Add test cases for safe_eval.sh

safe_set is the routine that does all the work.

In safe_set; if we replace one=`cmd arg` or two=$(cmd arg) add quotes
around the result eg. one="_cmd arg_"
Also lines containing `` or $() are too likely to result in syntax
errors, so just delete them.

Differential Revision:	https://reviews.freebsd.org/D56795

libexec/rc/safe_eval.sh

@@ -28,11 +28,16 @@ fi
 # return a safe variable setting
 # any non-alphanumeric chars other than those in "xtras"
 # will be replaced with '_'
+# Lines containing `` or $() are too likely to result in syntax errors
+# so just delete them.
 #
 # "xtras" should be used with caution and cannot include ';'
 # 
 safe_set() {
-    ${SED:-sed} 's/^[ 	]*//;s/[ 	]*#.*//;s/^:.*//;/^[A-Za-z_][A-Za-z0-9_]*=/!d;s;[^A-Za-z0-9_. 	"'"$1"'$,/=:+-];_;g'
+    ${SED:-sed} -e 's/^[ 	]*//;s/[ 	]*#.*//;s/^:.*//' \
+    -e '/`/d' -e '/\$(/d' \
+    -e '/^[A-Za-z_][A-Za-z0-9_]*=/!d;s;[^A-Za-z0-9_. 	"'"$1"'$,/=:+-];_;g;' \
+    -e '/=.*_.*[ 	]/s,=\(.*\),="\1",;s,"",",g'
 }
 
 ##

libexec/rc/tests/Makefile

@@ -1,3 +1,9 @@
-ATF_TESTS_SH+=  rc_subr_test
+ATF_TESTS_SH+=  rc_subr_test safe_eval_test
+
+# allow running this as part of the build - in DIRDEPS_BUILD at least
+.if ${.MAKE.LEVEL} > 0 && ${MACHINE:Nhost*} == ""
+SAFE_EVAL:= ${_PARSEDIR:U${.PARSEDIR:tA}:H}/safe_eval.sh
+.export SAFE_EVAL
+.endif
 
 .include <bsd.test.mk>

libexec/rc/tests/safe_eval_test.sh

@@ -0,0 +1,65 @@
+#-
+# SPDX-License-Identifier: BSD-2-Clause
+#
+# Copyright 2026 Simon J Gerraty
+#
+
+atf_test_case safe_set_reject
+safe_set_reject_head()
+{
+	atf_set "descr" "Verify that safe_set rejects shell meta chars"
+}
+
+safe_set_reject_body()
+{
+	__name="$(atf_get ident)"
+	__input=$(mktemp -t "${__name}.input")
+
+	cat <<'EOF' > "$__input"
+: ignore=this
+# ignore this too
+# avoid # in the middle of a quoted value like:
+# oops="this # will cause synatx error"
+quoted="this and that"
+simple=ok          # trailing comments ignored
+  also=ok          # leading white-space ignored
+	 also_wik=ok
+host=`hostname`'   # backtics - delete line
+os=$(uname -s)     # $() - delete line
+oops=one;hostname' # replace ; with _ so: one_hostname
+regex="prefix[abc-]*" # []* replaced with _
+EOF
+
+	__output=$(safe_set < "$__input" | tr '"\012' '\047;')
+	atf_check_equal "$__output" "quoted='this and that';simple=ok;also=ok;also_wik=ok;oops=one_hostname_;regex='prefix_abc-__';"
+}
+
+
+atf_test_case safe_set_xtras
+safe_set_xtras_head()
+{
+	atf_set "descr" "Verify that safe_set handles extra allowed chars"
+}
+
+safe_set_xtras_body()
+{
+	__name="$(atf_get ident)"
+	__input=$(mktemp -t "${__name}.input")
+
+	cat <<'EOF' > "$__input"
+: ignore=this
+# ignore this too
+regex="prefix[abc-]*"
+EOF
+
+	__output=$(safe_set "[]*" < "$__input" | tr '"\012' '\047;')
+	atf_check_equal "$__output" "regex='prefix[abc-]*';"
+}
+
+atf_init_test_cases()
+{
+	SAFE_EVAL=${SAFE_EVAL:-/libexec/safe_eval.sh}
+	. $SAFE_EVAL
+	atf_add_test_case safe_set_reject
+	atf_add_test_case safe_set_xtras
+}