Backport b2eef0b1b7b5 (Merge of bug25021; Bug 24994 can cause log files to grow in size exponentially)

Author: Simon MacMullen

src/rabbit_file.erl

@@ -168,7 +168,24 @@ make_binary(List) ->
             {error, Reason}
     end.
 
+%% TODO the semantics of this function are rather odd. But see bug 25021.
 append_file(File, Suffix) ->
+    case read_file_info(File) of
+        {ok, FInfo}     -> append_file(File, FInfo#file_info.size, Suffix);
+        {error, enoent} -> append_file(File, 0, Suffix);
+        Error           -> Error
+    end.
+
+append_file(_, _, "") ->
+    ok;
+append_file(File, 0, Suffix) ->
+    with_fhc_handle(fun () ->
+                            case prim_file:open([File, Suffix], [append]) of
+                                {ok, Fd} -> prim_file:close(Fd);
+                                Error    -> Error
+                            end
+                    end);
+append_file(File, _, Suffix) ->
     case with_fhc_handle(2, fun () ->
                                 file:copy(File, {[File, Suffix], [append]})
                             end) of