[PATCH RESEND 1/4] tools lib traceevent: Check string is really printable

Namhyung Kim
2012-06-27T00:45:47Z

From: Namhyung Kim <namhyung.kim@lge.com>

When libtraceevent parses format fields, it assumes that
array of 1 byte is string but it's not always true. The
kvm_emulate_insn contains 15 u8 array of insn that contains
(binary) instructions. Thus when it's printed, it'll have
broken output like below:

kvm_emulate_insn: [FAILED TO PARSE] rip=3238197797 csbase=0 len=2 \
insn=<89>P^]<B4>& flags=5 failed=0

With this patch:

kvm_emulate_insn: [FAILED TO PARSE] rip=3238197797 csbase=0 len=2 \
insn=ARRAY[89, 10, 5d, c3, 8d, b4, 26, 00, 00, 00, 00, 55, 89, e5, 3e] flags=5 failed=0

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/n/tip-ki5fuys70vig80gzsz3g58r1@git.kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
tools/lib/traceevent/event-parse.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 853b604b6240..eb195cbc841c 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -3655,6 +3655,16 @@ static void print_mac_arg(struct trace_seq *s, int mac, void *data, int size,
trace_seq_printf(s, fmt, buf[0], buf[1], buf[2], buf[3], buf[4], buf[5]);
}

+static int is_printable_array(char *p, unsigned int len)
+{
+ unsigned int i;
+
+ for (i = 0; i < len && p[i]; i++)
+ if (!isprint(p[i]))
+ return 0;
+ return 1;
+}
+
static void print_event_fields(struct trace_seq *s, void *data, int size,
struct event_format *event)
{
@@ -3674,7 +3684,8 @@ static void print_event_fields(struct trace_seq *s, void *data, int size,
len = offset >> 16;
offset &= 0xffff;
}
- if (field->flags & FIELD_IS_STRING) {
+ if (field->flags & FIELD_IS_STRING &&
+ is_printable_array(data + offset, len)) {
trace_seq_printf(s, "%s", (char *)data + offset);
} else {
trace_seq_puts(s, "ARRAY[");
@@ -3685,6 +3696,7 @@ static void print_event_fields(struct trace_seq *s, void *data, int size,
*((unsigned char *)data + offset + i));
}
trace_seq_putc(s, ']');
+ field->flags &= ~FIELD_IS_STRING;
}
} else {
val = pevent_read_number(event->pevent, data + field->offset,
--
1.7.10.2