freebsd-dev/usr.sbin/bsdconfig/share/dialog.subr

if [ ! "$_DIALOG_SUBR" ]; then _DIALOG_SUBR=1
#
# Copyright (c) 2006-2013 Devin Teske
# 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 AUTHOR AND 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 AUTHOR 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.
#
# $FreeBSD$
#
############################################################ INCLUDES

BSDCFG_SHARE="/usr/share/bsdconfig"
. $BSDCFG_SHARE/common.subr || exit 1
f_dprintf "%s: loading includes..." dialog.subr
f_include $BSDCFG_SHARE/strings.subr
f_include $BSDCFG_SHARE/variable.subr

BSDCFG_LIBE="/usr/libexec/bsdconfig"
f_include_lang $BSDCFG_LIBE/include/messages.subr

############################################################ CONFIGURATION

#
# Default file descriptor to link to stdout for dialog(1) passthru allowing
# execution of dialog from within a sub-shell (so-long as its standard output
# is explicitly redirected to this file descriptor).
#
: ${DIALOG_TERMINAL_PASSTHRU_FD:=${TERMINAL_STDOUT_PASSTHRU:-3}}

############################################################ GLOBALS

#
# Default name of dialog(1) utility
# NOTE: This is changed to "Xdialog" by the optional `-X' argument
#
DIALOG="dialog"

#
# Default dialog(1) title and backtitle text
#
DIALOG_TITLE="$pgm"
DIALOG_BACKTITLE="bsdconfig"

#
# Settings used while interacting with dialog(1)
#
DIALOG_MENU_TAGS="123456789ABCDEFGHIJKLMNOPQRSTUVWYZabcdefghijklmnopqrstuvwxyz"

#
# Declare that we are fully-compliant with Xdialog(1) by unset'ing all
# compatibility settings.
#
unset XDIALOG_HIGH_DIALOG_COMPAT
unset XDIALOG_FORCE_AUTOSIZE
unset XDIALOG_INFOBOX_TIMEOUT

#
# Default behavior is to call f_dialog_init() automatically when loaded.
#
: ${DIALOG_SELF_INITIALIZE=1}

#
# Default terminal size (used if/when running without a controlling terminal)
#
: ${DEFAULT_TERMINAL_SIZE:=24 80}

#
# Minimum width(s) for various dialog(1) implementations (sensible global
# default(s) for all widgets of a given variant)
#
: ${DIALOG_MIN_WIDTH:=24}
: ${XDIALOG_MIN_WIDTH:=35}

#
# When manually sizing Xdialog(1) widgets such as calendar and timebox, you'll
# need to know the size of the embedded GUI objects because the height passed
# to Xdialog(1) for these widgets has to be tall enough to accomodate them.
#
# These values are helpful when manually sizing with dialog(1) too, but in a
# different way. dialog(1) does not make you accomodate the custom items in the
# height (but does for width) -- a height of 3 will display three lines and a
# full calendar, for example (whereas Xdialog will truncate the calendar if
# given a height of 3). For dialog(1), use these values for making sure that
# the height does not exceed max_height (obtained by f_dialog_max_size()).
#
DIALOG_CALENDAR_HEIGHT=15
DIALOG_TIMEBOX_HEIGHT=6

############################################################ GENERIC FUNCTIONS

# f_dialog_data_sanitize $var_to_edit ...
#
# When using dialog(1) or Xdialog(1) sometimes unintended warnings or errors
# are generated from underlying libraries. For example, if $LANG is set to an
# invalid or unknown locale, the warnings from the Xdialog(1) libraries will
# clutter the output. This function helps by providing a centralied function
# that removes spurious warnings from the dialog(1) (or Xdialog(1)) response.
#
# Simply pass the name of one or more variables that need to be sanitized.
# After execution, the variables will hold their newly-sanitized data.
#
f_dialog_data_sanitize()
{
	if [ "$#" -eq 0 ]; then
		f_dprintf "%s: called with zero arguments" \
		          f_dialog_response_sanitize
		return $FAILURE
	fi

	local __var_to_edit
	for __var_to_edit in $*; do
		# Skip warnings and trim leading/trailing whitespace
		setvar $__var_to_edit "$( f_getvar $__var_to_edit | awk '
			BEGIN { data = 0 }
			{
				if ( ! data )
				{
					if ( $0 ~ /^$/ ) next
					if ( $0 ~ /^Gdk-WARNING \*\*:/ ) next
					data = 1
				}
				print
			}
		' )"
	done
}

# f_dialog_line_sanitize $var_to_edit ...
#
# When using dialog(1) or Xdialog(1) sometimes unintended warnings or errors
# are generated from underlying libraries. For example, if $LANG is set to an
# invalid or unknown locale, the warnings from the Xdialog(1) libraries will
# clutter the output. This function helps by providing a centralied function
# that removes spurious warnings from the dialog(1) (or Xdialog(1)) response.
#
# Simply pass the name of one or more variables that need to be sanitized.
# After execution, the variables will hold their newly-sanitized data.
#
# This function, unlike f_dialog_data_sanitize(), also removes leading/trailing
# whitespace from each line.
#
f_dialog_line_sanitize()
{
	if [ "$#" -eq 0 ]; then
		f_dprintf "%s: called with zero arguments" \
		          f_dialog_response_sanitize
		return $FAILURE
	fi

	local __var_to_edit
	for __var_to_edit in $*; do
		# Skip warnings and trim leading/trailing whitespace
		setvar $__var_to_edit "$( f_getvar $__var_to_edit | awk '
			BEGIN { data = 0 }
			{
				if ( ! data )
				{
					if ( $0 ~ /^$/ ) next
					if ( $0 ~ /^Gdk-WARNING \*\*:/ ) next
					data = 1
				}
				sub(/^[[:space:]]*/, "")
				sub(/[[:space:]]*$/, "")
				print
			}
		' )"
	done
}

############################################################ TITLE FUNCTIONS

# f_dialog_title [$new_title]
#
# Set the title of future dialog(1) ($DIALOG_TITLE) or backtitle of Xdialog(1)
# ($DIALOG_BACKTITLE) invocations. If no arguments are given or the first
# argument is NULL, the current title is returned.
#
# Each time this function is called, a backup of the current values is made
# allowing a one-time (single-level) restoration of the previous title using the
# f_dialog_title_restore() function (below).
#
f_dialog_title()
{
	local new_title="$1"

	if [ "${1+set}" ]; then
		if [ "$USE_XDIALOG" ]; then
			_DIALOG_BACKTITLE="$DIALOG_BACKTITLE"
			DIALOG_BACKTITLE="$new_title"
		else
			_DIALOG_TITLE="$DIALOG_TITLE"
			DIALOG_TITLE="$new_title"
		fi
	else
		if [ "$USE_XDIALOG" ]; then
			echo "$DIALOG_BACKTITLE"
		else
			echo "$DIALOG_TITLE"
		fi
	fi
}

# f_dialog_title_restore
#
# Restore the previous title set by the last call to f_dialog_title().
# Restoration is non-recursive and only works to restore the most-recent title.
#
f_dialog_title_restore()
{
	if [ "$USE_XDIALOG" ]; then
		DIALOG_BACKTITLE="$_DIALOG_BACKTITLE"
	else
		DIALOG_TITLE="$_DIALOG_TITLE"
	fi
}

# f_dialog_backtitle [$new_backtitle]
#
# Set the backtitle of future dialog(1) ($DIALOG_BACKTITLE) or title of
# Xdialog(1) ($DIALOG_TITLE) invocations. If no arguments are given or the
# first argument is NULL, the current backtitle is returned.
#
f_dialog_backtitle()
{
	local new_backtitle="$1"

	if [ "${1+set}" ]; then
		if [ "$USE_XDIALOG" ]; then
			_DIALOG_TITLE="$DIALOG_TITLE"
			DIALOG_TITLE="$new_backtitle"
		else
			_DIALOG_BACKTITLE="$DIALOG_BACKTITLE"
			DIALOG_BACKTITLE="$new_backtitle"
		fi
	else
		if [ "$USE_XDIALOG" ]; then
			echo "$DIALOG_TITLE"
		else
			echo "$DIALOG_BACKTITLE"
		fi
	fi
}

# f_dialog_backtitle_restore
#
# Restore the previous backtitle set by the last call to f_dialog_backtitle().
# Restoration is non-recursive and only works to restore the most-recent
# backtitle.
#
f_dialog_backtitle_restore()
{
	if [ "$USE_XDIALOG" ]; then
		DIALOG_TITLE="$_DIALOG_TITLE"
	else
		DIALOG_BACKTITLE="$_DIALOG_BACKTITLE"
	fi
}

############################################################ SIZE FUNCTIONS

# f_dialog_max_size $var_height $var_width
#
# Get the maximum height and width for a dialog widget and store the values in
# $var_height and $var_width (respectively).
#
f_dialog_max_size()
{
	local __var_height="$1" __var_width="$2" __max_size
	[ "$__var_height" -o "$__var_width" ] || return $FAILURE
	if [ "$USE_XDIALOG" ]; then
		__max_size="$XDIALOG_MAXSIZE" # see CONFIGURATION
	else
		__max_size=$( stty size 2> /dev/null ) # usually "24 80"
		: ${__max_size:=$DEFAULT_TERMINAL_SIZE}
	fi
	[ "$__var_height" ] && setvar "$__var_height" "${__max_size%%[$IFS]*}"
	[ "$__var_width" ] && setvar "$__var_width" "${__max_size##*[$IFS]}"
}

# f_dialog_size_constrain $var_height $var_width [$min_height [$min_width]]
#
# Modify $var_height to be no-less-than $min_height (if given; zero otherwise)
# and no-greater-than terminal height (or screen height if $USE_XDIALOG is
# set).
#
# Also modify $var_width to be no-less-than $XDIALOG_MIN_WIDTH (or
# $XDIALOG_MIN_WIDTH if $_USE_XDIALOG is set) and no-greater-than terminal
# or screen width. The use of $[X]DIALOG_MIN_WIDTH can be overridden by
# passing $min_width.
#
# Return status is success unless one of the passed arguments is invalid
# or all of the $var_* arguments are either NULL or missing.
#
f_dialog_size_constrain()
{
	local __var_height="$1" __var_width="$2"
	local __min_height="$3" __min_width="$4"
	local __retval=$SUCCESS

