On 07/10/2021 18:52, Jiri Olsa wrote:

On Thu, Oct 07, 2021 at 12:05:41PM +0100, James Clark wrote:

quoted

Return an error when a trailing comma is found or a new item is
encountered before a comma or an opening brace. This ensures that the
perf json files conform more closely to the spec at https://www.json.org

Signed-off-by: James Clark <redacted>
---
 tools/perf/pmu-events/jsmn.c | 42 ++++++++++++++++++++++++++++++++++--
 1 file changed, 40 insertions(+), 2 deletions(-)

diff --git a/tools/perf/pmu-events/jsmn.c b/tools/perf/pmu-events/jsmn.c
index 11d1fa18bfa5..8124d2d3ff0c 100644
--- a/tools/perf/pmu-events/jsmn.c
+++ b/tools/perf/pmu-events/jsmn.c

@@ -176,6 +176,14 @@ jsmnerr_t jsmn_parse(jsmn_parser *parser, const char *js, size_t len,
 	jsmnerr_t r;
 	int i;
 	jsmntok_t *token;
+#ifdef JSMN_STRICT

I might have missed some discussion on this, but do we need the
JSMN_STRICT define, if you enable it in the next patch?
why can't we be more strict by default.. do you plan to disable
it in future?

I didn't plan on disabling it, I was just trying to keep to the existing style of the
jsmn project.

I could have added the trailing comma detection by default and not inside any
#ifdef JSMN_STRICT blocks, but I would like to enable JSMN_STRICT anyway, because it
enables some additional built in checking that was already there. So I thought it
made sense to put my new strict stuff inside the existing strict option.

One option would be to remove all (including the existing) #ifdef JSMN_STRICT blocks
and have everything strict by default. But it would be a further deviation from jsmn.

Thanks
James

thanks,
jirka

quoted

+	/*
+	 * Keeps track of whether a new object/list/primitive is expected. New items are only
+	 * allowed after an opening brace, comma or colon. A closing brace after a comma is not
+	 * valid JSON.
+	 */
+	int expecting_item = 1;
+#endif
 
 	for (; parser->pos < len; parser->pos++) {
 		char c;

@@ -185,6 +193,10 @@ jsmnerr_t jsmn_parse(jsmn_parser *parser, const char *js, size_t len,
 		switch (c) {
 		case '{':
 		case '[':
+#ifdef JSMN_STRICT
+			if (!expecting_item)
+				return JSMN_ERROR_INVAL;
+#endif
 			token = jsmn_alloc_token(parser, tokens, num_tokens);
 			if (token == NULL)
 				return JSMN_ERROR_NOMEM;

@@ -196,6 +208,10 @@ jsmnerr_t jsmn_parse(jsmn_parser *parser, const char *js, size_t len,
 			break;
 		case '}':
 		case ']':
+#ifdef JSMN_STRICT
+			if (expecting_item)
+				return JSMN_ERROR_INVAL;
+#endif
 			type = (c == '}' ? JSMN_OBJECT : JSMN_ARRAY);
 			for (i = parser->toknext - 1; i >= 0; i--) {
 				token = &tokens[i];

@@ -219,6 +235,11 @@ jsmnerr_t jsmn_parse(jsmn_parser *parser, const char *js, size_t len,
 			}
 			break;
 		case '\"':
+#ifdef JSMN_STRICT
+			if (!expecting_item)
+				return JSMN_ERROR_INVAL;
+			expecting_item = 0;
+#endif
 			r = jsmn_parse_string(parser, js, len, tokens,
 					      num_tokens);
 			if (r < 0)

@@ -229,11 +250,15 @@ jsmnerr_t jsmn_parse(jsmn_parser *parser, const char *js, size_t len,
 		case '\t':
 		case '\r':
 		case '\n':
-		case ':':
-		case ',':
 		case ' ':
 			break;
 #ifdef JSMN_STRICT
+		case ':':
+		case ',':
+			if (expecting_item)
+				return JSMN_ERROR_INVAL;
+			expecting_item = 1;
+			break;
 			/*
 			 * In strict mode primitives are:
 			 * numbers and booleans.

@@ -253,6 +278,9 @@ jsmnerr_t jsmn_parse(jsmn_parser *parser, const char *js, size_t len,
 		case 'f':
 		case 'n':
 #else
+		case ':':
+		case ',':
+			break;
 			/*
 			 * In non-strict mode every unquoted value
 			 * is a primitive.

@@ -260,6 +288,12 @@ jsmnerr_t jsmn_parse(jsmn_parser *parser, const char *js, size_t len,
 			/*FALL THROUGH */
 		default:
 #endif
+
+#ifdef JSMN_STRICT
+			if (!expecting_item)
+				return JSMN_ERROR_INVAL;
+			expecting_item = 0;
+#endif
 			r = jsmn_parse_primitive(parser, js, len, tokens,
 						 num_tokens);
 			if (r < 0)

@@ -282,7 +316,11 @@ jsmnerr_t jsmn_parse(jsmn_parser *parser, const char *js, size_t len,
 			return JSMN_ERROR_PART;
 	}
 
+#ifdef JSMN_STRICT
+	return expecting_item ? JSMN_ERROR_INVAL : JSMN_SUCCESS;
+#else
 	return JSMN_SUCCESS;
+#endif
 }
 
 /*

-- 
2.28.0

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