On 08/08/2018 07:03 AM, Markus Armbruster wrote:
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 <arm...@redhat.com>
---
include/qapi/qmp/json-lexer.h | 4 ++--
qobject/json-lexer.c | 42 ++++++++++++++++++++++++++---------
qobject/json-parser.c | 4 ----
qobject/json-streamer.c | 2 +-
tests/qmp-test.c | 4 ++++
5 files changed, 39 insertions(+), 17 deletions(-)
@@ -271,17 +272,38 @@ static const uint8_t json_lexer[][256] = {
[','] = JSON_COMMA,
[':'] = JSON_COLON,
['a' ... 'z'] = IN_KEYWORD,
+ [' '] = IN_WHITESPACE,
+ ['\t'] = IN_WHITESPACE,
+ ['\r'] = IN_WHITESPACE,
+ ['\n'] = IN_WHITESPACE,
+ },
+
+ [IN_START_INTERPOL] = {
+ ['"'] = IN_DQ_STRING,
...
+ ['\n'] = IN_WHITESPACE,
+ /* matches IN_START up to here */
['%'] = IN_INTERPOL,
You could compress this as:
[IN_START_INTERPOL ... IN_START] = {
['"'] = ...
['\n'] = ...
},
[IN_START_INTERPOL]['%'] = IN_INTERPOL,
rather than duplicating the common list twice. (We already exploit gcc's
range initialization, and the fact that you can initialize a broader
range and then re-initialize a more specific subset later)
+++ 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);
I'm impressed at how easily you got the lexer to parse two different
token grammars, and agree that doing it in the lexer when we don't want
interpolation is a nicer place.
Reviewed-by: Eric Blake <ebl...@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
