Stream_Error with test cases 8G76 and 98YD (and fuzzing results) and simple test program

[touisteur]

Hi, running the following simple example program, causes a crash with YAML.STREAM_ERROR exception.

with Utils;
with Ada.Text_IO;
with Ada.Command_Line;
with GNAT.Exception_Actions;
with Ada.Exceptions;
with Yaml.Dom;
with Yaml.Dom.Vectors;
with Yaml.Dom.Loading;
with Yaml.Dom.Dumping;
with Yaml.Events.Queue;
procedure Yaml_Test
is
  S : constant String := Utils.File_Content (Ada.Command_Line.Argument (1));
begin
  Ada.Text_IO.Put_Line (S);
  declare
     V : constant Yaml.Dom.Vectors.Vector := Yaml.Dom.Loading.From_String (S);
     E : constant Yaml.Events.Queue.Reference :=
       Yaml.Dom.Dumping.To_Event_Queue (V);
     pragma Unreferenced (E);
  begin
     null;
  end;
exception
  when Occurence : others =>
     Ada.Text_IO.Put_Line (Ada.Exceptions.Exception_Information (Occurence));
     GNAT.Exception_Actions.Core_Dump (Occurence);
end Yaml_Test;

I cite one of your e-mails:

This error means that a malformed event stream has been encountered. Parsing a YAML input stream or serializing a DOM structure should always create a valid event stream unless it raises an exception – hence getting Yaml.Stream_Error would actually show that there's an internal error in one of those components.

Yaml.Stream_Error would only be an error with external cause if you generate an event stream manually in your code.

See also stream-error-crashes.zip.

I get the following:

• raised YAML.STREAM_ERROR : Unexpected event (expected document end): ALIAS​​
• raised YAML.STREAM_ERROR : Unexpected event (expected document end): MAPPING_START​
• raised YAML.STREAM_ERROR : Unexpected event (expected document end): SCALAR​
• raised YAML.STREAM_ERROR : Unexpected event (expected document end): SEQUENCE_START​
• raised YAML.STREAM_ERROR : Unexpected event (expected document start): STREAM_END