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[Qemu-devel] [PATCH v2 37/60] json: Treat unwanted interpolation as lexi
From: |
Markus Armbruster |
Subject: |
[Qemu-devel] [PATCH v2 37/60] json: Treat unwanted interpolation as lexical error |
Date: |
Fri, 17 Aug 2018 17:05:36 +0200 |
The JSON parser optionally supports interpolation. The lexer
recognizes interpolation tokens unconditionally. The parser rejects
them when interpolation is disabled, in parse_interpolation().
However, it neglects to set an error then, which can make
json_parser_parse() fail without setting an error.
Move the check for unwanted interpolation from the parser's
parse_interpolation() into the lexer's finite state machine. When
interpolation is disabled, '%' is now handled like any other
unexpected character.
The next commit will improve how such lexical errors are handled.
Signed-off-by: Markus Armbruster <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
---
include/qapi/qmp/json-lexer.h | 4 ++--
qobject/json-lexer.c | 30 ++++++++++++++++++------------
qobject/json-parser.c | 4 ----
qobject/json-streamer.c | 2 +-
tests/qmp-test.c | 4 ++++
5 files changed, 25 insertions(+), 19 deletions(-)
diff --git a/include/qapi/qmp/json-lexer.h b/include/qapi/qmp/json-lexer.h
index ff3a6f80f0..5586d12f26 100644
--- a/include/qapi/qmp/json-lexer.h
+++ b/include/qapi/qmp/json-lexer.h
@@ -33,12 +33,12 @@ typedef enum json_token_type {
} JSONTokenType;
typedef struct JSONLexer {
- int state;
+ int start_state, state;
GString *token;
int x, y;
} JSONLexer;
-void json_lexer_init(JSONLexer *lexer);
+void json_lexer_init(JSONLexer *lexer, bool enable_interpolation);
void json_lexer_feed(JSONLexer *lexer, const char *buffer, size_t size);
diff --git a/qobject/json-lexer.c b/qobject/json-lexer.c
index 5b1f720331..cf15266cbe 100644
--- a/qobject/json-lexer.c
+++ b/qobject/json-lexer.c
@@ -92,7 +92,7 @@
* Like double-quoted strings, except they're delimited by %x27
* (apostrophe) instead of %x22 (quotation mark), and can't contain
* unescaped apostrophe, but can contain unescaped quotation mark.
- * - Interpolation:
+ * - Interpolation, if enabled:
* interpolation = %((l|ll|I64)[du]|[ipsf])
*
* Note:
@@ -123,9 +123,11 @@ enum json_lexer_state {
IN_INTERPOL_I64,
IN_WHITESPACE,
IN_START,
+ IN_START_INTERPOL, /* must be IN_START + 1 */
};
-QEMU_BUILD_BUG_ON((int)JSON_MIN <= (int)IN_START);
+QEMU_BUILD_BUG_ON((int)JSON_MIN <= (int)IN_START_INTERPOL);
+QEMU_BUILD_BUG_ON(IN_START_INTERPOL != IN_START + 1);
#define TERMINAL(state) [0 ... 0x7F] = (state)
@@ -257,8 +259,12 @@ static const uint8_t json_lexer[][256] = {
['I'] = IN_INTERPOL_I,
},
- /* top level rule */
- [IN_START] = {
+ /*
+ * Two start states:
+ * - IN_START recognizes JSON tokens with our string extensions
+ * - IN_START_INTERPOL additionally recognizes interpolation.
