按规划持续工作

wasm-port/tools/extract_sources.sh

@@ -17,7 +17,13 @@ copy_file() {
   fi
 
   mkdir -p "$(dirname "$dst")"
-  cp "$src" "$dst"
+  if [[ -f "$dst" ]] && cmp -s "$src" "$dst"; then
+    touch -r "$src" "$dst"
+    echo "unchanged $src_rel"
+    return
+  fi
+
+  cp -p "$src" "$dst"
   echo "copied $src_rel"
 }