bsdconfig/share/sysrc.subr

if [ ! "$_SYSRC_SUBR" ]; then _SYSRC_SUBR=1
#
# Copyright (c) 2006-2012 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: head/usr.sbin/bsdconfig/share/sysrc.subr 241149 2012-10-03 02:32:47Z dteske $
#
############################################################ INCLUDES

BSDCFG_SHARE="/usr/share/bsdconfig"
[ "$_COMMON_SUBR" ] || . $BSDCFG_SHARE/common.subr || exit 1

BSDCFG_LIBE="/usr/libexec/bsdconfig"
[ ! "$_SYSRC_JAILED" ] && f_include_lang $BSDCFG_LIBE/include/messages.subr

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

#
# Standard pathnames (inherit values from shell if available)
#
: ${RC_DEFAULTS:="/etc/defaults/rc.conf"}

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

#
# Global exit status variables
#
SUCCESS=0
FAILURE=1

#
# 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_clean_env [ --except $varname ... ]
#
# Unset all environment variables in the current scope. An optional list of
# arguments can be passed, indicating which variables to avoid unsetting; the
# `--except' is required to enable the exclusion-list as the remainder of
# positional arguments.
#
# Be careful not to call this in a shell that you still expect to perform
# $PATH expansion in, because this will blow $PATH away. This is best used
# within a sub-shell block "(...)" or "$(...)" or "`...`".
#
f_clean_env()
{
	local var arg except=

	#
	# Should we process an exclusion-list?
	#
	if [ "$1" = "--except" ]; then
		except=1
		shift 1
	fi

	#
	# Loop over a list of variable names from set(1) built-in.
	#
	for var in $( set | awk -F= \
		'/^[[:alpha:]_][[:alnum:]_]*=/ {print $1}' \
		| grep -v '^except$'
	); do
		#
		# In POSIX bourne-shell, attempting to unset(1) OPTIND results
		# in "unset: Illegal number:" and causes abrupt termination.
		#
		[ "$var" = OPTIND ] && continue

		#
		# Process the exclusion-list?
		#
		if [ "$except" ]; then
			for arg in "$@" ""; do
				[ "$var" = "$arg" ] && break
			done
			[ "$arg" ] && continue
		fi

		unset "$var"
	done
}

# f_sysrc_get $varname
#
# Get a system configuration setting from the collection of system-
# configuration files (in order: /etc/defaults/rc.conf /etc/rc.conf
# and /etc/rc.conf).
#
# NOTE: Additional shell parameter-expansion formats are supported. For
# example, passing an argument of "hostname%%.*" (properly quoted) will
# return the hostname up to (but not including) the first `.' (see sh(1),
# "Parameter Expansion" for more information on additional formats).
#
f_sysrc_get()
{
	# Sanity check
	[ -f "$RC_DEFAULTS" -a -r "$RC_DEFAULTS" ] || return $FAILURE

	# Taint-check variable name
	case "$1" in
	[0-9]*)
		# Don't expand possible positional parameters
		return $FAILURE;;
	*)
		[ "$1" ] || return $FAILURE
	esac

	( # Execute within sub-shell to protect parent environment

		#
		# Clear the environment of all variables, preventing the
		# expansion of normals such as `PS1', `TERM', etc.
		#
		f_clean_env --except IFS RC_CONFS RC_DEFAULTS

		. "$RC_DEFAULTS" > /dev/null 2>&1

		unset RC_DEFAULTS
			# no longer needed

		#
		# If the query is for `rc_conf_files' then store the value that
		# we inherited from sourcing RC_DEFAULTS (above) so that we may
		# conditionally restore this value after source_rc_confs in the
		# event that RC_CONFS does not customize the value.
		#
		if [ "$1" = "rc_conf_files" ]; then
			_rc_conf_files="$rc_conf_files"
		fi