	# Return failure unless at least one var_* argument is passed
	[ "$__var_height" -o "$__var_width" ] || return $FAILURE

	#
	# Print debug warnings if any given (non-NULL) argument are invalid
	# NOTE: Don't change the name of $__{var,min,}{height,width}
	#
	local __height __width
	local __arg __cp __fname=f_dialog_size_constrain 
	for __arg in height width; do
		debug= f_getvar __var_$__arg __cp
		[ "$__cp" ] || continue
		if ! debug= f_getvar "$__cp" __$__arg; then
			f_dprintf "%s: var_%s variable \`%s' not set" \
			          $__fname $__arg "$__cp"
			__retval=$FAILURE
		elif ! eval f_isinteger \$__$__arg; then
			f_dprintf "%s: var_%s variable value not a number" \
			          $__fname $__arg
			__retval=$FAILURE
		fi
	done
	for __arg in height width; do
		debug= f_getvar __min_$__arg __cp
		[ "$__cp" ] || continue
		f_isinteger "$__cp" && continue
		f_dprintf "%s: min_%s value not a number" $__fname $__arg
		__retval=$FAILURE
		setvar __min_$__arg ""
	done

	# Obtain maximum height and width values
	# NOTE: Function name appended to prevent __var_{height,width} values
	#       from becoming local (and thus preventing setvar from working).
	local __max_height_size_constain __max_width_size_constrain
	f_dialog_max_size \
		__max_height_size_constrain __max_width_size_constrain

	# Adjust height if desired
	if [ "$__var_height" ]; then
		if [ $__height -lt ${__min_height:-0} ]; then
			setvar "$__var_height" $__min_height
		elif [ $__height -gt $__max_height_size_constrain ]; then
			setvar "$__var_height" $__max_height_size_constrain
		fi
	fi

	# Adjust width if desired
	if [ "$__var_width" ]; then
		if [ "$USE_XDIALOG" ]; then
			: ${__min_width:=${XDIALOG_MIN_WIDTH:-35}}
		else
			: ${__min_width:=${DIALOG_MIN_WIDTH:-24}}
		fi
		if [ $__width -lt $__min_width ]; then
			setvar "$__var_width" $__min_width
		elif [ $__width -gt $__max_width_size_constrain ]; then
			setvar "$__var_width" $__max_width_size_constrain
		fi
	fi

	if [ "$debug" ]; then
		# Print final constrained values to debugging
		f_quietly f_getvar "$__var_height"
		f_quietly f_getvar "$__var_width"
	fi

	return $__retval # success if no debug warnings were printed
}

# f_dialog_menu_constrain $var_height $var_width $var_rows "$prompt" \
#                         [$min_height [$min_width [$min_rows]]]
#
# Modify $var_height to be no-less-than $min_height (if given; zero otherwise)
# and no-greater-than terminal height (or screen height if $USE_XDIALOG is
# set).
#
# Also modify $var_width to be no-less-than $XDIALOG_MIN_WIDTH (or
# $XDIALOG_MIN_WIDTH if $_USE_XDIALOG is set) and no-greater-than terminal
# or screen width. The use of $[X]DIALOG_MIN_WIDTH can be overridden by
# passing $min_width.
#
# Last, modify $var_rows to be no-less-than $min_rows (if specified; zero
# otherwise) and no-greater-than (max_height - 8) where max_height is the
# terminal height (or screen height if $USE_XDIALOG is set). If $prompt is NULL
# or missing, dialog(1) allows $var_rows to be (max_height - 7), maximizing the
# number of visible rows.
#
# Return status is success unless one of the passed arguments is invalid
# or all of the $var_* arguments are either NULL or missing.
#
f_dialog_menu_constrain()
{
	local __var_height="$1" __var_width="$2" __var_rows="$3" __prompt="$4"
	local __min_height="$5" __min_width="$6" __min_rows="$7"

	# Return failure unless at least one var_* argument is passed
	[ "$__var_height" -o "$__var_width" -o "$__var_rows" ] ||
		return $FAILURE

	#
	# Print debug warnings if any given (non-NULL) argument are invalid
	# NOTE: Don't change the name of $__{var,min,}{height,width,rows}
	#
	local __height __width __rows
	local __arg __cp __fname=f_dialog_menu_constrain 
	for __arg in height width rows; do
		debug= f_getvar __var_$__arg __cp
		[ "$__cp" ] || continue
		if ! debug= f_getvar "$__cp" __$__arg; then
			f_dprintf "%s: var_%s variable \`%s' not set" \
			          $__fname $__arg "$__cp"
			__retval=$FAILURE
		elif ! eval f_isinteger \$__$__arg; then
			f_dprintf "%s: var_%s variable value not a number" \
			          $__fname $__arg
			__retval=$FAILURE
		fi
	done
	for __arg in height width rows; do
		debug= f_getvar __min_$__arg __cp
		[ "$__cp" ] || continue
		f_isinteger "$__cp" && continue
		f_dprintf "%s: min_%s value not a number" $__fname $__arg
		__retval=$FAILURE
		setvar __min_$__arg ""
	done

	# Obtain maximum height and width values
	# NOTE: Function name appended to prevent __var_{height,width} values
	#       from becoming local (and thus preventing setvar from working).
	local __max_height_menu_constrain __max_width_menu_constrain
	f_dialog_max_size \
		__max_height_menu_constrain __max_width_menu_constrain

	# Adjust height if desired
	if [ "$__var_height" ]; then
		if [ $__height -lt ${__min_height:-0} ]; then
			setvar "$__var_height" $__min_height
		elif [ $__height -gt $__max_height_menu_constrain ]; then
			setvar "$__var_height" $__max_height_menu_constrain
		fi
	fi

	# Adjust width if desired
	if [ "$__var_width" ]; then
		if [ "$USE_XDIALOG" ]; then
			: ${__min_width:=${XDIALOG_MIN_WIDTH:-35}}
		else
			: ${__min_width:=${DIALOG_MIN_WIDTH:-24}}
		fi
		if [ $__width -lt $__min_width ]; then
			setvar "$__var_width" $__min_width
		elif [ $__width -gt $__max_width_menu_constrain ]; then
			setvar "$__var_width" $__max_width_menu_constrain
		fi
	fi

	# Adjust rows if desired
	if [ "$__var_rows" ]; then
		if [ "$USE_XDIALOG" ]; then
			: ${__min_rows:=1}
		else
			: ${__min_rows:=0}
		fi

		local __max_rows=$(( $__max_height_menu_constrain - 8 ))
		# If prompt_len is zero (no prompt), bump the max-rows by 1
		# Default assumption is (if no argument) that there's no prompt
		[ ${__prompt_len:-0} -gt 0 ] ||
			__max_rows=$(( $__max_rows + 1 ))

		if [ $__rows -lt $__min_rows ]; then
			setvar "$__var_rows" $__min_rows
		elif [ $__rows -gt $__max_rows ]; then
			setvar "$__var_rows" $__max_rows
		fi
	fi

	if [ "$debug" ]; then
		# Print final constrained values to debuggin
		f_quietly f_getvar "$__var_height"
		f_quietly f_getvar "$__var_width"
		f_quietly f_getvar "$__var_rows"
	fi

	return $__retval # success if no debug warnings were printed
}

# f_dialog_infobox_size [-n] $var_height $var_width \
#                       $title $backtitle $prompt [$hline]
#
# Not all versions of dialog(1) perform auto-sizing of the width and height of
# `--infobox' boxes sensibly.
#
# This function helps solve this issue by taking two sets of sequential
# arguments. The first set of arguments are the variable names to use when
# storing the calculated height and width. The second set of arguments are the
# title, backtitle, prompt, and [optionally] hline. The optimal height and
# width for the described widget (not exceeding the actual terminal height or
# width) is stored in $var_height and $var_width (respectively).
#
# If the first argument is `-n', the calculated sizes ($var_height and
# $var_width) are not constrained to minimum/maximum values.
#
# Newline character sequences (``\n'') in $prompt are expanded as-is done by
# dialog(1).
#
f_dialog_infobox_size()
{
	local __constrain=1
	[ "$1" = "-n" ] && __constrain= && shift 1 # -n
	local __var_height="$1" __var_width="$2"
	local __title="$3" __btitle="$4" __prompt="$5" __hline="$6"

	# Return unless at least one size aspect has been requested
	[ "$__var_height" -o "$__var_width" ] || return $FAILURE

	# Default height/width of zero for auto-sizing
	local __height=0 __width=0 __n

	# Adjust height if desired
	if [ "$__var_height" ]; then
		#
		# Set height based on number of rows in prompt
		#
		__n=$( echo -n "$__prompt" | f_number_of_lines )
		__n=$(( $__n + 2 ))
		[ $__n -gt $__height ] && __height=$__n

		#
		# For Xdialog(1) bump height if backtitle is enabled (displayed
		# in the X11 window with a separator line between the backtitle
		# and msg text).
		#
		if [ "$USE_XDIALOG" -a "$__btitle" ]; then
			__n=$( echo "$__btitle" | f_number_of_lines )
			__height=$(( $__height + $__n + 2 ))
		fi

		setvar "$__var_height" $__height
	fi

	# Adjust width if desired
	if [ "$__var_width" ]; then
		#
		# Bump width for long titles
		#
		__n=$(( ${#__title} + 4 ))
		[ $__n -gt $__width ] && __width=$__n

		#
		# If using Xdialog(1), bump width for long backtitles (which
		# appear within the window).
		#
		if [ "$USE_XDIALOG" ]; then
			__n=$(( ${#__btitle} + 4 ))
			[ $__n -gt $__width ] && __width=$__n
		fi

