tools lib traceevent: Introduce pevent_filter_strerror()

The pevent_filter_strerror() function is for receiving actual error
message from pevent_errno value.  To do that, add a static buffer to
event_filter for saving internal error message

If a failed function saved other information in the static buffer
returns the information, otherwise returns generic error message.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1386833777-3790-15-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/tools/lib/traceevent/event-parse.h b/tools/lib/traceevent/event-parse.h
index 3ad784f5f647..cf5db9013f2c 100644
--- a/tools/lib/traceevent/event-parse.h
+++ b/tools/lib/traceevent/event-parse.h
@@ -851,10 +851,13 @@ struct filter_type {
         struct filter_arg       *filter;
 };
 
+#define PEVENT_FILTER_ERROR_BUFSZ  1024
+
 struct event_filter {
         struct pevent           *pevent;
         int                     filters;
         struct filter_type      *event_filters;
+        char                    error_buffer[PEVENT_FILTER_ERROR_BUFSZ];
 };
 
 struct event_filter *pevent_filter_alloc(struct pevent *pevent);
@@ -874,10 +877,12 @@ enum filter_trivial_type {
 enum pevent_errno pevent_filter_add_filter_str(struct event_filter *filter,
                                                const char *filter_str);
 
-
 enum pevent_errno pevent_filter_match(struct event_filter *filter,
                                       struct pevent_record *record);
 
+int pevent_filter_strerror(struct event_filter *filter, enum pevent_errno err,
+                           char *buf, size_t buflen);
+
 int pevent_event_filtered(struct event_filter *filter,
                           int event_id);