Add an "excessively large object" safeguard.

service/src/test/java/org/whispersystems/textsecuregcm/util/S3ObjectMonitorTest.java

@@ -10,8 +10,9 @@ import java.util.UUID;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.function.Consumer;
 
-import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
@@ -32,7 +33,9 @@ class S3ObjectMonitorTest {
     final S3ObjectMonitor objectMonitor = new S3ObjectMonitor(
         s3Client,
         bucket,
-        objectKey, mock(ScheduledExecutorService.class),
+        objectKey,
+        16 * 1024 * 1024,
+        mock(ScheduledExecutorService.class),
         Duration.ofMinutes(1),
         listener);
 
@@ -46,4 +49,37 @@ class S3ObjectMonitorTest {
 
     verify(listener).accept(s3Object);
   }
+
+  @Test
+  void refreshOversizedObject() {
+    final AmazonS3 s3Client = mock(AmazonS3.class);
+    final ObjectMetadata metadata = mock(ObjectMetadata.class);
+    final S3Object s3Object = mock(S3Object.class);
+
+    final String bucket = "s3bucket";
+    final String objectKey = "greatest-smooth-jazz-hits-of-all-time.zip";
+    final long maxObjectSize = 16 * 1024 * 1024;
+
+    //noinspection unchecked
+    final Consumer<S3Object> listener = mock(Consumer.class);
+
+    final S3ObjectMonitor objectMonitor = new S3ObjectMonitor(
+        s3Client,
+        bucket,
+        objectKey,
+        maxObjectSize,
+        mock(ScheduledExecutorService.class),
+        Duration.ofMinutes(1),
+        listener);
+
+    when(metadata.getETag()).thenReturn(UUID.randomUUID().toString());
+    when(metadata.getContentLength()).thenReturn(maxObjectSize + 1);
+    when(s3Object.getObjectMetadata()).thenReturn(metadata);
+    when(s3Client.getObjectMetadata(bucket, objectKey)).thenReturn(metadata);
+    when(s3Client.getObject(bucket, objectKey)).thenReturn(s3Object);
+
+    objectMonitor.refresh();
+
+    verify(listener, never()).accept(any());
+  }
 }