1 files changed, 50 insertions, 0 deletions
diff --git a/scripts/support.py b/scripts/support.py
new file mode 100755
index 000000000..95d663fe0
--- /dev/null
+++ b/scripts/support.py
@@ -0,0 +1,50 @@
+#! /usr/bin/env python
+
+#   Copyright 2016 WebAssembly Community Group participants
+#
+#   Licensed under the Apache License, Version 2.0 (the "License");
+#   you may not use this file except in compliance with the License.
+#   You may obtain a copy of the License at
+#
+#       http://www.apache.org/licenses/LICENSE-2.0
+#
+#   Unless required by applicable law or agreed to in writing, software
+#   distributed under the License is distributed on an "AS IS" BASIS,
+#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#   See the License for the specific language governing permissions and
+#   limitations under the License.
+
+import filecmp
+import os
+import shutil
+import subprocess
+import sys
+import tempfile
+
+
+def untar(tarfile, outdir):
+  """Returns True if the untar dir differs from a pre-existing dir."""
+  tmp_dir = tempfile.mkdtemp()
+  try:
+    with tempfile.TemporaryFile(mode='w+') as f:
+      try:
+        subprocess.check_call(['tar', '-xvf', tarfile], cwd=tmp_dir, stdout=f)
+      except:
+        f.seek(0)
+        sys.stderr.write(f.read())
+        raise
+    untar_outdir = os.path.join(tmp_dir, os.path.basename(outdir))
+    if os.path.exists(outdir):
+      diff = filecmp.dircmp(untar_outdir, outdir)
+      if not (diff.left_only + diff.right_only + diff.diff_files +
+              diff.common_funny + diff.funny_files):
+        # outdir already existed with exactly the same content.
+        return False
+      shutil.rmtree(outdir)
+    # The untar files are different, or there was no previous outdir.
+    print 'Updating', outdir
+    shutil.move(untar_outdir, outdir)
+    return True
+  finally:
+    if os.path.isdir(tmp_dir):
+      shutil.rmtree(tmp_dir)