		#
		# Bump width for long prompts
		#
		__n=$( echo "$__prompt" | f_longest_line_length )
		__n=$(( $__n + 4 )) # add width for border
		[ $__n -gt $__width ] && __width=$__n

		#
		# Bump width for long hlines. Xdialog(1) supports `--hline' but
		# it's currently not used (so don't do anything here if using
		# Xdialog(1)).
		#
		if [ ! "$USE_XDIALOG" ]; then
			__n=$(( ${#__hline} + 10 ))
			[ $__n -gt $__width ] && __width=$__n
		fi

		# Bump width by 16.6% if using Xdialog(1)
		[ "$USE_XDIALOG" ] && __width=$(( $__width + $__width / 6 ))

		setvar "$__var_width" $__width
	fi

	# Constrain values to sensible minimums/maximums unless `-n' was passed
	# Return success if no-constrain, else return status from constrain
	[ ! "$__constrain" ] ||
		f_dialog_size_constrain "$__var_height" "$__var_width"
}

# f_dialog_buttonbox_size [-n] $var_height $var_width \
#                         $title $backtitle $prompt [$hline]
#
# Not all versions of dialog(1) perform auto-sizing of the width and height of
# `--msgbox' and `--yesno' boxes sensibly.
#
# This function helps solve this issue by taking two sets of sequential
# arguments. The first set of arguments are the variable names to use when
# storing the calculated height and width. The second set of arguments are the
# title, backtitle, prompt, and [optionally] hline. The optimal height and
# width for the described widget (not exceeding the actual terminal height or
# width) is stored in $var_height and $var_width (respectively).
#
# If the first argument is `-n', the calculated sizes ($var_height and
# $var_width) are not constrained to minimum/maximum values.
#
# Newline character sequences (``\n'') in $prompt are expanded as-is done by
# dialog(1).
#
f_dialog_buttonbox_size()
{
	local __constrain=1
	[ "$1" = "-n" ] && __constrain= && shift 1 # -n
	local __var_height="$1" __var_width="$2"
	local __title="$3" __btitle="$4" __prompt="$5" __hline="$6"

	# Return unless at least one size aspect has been requested
	[ "$__var_height" -o "$__var_width" ] || return $FAILURE

	# Calculate height/width of infobox (adjusted/constrained below)
	# NOTE: Function name appended to prevent __var_{height,width} values
	#       from becoming local (and thus preventing setvar from working).
	local __height_bbox_size __width_bbox_size
	f_dialog_infobox_size -n \
		"${__var_height:+__height_bbox_size}" \
		"${__var_width:+__width_bbox_size}" \
		"$__title" "$__btitle" "$__prompt" "$__hline"

	# Adjust height if desired
	if [ "$__var_height" ]; then
		# Add height to accomodate the buttons
		__height_bbox_size=$(( $__height_bbox_size + 2 ))

		# Adjust for clipping with Xdialog(1) on Linux/GTK2
		[ "$USE_XDIALOG" ] &&
			__height_bbox_size=$(( $__height_bbox_size + 3 ))

		setvar "$__var_height" $__height_bbox_size
	fi

	# No adjustemnts to width, just pass-thru the infobox width
	if [ "$__var_width" ]; then
		setvar "$__var_width" $__width_bbox_size
	fi

	# Constrain values to sensible minimums/maximums unless `-n' was passed
	# Return success if no-constrain, else return status from constrain
	[ ! "$__constrain" ] ||
		f_dialog_size_constrain "$__var_height" "$__var_width"
}

# f_dialog_inputbox_size [-n] $var_height $var_width \
#                        $title $backtitle $prompt $init [$hline]
#
# Not all versions of dialog(1) perform auto-sizing of the width and height of
# `--inputbox' boxes sensibly.
#
# This function helps solve this issue by taking two sets of sequential
# arguments. The first set of arguments are the variable names to use when
# storing the calculated height and width. The second set of arguments are the
# title, backtitle, prompt, and [optionally] hline. The optimal height and
# width for the described widget (not exceeding the actual terminal height or
# width) is stored in $var_height and $var_width (respectively).
#
# If the first argument is `-n', the calculated sizes ($var_height and
# $var_width) are not constrained to minimum/maximum values.
#
# Newline character sequences (``\n'') in $prompt are expanded as-is done by
# dialog(1).
#
f_dialog_inputbox_size()
{
	local __constrain=1
	[ "$1" = "-n" ] && __constrain= && shift 1 # -n
	local __var_height="$1" __var_width="$2"
	local __title="$3" __btitle="$4" __prompt="$5" __init="$6" __hline="$7"

	# Return unless at least one size aspect has been requested
	[ "$__var_height" -o "$__var_width" ] || return $FAILURE

	# Calculate height/width of buttonbox (adjusted/constrained below)
	# NOTE: Function name appended to prevent __var_{height,width} values
	#       from becoming local (and thus preventing setvar from working).
	local __height_ibox_size __width_ibox_size
	f_dialog_buttonbox_size -n \
		"${__var_height:+__height_ibox_size}" \
		"${__var_width:+__width_ibox_size}" \
		"$__title" "$__btitle" "$__prompt" "$__hline"

	# Adjust height if desired
	if [ "$__var_height" ]; then
		# Add height for input box (not needed for Xdialog(1))
		[ ! "$USE_XDIALOG" ] &&
			__height_ibox_size=$(( $__height_ibox_size + 3 ))

		setvar "$__var_height" $__height_ibox_size
	fi

	# Adjust width if desired
	if [ "$__var_width" ]; then
		# Bump width for initial text (something neither dialog(1) nor
		# Xdialog(1) do, but worth it!; add 16.6% if using Xdialog(1))
		local __n=$(( ${#__init} + 7 ))
		[ "$USE_XDIALOG" ] && __n=$(( $__n + $__n / 6 ))
		[ $__n -gt $__width_ibox_size ] && __width_ibox_size=$__n

		setvar "$__var_width" $__width_ibox_size
	fi

	# Constrain values to sensible minimums/maximums unless `-n' was passed
	# Return success if no-constrain, else return status from constrain
	[ ! "$__constrain" ] ||
		f_dialog_size_constrain "$__var_height" "$__var_width"
}

# f_xdialog_2inputsbox_size [-n] $var_height $var_width \
#                           $title $backtitle $prompt \
#                           $label1 $init1 $label2 $init2
#
# Xdialog(1) does not perform auto-sizing of the width and height of
# `--2inputsbox' boxes sensibly.
#
# This function helps solve this issue by taking two sets of sequential
# arguments. The first set of arguments are the variable names to use when
# storing the calculated height and width. The second set of arguments are the
# title, backtitle, prompt, label for the first field, initial text for said
# field, label for the second field, and initial text for said field. The
# optimal height and width for the described widget (not exceeding the actual
# terminal height or width) is stored in $var_height and $var_width
# (respectively).
#
# If the first argument is `-n', the calculated sizes ($var_height and
# $var_width) are not constrained to minimum/maximum values.
#
# Newline character sequences (``\n'') in $prompt are expanded as-is done by
# Xdialog(1).
#
f_xdialog_2inputsbox_size()
{
	local __constrain=1
	[ "$1" = "-n" ] && __constrain= && shift 1 # -n
	local __var_height="$1" __var_width="$2"
	local __title="$3" __btitle="$4" __prompt="$5"
	local __label1="$6" __init1="$7" __label2="$8" __init2="$9"

	# Return unless at least one size aspect has been requested
	[ "$__var_height" -o "$__var_width" ] || return $FAILURE

	# Calculate height/width of inputbox (adjusted/constrained below)
	# NOTE: Function name appended to prevent __var_{height,width} values
	#       from becoming local (and thus preventing setvar from working).
	local __height_2ibox_size __width_2ibox_size
	f_dialog_inputbox_size -n \
		"${__var_height:+__height_2ibox_size}" \
		"${__var_width:+__width_2ibox_size}" \
		"$__title" "$__btitle" "$__prompt" "$__hline" "$__init1"
	
	# Adjust height if desired
	if [ "$__var_height" ]; then
		# Add height for 1st label, 2nd label, and 2nd input box
		__height_2ibox_size=$(( $__height_2ibox_size + 2 + 2 + 2  ))
		setvar "$__var_height" $__height_2ibox_size
	fi

	# Adjust width if desired
	if [ "$__var_width" ]; then
		local __n

		# Bump width for first label text (+16.6% since Xdialog(1))
		__n=$(( ${#__label1} + 7 ))
		__n=$(( $__n + $__n / 6 ))
		[ $__n -gt $__width_2ibox_size ] && __width_2ibox_size=$__n

		# Bump width for second label text (+16.6% since Xdialog(1))
		__n=$(( ${#__label2} + 7 ))
		__n=$(( $__n + $__n / 6 ))
		[ $__n -gt $__width_2ibox_size ] && __width_2ibox_size=$__n

		# Bump width for 2nd initial text (something neither dialog(1)
		# nor Xdialog(1) do, but worth it!; +16.6% since Xdialog(1))
		__n=$(( ${#__init2} + 7 ))
		__n=$(( $__n + $__n / 6 ))
		[ $__n -gt $__width_2ibox_size ] && __width_2ibox_size=$__n

		setvar "$__var_width" $__width_2ibox_size
	fi

	# Constrain values to sensible minimums/maximums unless `-n' was passed
	# Return success if no-constrain, else return status from constrain
	[ ! "$__constrain" ] ||
		f_dialog_size_constrain "$__var_height" "$__var_width"
}

