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1 | .\" Copyright (c) 1983 Regents of the University of California. |
2 | .\" All rights reserved. The Berkeley software License Agreement | |
3 | .\" specifies the terms and conditions for redistribution. | |
4 | .\" | |
bdad3a5a | 5 | .\" @(#)accept.2 6.3 (Berkeley) %G% |
95f52c01 | 6 | .\" |
f850922e | 7 | .TH ACCEPT 2 "" |
95f52c01 KM |
8 | .UC 5 |
9 | .SH NAME | |
10 | accept \- accept a connection on a socket | |
11 | .SH SYNOPSIS | |
12 | .ft B | |
13 | .nf | |
14 | #include <sys/types.h> | |
15 | #include <sys/socket.h> | |
16 | .PP | |
17 | .ft B | |
18 | ns = accept(s, addr, addrlen) | |
19 | int ns, s; | |
20 | struct sockaddr *addr; | |
21 | int *addrlen; | |
22 | .fi | |
23 | .SH DESCRIPTION | |
24 | The argument | |
25 | .I s | |
a9f72a26 | 26 | is a socket that has been created with |
95f52c01 KM |
27 | .IR socket (2), |
28 | bound to an address with | |
29 | .IR bind (2), | |
30 | and is listening for connections after a | |
31 | .IR listen (2). | |
32 | .I Accept | |
33 | extracts the first connection | |
34 | on the queue of pending connections, creates | |
35 | a new socket with the same properties of | |
36 | .I s | |
37 | and allocates a new file descriptor, | |
38 | .IR ns , | |
39 | for the socket. If no pending connections are | |
40 | present on the queue, and the socket is not marked | |
41 | as non-blocking, | |
42 | .I accept | |
43 | blocks the caller until a connection is present. | |
44 | If the socket is marked non-blocking and no pending | |
45 | connections are present on the queue, | |
46 | .I accept | |
47 | returns an error as described below. | |
48 | The accepted socket, | |
49 | .IR ns , | |
50 | may not be used | |
51 | to accept more connections. The original socket | |
52 | .I s | |
53 | remains open. | |
54 | .PP | |
55 | The argument | |
56 | .I addr | |
a9f72a26 | 57 | is a result parameter that is filled in with |
95f52c01 KM |
58 | the address of the connecting entity, |
59 | as known to the communications layer. | |
60 | The exact format of the | |
61 | .I addr | |
62 | parameter is determined by the domain in which the communication | |
63 | is occurring. | |
64 | The | |
65 | .I addrlen | |
66 | is a value-result parameter; it should initially contain the | |
67 | amount of space pointed to by | |
68 | .IR addr ; | |
69 | on return it will contain the actual length (in bytes) of the | |
70 | address returned. | |
71 | This call | |
72 | is used with connection-based socket types, currently with SOCK_STREAM. | |
73 | .PP | |
74 | It is possible to | |
75 | .IR select (2) | |
76 | a socket for the purposes of doing an | |
77 | .I accept | |
78 | by selecting it for read. | |
79 | .SH "RETURN VALUE | |
bdad3a5a | 80 | The call returns \-1 on error. If it succeeds, it returns a non-negative |
a9f72a26 | 81 | integer that is a descriptor for the accepted socket. |
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82 | .SH ERRORS |
83 | The \fIaccept\fP will fail if: | |
84 | .TP 20 | |
85 | [EBADF] | |
86 | The descriptor is invalid. | |
87 | .TP 20 | |
88 | [ENOTSOCK] | |
89 | The descriptor references a file, not a socket. | |
90 | .TP 20 | |
91 | [EOPNOTSUPP] | |
92 | The referenced socket is not of type SOCK_STREAM. | |
93 | .TP 20 | |
94 | [EFAULT] | |
95 | The \fIaddr\fP parameter is not in a writable part of the | |
96 | user address space. | |
97 | .TP 20 | |
98 | [EWOULDBLOCK] | |
99 | The socket is marked non-blocking and no connections | |
100 | are present to be accepted. | |
101 | .SH SEE ALSO | |
102 | bind(2), connect(2), listen(2), select(2), socket(2) |