Fix bug where filenames with no extension cause an infinite loop

CHANGELOG.txt

@@ -35,6 +35,7 @@ Changelog
  * Fix: Wagtail's UserProfile model now sets a related_name of ``wagtail_userprofile`` to avoid naming collisions with other user profile models (Matt Westcott)
  * Fix: Non-text content is now preserved when adding or editing a link within rich text (Matt Westcott)
  * Fix: Fixed preview when `SECURE_SSL_REDIRECT = True` (Aymeric Augustin)
+ * Fix: Prevent hang when truncating an image filename without an extension (Ricky Robinett)
 
 
 1.6.3 (30.09.2016)

CONTRIBUTORS.rst

@@ -170,6 +170,7 @@ Contributors
 * Stein Strindhaug
 * Žan Anderle
 * Mattias Loverot
+* Ricky Robinett
 
 Translators
 ===========

docs/releases/1.7.rst

@@ -70,6 +70,7 @@ Bug fixes
  * Wagtail's UserProfile model now sets a related_name of ``wagtail_userprofile`` to avoid naming collisions with other user profile models (Matt Westcott)
  * Non-text content is now preserved when adding or editing a link within rich text (Matt Westcott)
  * Fixed preview when ``SECURE_SSL_REDIRECT = True`` (Aymeric Augustin)
+ * Prevent hang when truncating an image filename without an extension (Ricky Robinett)
 
 
 Upgrade considerations

wagtail/wagtailimages/models.py

@@ -127,7 +127,10 @@ class AbstractImage(CollectionMember, index.Indexed, models.Model):
         # https://code.djangoproject.com/ticket/9893
         while len(os.path.join(folder_name, filename)) >= 95:
             prefix, dot, extension = filename.rpartition('.')
-            filename = prefix[:-1] + dot + extension
+            if prefix:
+                filename = prefix[:-1] + dot + extension
+            else:
+                filename = extension[:-1]
         return os.path.join(folder_name, filename)
 
     def get_usage(self):

wagtail/wagtailimages/tests/test_models.py

@@ -492,3 +492,35 @@ class TestIssue312(TestCase):
             height=rend1.height,
             focal_point_key=rend1.focal_point_key,
         )
+
+
+class TestFilenameReduction(TestCase):
+    """
+    This tests for a bug which results in filenames without extensions
+    causing an infinite loop
+    """
+    def test_filename_reduction_no_ext(self):
+        # Create an image with a big filename and no extension
+        image = Image.objects.create(
+            title="Test image",
+            file=get_test_image_file(
+                'thisisaverylongfilename-abcdefghijklmnopqrstuvwxyz-supercalifragilisticexpialidocioussuperlong'
+            )
+        )
+
+        # Saving file will result in infinite loop when bug is present
+        image.save()
+        self.assertEqual("original_images/thisisaverylongfilename-abcdefghijklmnopqrstuvwxyz-supercalifragilisticexpiali", image.file.name)
+
+    # Test for happy path. Long filename with extension
+    def test_filename_reduction_ext(self):
+        # Create an image with a big filename and extensions
+        image = Image.objects.create(
+            title="Test image",
+            file=get_test_image_file(
+                'thisisaverylongfilename-abcdefghijklmnopqrstuvwxyz-supercalifragilisticexpialidocioussuperlong.png'
+            )
+        )
+
+        image.save()
+        self.assertEqual("original_images/thisisaverylongfilename-abcdefghijklmnopqrstuvwxyz-supercalifragilisticexp.png", image.file.name)