xref: /freebsd-9.3-release/usr.sbin/bsdconfig/share/strings.subr

if [ ! "$_STRINGS_SUBR" ]; then _STRINGS_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: stable/9/usr.sbin/bsdconfig/share/strings.subr 252995 2013-07-07 19:13:34Z dteske $
#
############################################################ GLOBALS

#
# Valid characters that can appear in an sh(1) variable name
#
# Please note that the character ranges A-Z and a-z should be avoided because
# these can include accent characters (which are not valid in a variable name).
# For example, A-Z matches any character that sorts after A but before Z,
# including A and Z. Although ASCII order would make more sense, that is not
# how it works.
#
VALID_VARNAME_CHARS="0-9ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_"

############################################################ FUNCTIONS

# f_substr "$string" $start [ $length ]
#
# Simple wrapper to awk(1)'s `substr' function.
#
f_substr()
{
	local string="$1" start="${2:-0}" len="${3:-0}"
	echo "$string" | awk "{ print substr(\$0, $start, $len) }"
}

# f_snprintf $var_to_set $size $format ...
#
# Similar to snprintf(3), write at most $size number of bytes into $var_to_set
# using printf(1) syntax (`$format ...'). The value of $var_to_set is NULL
# unless at-least one byte is stored from the output.
#
f_snprintf()
{
	local __var_to_set="$1" __size="$2"
	shift 2 # var_to_set/size
	eval "$__var_to_set"=\$\( printf \"\$@\" \| awk -v max=\"\$__size\" \''
	{
		len = length($0)
		max -= len
		print substr($0,0,(max > 0 ? len : max + len))
		if ( max < 0 ) exit
		max--
	}'\' \)
}

# f_vsnprintf $var_to_set $size $format $format_args
#
# Similar to vsnprintf(3), write at most $size number of bytes into $var_to_set
# using printf(1) syntax (`$format $format_args'). The value of $var_to_set is
# NULL unless at-least one byte is stored from the output.
#
# Example 1:
#
# 	limit=7 format="%s"
# 	format_args="'abc   123'" # 3-spaces between abc and 123
# 	f_vsnprintf foo $limit "$format" "$format_args" # foo=[abc   1]
#
# Example 2:
#
# 	limit=12 format="%s %s"
# 	format_args="   'doghouse'      'foxhound'   "
# 		# even more spaces added to illustrate escape-method
# 	f_vsnprintf foo $limit "$format" "$format_args" # foo=[doghouse fox]
#
# Example 3:
#
# 	limit=13 format="%s %s"
# 	f_shell_escape arg1 'aaa"aaa' # arg1=[aaa"aaa] (no change)
# 	f_shell_escape arg2 "aaa'aaa" # arg2=[aaa'\''aaa] (escaped s-quote)
# 	format_args="'$arg1' '$arg2'" # use single-quotes to surround args
# 	f_vsnprintf foo $limit "$format" "$format_args" # foo=[aaa"aaa aaa'a]
#
# In all of the above examples, the call to f_vsnprintf() does not change. Only
# the contents of $limit, $format, and $format_args changes in each example.
#
f_vsnprintf()
{
	eval f_snprintf \"\$1\" \"\$2\" \"\$3\" $4
}

# f_longest_line_length
#
# Simple wrapper to an awk(1) script to print the length of the longest line of
# input (read from stdin). Supports the newline escape-sequence `\n' for
# splitting a single line into multiple lines.
#
f_longest_line_length_awk='
BEGIN { longest = 0 }
{
	if (split($0, lines, /\\n/) > 1)
	{
		for (n in lines)
		{
			len = length(lines[n])
			longest = ( len > longest ? len : longest )
		}
	}
	else
	{
		len = length($0)
		longest = ( len > longest ? len : longest )
	}
}
END { print longest }
'
f_longest_line_length()
{
	awk "$f_longest_line_length_awk"
}

# f_number_of_lines
#
# Simple wrapper to an awk(1) script to print the number of lines read from
# stdin. Supports newline escape-sequence `\n' for splitting a single line into
# multiple lines.
#
f_number_of_lines_awk='
BEGIN { num_lines = 0 }
{
	num_lines += split(" "$0, unused, /\\n/)
}
END { print num_lines }
'
f_number_of_lines()
{
	awk "$f_number_of_lines_awk"
}

# f_isinteger $arg
#
# Returns true if argument is a positive/negative whole integer.
#
f_isinteger()
{
	local arg="$1"

	# Prevent division-by-zero
	[ "$arg" = "0" ] && return $SUCCESS

	# Attempt to perform arithmetic divison (an operation which will exit
	# with error unless arg is a valid positive/negative whole integer).
	#
	( : $((0/$arg)) ) > /dev/null 2>&1
}

