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-rw-r--r--qobject/json-lexer.c43
1 files changed, 29 insertions, 14 deletions
diff --git a/qobject/json-lexer.c b/qobject/json-lexer.c
index 28582e17d9..39c7ce7adc 100644
--- a/qobject/json-lexer.c
+++ b/qobject/json-lexer.c
@@ -101,6 +101,7 @@
enum json_lexer_state {
IN_ERROR = 0, /* must really be 0, see json_lexer[] */
+ IN_RECOVERY,
IN_DQ_STRING_ESCAPE,
IN_DQ_STRING,
IN_SQ_STRING_ESCAPE,
@@ -130,6 +131,28 @@ QEMU_BUILD_BUG_ON(IN_START_INTERP != IN_START + 1);
static const uint8_t json_lexer[][256] = {
/* Relies on default initialization to IN_ERROR! */
+ /* error recovery */
+ [IN_RECOVERY] = {
+ /*
+ * Skip characters until a structural character, an ASCII
+ * control character other than '\t', or impossible UTF-8
+ * bytes '\xFE', '\xFF'. Structural characters and line
+ * endings are promising resynchronization points. Clients
+ * may use the others to force the JSON parser into known-good
+ * state; see docs/interop/qmp-spec.txt.
+ */
+ [0 ... 0x1F] = IN_START | LOOKAHEAD,
+ [0x20 ... 0xFD] = IN_RECOVERY,
+ [0xFE ... 0xFF] = IN_START | LOOKAHEAD,
+ ['\t'] = IN_RECOVERY,
+ ['['] = IN_START | LOOKAHEAD,
+ [']'] = IN_START | LOOKAHEAD,
+ ['{'] = IN_START | LOOKAHEAD,
+ ['}'] = IN_START | LOOKAHEAD,
+ [':'] = IN_START | LOOKAHEAD,
+ [','] = IN_START | LOOKAHEAD,
+ },
+
/* double quote string */
[IN_DQ_STRING_ESCAPE] = {
[0x20 ... 0xFD] = IN_DQ_STRING,
@@ -301,26 +324,18 @@ static void json_lexer_feed_char(JSONLexer *lexer, char ch, bool flush)
/* fall through */
case JSON_SKIP:
g_string_truncate(lexer->token, 0);
+ /* fall through */
+ case IN_START:
new_state = lexer->start_state;
break;
case IN_ERROR:
- /* XXX: To avoid having previous bad input leaving the parser in an
- * unresponsive state where we consume unpredictable amounts of
- * subsequent "good" input, percolate this error state up to the
- * parser by emitting a JSON_ERROR token, then reset lexer state.
- *
- * Also note that this handling is required for reliable channel
- * negotiation between QMP and the guest agent, since chr(0xFF)
- * is placed at the beginning of certain events to ensure proper
- * delivery when the channel is in an unknown state. chr(0xFF) is
- * never a valid ASCII/UTF-8 sequence, so this should reliably
- * induce an error/flush state.
- */
json_message_process_token(lexer, lexer->token, JSON_ERROR,
lexer->x, lexer->y);
+ new_state = IN_RECOVERY;
+ /* fall through */
+ case IN_RECOVERY:
g_string_truncate(lexer->token, 0);
- lexer->state = lexer->start_state;
- return;
+ break;
default:
break;
}