Add read_data function to store_api

Change-Id: Id51f97a1b0828235618c6805c619ac5e3a9ea91a

glare/common/store_api.py

@@ -118,3 +118,20 @@ def delete_blob(uri, context):
 
 def get_known_schemes():
     return list(backend.get_known_schemes()) + ['sql']
+
+
+def read_data(flobj, limit=16777216):
+    """Read data into memory from the file-like object.
+
+    :param flobj: file-like object that contains data
+    :param limit: max file size that can be read into memory
+    :return: string with data from the object
+    """
+    bytes_read = 0
+    data = b''
+    for chunk in flobj:
+        bytes_read += len(chunk)
+        if bytes_read > limit:
+            raise exception.RequestEntityTooLarge()
+        data += chunk
+    return data

glare/tests/unit/test_store_api.py

@@ -0,0 +1,74 @@
+# Copyright 2017 - Nokia Networks
+#
+#    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 os
+import tempfile
+
+from six import BytesIO
+
+from glare.common import exception as exc
+from glare.common import store_api
+from glare.tests.unit import base
+
+
+class TestStoreAPI(base.BaseTestArtifactAPI):
+
+    def test_read_data(self):
+        """Read data from file, http and database."""
+
+        # test local temp file
+        tfd, path = tempfile.mkstemp()
+        try:
+            os.write(tfd, b'a' * 1000)
+            flobj = store_api.load_from_store(
+                "file://" + path,
+                self.req.context
+            )
+            self.assertEqual(b'a' * 1000, store_api.read_data(flobj))
+            flobj = store_api.load_from_store(
+                "file://" + path,
+                self.req.context
+            )
+            self.assertRaises(exc.RequestEntityTooLarge,
+                              store_api.read_data, flobj, limit=999)
+        finally:
+            os.remove(path)
+
+        # test sql object
+        values = {'name': 'ttt', 'version': '1.0'}
+        self.sample_artifact = self.controller.create(
+            self.req, 'sample_artifact', values)
+        self.controller.upload_blob(
+            self.req, 'sample_artifact', self.sample_artifact['id'], 'blob',
+            BytesIO(b'a' * 100), 'application/octet-stream')
+        flobj = self.controller.download_blob(
+            self.req, 'sample_artifact', self.sample_artifact['id'], 'blob')
+        self.assertEqual(b'a' * 100, store_api.read_data(flobj['data']))
+        flobj = self.controller.download_blob(
+            self.req, 'sample_artifact', self.sample_artifact['id'], 'blob')
+        self.assertRaises(exc.RequestEntityTooLarge,
+                          store_api.read_data, flobj['data'], limit=99)
+
+        # test external http
+        flobj = store_api.load_from_store(
+            'https://www.apache.org/licenses/LICENSE-2.0.txt',
+            self.req.context
+        )
+        self.assertEqual(3967, len(store_api.read_data(flobj)))
+        flobj = store_api.load_from_store(
+            'https://www.apache.org/licenses/LICENSE-2.0.txt',
+            self.req.context
+        )
+        self.assertRaises(exc.RequestEntityTooLarge,
+                          store_api.read_data, flobj, limit=3966)