1994-05-24 10:09:53 +00:00
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/*-
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* Copyright (c) 1982, 1986, 1990, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)filio.h 8.1 (Berkeley) 3/28/94
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1999-08-28 01:08:13 +00:00
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* $FreeBSD$
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1994-05-24 10:09:53 +00:00
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*/
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#ifndef _SYS_FILIO_H_
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#define _SYS_FILIO_H_
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#include <sys/ioccom.h>
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/* Generic file-descriptor ioctl's. */
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#define FIOCLEX _IO('f', 1) /* set close on exec on fd */
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#define FIONCLEX _IO('f', 2) /* remove close on exec */
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#define FIONREAD _IOR('f', 127, int) /* get # bytes to read */
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#define FIONBIO _IOW('f', 126, int) /* set/clear non-blocking i/o */
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#define FIOASYNC _IOW('f', 125, int) /* set/clear async i/o */
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#define FIOSETOWN _IOW('f', 124, int) /* set owner */
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#define FIOGETOWN _IOR('f', 123, int) /* get owner */
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1999-08-27 16:35:37 +00:00
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#define FIODTYPE _IOR('f', 122, int) /* get d_flags type part */
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1999-12-07 22:25:28 +00:00
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#define FIOGETLBA _IOR('f', 121, int) /* get start blk # */
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2005-03-08 21:32:19 +00:00
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struct fiodgname_arg {
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int len;
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void *buf;
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};
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#define FIODGNAME _IOW('f', 120, struct fiodgname_arg) /* get dev. name */
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There are a number of ways an application can check if there are
inbound data waiting on a filedescriptor, such as a pipe or a socket,
for instance by using select(2), poll(2), kqueue(2), ioctl(FIONREAD)
etc.
But we have no way of finding out if written data have yet to be
disposed of, for instance, transmitted (and ack'ed!) to some remote
host, or read by the applicantion at the far end of the pipe.
The closest we get, is calling shutdown(2) on a TCP socket in
non-blocking mode, but this has the undesirable sideeffect of
preventing future communication.
Add a complement to FIONREAD, called FIONWRITE, which returns the
number of bytes not yet properly disposed of. Implement it for
all sockets.
Background:
A HTTP server will want to time out connections, if no new request
arrives within a certain period after the last transmitted response
has actually been sent (and ack'ed).
For a busy HTTP server, this timeout can be subsecond duration.
In order to signal to a load-balancer that the connection is truly
dead, TCP_RST will be the preferred method, as this avoids the need
for a RTT delay for FIN handshaking, with a client which, surprisingly
often, no longer at the remote IP number.
If a slow, distant client is being served a response which is big
enough to fill the window, but small enough to fit in the socket
buffer, the write(2) call will return immediately.
If the session timeout is armed at that time, all bytes in the
response may not have been transmitted by the time it fires.
FIONWRITE allows the timeout to check that no data is outstanding
on the connection, before it TCP_RST's it.
Input & Idea from: rwatson
Approved by: re (kib)
2009-06-28 11:28:14 +00:00
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#define FIONWRITE _IOR('f', 119, int) /* get # bytes (yet) to write */
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2009-06-30 13:38:49 +00:00
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#define FIONSPACE _IOR('f', 118, int) /* get space in send queue */
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2007-04-05 21:10:53 +00:00
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/* Handle lseek SEEK_DATA and SEEK_HOLE for holey file knowledge. */
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#define FIOSEEKDATA _IOWR('f', 97, off_t) /* SEEK_DATA */
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#define FIOSEEKHOLE _IOWR('f', 98, off_t) /* SEEK_HOLE */
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1994-05-24 10:09:53 +00:00
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#endif /* !_SYS_FILIO_H_ */
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