3a19918442
when TEKEN_CONS25 is configured. Fix this by adding a function to set the flag that enables the fix and always calling this function for syscons. Expand the man page for teken_set_cons25(). This function is not very useful since it can only set but not clear 1 flag. In practice, it is only used when TEKEN_CONS25 is configured and all that does is choose the the default emulation for syscons at compile time.
250 lines
7.3 KiB
Groff
250 lines
7.3 KiB
Groff
.\" Copyright (c) 2011 Ed Schouten <ed@FreeBSD.org>
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.\" All rights reserved.
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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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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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.\" $FreeBSD$
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.\"
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.Dd Mar 13, 2017
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.Dt TEKEN 3
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.Os
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.Sh NAME
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.Nm teken
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.Nd xterm-like terminal emulation interface
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.Sh LIBRARY
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.Lb libteken
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.Sh SYNOPSIS
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.In teken.h
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.Ft void
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.Fn teken_init "teken_t *t" "const teken_funcs_t *funcs" "void *thunk"
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.Ft void
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.Fn teken_input "teken_t *t" "const void *buf" "size_t nbytes"
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.Ft const teken_pos_t *
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.Fn teken_get_winsize "teken_t *t"
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.Ft void
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.Fn teken_set_winsize "teken_t *t" "const teken_pos_t *size"
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.Ft const teken_pos_t *
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.Fn teken_get_cursor "const teken_t *t"
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.Ft void
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.Fn teken_set_cursor "teken_t *t" "const teken_pos_t *pos"
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.Ft const teken_attr_t *
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.Fn teken_get_curattr "const teken_t *t"
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.Ft void
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.Fn teken_set_curattr "teken_t *t" "const teken_attr_t *attr"
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.Ft const teken_attr_t *
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.Fn teken_get_defattr "const teken_t *t"
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.Ft void
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.Fn teken_set_defattr "teken_t *t" "const teken_attr_t *attr"
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.Ft const char *
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.Fn teken_get_sequence "const teken_t *t" "unsigned int id"
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.Ft teken_color_t
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.Fn teken_256to16 "teken_color_t color"
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.Ft teken_color_t
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.Fn teken_256to8 "teken_color_t color"
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.Ft void
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.Fn teken_get_defattr_cons25 "const teken_t *t" "int *fg" "int *bg"
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.Ft void
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.Fn teken_set_8bit "teken_t *t"
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.Ft void
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.Fn teken_set_cons25 "teken_t *t"
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.Ft void
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.Fn teken_set_cons25keys "teken_t *t"
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.Sh DESCRIPTION
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The
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.Nm
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library implements the input parser of a 256-color xterm-like terminal.
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It converts a stream of UTF-8 encoded characters into a series of
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primitive drawing instructions that can be used by a console driver or
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terminal emulator to render a terminal application.
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.Pp
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The
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.Fn teken_init
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function is used to initialize terminal state object
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.Fa t ,
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having type
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.Vt teken_t .
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The supplied
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.Vt teken_funcs_t
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structure
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.Fa funcs
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contains a set of callback functions, which are called when supplying
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data to
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.Fn teken_input .
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The
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.Fa thunk
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argument stores an arbitrary pointer, which is passed to each invocation
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of the callback functions.
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.Pp
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The
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.Vt teken_funcs_t
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structure stores the following callbacks:
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.Bd -literal -offset indent
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typedef struct {
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tf_bell_t *tf_bell; /* Audible/visible bell. */
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tf_cursor_t *tf_cursor; /* Move cursor to x/y. */
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tf_putchar_t *tf_putchar; /* Put Unicode character at x/y. */
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tf_fill_t *tf_fill; /* Fill rectangle with character. */
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tf_copy_t *tf_copy; /* Copy rectangle to new location. */
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tf_param_t *tf_param; /* Miscellaneous options. */
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tf_respond_t *tf_respond; /* Send response string to user. */
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} teken_funcs_t;
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.Ed
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.Pp
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All callbacks must be provided, though unimplemented callbacks may some
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times be sufficient.