# f_dialog_menu_size [-n] $var_height $var_width $var_rows \
#                    $title $backtitle $prompt $hline \
#                    $tag1 $item1 $tag2 $item2 ...
#
# Not all versions of dialog(1) perform auto-sizing of the width and height of
# `--menu' boxes sensibly.
#
# This function helps solve this issue by taking three sets of sequential
# arguments. The first set of arguments are the variable names to use when
# storing the calculated height, width, and rows. The second set of arguments
# are the title, backtitle, prompt, and hline. The [optional] third set of
# arguments are the menu list itself (comprised of tag/item couplets). The
# optimal height, width, and rows for the described widget (not exceeding the
# actual terminal height or width) is stored in $var_height, $var_width, and
# $var_rows (respectively).
#
# If the first argument is `-n', the calculated sizes ($var_height, $var_width,
# and $var_rows) are not constrained to minimum/maximum values.
#
f_dialog_menu_size()
{
	local __constrain=1
	[ "$1" = "-n" ] && __constrain= && shift 1 # -n
	local __var_height="$1" __var_width="$2" __var_rows="$3"
	local __title="$4" __btitle="$5" __prompt="$6" __hline="$7"
	shift 7 # var_height/var_width/var_rows/title/btitle/prompt/hline

	# Return unless at least one size aspect has been requested
	[ "$__var_height" -o "$__var_width" -o "$__var_rows" ] ||
		return $FAILURE

	# Calculate height/width of infobox (adjusted/constrained below)
	# NOTE: Function name appended to prevent __var_{height,width} values
	#       from becoming local (and thus preventing setvar from working).
	local __height_menu_size __width_menu_size
	f_dialog_infobox_size -n \
		"${__var_height:+__height_menu_size}" \
		"${__var_width:+__width_menu_size}" \
		"$__title" "$__btitle" "$__prompt" "$__hline"

	#
	# Always process the menu-item arguments to get the longest tag-length,
	# longest item-length (both used to bump the width), and the number of
	# rows (used to bump the height).
	#
	local __longest_tag=0 __longest_item=0 __rows=0
	while [ $# -ge 2 ]; do
		local __tag="$1" __item="$2"
		shift 2 # tag/item
		[ ${#__tag} -gt $__longest_tag ] && __longest_tag=${#__tag}
		[ ${#__item} -gt $__longest_item ] && __longest_item=${#__item}
		__rows=$(( $__rows + 1 ))
	done

	# Adjust rows early (for up-comning height calculation)
	if [ "$__var_height" -o "$__var_rows" ]; then
		# Add a row for visual aid if using Xdialog(1)
		[ "$USE_XDIALOG" ] && __rows=$(( $__rows + 1 ))
	fi

	# Adjust height if desired
	if [ "$__var_height" ]; then
		# Add rows to height
		if [ "$USE_XDIALOG" ]; then
			__height_menu_size=$((
				$__height_menu_size + $__rows + 7 ))
		else
			__height_menu_size=$((
				$__height_menu_size + $__rows + 4 ))
		fi
		setvar "$__var_height" $__height_menu_size
	fi

	# Adjust width if desired
	if [ "$__var_width" ]; then
		# The sum total between the longest tag-length and the
		# longest item-length should be used to bump menu width
		local __n=$(( $__longest_tag + $__longest_item + 10 ))
		[ "$USE_XDIALOG" ] && __n=$(( $__n + $__n / 6 )) # plus 16.6%
		[ $__n -gt $__width_menu_size ] && __width_menu_size=$__n

		setvar "$__var_width" $__width_menu_size
	fi

	# Store adjusted rows if desired
	[ "$__var_rows" ] && setvar "$__var_rows" $__rows

	# Constrain height, width, and rows to sensible minimum/maximum values
	# Return success if no-constrain, else return status from constrain
	[ ! "$__constrain" ] || f_dialog_menu_constrain \
		"$__var_height" "$__var_width" "$__var_rows" "$__prompt"
}

# f_dialog_menu_with_help_size [-n] $var_height $var_width $var_rows \
#                              $title $backtitle $prompt $hline \
#                              $tag1 $item1 $help1 $tag2 $item2 $help2 ...
#
# Not all versions of dialog(1) perform auto-sizing of the width and height of
# `--menu' boxes sensibly.
#
# This function helps solve this issue by taking three sets of sequential
# arguments. The first set of arguments are the variable names to use when
# storing the calculated height, width, and rows. The second set of arguments
# are the title, backtitle, prompt, and hline. The [optional] third set of
# arguments are the menu list itself (comprised of tag/item/help triplets). The
# optimal height, width, and rows for the described widget (not exceeding the
# actual terminal height or width) is stored in $var_height, $var_width, and
# $var_rows (respectively).
#
# If the first argument is `-n', the calculated sizes ($var_height, $var_width,
# and $var_rows) are not constrained to minimum/maximum values.
#
f_dialog_menu_with_help_size()
{
	local __constrain=1
	[ "$1" = "-n" ] && __constrain= && shift 1 # -n
	local __var_height="$1" __var_width="$2" __var_rows="$3"
	local __title="$4" __btitle="$5" __prompt="$6" __hline="$7"
	shift 7 # var_height/var_width/var_rows/title/btitle/prompt/hline

	# Return unless at least one size aspect has been requested
	[ "$__var_height" -o "$__var_width" -o "$__var_rows" ] ||
		return $FAILURE

	# Calculate height/width of infobox (adjusted/constrained below)
	# NOTE: Function name appended to prevent __var_{height,width} values
	#       from becoming local (and thus preventing setvar from working).
	local __height_menu_with_help_size __width_menu_with_help_size
	f_dialog_infobox_size -n \
		"${__var_height:+__height_menu_with_help_size}" \
		"${__var_width:+__width_menu_with_help_size}" \
		"$__title" "$__btitle" "$__prompt" "$__hline"

	#
	# Always process the menu-item arguments to get the longest tag-length,
	# longest item-length, longest help-length (help-length only considered
	# if using Xdialog(1), as it places the help string in the widget) --
	# all used to bump the width -- and the number of rows (used to bump
	# the height).
	#
	local __longest_tag=0 __longest_item=0 __longest_help=0 __rows=0
	while [ $# -ge 3 ]; do
		local __tag="$1" __item="$2" __help="$3"
		shift 3 # tag/item/help
		[ ${#__tag} -gt $__longest_tag ] && __longest_tag=${#__tag}
		[ ${#__item} -gt $__longest_item ] && __longest_item=${#__item}
		[ ${#__help} -gt $__longest_help ] && __longest_help=${#__help}
		__rows=$(( $__rows + 1 ))
	done

	# Adjust rows early (for up-coming height calculation)
	if [ "$__var_height" -o "$__var_rows" ]; then
		# Add a row for visual aid if using Xdialog(1)
		[ "$USE_XDIALOG" ] && __rows=$(( $__rows + 1 ))
	fi

	# Adjust height if desired
	if [ "$__var_height" ]; then
		# Add rows to height
		if [ "$USE_XDIALOG" ]; then
			__height_menu_with_help_size=$((
				$__height_menu_with_help_size + $__rows + 8 ))
		else
			__height_menu_with_help_size=$((
				$__height_menu_with_help_size + $__rows + 4 ))
		fi
		setvar "$__var_height" $__height_menu_with_help_size
	fi

	# Adjust width if desired
	if [ "$__var_width" ]; then
		# The sum total between the longest tag-length and the
		# longest item-length should be used to bump menu width
		local __n=$(( $__longest_tag + $__longest_item + 10 ))
		[ "$USE_XDIALOG" ] && __n=$(( $__n + $__n / 6 )) # plus 16.6%
		[ $__n -gt $__width_menu_with_help_size ] &&
			__width_menu_with_help_size=$__n

		# Update width for help text if using Xdialog(1)
		if [ "$USE_XDIALOG" ]; then
			__n=$(( $__longest_help + 10 ))
			__n=$(( $__n + $__n / 6 )) # plus 16.6%
			[ $__n -gt $__width_menu_with_help_size ] &&
				__width_menu_with_help_size=$__n
		fi

		setvar "$__var_width" $__width_menu_with_help_size
	fi

	# Store adjusted rows if desired
	[ "$__var_rows" ] && setvar "$__var_rows" $__rows

	# Constrain height, width, and rows to sensible minimum/maximum values
	# Return success if no-constrain, else return status from constrain
	[ ! "$__constrain" ] || f_dialog_menu_constrain \
		"$__var_height" "$__var_width" "$__var_rows" "$__prompt"
}

# f_dialog_radiolist_size [-n] $var_height $var_width $var_rows \
#                         $title $backtitle $prompt $hline \
#                         $tag1 $item1 $status1 $tag2 $item2 $status2 ...
#
# Not all versions of dialog(1) perform auto-sizing of the width and height of
# `--radiolist' boxes sensibly.
#
# This function helps solve this issue by taking three sets of sequential
# arguments. The first set of arguments are the variable names to use when
# storing the calculated height, width, and rows. The second set of arguments
# are the title, backtitle, prompt, and hline. The [optional] third set of
# arguments are the radio list itself (comprised of tag/item/status triplets).
# The optimal height, width, and rows for the described widget (not exceeding
# the actual terminal height or width) is stored in $var_height, $var_width,
# and $var_rows (respectively).
#
# If the first argument is `-n', the calculated sizes ($var_height, $var_width,
# and $var_rows) are not constrained to minimum/maximum values.
#
f_dialog_radiolist_size()
{
	local __constrain=1
	[ "$1" = "-n" ] && __constrain= && shift 1 # -n
	local __var_height="$1" __var_width="$2" __var_rows="$3"
	local __title="$4" __btitle="$5" __prompt="$6" __hline="$7"
	shift 7 # var_height/var_width/var_rows/title/btitle/prompt/hline

	# Return unless at least one size aspect has been requested
	[ "$__var_height" -o "$__var_width" -o "$__var_rows" ] ||
		return $FAILURE

	# Calculate height/width of infobox (adjusted/constrained below)
	# NOTE: Function name appended to prevent __var_{height,width} values
	#       from becoming local (and thus preventing setvar from working).
	local __height_rlist_size __width_rlist_size
	f_dialog_infobox_size -n \
		"${__var_height:+__height_rlist_size}" \
		"${__var_width:+__width_rlist_size}" \
		"$__title" "$__btitle" "$__prompt" "$__hline"

