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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 19:40:15 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 19:40:15 +0000
commit399644e47874bff147afb19c89228901ac39340e (patch)
tree1c4c0b733f4c16b5783b41bebb19194a9ef62ad1 /man2/getsockopt.2
parentInitial commit. (diff)
downloadmanpages-399644e47874bff147afb19c89228901ac39340e.tar.xz
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Adding upstream version 6.05.01.upstream/6.05.01
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+.\" Copyright (c) 1983, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\" $Id: getsockopt.2,v 1.1 1999/05/24 14:57:04 freitag Exp $
+.\"
+.\" Modified Sat Jul 24 16:19:32 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Mon Apr 22 02:29:06 1996 by Martin Schulze (joey@infodrom.north.de)
+.\" Modified Tue Aug 27 10:52:51 1996 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified Thu Jan 23 13:29:34 1997 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified Sun Mar 28 21:26:46 1999 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified 1999 by Andi Kleen <ak@muc.de>.
+.\" Removed most stuff because it is in socket.7 now.
+.\"
+.TH getsockopt 2 2023-04-03 "Linux man-pages 6.05.01"
+.SH NAME
+getsockopt, setsockopt \- get and set options on sockets
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.PP
+.BI "int getsockopt(int " sockfd ", int " level ", int " optname ,
+.BI " void " optval "[restrict *." optlen ],
+.BI " socklen_t *restrict " optlen );
+.BI "int setsockopt(int " sockfd ", int " level ", int " optname ,
+.BI " const void " optval [. optlen ],
+.BI " socklen_t " optlen );
+.fi
+.SH DESCRIPTION
+.BR getsockopt ()
+and
+.BR setsockopt ()
+manipulate options for the socket referred to by the file descriptor
+.IR sockfd .
+Options may exist at multiple
+protocol levels; they are always present at the uppermost
+socket level.
+.PP
+When manipulating socket options, the level at which the
+option resides and the name of the option must be specified.
+To manipulate options at the sockets API level,
+.I level
+is specified as
+.BR SOL_SOCKET .
+To manipulate options at any
+other level the protocol number of the appropriate protocol
+controlling the option is supplied.
+For example,
+to indicate that an option is to be interpreted by the
+.B TCP
+protocol,
+.I level
+should be set to the protocol number of
+.BR TCP ;
+see
+.BR getprotoent (3).
+.PP
+The arguments
+.I optval
+and
+.I optlen
+are used to access option values for
+.BR setsockopt ().
+For
+.BR getsockopt ()
+they identify a buffer in which the value for the
+requested option(s) are to be returned.
+For
+.BR getsockopt (),
+.I optlen
+is a value-result argument, initially containing the
+size of the buffer pointed to by
+.IR optval ,
+and modified on return to indicate the actual size of
+the value returned.
+If no option value is to be supplied or returned,
+.I optval
+may be NULL.
+.PP
+.I Optname
+and any specified options are passed uninterpreted to the appropriate
+protocol module for interpretation.
+The include file
+.I <sys/socket.h>
+contains definitions for socket level options, described below.
+Options at
+other protocol levels vary in format and name; consult the appropriate
+entries in section 4 of the manual.
+.PP
+Most socket-level options utilize an
+.I int
+argument for
+.IR optval .
+For
+.BR setsockopt (),
+the argument should be nonzero to enable a boolean option, or zero if the
+option is to be disabled.
+.PP
+For a description of the available socket options see
+.BR socket (7)
+and the appropriate protocol man pages.
+.SH RETURN VALUE
+On success, zero is returned for the standard options.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.PP
+Netfilter allows the programmer
+to define custom socket options with associated handlers; for such
+options, the return value on success is the value returned by the handler.
+.SH ERRORS
+.TP
+.B EBADF
+The argument
+.I sockfd
+is not a valid file descriptor.
+.TP
+.B EFAULT
+The address pointed to by
+.I optval
+is not in a valid part of the process address space.
+For
+.BR getsockopt (),
+this error may also be returned if
+.I optlen
+is not in a valid part of the process address space.
+.TP
+.B EINVAL
+.I optlen
+invalid in
+.BR setsockopt ().
+In some cases this error can also occur for an invalid value in
+.I optval
+(e.g., for the
+.B IP_ADD_MEMBERSHIP
+option described in
+.BR ip (7)).
+.TP
+.B ENOPROTOOPT
+The option is unknown at the level indicated.
+.TP
+.B ENOTSOCK
+The file descriptor
+.I sockfd
+does not refer to a socket.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001,
+SVr4, 4.4BSD (first appeared in 4.2BSD).
+.\" SVr4 documents additional ENOMEM and ENOSR error codes, but does
+.\" not document the
+.\" .BR SO_SNDLOWAT ", " SO_RCVLOWAT ", " SO_SNDTIMEO ", " SO_RCVTIMEO
+.\" options
+.SH BUGS
+Several of the socket options should be handled at lower levels of the
+system.
+.SH SEE ALSO
+.BR ioctl (2),
+.BR socket (2),
+.BR getprotoent (3),
+.BR protocols (5),
+.BR ip (7),
+.BR packet (7),
+.BR socket (7),
+.BR tcp (7),
+.BR udp (7),
+.BR unix (7)