close file stream

Close file stream, since the in the restrict mode the runtime will check
whether all the resource is closed when it is out of scope.

Test: ABTD ImsStackJavaTests
Bug: 349874828
Change-Id: Ib297622bae730bf99e4d5d1b3adeff3fee805a93

tools/aconfig/aconfig_storage_read_api/srcs/android/aconfig/storage/StorageInternalReader.java

@@ -18,6 +18,7 @@ package android.aconfig.storage;
 
 import android.compat.annotation.UnsupportedAppUsage;
 
+import java.io.Closeable;
 import java.io.FileInputStream;
 import java.nio.MappedByteBuffer;
 import java.nio.channels.FileChannel;
@@ -68,13 +69,26 @@ public class StorageInternalReader {
 
     // Map a storage file given file path
     private static MappedByteBuffer mapStorageFile(String file) {
+        FileInputStream stream = null;
         try {
-            FileInputStream stream = new FileInputStream(file);
+            stream = new FileInputStream(file);
             FileChannel channel = stream.getChannel();
             return channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size());
         } catch (Exception e) {
             throw new AconfigStorageException(
                     String.format("Fail to mmap storage file %s", file), e);
+        } finally {
+            quietlyDispose(stream);
+        }
+    }
+
+    private static void quietlyDispose(Closeable closable) {
+        try {
+            if (closable != null) {
+                closable.close();
+            }
+        } catch (Exception e) {
+            // no need to care, at least as of now
         }
     }
 }