1.\" Copyright (c) 1996-1999 Whistle Communications, Inc. 2.\" All rights reserved. 3.\" 4.\" Subject to the following obligations and disclaimer of warranty, use and 5.\" redistribution of this software, in source or object code forms, with or 6.\" without modifications are expressly permitted by Whistle Communications; 7.\" provided, however, that: 8.\" 1. Any and all reproductions of the source or object code must include the 9.\" copyright notice above and the following disclaimer of warranties; and 10.\" 2. No rights are granted, in any manner or form, to use Whistle 11.\" Communications, Inc. trademarks, including the mark "WHISTLE 12.\" COMMUNICATIONS" on advertising, endorsements, or otherwise except as 13.\" such appears in the above copyright notice or in the software. 14.\" 15.\" THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND 16.\" TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO 17.\" REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, 18.\" INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF 19.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. 20.\" WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY 21.\" REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS 22.\" SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE. 23.\" IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES 24.\" RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING 25.\" WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 26.\" PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR 27.\" SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY 28.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30.\" THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY 31.\" OF SUCH DAMAGE. 32.\" 33.\" Author: Archie Cobbs <archie@FreeBSD.org> 34.\" $Whistle: ng_tty.8,v 1.5 1999/01/25 23:46:28 archie Exp $ 35.\" 36.Dd December 25, 2008 37.Dt NG_TTY 4 38.Os 39.Sh NAME 40.Nm ng_tty 41.Nd netgraph node type that is also a TTY hook 42.Sh SYNOPSIS 43.In sys/types.h 44.In sys/ttycom.h 45.In netgraph/ng_tty.h 46.Sh DESCRIPTION 47The 48.Nm tty 49node type is both a netgraph node type and a TTY hook. 50.Pp 51The node has a single hook called 52.Dv hook . 53Incoming bytes received on the tty device are sent out on this hook, 54and frames received on 55.Dv hook 56are transmitted out on the tty device. 57No modification to the data is performed in either direction. 58While the hook is installed on a tty, the normal read and write 59operations are unavailable, returning 60.Er EIO . 61.Pp 62Incoming data is delivered directly to ng_tty via the tty bypass hook as a 63buffer pointer and length, this is converted to a mbuf and passed to the peer. 64.Pp 65The node supports an optional 66.Dq hot character . 67If the driver can not deliver data directly to the tty bypass hook then each 68character is input one at a time. 69If set to non-zero and bypass mode is unavailable, incoming 70data from the tty device is queued until this character is seen. 71This avoids sending lots of mbufs containing a small number of bytes, 72but introduces potentially infinite latency. 73The default hot character is 0x7e, consistent with 74.Dv hook 75being connected to a 76.Xr ng_async 4 77type node. 78The hot character has no effect on the transmission of data. 79.Sh HOOKS 80This node type supports the following hooks: 81.Bl -tag -width ".Va hook" 82.It Va hook 83.Xr tty 4 84serial data contained in 85.Dv mbuf 86structures, with arbitrary inter-frame boundaries. 87.El 88.Sh CONTROL MESSAGES 89This node type supports the generic control messages, plus the following: 90.Bl -tag -width foo 91.It Dv NGM_TTY_SET_HOTCHAR 92This command takes an integer argument and sets the hot character 93from the lower 8 bits. 94A hot character of zero disables queueing, 95so that all received data is forwarded immediately. 96.It Dv NGM_TTY_GET_HOTCHAR 97Returns an integer containing the current hot character in the lower 98eight bits. 99.It Dv NGM_TTY_SET_TTY 100This command takes integer process ID and file descriptor of open tty 101and registers the tty hooks. 102.El 103.Sh SHUTDOWN 104This node shuts down when the corresponding device is closed. 105.Sh SEE ALSO 106.Xr ioctl 2 , 107.Xr netgraph 4 , 108.Xr ng_async 4 , 109.Xr tty 4 , 110.Xr ngctl 8 111.Sh HISTORY 112The 113.Nm 114node type was implemented in 115.Fx 4.0 . 116.Sh AUTHORS 117.An Archie Cobbs Aq Mt archie@FreeBSD.org 118.An Andrew Thompson Aq Mt thompsa@FreeBSD.org 119.Sh BUGS 120The serial driver code also has a notion of a 121.Dq hot character . 122Unfortunately, this value is statically defined in terms of the 123line discipline and cannot be changed. 124Therefore, if a hot character other than 0x7e (the default) is set for the 125.Nm 126node, the node has no way to convey this information to the 127serial driver, and sub-optimal performance may result. 128