	#
	# Always process the menu-item arguments to get the longest tag-length,
	# longest item-length (both used to bump the width), and the number of
	# rows (used to bump the height).
	#
	local __longest_tag=0 __longest_item=0 __rows=0
	while [ $# -ge 3 ]; do
		local __tag="$1" __item="$2"
		shift 3 # tag/item/status
		[ ${#__tag} -gt $__longest_tag ] && __longest_tag=${#__tag}
		[ ${#__item} -gt $__longest_item ] && __longest_item=${#__item}
		__rows=$(( $__rows + 1 ))
	done

	# Adjust rows early (for up-coming height calculation)
	if [ "$__var_height" -o "$__var_rows" ]; then
		# Add a row for visual aid if using Xdialog(1)
		[ "$USE_XDIALOG" ] && __rows=$(( $__rows + 1 ))
	fi

	# Adjust height if desired
	if [ "$__var_height" ]; then
		# Add rows to height
		if [ "$USE_XDIALOG" ]; then
			__height_rlist_size=$((
				$__height_rlist_size + $__rows + 7 ))
		else
			__height_rlist_size=$((
				$__height_rlist_size + $__rows + 4 ))
		fi
		setvar "$__var_height" $__height_rlist_size
	fi

	# Adjust width if desired
	if [ "$__var_width" ]; then
		# Sum total between longest tag-length, longest item-length,
		# and radio-button width should be used to bump menu width
		local __n=$(( $__longest_tag + $__longest_item + 13 ))
		[ "$USE_XDIALOG" ] && __n=$(( $__n + $__n / 6 )) # plus 16.6%
		[ $__n -gt $__width_rlist_size ] && __width_rlist_size=$__n

		setvar "$__var_width" $__width_rlist_size
	fi

	# Store adjusted rows if desired
	[ "$__var_rows" ] && setvar "$__var_rows" $__rows

	# Constrain height, width, and rows to sensible minimum/maximum values
	# Return success if no-constrain, else return status from constrain
	[ ! "$__constrain" ] || f_dialog_menu_constrain \
		"$__var_height" "$__var_width" "$__var_rows" "$__prompt"
}

# f_dialog_checklist_size [-n] $var_height $var_width $var_rows \
#                         $title $backtitle $prompt $hline \
#                         $tag1 $item1 $status1 $tag2 $item2 $status2 ...
#
# Not all versions of dialog(1) perform auto-sizing of the width and height of
# `--checklist' boxes sensibly.
#
# This function helps solve this issue by taking three sets of sequential
# arguments. The first set of arguments are the variable names to use when
# storing the calculated height, width, and rows. The second set of arguments
# are the title, backtitle, prompt, and hline. The [optional] third set of
# arguments are the check list itself (comprised of tag/item/status triplets).
# The optimal height, width, and rows for the described widget (not exceeding
# the actual terminal height or width) is stored in $var_height, $var_width,
# and $var_rows (respectively). 
#
# If the first argument is `-n', the calculated sizes ($var_height, $var_width,
# and $var_rows) are not constrained to minimum/maximum values.
#
f_dialog_checklist_size()
{
	f_dialog_radiolist_size "$@"
}

# f_dialog_radiolist_with_help_size [-n] $var_height $var_width $var_rows \
#                                   $title $backtitle $prompt $hline \
#                                   $tag1 $item1 $status1 $help1 \
#                                   $tag2 $item2 $status2 $help2 ...
#
# Not all versions of dialog(1) perform auto-sizing of the width and height of
# `--radiolist' boxes sensibly.
#
# This function helps solve this issue by taking three sets of sequential
# arguments. The first set of arguments are the variable names to use when
# storing the calculated height, width, and rows. The second set of arguments
# are the title, backtitle, prompt, and hline. The [optional] third set of
# arguments are the radio list itself (comprised of tag/item/status/help
# quadruplets). The optimal height, width, and rows for the described widget
# (not exceeding the actual terminal height or width) is stored in $var_height,
# $var_width, and $var_rows (respectively).
#
# If the first argument is `-n', the calculated sizes ($var_height, $var_width,
# and $var_rows) are not constrained to minimum/maximum values.
#
f_dialog_radiolist_with_help_size()
{
	local __constrain=1
	[ "$1" = "-n" ] && __constrain= && shift 1 # -n
	local __var_height="$1" __var_width="$2" __var_rows="$3"
	local __title="$4" __btitle="$5" __prompt="$6" __hline="$7"
	shift 7 # var_height/var_width/var_rows/title/btitle/prompt/hline

	# Return unless at least one size aspect has been requested
	[ "$__var_height" -o "$__var_width" -o "$__var_rows" ] ||
		return $FAILURE

	# Calculate height/width of infobox (adjusted/constrained below)
	# NOTE: Function name appended to prevent __var_{height,width} values
	#       from becoming local (and thus preventing setvar from working).
	local __height_rlist_with_help_size __width_rlist_with_help_size
	f_dialog_infobox_size -n \
		"${__var_height:+__height_rlist_with_help_size}" \
		"${__var_width:+__width_rlist_with_help_size}" \
		"$__title" "$__btitle" "$__prompt" "$__hline"

	#
	# Always process the menu-item arguments to get the longest tag-length,
	# longest item-length, longest help-length (help-length only considered
	# if using Xdialog(1), as it places the help string in the widget) --
	# all used to bump the width -- and the number of rows (used to bump
	# the height).
	#
	local __longest_tag=0 __longest_item=0 __longest_help=0 __rows=0
	while [ $# -ge 4 ]; do
		local __tag="$1" __item="$2" __status="$3" __help="$4"
		shift 4 # tag/item/status/help
		[ ${#__tag} -gt $__longest_tag ] && __longest_tag=${#__tag}
		[ ${#__item} -gt $__longest_item ] && __longest_item=${#__item}
		[ ${#__help} -gt $__longest_help ] && __longest_help=${#__help}
		__rows=$(( $__rows + 1 ))
	done

	# Adjust rows early (for up-coming height calculation)
	if [ "$__var_height" -o "$__var_rows" ]; then
		# Add a row for visual aid if using Xdialog(1)
		[ "$USE_XDIALOG" ] && __rows=$(( $__rows + 1 ))
	fi

	# Adjust height if desired
	if [ "$__var_height" ]; then
		# Add rows to height
		if [ "$USE_XDIALOG" ]; then
			__height_rlist_with_help_size=$((
				$__height_rlist_with_help_size + $__rows + 7 ))
		else
			__height_rlist_with_help_size=$((
				$__height_rlist_with_help_size + $__rows + 4 ))
		fi
		setvar "$__var_height" $__height
	fi

	# Adjust width if desired
	if [ "$__var_width" ]; then
		# Sum total between longest tag-length, longest item-length,
		# and radio-button width should be used to bump menu width
		local __n=$(( $__longest_tag + $__longest_item + 13 ))
		[ "$USE_XDIALOG" ] && __n=$(( $__n + $__n / 6 )) # plus 16.6%
		[ $__n -gt $__width_rlist_with_help_size ] &&
			__width_rlist_with_help_size=$__n

		# Update width for help text if using Xdialog(1)
		if [ "$USE_XDIALOG" ]; then
			__n=$(( $__longest_help + 10 ))
			__n=$(( $__n + $__n / 6 )) # plus 16.6%
			[ $__n -gt $__width_rlist_with_help_size ] &&
				__width_rlist_with_help_size=$__n
		fi

		setvar "$__var_width" $__width_rlist_with_help_size
	fi

	# Store adjusted rows if desired
	[ "$__var_rows" ] && setvar "$__var_rows" $__rows

	# Constrain height, width, and rows to sensible minimum/maximum values
	# Return success if no-constrain, else return status from constrain
	[ ! "$__constrain" ] || f_dialog_menu_constrain \
		"$__var_height" "$__var_width" "$__var_rows" "$__prompt"
}

# f_dialog_checklist_with_help_size [-n] $var_height $var_width $var_rows \
#                                   $title $backtitle $prompt $hline \
#                                   $tag1 $item1 $status1 $help1 \
#                                   $tag2 $item2 $status2 $help2 ...
#
# Not all versions of dialog(1) perform auto-sizing of the width and height of
# `--checklist' boxes sensibly.
#
# This function helps solve this issue by taking three sets of sequential
# arguments. The first set of arguments are the variable names to use when
# storing the calculated height, width, and rows. The second set of arguments
# are the title, backtitle, prompt, and hline. The [optional] third set of
# arguments are the check list itself (comprised of tag/item/status/help
# quadruplets). The optimal height, width, and rows for the described widget
# (not exceeding the actual terminal height or width) is stored in $var_height,
# $var_width, and $var_rows (respectively).
#
# If the first argument is `-n', the calculated sizes ($var_height, $var_width,
# and $var_rows) are not constrained to minimum/maximum values.
#
f_dialog_checklist_with_help_size()
{
	f_dialog_radiolist_with_help_size "$@"
}

# f_dialog_calendar_size [-n] $var_height $var_width \
#                        $title $backtitle $prompt [$hline]
#
# Not all versions of dialog(1) perform auto-sizing of the width and height of
# `--calendar' boxes sensibly.
#
# This function helps solve this issue by taking two sets of sequential
# arguments. The first set of arguments are the variable names to use when
# storing the calculated height and width. The second set of arguments are the
# title, backtitle, prompt, and [optionally] hline. The optimal height and
# width for the described widget (not exceeding the actual terminal height or
# width) is stored in $var_height and $var_width (respectively).
#
# If the first argument is `-n', the calculated sizes ($var_height and
# $var_width) are not constrained to minimum/maximum values.
#
# Newline character sequences (``\n'') in $prompt are expanded as-is done by
# dialog(1).
#
f_dialog_calendar_size()
{
	local __constrain=1
	[ "$1" = "-n" ] && __constrain= && shift 1 # -n
	local __var_height="$1" __var_width="$2"
	local __title="$3" __btitle="$4" __prompt="$5" __hline="$6"

