Bug #365439: Add set_unless_changed() and unset_unless_changed().

2 files changed, 30 insertions, 2 deletions

diff --git a/bin/ebuild.sh b/bin/ebuild.sh
index c79d4c3d0..e652cb55b 100755
--- a/bin/ebuild.sh
+++ b/bin/ebuild.sh
@@ -1639,6 +1639,34 @@ _ebuild_phase_funcs() {
 	esac
 }
 
+# Set given variable unless this variable has been already set (e.g. during emerge
+# invocation) to a value different than value set in make.conf.
+set_unless_changed() {
+	if [[ $# -ne 2 ]]; then
+		die "${FUNCNAME}() requires 2 arguments: VARIABLE VALUE"
+	fi
+
+	local variable="$1" value="$2"
+
+	if eval "[[ \${${variable}} == \$(env -u ${variable} portageq envvar ${variable}) ]]"; then
+		eval "${variable}=\"${value}\""
+	fi
+}
+
+# Unset given variable unless this variable has been set (e.g. during emerge
+# invocation) to a value different than value set in make.conf.
+unset_unless_changed() {
+	if [[ $# -ne 1 ]]; then
+		die "${FUNCNAME}() requires 1 argument: VARIABLE"
+	fi
+
+	local variable="$1"
+
+	if eval "[[ \${${variable}} == \$(env -u ${variable} portageq envvar ${variable}) ]]"; then
+		unset ${variable}
+	fi
+}
+
 PORTAGE_BASHRCS_SOURCED=0
 
 # @FUNCTION: source_all_bashrcs
diff --git a/bin/isolated-functions.sh b/bin/isolated-functions.sh
index 2f144a084..24443ac1b 100644
--- a/bin/isolated-functions.sh
+++ b/bin/isolated-functions.sh
@@ -585,8 +585,8 @@ save_ebuild_env() {
 			dyn_preinst dyn_help debug-print debug-print-function \
 			debug-print-section inherit EXPORT_FUNCTIONS remove_path_entry \
 			save_ebuild_env filter_readonly_variables preprocess_ebuild_env \
-			source_all_bashrcs ebuild_main \
-			ebuild_phase ebuild_phase_with_hooks \
+			set_unless_changed unset_unless_changed source_all_bashrcs \
+			ebuild_main ebuild_phase ebuild_phase_with_hooks \
 			_ebuild_arg_to_phase _ebuild_phase_funcs default \
 			_pipestatus \
 			${QA_INTERCEPTORS}