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Diffstat (limited to 'lib/libc/net/sockatmark.3')
| -rw-r--r-- | lib/libc/net/sockatmark.3 | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/lib/libc/net/sockatmark.3 b/lib/libc/net/sockatmark.3 new file mode 100644 index 000000000000..f499eb0b902d --- /dev/null +++ b/lib/libc/net/sockatmark.3 @@ -0,0 +1,136 @@ +.\" 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. +.\" +.Dd July 3, 2022 +.Dt SOCKATMARK 3 +.Os +.Sh NAME +.Nm sockatmark +.Nd determine whether the read pointer is at the OOB mark +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In sys/socket.h +.Ft int +.Fn sockatmark "int s" +.Sh DESCRIPTION +To find out if the read pointer is currently pointing at +the mark in the data stream, the +.Fn sockatmark +function is provided. +If +.Fn sockatmark +returns 1, the next read will return data +after the mark. +Otherwise (assuming out of band data has arrived), +the next read will provide data sent by the client prior +to transmission of the out of band signal. +The routine used +in the 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 out = FWRITE, mark; + char waste[BUFSIZ]; + + /* flush local terminal output */ + ioctl(1, TIOCFLUSH, (char *)&out); + 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 RETURN VALUES +Upon successful completion, the +.Fn sockatmark +function returns the value 1 if the read pointer is pointing at +the OOB 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 ERRORS +The +.Fn sockatmark +call fails if: +.Bl -tag -width Er +.It Bq Er EBADF +The +.Fa s +argument +is not a valid descriptor. +.It Bq Er ENOTTY +The +.Fa s +argument +is a descriptor for a file, not a socket. +.El +.Sh SEE ALSO +.Xr recv 2 , +.Xr send 2 +.Rs +.%T "An Introductory 4.4BSD Interprocess Communication Tutorial" +.%A Stuart Sechrest +.Re +.%U https://docs.freebsd.org/44doc/psd/20.ipctut/paper.pdf +.Rs +.%T "An Advanced 4.4BSD Interprocess Communication Tutorial" +.%A Samuel J. Leffler +.%A Robert S. Fabry +.%A William N. Joy +.%A Phil Lapsley +.%A Steve Miller +.%A Chris Torek +.%U https://docs.freebsd.org/44doc/psd/21.ipc/paper.pdf +.Re +.Sh HISTORY +The +.Fn sockatmark +function was introduced by +.St -p1003.1-2001 , +to standardize the historical +.Dv SIOCATMARK +.Xr ioctl 2 . +The +.Er ENOTTY +error instead of the usual +.Er ENOTSOCK +is to match the historical behavior of +.Dv SIOCATMARK . |