	# Return unless at least one size aspect has been requested
	[ "$__var_height" -o "$__var_width" ] || return $FAILURE

	#
	# Obtain/Adjust minimum and maximum thresholds
	# NOTE: Function name appended to prevent __var_{height,width} values
	#       from becoming local (and thus preventing setvar from working).
	#
	local __max_height_cal_size __max_width_cal_size
	f_dialog_max_size __max_height_cal_size __max_width_cal_size
	__max_width_cal_size=$(( $__max_width_cal_size - 2 ))
		# the calendar box will refuse to display if too wide
	local __min_width
	if [ "$USE_XDIALOG" ]; then
		__min_width=55
	else
		__min_width=40
		__max_height_cal_size=$((
			$__max_height_cal_size - $DIALOG_CALENDAR_HEIGHT ))
		# When using dialog(1), we can't predict whether the user has
		# disabled shadow's in their `$HOME/.dialogrc' file, so we'll
		# subtract one for the potential shadow around the widget
		__max_height_cal_size=$(( $__max_height_cal_size - 1 ))
	fi

	# Calculate height if desired
	if [ "$__var_height" ]; then
		local __height
		__height=$( echo "$__prompt" | f_number_of_lines )

		if [ "$USE_XDIALOG" ]; then
			# Add height to accomodate for embedded calendar widget
			__height=$(( $__height + $DIALOG_CALENDAR_HEIGHT - 1 ))

			# Also, bump height if backtitle is enabled
			if [ "$__btitle" ]; then
				local __n
				__n=$( echo "$__btitle" | f_number_of_lines )
				__height=$(( $__height + $__n + 2 ))
			fi
		else
			[ "$__prompt" ] && __height=$(( $__height + 1 ))
		fi

		# Enforce maximum height, unless `-n' was passed
		[ "$__constrain" -a $__height -gt $__max_height_cal_size ] &&
			__height=$__max_height_cal_size

		setvar "$__var_height" $__height
	fi

	# Calculate width if desired
	if [ "$__var_width" ]; then
		# NOTE: Function name appended to prevent __var_{height,width}
		#       values from becoming local (and thus preventing setvar
		#       from working).
		local __width_cal_size
		f_dialog_infobox_size -n "" __width_cal_size \
			"$__title" "$__btitle" "$__prompt" "$__hline"

		# Enforce minimum/maximum width, unless `-n' was passed
		if [ "$__constrain" ]; then
			if [ $__width_cal_size -lt $__min_width ]; then
				__width_cal_size=$__min_width
			elif [ $__width_cal_size -gt $__max_width_cal_size ]
			then
				__width_cal_size=$__max_width_size
			fi
		fi

		setvar "$__var_width" $__width_cal_size
	fi

	return $SUCCESS
}

# f_dialog_timebox_size [-n] $var_height $var_width \
#                       $title $backtitle $prompt [$hline]
#
# Not all versions of dialog(1) perform auto-sizing of the width and height of
# `--timebox' boxes sensibly.
#
# This function helps solve this issue by taking two sets of sequential
# arguments. The first set of arguments are the variable names to use when
# storing the calculated height and width. The second set of arguments are the
# title, backtitle, prompt, and [optionally] hline. The optional height and
# width for the described widget (not exceeding the actual terminal height or
# width) is stored in $var_height and $var_width (respectively).
#
# If the first argument is `-n', the calculated sizes ($var_height and
# $var_width) are not constrained to minimum/maximum values.
#
# Newline character sequences (``\n'') in $prompt are expanded as-is done by
# dialog(1).
#
f_dialog_timebox_size()
{
	local __constrain=1
	[ "$1" = "-n" ] && __constrain= && shift 1 # -n
	local __var_height="$1" __var_width="$2"
	local __title="$3" __btitle="$4" __prompt="$5" __hline="$6"

	# Return unless at least one size aspect has been requested
	[ "$__var_height" -o "$__var_width" ] || return $FAILURE

	#
	# Obtain/Adjust minimum and maximum thresholds
	# NOTE: Function name appended to prevent __var_{height,width} values
	#       from becoming local (and thus preventing setvar from working).
	#
	local __max_height_tbox_size __max_width_tbox_size
	f_dialog_max_size __max_height_tbox_size __max_width_tbox_size
	__max_width_tbox_size=$(( $__max_width_tbox_size - 2 ))
		# the timebox widget refuses to display if too wide
	local __min_width
	if [ "$USE_XDIALOG" ]; then
		__min_width=40
	else
		__min_width=20
		__max_height_tbox_size=$(( \
			$__max_height_tbox_size - $DIALOG_TIMEBOX_HEIGHT ))
		# When using dialog(1), we can't predict whether the user has
		# disabled shadow's in their `$HOME/.dialogrc' file, so we'll
		# subtract one for the potential shadow around the widget
		__max_height_tbox_size=$(( $__max_height_tbox_size - 1 ))
	fi

	# Calculate height if desired
	if [ "$__var_height" -a "$USE_XDIALOG" ]; then
		# When using Xdialog(1), the height seems to have
		# no effect. All values provide the same results.
		setvar "$__var_height" 0 # autosize
	elif [ "$__var_height" ]; then
		local __height
		__height=$( echo "$__prompt" | f_number_of_lines )
		__height=$(( $__height ${__prompt:++1} + 1 ))

		# Enforce maximum height, unless `-n' was passed
		[ "$__constrain" -a $__height -gt $__max_height_tbox_size ] &&
			__height=$__max_height_tbox_size

		setvar "$__var_height" $__height
	fi

	# Calculate width if desired
	if [ "$__var_width" ]; then
		# NOTE: Function name appended to prevent __var_{height,width}
		#       values from becoming local (and thus preventing setvar
		#       from working).
		local __width_tbox_size
		f_dialog_infobox_size -n "" __width_tbox_size \
			"$__title" "$__btitle" "$__prompt" "$__hline"

		# Enforce the minimum width for displaying the timebox
		if [ "$__constrain" ]; then
			if [ $__width_tbox_size -lt $__min_width ]; then
				__width_tbox_size=$__min_width
			elif [ $__width_tbox_size -ge $__max_width_tbox_size ]
			then
				__width_tbox_size=$__max_width_tbox_size
			fi
		fi

		setvar "$__var_width" $__width_tbox_size
	fi

	return $SUCCESS
}

############################################################ CLEAR FUNCTIONS

# f_dialog_clear
#
# Clears any/all previous dialog(1) displays.
#
f_dialog_clear()
{
	$DIALOG --clear
}

############################################################ INFO FUNCTIONS

# f_dialog_info $info_text ...
#
# Throw up a dialog(1) infobox. The infobox remains until another dialog is
# displayed or `dialog --clear' (or f_dialog_clear) is called.
#
f_dialog_info()
{
	local info_text="$*" height width
	f_dialog_infobox_size height width \
		"$DIALOG_TITLE" "$DIALOG_BACKTITLE" "$info_text"
	$DIALOG \
		--title "$DIALOG_TITLE"         \
		--backtitle "$DIALOG_BACKTITLE" \
		${USE_XDIALOG:+--ignore-eof}    \
		${USE_XDIALOG:+--no-buttons}    \
		--infobox "$info_text" $height $width
}

# f_xdialog_info $info_text ...
#
# Throw up an Xdialog(1) infobox and do not dismiss it until stdin produces
# EOF. This implies that you must execute this either as an rvalue to a pipe,
# lvalue to indirection or in a sub-shell that provides data on stdin.
#
f_xdialog_info()
{
	local info_text="$*" height width
	f_dialog_infobox_size height width \
		"$DIALOG_TITLE" "$DIALOG_BACKTITLE" "$info_text"
	$DIALOG \
		--title "$DIALOG_TITLE"               \
		--backtitle "$DIALOG_BACKTITLE"       \
		--no-close --no-buttons               \
		--infobox "$info_text" $height $width \
		-1 # timeout of -1 means abort when EOF on stdin
}

############################################################ MSGBOX FUNCTIONS

# f_dialog_msgbox $msg_text [$hline]
#
# Throw up a dialog(1) msgbox. The msgbox remains until the user presses ENTER
# or ESC, acknowledging the modal dialog.
#
# If the user presses ENTER, the exit status is zero (success), otherwise if
# the user presses ESC the exit status is 255.
#
f_dialog_msgbox()
{
	local msg_text="$1" hline="$2" height width
	f_dialog_buttonbox_size height width \
		"$DIALOG_TITLE" "$DIALOG_BACKTITLE" "$msg_text" "$hline"
	$DIALOG \
		--title "$DIALOG_TITLE"         \
		--backtitle "$DIALOG_BACKTITLE" \
		--hline "$hline"                \
		--ok-label "$msg_ok"            \
		--msgbox "$msg_text" $height $width
}

############################################################ TEXTBOX FUNCTIONS

# f_dialog_textbox $file
#
# Display the contents of $file (or an error if $file does not exist, etc.) in
# a dialog(1) textbox (which has a scrollable region for the text). The textbox
# remains until the user presses ENTER or ESC, acknowledging the modal dialog.
#
# If the user presses ENTER, the exit status is zero (success), otherwise if
# the user presses ESC the exit status is 255.
#
f_dialog_textbox()
{
	local file="$1"
	local contents height width retval

	contents=$( cat "$file" 2>&1 )
	retval=$?

	f_dialog_buttonbox_size height width \
		"$DIALOG_TITLE" "$DIALOG_BACKTITLE" "$contents"

	if [ $retval -eq $SUCCESS ]; then
		$DIALOG \
			--title "$DIALOG_TITLE"         \
			--backtitle "$DIALOG_BACKTITLE" \
			--exit-label "$msg_ok"          \
			--no-cancel                     \
			--textbox "$file" $height $width
	else
		$DIALOG \
			--title "$DIALOG_TITLE"         \
			--backtitle "$DIALOG_BACKTITLE" \
			--ok-label "$msg_ok"            \
			--msgbox "$contents" $height $width
	fi
}

