1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
|
.\" Copyright (c) 2002 William C. Fenner. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" From FreeBSD: r108087 2002-12-19 01:40:28 -0800
.\" $OpenBSD: sockatmark.3,v 1.1 2014/08/31 02:27:37 guenther Exp $
.\"
.Dd $Mdocdate: August 31 2014 $
.Dt SOCKATMARK 3
.Os
.Sh NAME
.Nm sockatmark
.Nd determine whether the read pointer is at the out-of-band data mark
.Sh SYNOPSIS
.In sys/socket.h
.Ft int
.Fn sockatmark "int s"
.Sh DESCRIPTION
The
.Fn sockatmark
function returns 1 if the read pointer for the socket
.Fa s
is currently at the out-of-band data mark.
Otherwise, it returns 0 if the socket doesn't have an out-of-band
data mark or if there is normal data to be received before the mark.
.Sh RETURN VALUES
Upon successful completion, the
.Fn sockatmark
function returns the value 1 if the read pointer is pointing at
the out-of-band data mark, 0 if it is not.
Otherwise the value \-1 is returned
and the global variable
.Va errno
is set to
indicate the error.
.Sh EXAMPLES
The routine used in the historical remote login process to flush
output on receipt of an interrupt or quit signal is shown below.
It reads the normal data up to the mark (to discard it),
then reads the out-of-band byte.
.Bd -literal -offset indent
#include <sys/socket.h>
\&...
oob()
{
int mark;
char waste[BUFSIZ];
for (;;) {
if ((mark = sockatmark(rem)) < 0) {
perror("sockatmark");
break;
}
if (mark)
break;
(void) read(rem, waste, sizeof (waste));
}
if (recv(rem, &mark, 1, MSG_OOB) < 0) {
perror("recv");
...
}
...
}
.Ed
.Sh ERRORS
The
.Fn sockatmark
call fails if:
.Bl -tag -width Er
.It Bq Er EBADF
.Fa s
is not a valid descriptor.
.It Bq Er ENOTTY
.Fa s
is valid but does not refer to a socket.
.El
.Sh SEE ALSO
.Xr recv 2 ,
.Xr send 2
.Sh STANDARDS
The
.Fn sockatmark
function conforms to
.St -p1003.1-2008 .
.Sh HISTORY
The
.Fn sockatmark
function was introduced by
.St -p1003.1-2001
to standardize the historical
.Dv SIOCATMARK
.Xr ioctl 2 .
The
.Fn sockatmark
function appeared in
.Ox 5.7 .
.Pp
The
.Er ENOTTY
error is returned instead of the usual
.Er ENOTSOCK
error to match the historical behavior of
.Dv SIOCATMARK .
|
