json-streamer: add handling for JSON_ERROR token/state

This allows a JSON_ERROR state to be passed to the streamer to force a
flush of the current tokens and pass a NULL token list to the parser
rather that have it churn on bad data. (Alternatively we could just not
pass it to the parser at all, but it may be useful to push there errors
up the stack. NULL token lists are not currently handled by the parser,
the next patch will address that)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

json-streamer.c

@@ -56,29 +56,40 @@ static void json_message_process_token(JSONLexer *lexer, QString *token, JSONTok
 
     qlist_append(parser->tokens, dict);
 
-    if (parser->brace_count < 0 ||
+    if (type == JSON_ERROR) {
+        goto out_emit_bad;
+    } else if (parser->brace_count < 0 ||
         parser->bracket_count < 0 ||
         (parser->brace_count == 0 &&
          parser->bracket_count == 0)) {
-        parser->brace_count = 0;
-        parser->bracket_count = 0;
-        parser->emit(parser, parser->tokens);
-        QDECREF(parser->tokens);
-        parser->tokens = qlist_new();
-        parser->token_size = 0;
+        goto out_emit;
     } else if (parser->token_size > MAX_TOKEN_SIZE ||
                parser->bracket_count > MAX_NESTING ||
                parser->brace_count > MAX_NESTING) {
         /* Security consideration, we limit total memory allocated per object
          * and the maximum recursion depth that a message can force.
          */
-        parser->brace_count = 0;
-        parser->bracket_count = 0;
-        parser->emit(parser, parser->tokens);
+        goto out_emit;
+    }
+
+    return;
+
+out_emit_bad:
+    /* clear out token list and tell the parser to emit and error
+     * indication by passing it a NULL list
+     */
+    QDECREF(parser->tokens);
+    parser->tokens = NULL;
+out_emit:
+    /* send current list of tokens to parser and reset tokenizer */
+    parser->brace_count = 0;
+    parser->bracket_count = 0;
+    parser->emit(parser, parser->tokens);
+    if (parser->tokens) {
         QDECREF(parser->tokens);
-        parser->tokens = qlist_new();
-        parser->token_size = 0;
     }
+    parser->tokens = qlist_new();
+    parser->token_size = 0;
 }
 
 void json_message_parser_init(JSONMessageParser *parser,