linux-kernel - [PATCH 1/3] perf script python: Fix string vs byte array resolving

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Message-Id: <1468567797-27564-2-git-send-email-jolsa@kernel.org>
Date:	Fri, 15 Jul 2016 09:29:55 +0200
From:	Jiri Olsa <jolsa@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	"Steven Rostedt (Red Hat)" <rostedt@...dmis.org>,
	Jiri Pirko <jiri@...lanox.com>,
	lkml <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: [PATCH 1/3] perf script python: Fix string vs byte array resolving

Jirka reported that python code returns all arrays as strings.
This makes impossible to get all items for byte array tracepoint
field containing 0x00 value item.

Fixing this by scanning full length of the array and returning
it as PyByteArray object in case non printable byte is found.

Cc: Steven Rostedt (Red Hat) <rostedt@...dmis.org>
Cc: Jiri Pirko <jiri@...lanox.com>
Link: http://lkml.kernel.org/n/tip-22f4vhhz5uytegkggy1on8u3@git.kernel.org
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 .../util/scripting-engines/trace-event-python.c    | 37 ++++++++++++++++++----
 1 file changed, 31 insertions(+), 6 deletions(-)

diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
index 6ac6b7a33f42..1bc995de5a6d 100644
--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -386,6 +386,19 @@ exit:
 	return pylist;
 }
 
+static int is_printable_array(char *p, unsigned int len)
+{
+	unsigned int i;
+
+	if (p[len - 1] == 0)
+		len--;
+
+	for (i = 0; i < len - 1; i++)
+		if (!isprint(p[i]) && !isspace(p[i]))
+			return 0;
+
+	return 1;
+}
 
 static void python_process_tracepoint(struct perf_sample *sample,
 				      struct perf_evsel *evsel,
@@ -457,14 +470,26 @@ static void python_process_tracepoint(struct perf_sample *sample,
 		pydict_set_item_string_decref(dict, "common_callchain", callchain);
 	}
 	for (field = event->format.fields; field; field = field->next) {
-		if (field->flags & FIELD_IS_STRING) {
-			int offset;
+		unsigned int offset, len;
+		unsigned long long val;
+
+		if (field->flags & FIELD_IS_ARRAY) {
+			offset = field->offset;
+			len    = field->size;
 			if (field->flags & FIELD_IS_DYNAMIC) {
-				offset = *(int *)(data + field->offset);
+				val     = pevent_read_number(scripting_context->pevent,
+							     data + offset, len);
+				offset  = val;
+				len     = offset >> 16;
 				offset &= 0xffff;
-			} else
-				offset = field->offset;
-			obj = PyString_FromString((char *)data + offset);
+			}
+			if (field->flags & FIELD_IS_STRING &&
+			    is_printable_array(data + offset, len)) {
+				obj = PyString_FromString((char *) data + offset);
+			} else {
+				obj = PyByteArray_FromStringAndSize((const char *) data + offset, len);
+				field->flags &= ~FIELD_IS_STRING;
+			}
 		} else { /* FIELD_IS_NUMERIC */
 			obj = get_field_numeric_entry(event, field, data);
 		}
-- 
2.4.11