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The actual types of these callbacks can be found in
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.In teken.h .
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.Pp
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By default,
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.Fn teken_init
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initializes the
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.Vt teken_t
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structure to emulate a terminal having 24 rows and 80 columns.
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The
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.Fn teken_get_winsize
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and
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.Fn teken_set_winsize
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functions can be used to obtain and modify the dimensions of the
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terminal.
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.Pp
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Even though the cursor position is normally controlled by input of data
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through
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.Fn teken_input
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and returned by the
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.Fn tf_cursor
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callback, it can be obtained and modified manually using the
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.Fn teken_get_cursor
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and
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.Fn teken_set_cursor
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functions.
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The same holds for
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.Fn teken_get_curattr
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and
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.Fn teken_set_curattr ,
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which can be used to change the currently selected font attributes and
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foreground and background color.
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.Pp
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By default,
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.Nm
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emulates a white-on-black terminal, which means the default foreground
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color is white, while the background color is black.
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These defaults can be modified using
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.Fn teken_get_defattr
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and
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.Fn teken_set_defattr .
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.Pp
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The
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.Fn teken_get_sequence
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function is a utility function that can be used to obtain escape
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sequences of special keyboard keys, generated by user input.
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The
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.Fa id
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parameter must be one of the
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.Dv TKEY_*
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parameters listed in
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.In teken.h .
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.Sh LEGACY FEATURES
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This library also provides a set of functions that shouldn't be used in
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any modern applications.
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.Pp
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The
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.Fn teken_256to16
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function converts an xterm-256 256-color code to an xterm 16-color code
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whose color with default palettes is as similar as possible (not very
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similar).
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The lower 3 bits of the result are the ANSI color and the next lowest
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bit is brightness.
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Other layers (hardare and software) that only support 16 colors can use
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this to avoid knowing the details of 256-color codes.
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.Pp
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The
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.Fn teken_256to8
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function is similar to
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.Fn teken_256to16
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except it converts to an ANSI 8-color code.
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This is more accurate than discarding the brigtness bit in the result of
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.Fn teken_256to16 .
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.Pp
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The
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.Fn teken_get_defattr_cons25
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function obtains the default terminal attributes as a pair of foreground
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and background colors, using ANSI color numbering.
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.Pp
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The
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.Fn teken_set_8bit
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function disables UTF-8 processing and switches to 8-bit character mode,
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which can be used to support character sets like CP437 and ISO-8859-1.
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.Pp
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The
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.Fn teken_set_cons25
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function sets the terminal emulation to
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.Dv cons25 ,
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which was the default for
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.Xr syscons 4
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in versions of
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.Fx
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prior to 9.0.
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This function is only useful for initialization.
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The emulation can be changed at any time using an escape sequence,
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and this function is not used then.
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.Pp
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The
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.Fn teken_set_cons25keys
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function tells the
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.Fn teken_get_sequence
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function to not interpret special keys in
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.Dv cons25
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mode.
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.Sh SEE ALSO
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.Xr ncurses 3 ,
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.Xr termcap 3 ,
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.Xr syscons 4
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.Sh HISTORY
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The
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.Nm
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library appeared in
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.Fx 8.0 ,
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though it was only available and used inside the kernel.
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In
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.Fx 9.0 ,
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the
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.Nm
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library appeared in userspace.
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.Sh AUTHORS
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.An Ed Schouten Aq ed@FreeBSD.org
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.Sh SECURITY CONSIDERATIONS
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The
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.Fn tf_respond
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callback is used to respond to device status requests commands generated
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by an application.
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In the past, there have been various security issues, where a malicious
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application sends a device status request before termination, causing
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the generated response to be interpreted by applications such as
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.Xr sh 1 .
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.Pp
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.Nm
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only implements a small subset of responses which are unlikely to cause
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any harm.
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Still, it is advised to leave
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.Fn tf_respond
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unimplemented.
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