Fixes "I/O Operation on Closed File error"

https://github.com/matthewwithanm/django-imagekit/issues/391#issuecomment-766708283

bookwyrm/storage_backends.py

@@ -1,4 +1,6 @@
 """Handles backends for storages"""
+import os
+from tempfile import SpooledTemporaryFile
 from storages.backends.s3boto3 import S3Boto3Storage
 
 
@@ -15,3 +17,33 @@ class ImagesStorage(S3Boto3Storage):  # pylint: disable=abstract-method
     location = "images"
     default_acl = "public-read"
     file_overwrite = False
+
+    """
+    This is our custom version of S3Boto3Storage that fixes a bug in
+    boto3 where the passed in file is closed upon upload.
+    From:
+    https://github.com/matthewwithanm/django-imagekit/issues/391#issuecomment-275367006
+    https://github.com/boto/boto3/issues/929
+    https://github.com/matthewwithanm/django-imagekit/issues/391
+    """
+
+    def _save(self, name, content):
+        """
+        We create a clone of the content file as when this is passed to
+        boto3 it wrongly closes the file upon upload where as the storage
+        backend expects it to still be open
+        """
+        # Seek our content back to the start
+        content.seek(0, os.SEEK_SET)
+
+        # Create a temporary file that will write to disk after a specified
+        # size. This file will be automatically deleted when closed by
+        # boto3 or after exiting the `with` statement if the boto3 is fixed
+        with SpooledTemporaryFile() as content_autoclose:
+
+            # Write our original content into our copy that will be closed by boto3
+            content_autoclose.write(content.read())
+
+            # Upload the object which will auto close the
+            # content_autoclose instance
+            return super(ImagesStorage, self)._save(name, content_autoclose)