# f_uriencode [$text]
#
# Encode $text for the purpose of embedding safely into a URL. Non-alphanumeric
# characters are converted to `%XX' sequence where XX represents the hexa-
# decimal ordinal of the non-alphanumeric character. If $text is missing, data
# is instead read from standard input.
#
f_uriencode_awk='
BEGIN {
	output = ""
	for (n = 0; n < 256; n++) pack[sprintf("%c", n)] = sprintf("%%%02x", n)
}
{
	sline = ""
	slen = length($0)
	for (n = 1; n <= slen; n++) {
		char = substr($0, n, 1)
		if ( char !~ /^[[:alnum:]_]$/ ) char = pack[char]
		sline = sline char
	}
	output = output ( output ? "%0a" : "" ) sline
}
END { print output }
'
f_uriencode()
{
	if [ $# -gt 0 ]; then
		echo "$1" | awk "$f_uriencode_awk"
	else
		awk "$f_uriencode_awk"
	fi
}

# f_uridecode [$text]
#
# Decode $text from a URI. Encoded characters are converted from their `%XX'
# sequence into original unencoded ASCII sequences. If $text is missing, data
# is instead read from standard input.
#
f_uridecode_awk='
BEGIN { for (n = 0; n < 256; n++) chr[n] = sprintf("%c", n) }
{
	sline = ""
	slen = length($0)
	for (n = 1; n <= slen; n++)
	{
		seq = substr($0, n, 3)
		if ( seq ~ /^%[[:xdigit:]][[:xdigit:]]$/ ) {
			hex = substr(seq, 2, 2)
			sline = sline chr[sprintf("%u", "0x"hex)]
			n += 2
		} else
			sline = sline substr(seq, 1, 1)
	}
	print sline
}
'
f_uridecode()
{
	if [ $# -gt 0 ]; then
		echo "$1" | awk "$f_uridecode_awk"
	else
		awk "$f_uridecode_awk"
	fi
}

# f_replaceall $string $find $replace [$var_to_set]
#
# Replace all occurrences of $find in $string with $replace. If $var_to_set is
# either missing or NULL, the variable name is produced on standard out for
# capturing in a sub-shell (which is less recommended due to performance
# degradation).
#
f_replaceall()
{
	local __left="" __right="$1"
	local __find="$2" __replace="$3" __var_to_set="$4"
	while :; do
		case "$__right" in *$__find*)
			__left="$__left${__right%%$__find*}$__replace"
			__right="${__right#*$__find}"
			continue
		esac
		break
	done
	__left="$__left${__right#*$__find}"
	if [ "$__var_to_set" ]; then
		setvar "$__var_to_set" "$__left"
	else
		echo "$__left"
	fi
}

# f_str2varname $string [$var_to_set]
#
# Convert a string into a suitable value to be used as a variable name
# by converting unsuitable characters into the underscrore [_]. If $var_to_set
# is either missing or NULL, the variable name is produced on standard out for
# capturing in a sub-shell (which is less recommended due to performance
# degradation).
#
f_str2varname()
{
	local __string="$1" __var_to_set="$2"
	f_replaceall "$__string" "[!$VALID_VARNAME_CHARS]" "_" "$__var_to_set"
}

# f_shell_escape $string [$var_to_set]
#
# Escape $string for shell eval statement(s) by replacing all single-quotes
# with a special sequence that creates a compound string when interpolated
# by eval with surrounding single-quotes.
#
# For example:
#
# 	foo="abc'123"
# 	f_shell_escape "$foo" bar # bar=[abc'\''123]
# 	eval echo \'$bar\' # produces abc'123
#
# This is helpful when processing an argument list that has to retain its
# escaped structure for later evaluations.
#
# WARNING: Surrounding single-quotes are not added; this is the responsibility
# of the code passing the escaped values to eval (which also aids readability).
#
f_shell_escape()
{
	local __string="$1" __var_to_set="$2"
	f_replaceall "$__string" "'" "'\\''" "$__var_to_set"
}

# f_shell_unescape $string [$var_to_set]
#
# The antithesis of f_shell_escape(), this function takes an escaped $string
# and expands it.
#
# For example:
#
# 	foo="abc'123"
# 	f_shell_escape "$foo" bar # bar=[abc'\''123]
# 	f_shell_unescape "$bar" # produces abc'123
#
f_shell_unescape()
{
	local __string="$1" __var_to_set="$2"
	f_replaceall "$__string" "'\\''" "'" "$__var_to_set"
}

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

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

fi # ! $_STRINGS_SUBR