initramfs to also use merge-rootfs

alpine/merge-rootfs.sh

@@ -75,21 +75,60 @@ check_template_vars() {
     [[ "$missing" -eq 0 ]]
 }
 
+preserve_exec_bit() {
+    local old="$1"
+    local new="$2"
+
+    if [[ -e "$old" && -x "$old" ]]; then
+        chmod +x "$new"
+    fi
+}
+
+get_envsubst_vars() {
+    local rel="$1"
+
+    case "$rel" in
+        bin/flash-emmc.sh.tmpl)
+            echo '${BUILD_TAG}'
+            ;;
+        *)
+            echo ''
+            ;;
+    esac
+}
+
 render_template() {
     local src="$1"
     local out="$2"
+    local allowed="${3:-}"
 
     mkdir -p "$(dirname "$out")"
-    check_template_vars "$src"
-    envsubst < "$src" > "$out"
+
+    if [[ -n "$allowed" ]]; then
+        envsubst "$allowed" < "$src" > "$out"
+    else
+		check_template_vars "$src"
+        envsubst < "$src" > "$out"
+    fi
+    if [[ -x "$src" ]]; then
+        chmod +x "$out"
+    fi
 }
 
 replace_file() {
     local src="$1"
     local dst="$2"
 
+    local had_exec=0
+    [[ -e "$dst" && -x "$dst" ]] && had_exec=1
+
     mkdir -p "$(dirname "$dst")"
     cp -a "$src" "$dst"
+
+    if [[ "$had_exec" -eq 1 ]]; then
+        chmod +x "$dst"
+    fi
+
     echo "Replaced file: $dst"
 }
 
@@ -101,11 +140,19 @@ merge_or_copy_file() {
     mkdir -p "$(dirname "$dst")"
 
     # scripts: replace
-    if [[ "$rel" == opt/scripts/* ]]; then
-        cp -a "$src" "$dst"
-        echo "Replaced script: $dst"
-        return
-    fi
+	if [[ "$rel" == opt/scripts/* ]]; then
+		local had_exec=0
+		[[ -e "$dst" && -x "$dst" ]] && had_exec=1
+
+		cp -a "$src" "$dst"
+
+		if [[ "$had_exec" -eq 1 ]]; then
+			chmod +x "$dst"
+		fi
+
+		echo "Replaced script: $dst"
+		return
+	fi
 
     # /etc: merge missing lines
     if [[ "$rel" == etc/* ]]; then
@@ -177,12 +224,12 @@ find "$SRC_ROOT" -mindepth 1 | while IFS= read -r src_path; do
         mode="override"
         rel_for_target="${rel_for_target%.override}"
 
-    elif [[ "$rel_for_target" == *.tmpl ]]; then
-        rel_for_target="${rel_for_target%.tmpl}"
-        rendered="$TMP_DIR/$rel_for_target"
-        render_template "$src_path" "$rendered"
-        src_for_merge="$rendered"
-    fi
+	elif [[ "$rel_for_target" == *.tmpl ]]; then
+		rel_for_target="${rel_for_target%.tmpl}"
+		rendered="$TMP_DIR/$rel_for_target"
+		render_template "$src_path" "$rendered" "$(get_envsubst_vars "$rel_path")"
+		src_for_merge="$rendered"
+	fi
 
     dst_path="$DST_ROOT/$rel_for_target"