add support for reading a database from buffers

Author: seemanne

maxminddb/reader.py

@@ -83,7 +83,11 @@ def __init__(
         elif mode == MODE_FD:
             self._buffer = database.read()  # type: ignore[union-attr]
             self._buffer_size = len(self._buffer)  # type: ignore[arg-type]
-            filename = database.name  # type: ignore[union-attr]
+            # io buffers are not guaranteed to have a name attribute
+            if hasattr(database, "name"):
+                filename = database.name  # type: ignore[union-attr]
+            else:
+                filename = f"<{type(database)}>"
         else:
             msg = (
                 f"Unsupported open mode ({mode}). Only MODE_AUTO, MODE_FILE, "

tests/reader_test.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import ipaddress
+import io
 import multiprocessing
 import os
 import pathlib
@@ -524,6 +525,14 @@ def test_closed_metadata(self) -> None:
         else:
             self.assertIsNotNone(metadata, "pure Python implementation returns value")
 
+    def test_reading_from_buffer(self) -> None:
+        filename = "tests/data/test-data/MaxMind-DB-test-ipv4-24.mmdb"
+        with open(filename, "rb") as f:
+            buf = io.BytesIO(f.read())
+        reader = open_database(buf, MODE_FD)
+        self._check_ip_v4(reader, filename)
+        reader.close()
+
     if os.name != "nt":
 
         def test_multiprocessing(self):