		#
		# If RC_CONFS is defined, set $rc_conf_files to an explicit
		# value, modifying the default behavior of source_rc_confs().
		#
		if [ "${RC_CONFS+set}" ]; then
			rc_conf_files="$RC_CONFS"
			_rc_confs_set=1
		fi

		source_rc_confs > /dev/null 2>&1

		#
		# If the query was for `rc_conf_files' AND after calling
		# source_rc_confs the value has not changed, then we should
		# restore the value to the one inherited from RC_DEFAULTS
		# before performing the final query (preventing us from
		# returning what was set via RC_CONFS when the intent was
		# instead to query the value from the file(s) specified).
		#
		if [ "$1" = "rc_conf_files" -a \
		     "$_rc_confs_set" -a \
		     "$rc_conf_files" = "$RC_CONFS" \
		]; then
			rc_conf_files="$_rc_conf_files"
			unset _rc_conf_files
			unset _rc_confs_set
		fi

		unset RC_CONFS
			# no longer needed

		#
		# This must be the last functional line for both the sub-shell
		# and the function to preserve the return status from formats
		# such as "${varname?}" and "${varname:?}" (see "Parameter
		# Expansion" in sh(1) for more information).
		#
		eval echo '"${'"$1"'}"' 2> /dev/null
	)
}

# f_sysrc_get_default $varname
#
# Get a system configuration default setting from the default rc.conf(5) file
# (or whatever RC_DEFAULTS points at).
#
f_sysrc_get_default()
{
	# Sanity check
	[ -f "$RC_DEFAULTS" -a -r "$RC_DEFAULTS" ] || return $FAILURE

	# Taint-check variable name
	case "$1" in
	[0-9]*)
		# Don't expand possible positional parameters
		return $FAILURE;;
	*)
		[ "$1" ] || return $FAILURE
	esac

	( # Execute within sub-shell to protect parent environment

		#
		# Clear the environment of all variables, preventing the
		# expansion of normals such as `PS1', `TERM', etc.
		#
		f_clean_env --except RC_DEFAULTS

		. "$RC_DEFAULTS" > /dev/null 2>&1

		unset RC_DEFAULTS
			# no longer needed

		#
		# This must be the last functional line for both the sub-shell
		# and the function to preserve the return status from formats
		# such as "${varname?}" and "${varname:?}" (see "Parameter
		# Expansion" in sh(1) for more information).
		#
		eval echo '"${'"$1"'}"' 2> /dev/null
	)
}

# f_sysrc_find $varname
#
# Find which file holds the effective last-assignment to a given variable
# within the rc.conf(5) file(s).
#
# If the variable is found in any of the rc.conf(5) files, the function prints
# the filename it was found in and then returns success. Otherwise output is
# NULL and the function returns with error status.
#
f_sysrc_find()
{
	local varname="${1%%[!$VALID_VARNAME_CHARS]*}"
	local regex="^[[:space:]]*$varname="
	local rc_conf_files="$( f_sysrc_get rc_conf_files )"
	local conf_files=
	local file

	# Check parameters
	case "$varname" in
	""|[0-9]*) return $FAILURE
	esac

	#
	# If RC_CONFS is defined, set $rc_conf_files to an explicit
	# value, modifying the default behavior of source_rc_confs().
	#
	[ "${RC_CONFS+set}" ] && rc_conf_files="$RC_CONFS"

	#
	# Reverse the order of files in rc_conf_files (the boot process sources
	# these in order, so we will search them in reverse-order to find the
	# last-assignment -- the one that ultimately effects the environment).
	#
	for file in $rc_conf_files; do
		conf_files="$file${conf_files:+ }$conf_files"
	done

	#
	# Append the defaults file (since directives in the defaults file
	# indeed affect the boot process, we'll want to know when a directive
	# is found there).
	#
	conf_files="$conf_files${conf_files:+ }$RC_DEFAULTS"

	#
	# Find which file matches assignment to the given variable name.
	#
	for file in $conf_files; do
		[ -f "$file" -a -r "$file" ] || continue
		if grep -Eq "$regex" $file; then
			echo $file
			return $SUCCESS
		fi
	done

	return $FAILURE # Not found
}

# f_sysrc_desc $varname
#
# Attempts to return the comments associated with varname from the rc.conf(5)
# defaults file `/etc/defaults/rc.conf' (or whatever RC_DEFAULTS points to).
#
# Multi-line comments are joined together. Results are NULL if no description
# could be found.
#
# This function is a two-parter. Below is the awk(1) portion of the function,
# afterward is the sh(1) function which utilizes the below awk script.
#
f_sysrc_desc_awk='
# Variables that should be defined on the invocation line:
# 	-v varname="varname"
#
BEGIN {
	regex = "^[[:space:]]*"varname"="
	found = 0
	buffer = ""
}
{
	if ( ! found )
	{
		if ( ! match($0, regex) ) next

