptors are currently open in the calling
89 process.
90 ENFILE The maximum number of file descriptors in the system are already
92 open.
93 ENOTSOCK
95 The socket argument does not refer to a socket.
96 EOPNOTSUPP
98 The socket type of the specified socket does not support accept‐
99 ing connections.
100 The accept() function may fail if:
103 ENOBUFS
105 No buffer space is available.
106 ENOMEM There was insufficient memory available to complete the opera‐
108 tion.
109 EPROTO A protocol error has occurred; for example, the STREAMS protocol
111 stack has not been initialized.
112 The following sections are informative.
115
117 None.
118
120 When a connection is available, select() indicates that the file
121 descriptor for the socket is ready for reading.
122
124 None.
125
127 None.
128
130 bind(), connect(), listen(), socket(), the Base Definitions volume of
131 IEEE Std 1003.1-2001, <sys/socket.h>
132
134 Portions of this text are reprinted and reproduced in electronic form
135 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
136 -- Portable Operating System Interface (POSIX), The Open Group Base
137 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
138 Electrical and Electronics Engineers, Inc and The Open Group. In the
139 event of any discrepancy between this version and the original IEEE and
140 The Open Group Standard, the original IEEE and The Open Group Standard
141 is the referee document. The original Standard can be obtained online
142 at http://www.opengroup.org/unix/online.html .
143IEEE/The Open Group 2003 ACCEPT(3P)