############################################################ YESNO FUNCTIONS

# f_dialog_yesno $msg_text [$hline]
#
# Display a dialog(1) Yes/No prompt to allow the user to make some decision.
# The yesno prompt remains until the user presses ENTER or ESC, acknowledging
# the modal dialog.
#
# If the user chooses YES the exit status is zero, or chooses NO the exit
# status is one, or presses ESC the exit status is 255.
#
f_dialog_yesno()
{
	local msg_text="$1" height width
	local hline="${2-$hline_arrows_tab_enter}"

	f_interactive || return 0 # If non-interactive, return YES all the time

	f_dialog_buttonbox_size height width \
		"$DIALOG_TITLE" "$DIALOG_BACKTITLE" "$msg_text" "$hline"

	if [ "$USE_XDIALOG" ]; then
		$DIALOG \
			--title "$DIALOG_TITLE"         \
			--backtitle "$DIALOG_BACKTITLE" \
			--hline "$hline"                \
			--ok-label "$msg_yes"           \
			--cancel-label "$msg_no"        \
			--yesno "$msg_text" $height $width
	else
		$DIALOG \
			--title "$DIALOG_TITLE"         \
			--backtitle "$DIALOG_BACKTITLE" \
			--hline "$hline"                \
			--yes-label "$msg_yes"          \
			--no-label "$msg_no"            \
			--yesno "$msg_text" $height $width
	fi
}

# f_dialog_noyes $msg_text [$hline]
#
# Display a dialog(1) No/Yes prompt to allow the user to make some decision.
# The noyes prompt remains until the user presses ENTER or ESC, acknowledging
# the modal dialog.
#
# If the user chooses YES the exit status is zero, or chooses NO the exit
# status is one, or presses ESC the exit status is 255.
#
# NOTE: This is just like the f_dialog_yesno function except "No" is default.
#
f_dialog_noyes()
{
	local msg_text="$1" height width
	local hline="${2-$hline_arrows_tab_enter}"

	f_interactive || return 1 # If non-interactive, return NO all the time

	f_dialog_buttonbox_size height width \
		"$DIALOG_TITLE" "$DIALOG_BACKTITLE" "$msg_text" "$hline"

	if [ "$USE_XDIALOG" ]; then
		$DIALOG \
			--title "$DIALOG_TITLE"         \
			--backtitle "$DIALOG_BACKTITLE" \
			--hline "$hline"                \
			--default-no                    \
			--ok-label "$msg_yes"           \
			--cancel-label "$msg_no"        \
			--yesno "$msg_text" $height $width
	else
		$DIALOG \
			--title "$DIALOG_TITLE"         \
			--backtitle "$DIALOG_BACKTITLE" \
			--hline "$hline"                \
			--defaultno                     \
			--yes-label "$msg_yes"          \
			--no-label "$msg_no"            \
			--yesno "$msg_text" $height $width
	fi
}

############################################################ INPUT FUNCTIONS

# f_dialog_inputstr_store [-s] $text
#
# Store some text from a dialog(1) inputbox to be retrieved later by
# f_dialog_inputstr_fetch(). If the first argument is `-s', the text is
# sanitized before being stored.
#
f_dialog_inputstr_store()
{
	local sanitize=
	[ "$1" = "-s" ] && sanitize=1 && shift 1 # -s
	local text="$1"

	# Sanitize the line before storing it if desired
	[ "$sanitize" ] && f_dialog_line_sanitize text

	setvar DIALOG_INPUTBOX_$$ "$text"
}

# f_dialog_inputstr_fetch [$var_to_set]
#
# Obtain the inputstr entered by the user from the most recently displayed
# dialog(1) inputbox (previously stored with f_dialog_inputstr_store() above).
# If $var_to_set is NULL or missing, output is printed to stdout (which is less
# recommended due to performance degradation; in a loop for example).
#
f_dialog_inputstr_fetch()
{
	local __var_to_set="$1" __cp

	debug= f_getvar DIALOG_INPUTBOX_$$ "${__var_to_set:-__cp}" # get data
	setvar DIALOG_INPUTBOX_$$ "" # scrub memory in case data was sensitive

	# Return the line on standard-out if desired
	[ "$__var_to_set" ] || echo "$__cp"

	return $SUCCESS
}

# f_dialog_input $var_to_set $prompt [$init [$hline]]
#
# Prompt the user with a dialog(1) inputbox to enter some value. The inputbox
# remains until the the user presses ENTER or ESC, or otherwise ends the
# editing session (by selecting `Cancel' for example).
#
# If the user presses ENTER, the exit status is zero (success), otherwise if
# the user presses ESC the exit status is 255, or if the user chose Cancel, the
# exit status is instead 1.
#
# NOTE: The hline should correspond to the type of data you want from the user.
# NOTE: Should not be used to edit multiline values.
#
f_dialog_input()
{
	local __var_to_set="$1" __prompt="$2" __init="$3" __hline="$4"

	# NOTE: Function name appended to prevent __var_{height,width} values
	#       from becoming local (and thus preventing setvar from working).
	local __height_input __width_input
	f_dialog_inputbox_size __height_input __width_input \
		"$DIALOG_TITLE" "$DIALOG_BACKTITLE" \
		"$__prompt" "$__init" "$__hline"

	local __opterm="--"
	[ "$USE_XDIALOG" ] && __opterm=

	local __dialog_input
	__dialog_input=$(
		$DIALOG \
			--title "$DIALOG_TITLE"         \
			--backtitle "$DIALOG_BACKTITLE" \
			--hline "$__hline"              \
			--ok-label "$msg_ok"            \
			--cancel-label "$msg_cancel"    \
			--inputbox "$__prompt"          \
			$__height_input $__width_input  \
			$__opterm "$__init"             \
			2>&1 >&$DIALOG_TERMINAL_PASSTHRU_FD
	)
	local __retval=$?

	# Remove warnings and leading/trailing whitespace from user input
	f_dialog_line_sanitize __dialog_input

	setvar "$__var_to_set" "$__dialog_input"
	return $__retval
}

############################################################ MENU FUNCTIONS

# f_dialog_menutag_store [-s] $text
#
# Store some text from a dialog(1) menu to be retrieved later by
# f_dialog_menutag_fetch(). If the first argument is `-s', the text is
# sanitized before being stored.
#
f_dialog_menutag_store()
{
	local sanitize=
	[ "$1" = "-s" ] && sanitize=1 && shift 1 # -s
	local text="$1"

	# Sanitize the menutag before storing it if desired
	[ "$sanitize" ] && f_dialog_data_sanitize text

	setvar DIALOG_MENU_$$ "$text"
}

# f_dialog_menutag_fetch [$var_to_set]
#
# Obtain the menutag chosen by the user from the most recently displayed
# dialog(1) menu (previously stored with f_dialog_menutag_store() above). If
# $var_to_set is NULL or missing, output is printed to stdout (which is less
# recommended due to performance degradation; in a loop for example).
#
f_dialog_menutag_fetch()
{
	local __var_to_set="$1" __cp

	debug= f_getvar DIALOG_MENU_$$ "${__var_to_set:-__cp}" # get the data
	setvar DIALOG_MENU_$$ "" # scrub memory in case data was sensitive

	# Return the data on standard-out if desired
	[ "$__var_to_set" ] || echo "$__cp"

	return $SUCCESS
}

# f_dialog_menuitem_store [-s] $text
#
# Store the item from a dialog(1) menu (see f_dialog_menutag2item()) to be
# retrieved later by f_dialog_menuitem_fetch(). If the first argument is `-s',
# the text is sanitized before being stored.
#
f_dialog_menuitem_store()
{
	local sanitize=
	[ "$1" = "-s" ] && sanitize=1 && shift 1 # -s
	local text="$1"

	# Sanitize the menuitem before storing it if desired
	[ "$sanitize" ] && f_dialog_data_sanitize text

	setvar DIALOG_MENUITEM_$$ "$text"
}

# f_dialog_menuitem_fetch [$var_to_set]
#
# Obtain the menuitem chosen by the user from the most recently displayed
# dialog(1) menu (previously stored with f_dialog_menuitem_store() above). If
# $var_to_set is NULL or missing, output is printed to stdout (which is less
# recommended due to performance degradation; in a loop for example).
#
f_dialog_menuitem_fetch()
{
	local __var_to_set="$1" __cp

	debug= f_getvar DIALOG_MENUITEM_$$ "${__var_to_set:-__cp}" # get data
	setvar DIALOG_MENUITEM_$$ "" # scrub memory in case data was sensitive

	# Return the data on standard-out if desired
	[ "$__var_to_set" ] || echo "$__cp"

	return $SUCCESS
}

# f_dialog_default_store [-s] $text
#
# Store some text to be used later as the --default-item argument to dialog(1)
# (or Xdialog(1)) for --menu, --checklist, and --radiolist widgets. Retrieve
# the text later with f_dialog_menutag_fetch(). If the first argument is `-s',
# the text is sanitized before being stored.
#
f_dialog_default_store()
{
	local sanitize=
	[ "$1" = "-s" ] && sanitize=1 && shift 1 # -s
	local text="$1"

	# Sanitize the defaulitem before storing it if desired
	[ "$sanitize" ] && f_dialog_data_sanitize text

	setvar DEFAULTITEM_$$ "$text"
}

# f_dialog_default_fetch [$var_to_set]
#
# Obtain text to be used with the --default-item argument of dialog(1) (or
# Xdialog(1)) (previously stored with f_dialog_default_store() above). If
# $var_to_set is NULL or missing, output is printed to stdout (which is less
# recommended due to performance degradation; in a loop for example).
#
f_dialog_default_fetch()
{
	local __var_to_set="$1" __cp

	debug= f_getvar DEFAULTITEM_$$ "${__var_to_set:-__cp}" # get the data
	setvar DEFAULTITEM_$$ "" # scrub memory in case data was sensitive

