conf.sh: add a mechanism to save environmental variables

This mimics the behavior of makepkg.

1 files changed, 33 insertions, 1 deletions

diff --git a/src/lib/conf.sh b/src/lib/conf.sh
index e68c9b8..3ec8a8d 100644
--- a/src/lib/conf.sh
+++ b/src/lib/conf.sh
@@ -61,14 +61,46 @@ list_files() {
 	esac
 }
 
+# Usage: list_envvars $slug
+# Lists the environmental variables that take precidence over the configuration
+# files for $slug.
+list_envvars() {
+	local slug=$1
+	case $slug in
+		makepkg)
+			printf '%s\n' \
+				PKGDEST SRCDEST SRCPKGDEST LOGDEST \
+				BUILDDIR \
+				PKGEXT SRCEXT \
+				GPGKEY PACKAGER
+			;;
+		*) :;;
+	esac
+}
+
 # Usage: load_files $slug
 # Loads the configuration files for $slug in the proper order.
 load_files() {
-	for file in $(list_files $1); do
+	local slug=$1
+	local var
+	local file
+
+	# Save the existing versions at _VARNAME
+	for var in $(list_envvars $slug); do
+		[[ -n ${!var:-} ]] && eval "_$var=\${$var}"
+	done
+
+	# Load the files
+	for file in $(list_files $slug); do
 		if [[ -r $file ]]; then
 			. "$file"
 		fi
 	done
+
+	# Restore the _SAVED versions
+	for var in $(list_envvars $slug); do
+		eval "$var=\${_$var:-\${$var:-}}"
+	done
 }
 
 # Usage: check_vars $slug VAR1 VAR2...