Makes zipping and unzipping work for empty folders for migration.

codalab/worker/file_util.py

@@ -8,6 +8,7 @@
 import bz2
 import hashlib
 import stat
+import zipfile
 
 from codalab.common import BINARY_PLACEHOLDER, UsageError
 from codalab.common import parse_linked_bundle_url
@@ -124,6 +125,9 @@ def zip_directory(
             # zip needs to be used with relative paths, so that the final directory structure
             # is correct -- https://stackoverflow.com/questions/11249624/zip-stating-absolute-paths-but-only-keeping-part-of-them.
             '.',
+            # -i . is needed for empty folders; -i ./\* so zip recursively.
+            '-i',
+            './\*',
         ]
 
         if ignore_file:
@@ -177,6 +181,12 @@ def unzip_directory(fileobj: IO[bytes], directory_path: str, force: bool = False
     with tempfile.NamedTemporaryFile() as f:
         shutil.copyfileobj(fileobj, f)
         f.flush()
+
+        with zipfile.ZipFile(f.name, 'r') as zip_file:
+            # Empty zip files cannot be unzipped: return early.
+            if len(zip_file.infolist()) == 0:
+                return
+
         proc = subprocess.Popen(
             ['unzip', '-q', f.name, '-d', directory_path],
             stdout=subprocess.PIPE,

tests/unit/worker/file_util_test.py

@@ -408,16 +408,6 @@ def test_always_ignore(self):
         self.assertFalse(os.path.exists(os.path.join(output_dir, 'dir', '__MACOSX')))
         self.assertFalse(os.path.exists(os.path.join(output_dir, 'dir', '._ignored2')))
 
-
-class TarArchiveTest(ArchiveTestBase, unittest.TestCase):
-    """Archive test for tar/gzip methods."""
-
-    def archive(self, *args, **kwargs):
-        return tar_gzip_directory(*args, **kwargs)
-
-    def unarchive(self, *args, **kwargs):
-        return un_tar_directory(*args, **kwargs)
-
     def test_do_not_always_ignore(self):
         temp_dir = tempfile.mkdtemp()
         self.addCleanup(lambda: remove_path(temp_dir))
@@ -431,6 +421,16 @@ def test_do_not_always_ignore(self):
         self.assertTrue(os.path.exists(os.path.join(output_dir, 'dir', '__MACOSX')))
 
 
+class TarArchiveTest(ArchiveTestBase, unittest.TestCase):
+    """Archive test for tar/gzip methods."""
+
+    def archive(self, *args, **kwargs):
+        return tar_gzip_directory(*args, **kwargs)
+
+    def unarchive(self, *args, **kwargs):
+        return un_tar_directory(*args, **kwargs)
+
+
 class ZipArchiveTest(ArchiveTestBase, unittest.TestCase):
     """Archive test for zip methods."""
 
@@ -444,10 +444,6 @@ def archive(self, *args, **kwargs):
     def unarchive(self, *args, **kwargs):
         return unzip_directory(*args, **kwargs)
 
-    def test_empty(self):
-        # zip doesn't create files when it's supposed to create an empty zip file.
-        pass
-
     def test_exclude_ignore(self):
         # TODO(Ashwin): make zip files properly work with exclude ignore.
         pass