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|---|---|---|
| efbcfcab KM |
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 | .\" | |
| a66e777a | 5 | .\" @(#)getsockopt.2 6.1 (Berkeley) %G% |
| efbcfcab | 6 | .\" |
| a66e777a | 7 | .TH GETSOCKOPT 2 "" |
| efbcfcab KM |
8 | .UC 5 |
| 9 | .SH NAME | |
| 10 | getsockopt, setsockopt \- get and set options on sockets | |
| 11 | .SH SYNOPSIS | |
| 12 | .nf | |
| 13 | .ft B | |
| 14 | #include <sys/types.h> | |
| 15 | #include <sys/socket.h> | |
| 16 | .PP | |
| 17 | .ft B | |
| 18 | getsockopt(s, level, optname, optval, optlen) | |
| 19 | int s, level, optname; | |
| 20 | char *optval; | |
| 21 | int *optlen; | |
| 22 | .sp | |
| 23 | setsockopt(s, level, optname, optval, optlen) | |
| 24 | int s, level, optname; | |
| 25 | char *optval; | |
| 26 | int optlen; | |
| 27 | .fi | |
| 28 | .SH DESCRIPTION | |
| 29 | .I Getsockopt | |
| 30 | and | |
| 31 | .I setsockopt | |
| 32 | manipulate | |
| 33 | .I options | |
| 34 | associated with a socket. Options may exist at multiple | |
| 35 | protocol levels; they are always present at the uppermost | |
| 36 | ``socket'' level. | |
| 37 | .PP | |
| 38 | When manipulating socket options the level at which the | |
| 39 | option resides and the name of the option must be specified. | |
| 40 | To manipulate options at the ``socket'' level, | |
| 41 | .I level | |
| 42 | is specified as SOL_SOCKET. To manipulate options at any | |
| 43 | other level the protocol number of the appropriate protocol | |
| 44 | controlling the option is supplied. For example, | |
| 45 | to indicate an option is to be interpreted by the TCP protocol, | |
| 46 | .I level | |
| 47 | should be set to the protocol number of TCP; see | |
| 48 | .IR getprotoent (3N). | |
| 49 | .PP | |
| 50 | The parameters | |
| 51 | .I optval | |
| 52 | and | |
| 53 | .I optlen | |
| 54 | are used to access option values for | |
| 55 | .IR setsockopt . | |
| 56 | For | |
| 57 | .I getsockopt | |
| 58 | they identify a buffer in which the value for the | |
| 59 | requested option(s) are to be returned. For | |
| 60 | .IR getsockopt , | |
| 61 | .I optlen | |
| 62 | is a value-result parameter, initially containing the | |
| 63 | size of the buffer pointed to by | |
| 64 | .IR optval , | |
| 65 | and modified on return to indicate the actual size of | |
| 66 | the value returned. If no option value is | |
| 67 | to be supplied or returned, | |
| 68 | .I optval | |
| 69 | may be supplied as 0. | |
| 70 | .PP | |
| 71 | .I Optname | |
| 72 | and any specified options are passed uninterpreted to the appropriate | |
| 73 | protocol module for interpretation. | |
| 74 | The include file | |
| 75 | .RI < sys/socket.h > | |
| 76 | contains definitions for ``socket'' level options; see | |
| 77 | .IR socket (2). | |
| 78 | Options at other protocol levels vary in format and | |
| 79 | name, consult the appropriate entries in (4P). | |
| 80 | .SH "RETURN VALUE" | |
| 81 | A 0 is returned if the call succeeds, \-1 if it fails. | |
| 82 | .SH ERRORS | |
| 83 | The call succeeds unless: | |
| 84 | .TP 20 | |
| 85 | [EBADF] | |
| 86 | The argument \fIs\fP is not a valid descriptor. | |
| 87 | .TP 20 | |
| 88 | [ENOTSOCK] | |
| 89 | The argument \fIs\fP is a file, not a socket. | |
| 90 | .TP 20 | |
| 91 | [ENOPROTOOPT] | |
| 92 | The option is unknown. | |
| 93 | .TP 20 | |
| 94 | [EFAULT] | |
| 95 | The options are not in a valid part of the | |
| 96 | process address space. | |
| 97 | .SH "SEE ALSO" | |
| 98 | socket(2), getprotoent(3N) |