1# SPDX-License-Identifier: BSD-2-Clause
2
3# RCSid:
4#	$Id: safe_eval.sh,v 1.12 2023/10/12 18:46:53 sjg Exp $
5#
6#	@(#) Copyright (c) 2023 Simon J. Gerraty
7#
8#	This file is provided in the hope that it will
9#	be of use.  There is absolutely NO WARRANTY.
10#	Permission to copy, redistribute or otherwise
11#	use this file is hereby granted provided that
12#	the above copyright notice and this notice are
13#	left intact.
14#
15#	Please send copies of changes and bug-fixes to:
16#	sjg@crufty.net
17
18_SAFE_EVAL_SH=:
19
20##
21# safe_set
22#
23# return a safe variable setting
24# any non-alphanumeric chars are replaced with '_'
25#
26safe_set() {
27    ${SED:-sed} 's/[ 	]*#.*//;/^[A-Za-z_][A-Za-z0-9_]*=/!d;s;[^A-Za-z0-9_. 	"$,/=-];_;g'
28}
29
30##
31# safe_eval [file]
32#
33# eval variable assignments only from file
34# taking care to eliminate any shell meta chars
35#
36safe_eval() {
37    eval `cat "$@" | safe_set`
38}
39
40##
41# safe_dot file [...]
42#
43# feed all "file" that exist to safe_eval
44#
45safe_dot() {
46    local ef= f
47
48    for f in "$@"
49    do
50        test -s $f || continue
51        ef="${ef:+$ef }$f"
52        dotted="$dotted $f"
53    done
54    test -z "$ef" && return 1
55    safe_eval $ef
56    return 0
57}
58
59case /$0 in
60*/safe_eval*)
61    case "$1" in
62    dot|eval|set) op=safe_$1; shift; $op "$@";;
63    *) safe_dot "$@";;
64    esac
65    ;;
66esac
67