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From: James Clark <james.clark@arm.com>
To: acme@kernel.org, john.garry@huawei.com, ak@linux.intel.com,
	linux-perf-users@vger.kernel.org
Cc: Nick.Forrington@arm.com, Andrew.Kilroy@arm.com,
	James Clark <james.clark@arm.com>, Will Deacon <will@kernel.org>,
	Mathieu Poirier <mathieu.poirier@linaro.org>,
	Leo Yan <leo.yan@linaro.org>, Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH 2/3] perf tools: Make the JSON parser more conformant when in strict mode
Date: Thu,  7 Oct 2021 12:05:41 +0100	[thread overview]
Message-ID: <20211007110543.564963-3-james.clark@arm.com> (raw)
In-Reply-To: <20211007110543.564963-1-james.clark@arm.com>

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 <james.clark@arm.com>
---
 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
+	/*
+	 * 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


  parent reply	other threads:[~2021-10-07 11:06 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-07 11:05 [PATCH 0/3] perf tools: Enable strict JSON parsing James Clark
2021-10-07 11:05 ` [PATCH 1/3] perf vendor-events: Fix all remaining invalid JSON files James Clark
2021-10-07 17:22   ` John Garry
2021-10-07 11:05 ` James Clark [this message]
2021-10-07 17:52   ` [PATCH 2/3] perf tools: Make the JSON parser more conformant when in strict mode Jiri Olsa
2021-10-08 10:08     ` James Clark
2021-10-08 13:12       ` Jiri Olsa
2021-10-08 18:56         ` Arnaldo Carvalho de Melo
2021-10-08 19:01           ` Arnaldo Carvalho de Melo
2021-10-07 11:05 ` [PATCH 3/3] perf tools: Enable strict JSON parsing James Clark
2021-10-07 23:51 ` [PATCH 0/3] " Andi Kleen
2021-10-08  7:43 ` kajoljain
2021-10-08 10:02   ` James Clark
2021-10-08 11:26     ` kajoljain
2021-10-08 19:00       ` Arnaldo Carvalho de Melo
2021-10-12 13:30         ` James Clark
2021-10-12 20:15           ` Arnaldo Carvalho de Melo
2021-10-13 16:57           ` Arnaldo Carvalho de Melo

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