		found = 1
		sub(/^[^#]*(#[[:space:]]*)?/, "")
		buffer = $0
		next
	}

	if ( !/^[[:space:]]*#/ ||
	      /^[[:space:]]*[[:alpha:]_][[:alnum:]_]*=/ ||
	      /^[[:space:]]*#[[:alpha:]_][[:alnum:]_]*=/ ||
	      /^[[:space:]]*$/ ) exit

	sub(/(.*#)*[[:space:]]*/, "")
	buffer = buffer" "$0
}
END {
	# Clean up the buffer
	sub(/^[[:space:]]*/, "", buffer)
	sub(/[[:space:]]*$/, "", buffer)

	print buffer
	exit ! found
}
'
f_sysrc_desc()
{
	awk -v varname="$1" "$f_sysrc_desc_awk" < "$RC_DEFAULTS"
}

# f_sysrc_set $varname $new_value
#
# Change a setting in the system configuration files (edits the files in-place
# to change the value in the last assignment to the variable). If the variable
# does not appear in the source file, it is appended to the end of the primary
# system configuration file `/etc/rc.conf'.
#
# This function is a two-parter. Below is the awk(1) portion of the function,
# afterward is the sh(1) function which utilizes the below awk script.
#
f_sysrc_set_awk='
# Variables that should be defined on the invocation line:
# 	-v varname="varname"
# 	-v new_value="new_value"
#
BEGIN {
	regex = "^[[:space:]]*"varname"="
	found = retval = 0
}
{
	# If already found... just spew
	if ( found ) { print; next }

	# Does this line match an assignment to our variable?
	if ( ! match($0, regex) ) { print; next }

	# Save important match information
	found = 1
	matchlen = RSTART + RLENGTH - 1

	# Store the value text for later munging
	value = substr($0, matchlen + 1, length($0) - matchlen)

	# Store the first character of the value
	t1 = t2 = substr(value, 0, 1)

	# Assignment w/ back-ticks, expression, or misc.
	# We ignore these since we did not generate them
	#
	if ( t1 ~ /[`$\\]/ ) { retval = 1; print; next }

	# Assignment w/ single-quoted value
	else if ( t1 == "'\''" ) {
		sub(/^'\''[^'\'']*/, "", value)
		if ( length(value) == 0 ) t2 = ""
		sub(/^'\''/, "", value)
	}

	# Assignment w/ double-quoted value
	else if ( t1 == "\"" ) {
		sub(/^"(.*\\\\+")*[^"]*/, "", value)
		if ( length(value) == 0 ) t2 = ""
		sub(/^"/, "", value)
	}

	# Assignment w/ non-quoted value
	else if ( t1 ~ /[^[:space:];]/ ) {
		t1 = t2 = "\""
		sub(/^[^[:space:]]*/, "", value)
	}

	# Null-assignment
	else if ( t1 ~ /[[:space:];]/ ) { t1 = t2 = "\"" }

	printf "%s%c%s%c%s\n", substr($0, 0, matchlen), \
		t1, new_value, t2, value
}
END { exit retval }
'
f_sysrc_set()
{
	local varname="$1" new_value="$2"

	# Check arguments
	[ "$varname" ] || return $FAILURE

	#
	# Find which rc.conf(5) file contains the last-assignment
	#
	local not_found=
	local file="$( f_sysrc_find "$varname" )"
	if [ "$file" = "$RC_DEFAULTS" -o ! "$file" ]; then
		#
		# We either got a null response (not found) or the variable
		# was only found in the rc.conf(5) defaults. In either case,
		# let's instead modify the first file from $rc_conf_files.
		#

		not_found=1

		#
		# If RC_CONFS is defined, use $RC_CONFS
		# rather than $rc_conf_files.
		#
		if [ "${RC_CONFS+set}" ]; then
			file="${RC_CONFS%%[$IFS]*}"
		else
			file=$( f_sysrc_get 'rc_conf_files%%[$IFS]*' )
		fi
	fi

	#
	# If not found, append new value to last file and return.
	#
	if [ "$not_found" ]; then
		echo "$varname=\"$new_value\"" >> "$file"
		return $?
	fi

	#
	# Perform sanity checks.
	#
	if [ ! -w "$file" ]; then
		f_err "$msg_cannot_create_permission_denied\n" \
		      "$pgm" "$file"
		return $FAILURE
	fi

	#
	# Create a new temporary file to write to.
	#
	local tmpfile="$( mktemp -t "$pgm" )"
	[ "$tmpfile" ] || return $FAILURE