	# Return the data on standard-out if desired
	[ "$__var_to_set" ] || echo "$__cp"

	return $SUCCESS
}

# f_dialog_menutag2item $tag_chosen $tag1 $item1 $tag2 $item2 ...
#
# To use the `--menu' option of dialog(1) you must pass an ordered list of
# tag/item pairs on the command-line. When the user selects a menu option the
# tag for that item is printed to stderr.
#
# This function allows you to dereference the tag chosen by the user back into
# the item associated with said tag.
#
# Pass the tag chosen by the user as the first argument, followed by the
# ordered list of tag/item pairs (HINT: use the same tag/item list as was
# passed to dialog(1) for consistency).
#
# If the tag cannot be found, NULL is returned.
#
f_dialog_menutag2item()
{
	local tag="$1" tagn item
	shift 1 # tag

	while [ $# -gt 0 ]; do
		tagn="$1"
		item="$2"
		shift 2 # tagn/item

		if [ "$tag" = "$tagn" ]; then
			echo "$item"
			return $SUCCESS
		fi
	done
	return $FAILURE
}

# f_dialog_menutag2item_with_help $tag_chosen $tag1 $item1 $help1 \
#                                             $tag2 $item2 $help2 ...
#
# To use the `--menu' option of dialog(1) with the `--item-help' option, you
# must pass an ordered list of tag/item/help triplets on the command-line. When
# the user selects a menu option the tag for that item is printed to stderr.
#
# This function allows you to dereference the tag chosen by the user back into
# the item associated with said tag (help is discarded/ignored).
#
# Pass the tag chosen by the user as the first argument, followed by the
# ordered list of tag/item/help triplets (HINT: use the same tag/item/help list
# as was passed to dialog(1) for consistency).
#
# If the tag cannot be found, NULL is returned.
#
f_dialog_menutag2item_with_help()
{
	local tag="$1" tagn item
	shift 1 # tag

	while [ $# -gt 0 ]; do
		tagn="$1"
		item="$2"
		shift 3 # tagn/item/help

		if [ "$tag" = "$tagn" ]; then
			echo "$item"
			return $SUCCESS
		fi
	done
	return $FAILURE
}

# f_dialog_menutag2index $tag_chosen $tag1 $item1 $tag2 $item2 ...
#
# To use the `--menu' option of dialog(1) you must pass an ordered list of
# tag/item pairs on the command-line. When the user selects a menu option the
# tag for that item is printed to stderr.
#
# This function allows you to dereference the tag chosen by the user back into
# the index associated with said tag. The index is the one-based tag/item pair
# array position within the ordered list of tag/item pairs passed to dialog(1).
#
# Pass the tag chosen by the user as the first argument, followed by the
# ordered list of tag/item pairs (HINT: use the same tag/item list as was
# passed to dialog(1) for consistency).
#
# If the tag cannot be found, NULL is returned.
#
f_dialog_menutag2index()
{
	local tag="$1" tagn n=1
	shift 1 # tag

	while [ $# -gt 0 ]; do
		tagn="$1"
		shift 2 # tagn/item

		if [ "$tag" = "$tagn" ]; then
			echo $n
			return $SUCCESS
		fi
		n=$(( $n + 1 ))
	done
	return $FAILURE
}

# f_dialog_menutag2index_with_help $tag_chosen $tag1 $item1 $help1 \
#                                              $tag2 $item2 $help2 ...
#
# To use the `--menu' option of dialog(1) with the `--item-help' option, you
# must pass an ordered list of tag/item/help triplets on the command-line. When
# the user selects a menu option the tag for that item is printed to stderr.
#
# This function allows you to dereference the tag chosen by the user back into
# the index associated with said tag. The index is the one-based tag/item/help
# triplet array position within the ordered list of tag/item/help triplets
# passed to dialog(1).
#
# Pass the tag chosen by the user as the first argument, followed by the
# ordered list of tag/item/help triplets (HINT: use the same tag/item/help list
# as was passed to dialog(1) for consistency).
#
# If the tag cannot be found, NULL is returned.
#
f_dialog_menutag2index_with_help()
{
	local tag="$1" tagn n=1
	shift 1 # tag

	while [ $# -gt 0 ]; do
		tagn="$1"
		shift 3 # tagn/item/help

		if [ "$tag" = "$tagn" ]; then
			echo $n
			return $SUCCESS
		fi
		n=$(( $n + 1 ))
	done
	return $FAILURE
}

############################################################ INIT FUNCTIONS

# f_dialog_init
#
# Initialize (or re-initialize) the dialog module after setting/changing any
# of the following environment variables:
#
# 	USE_XDIALOG   Either NULL or Non-NULL. If given a value will indicate
# 	              that Xdialog(1) should be used instead of dialog(1).
#
# 	SECURE        Either NULL or Non-NULL. If given a value will indicate
# 	              that (while running as root) sudo(8) authentication is
# 	              required to proceed.
#
f_dialog_init()
{
	DIALOG_SELF_INITIALIZE=

	#
	# Clone terminal stdout so we can redirect to it from within sub-shells
	#
	eval exec $DIALOG_TERMINAL_PASSTHRU_FD\>\&1

	#
	# Add `-S' and `-X' to the list of standard arguments supported by all
	#
	case "$GETOPTS_STDARGS" in
	*SX*) : good ;; # already present
	   *) GETOPTS_STDARGS="${GETOPTS_STDARGS}SX"
	esac

	#
	# Process stored command-line arguments
	#
	f_dprintf "f_dialog_init: ARGV=[%s] GETOPTS_STDARGS=[%s]" \
	          "$ARGV" "$GETOPTS_STDARGS"
	SECURE=$( set -- $ARGV
		while getopts \
			"$GETOPTS_STDARGS$GETOPTS_EXTRA$GETOPTS_ALLFLAGS" \
		flag > /dev/null; do
			case "$flag" in
			S) echo 1 ;;
			esac
		done
	)
	USE_XDIALOG=$( set -- $ARGV
		while getopts \
			"$GETOPTS_STDARGS$GETOPTS_EXTRA$GETOPTS_ALLFLAGS" \
		flag > /dev/null; do
			case "$flag" in
			S|X) echo 1 ;;
			esac
		done
	)
	f_dprintf "f_dialog_init: SECURE=[%s] USE_XDIALOG=[%s]" \
	          "$SECURE" "$USE_XDIALOG"

	#
	# Process `-X' command-line option
	#
	[ "$USE_XDIALOG" ] && DIALOG=Xdialog

	#
	# Sanity check, or die gracefully
	#
	if ! f_have $DIALOG; then
		unset USE_XDIALOG
		local failed_dialog="$DIALOG"
		DIALOG=dialog
		f_die 1 "$msg_no_such_file_or_directory" "$pgm" "$failed_dialog"
	fi

	#
	# If we're already running as root but we got there by way of sudo(8)
	# and we have X11, we should merge the xauth(1) credentials from our
	# original user.
	#
	if [ "$USE_XDIALOG" ] &&
	   [ "$( id -u )" = "0" ] &&
	   [ "$SUDO_USER" -a "$DISPLAY" ]
	then
		if ! f_have xauth; then
			# Die gracefully, as we [likely] can't use Xdialog(1)
			unset USE_XDIALOG
			DIALOG=dialog
			f_die 1 "$msg_no_such_file_or_directory" "$pgm" "xauth"
		fi
		HOSTNAME=$(hostname)
		local displaynum="${DISPLAY#*:}"
		eval xauth -if \~$SUDO_USER/.Xauthority extract - \
			\"\$HOSTNAME/unix:\$displaynum\" \
			\"\$HOSTNAME:\$displaynum\" | sudo sh -c 'xauth -ivf \
			~root/.Xauthority merge - > /dev/null 2>&1'
	fi

	#
	# Probe Xdialog(1) for maximum height/width constraints, or die
	# gracefully
	#
	if [ "$USE_XDIALOG" ]; then
		local maxsize
		if ! maxsize=$( LANG= LC_ALL= $DIALOG --print-maxsize 2>&1 )
		then
			# Xdialog(1) failed, fall back to dialog(1)
			unset USE_XDIALOG

			# Display the error message produced by Xdialog(1)
			local height width
			f_dialog_buttonbox_size height width \
				"$DIALOG_TITLE" "$DIALOG_BACKTITLE" "$maxsize"
			dialog \
				--title "$DIALOG_TITLE"         \
				--backtitle "$DIALOG_BACKTITLE" \
				--ok-label "$msg_ok"            \
				--msgbox "$maxsize" $height $width
			exit $FAILURE
		fi

		XDIALOG_MAXSIZE=$(
			set -- ${maxsize##*:}

			height=${1%,}
			width=$2

			echo $height $width
		)
	fi

	#
	# If using Xdialog(1), swap DIALOG_TITLE with DIALOG_BACKTITLE.
	# The reason for this is because many dialog(1) applications use
	# --backtitle for the program name (which is better suited as
	# --title with Xdialog(1)).
	#
	if [ "$USE_XDIALOG" ]; then
		local _DIALOG_TITLE="$DIALOG_TITLE"
		DIALOG_TITLE="$DIALOG_BACKTITLE"
		DIALOG_BACKTITLE="$_DIALOG_TITLE"
	fi

	f_dprintf "f_dialog_init: dialog(1) API initialized."
}

############################################################ MAIN

#
# Self-initialize unless requested otherwise
#
f_dprintf "%s: DIALOG_SELF_INITIALIZE=[%s]" \
          dialog.subr "$DIALOG_SELF_INITIALIZE"
case "$DIALOG_SELF_INITIALIZE" in
""|0|[Nn][Oo]|[Oo][Ff][Ff]|[Ff][Aa][Ll][Ss][Ee]) : do nothing ;;
*) f_dialog_init
esac

f_dprintf "%s: Successfully loaded." dialog.subr

fi # ! $_DIALOG_SUBR