+ */
+ [IN_START ... IN_START_INTERPOL] = {
['"'] = IN_DQ_STRING,
['\''] = IN_SQ_STRING,
['0'] = IN_ZERO,
@@ -271,17 +277,18 @@ static const uint8_t json_lexer[][256] = {
[','] = JSON_COMMA,
[':'] = JSON_COLON,
['a' ... 'z'] = IN_KEYWORD,
- ['%'] = IN_INTERPOL,
[' '] = IN_WHITESPACE,
['\t'] = IN_WHITESPACE,
['\r'] = IN_WHITESPACE,
['\n'] = IN_WHITESPACE,
},
+ [IN_START_INTERPOL]['%'] = IN_INTERPOL,
};
-void json_lexer_init(JSONLexer *lexer)
+void json_lexer_init(JSONLexer *lexer, bool enable_interpolation)
{
- lexer->state = IN_START;
+ lexer->start_state = lexer->state = enable_interpolation
+ ? IN_START_INTERPOL : IN_START;
lexer->token = g_string_sized_new(3);
lexer->x = lexer->y = 0;
}
@@ -321,7 +328,7 @@ static void json_lexer_feed_char(JSONLexer *lexer, char ch,
bool flush)
/* fall through */
case JSON_SKIP:
g_string_truncate(lexer->token, 0);
- new_state = IN_START;
+ new_state = lexer->start_state;
break;
case IN_ERROR:
/* XXX: To avoid having previous bad input leaving the parser in an
@@ -340,8 +347,7 @@ static void json_lexer_feed_char(JSONLexer *lexer, char ch,
bool flush)
json_message_process_token(lexer, lexer->token, JSON_ERROR,
lexer->x, lexer->y);
g_string_truncate(lexer->token, 0);
- new_state = IN_START;
- lexer->state = new_state;
+ lexer->state = lexer->start_state;
return;
default:
break;
@@ -356,7 +362,7 @@ static void json_lexer_feed_char(JSONLexer *lexer, char ch,
bool flush)
json_message_process_token(lexer, lexer->token, lexer->state,
lexer->x, lexer->y);
g_string_truncate(lexer->token, 0);
- lexer->state = IN_START;
+ lexer->state = lexer->start_state;
}
}
@@ -371,7 +377,7 @@ void json_lexer_feed(JSONLexer *lexer, const char *buffer,
size_t size)
void json_lexer_flush(JSONLexer *lexer)
{
- if (lexer->state != IN_START) {
+ if (lexer->state != lexer->start_state) {
json_lexer_feed_char(lexer, 0, true);
}
}
diff --git a/qobject/json-parser.c b/qobject/json-parser.c
index 1af1c1210c..56bbfe6810 100644
--- a/qobject/json-parser.c
+++ b/qobject/json-parser.c
@@ -427,10 +427,6 @@ static QObject *parse_interpolation(JSONParserContext
*ctxt, va_list *ap)
{
JSONToken *token;
- if (ap == NULL) {
- return NULL;
- }
-
token = parser_context_pop_token(ctxt);
assert(token && token->type == JSON_INTERPOL);
diff --git a/qobject/json-streamer.c b/qobject/json-streamer.c
index fa595a8761..a373e0114a 100644
--- a/qobject/json-streamer.c
+++ b/qobject/json-streamer.c
@@ -115,7 +115,7 @@ void json_message_parser_init(JSONMessageParser *parser,
parser->tokens = g_queue_new();
parser->token_size = 0;
- json_lexer_init(&parser->lexer);
+ json_lexer_init(&parser->lexer, !!ap);
}
void json_message_parser_feed(JSONMessageParser *parser,
diff --git a/tests/qmp-test.c b/tests/qmp-test.c
index 7b3ba17c4a..4ae2245484 100644
--- a/tests/qmp-test.c
+++ b/tests/qmp-test.c
@@ -94,6 +94,10 @@ static void test_malformed(QTestState *qts)
/* lexical error: interpolation */
qtest_qmp_send_raw(qts, "%%p\n");
+ /* two errors, one for "%", one for "p" */
+ resp = qtest_qmp_receive(qts);
+ g_assert_cmpstr(get_error_class(resp), ==, "GenericError");
+ qobject_unref(resp);
resp = qtest_qmp_receive(qts);
g_assert_cmpstr(get_error_class(resp), ==, "GenericError");
qobject_unref(resp);
--
2.17.1
- Re: [Qemu-devel] [PATCH v2 21/60] json: Reject invalid UTF-8 sequences, (continued)
- [Qemu-devel] [PATCH v2 24/60] json: Accept overlong \xC0\x80 as U+0000 ("modified UTF-8"), Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 13/60] check-qjson: Fix utf8_string() to test all invalid sequences, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 18/60] json: Revamp lexer documentation, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 27/60] json: Reject invalid \uXXXX, fix \u0000, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 36/60] json: Rename token JSON_ESCAPE & friends to JSON_INTERPOL, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 52/60] json: Eliminate lexer state IN_WHITESPACE, pseudo-token JSON_SKIP, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 20/60] check-qjson: Document we expect invalid UTF-8 to be rejected, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 35/60] json: Don't create JSON_ERROR tokens that won't be used, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 37/60] json: Treat unwanted interpolation as lexical error,
Markus Armbruster <=
- [Qemu-devel] [PATCH v2 29/60] check-qjson: Fix and enable utf8_string()'s disabled part, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 58/60] json: Keep interpolation state in JSONParserContext, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 60/60] json: Support %% in JSON strings when interpolating, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 26/60] json: Simplify parse_string(), Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 33/60] json: Redesign the callback to consume JSON values, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 11/60] check-qjson: Cover UTF-8 in single quoted strings, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 50/60] json: Unbox tokens queue in JSONMessageParser, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 32/60] json: Have lexer call streamer directly, Markus Armbruster, 2018/08/17