	#
	# Fixup permissions (else we're in for a surprise, as mktemp(1) creates
	# the temporary file with 0600 permissions, and if we simply mv(1) the
	# temporary file over the destination, the destination will inherit the
	# permissions from the temporary file).
	#
	local mode
	mode=$( stat -f '%#Lp' "$file" 2> /dev/null )
	f_quietly chmod "${mode:-0644}" "$tmpfile"

	#
	# Fixup ownership. The destination file _is_ writable (we tested
	# earlier above). However, this will fail if we don't have sufficient
	# permissions (so we throw stderr into the bit-bucket).
	#
	local owner
	owner=$( stat -f '%u:%g' "$file" 2> /dev/null )
	f_quietly chown "${owner:-root:wheel}" "$tmpfile"

	#
	# Operate on the matching file, replacing only the last occurrence.
	#
	local new_contents retval
	new_contents=$( tail -r $file 2> /dev/null )
	new_contents=$( echo "$new_contents" | awk -v varname="$varname" \
		-v new_value="$new_value" "$f_sysrc_set_awk" )
	retval=$?

	#
	# Write the temporary file contents.
	#
	echo "$new_contents" | tail -r > "$tmpfile" || return $FAILURE
	if [ $retval -ne $SUCCESS ]; then
		echo "$varname=\"$new_value\"" >> "$tmpfile"
	fi

	#
	# Taint-check our results.
	#
	if ! /bin/sh -n "$tmpfile"; then
		f_err "$msg_previous_syntax_errors\n" "$pgm" "$file"
		rm -f "$tmpfile"
		return $FAILURE
	fi

	#
	# Finally, move the temporary file into place.
	#
	mv "$tmpfile" "$file"
}

# f_sysrc_delete $varname
#
# Remove a setting from the system configuration files (edits files in-place).
# Deletes all assignments to the given variable in all config files. If the
# `-f file' option is passed, the removal is restricted to only those files
# specified, otherwise the system collection of rc_conf_files is used.
#
# This function is a two-parter. Below is the awk(1) portion of the function,
# afterward is the sh(1) function which utilizes the below awk script.
#
f_sysrc_delete_awk='
# Variables that should be defined on the invocation line:
# 	-v varname="varname"
#
BEGIN {
	regex = "^[[:space:]]*"varname"="
	found = 0
}
{
	if ( $0 ~ regex )
		found = 1
	else
		print
}
END { exit ! found }
'
f_sysrc_delete()
{
	local varname="$1"
	local file

	# Check arguments
	[ "$varname" ] || return $FAILURE

	#
	# Operate on each of the specified files
	#
	for file in ${RC_CONFS-$( f_sysrc_get rc_conf_files )}; do
		[ -e "$file" ] || continue

		#
		# Create a new temporary file to write to.
		#
		local tmpfile="$( mktemp -t "$pgm" )"
		[ "$tmpfile" ] || return $FAILURE

		#
		# Fixup permissions and ownership (mktemp(1) defaults to 0600
		# permissions) to instead match the destination file.
		#
		local mode owner
		mode=$( stat -f '%#Lp' "$file" 2> /dev/null )
		owner=$( stat -f '%u:%g' "$file" 2> /dev/null )
		f_quietly chmod "${mode:-0644}" "$tmpfile"
		f_quietly chown "${owner:-root:wheel}" "$tmpfile"

		#
		# Operate on the file, removing all occurrences, saving the
		# output in our temporary file.
		#
		awk -v varname="$varname" "$f_sysrc_delete_awk" "$file" \
			> "$tmpfile"
		if [ $? -ne $SUCCESS ]; then
			# The file didn't contain any assignments
			rm -f "$tmpfile"
			continue
		fi

		#
		# Taint-check our results.
		#
		if ! /bin/sh -n "$tmpfile"; then
			f_err "$msg_previous_syntax_errors\n" \
			      "$pgm" "$file"
			rm -f "$tmpfile"
			return $FAILURE
		fi

		#
		# Perform sanity checks
		#
		if [ ! -w "$file" ]; then
			f_err "$msg_permission_denied\n" "$pgm" "$file"
			rm -f "$tmpfile"
			return $FAILURE
		fi

		#
		# Finally, move the temporary file into place.
		#
		mv "$tmpfile" "$file"
	done
}

fi # ! $_SYSRC_SUBR