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Subject[PATCH v2] tools lib traceevent: Report better error message on bad function args
When Jiri Olsa was writing a function callback for
scsi_trace_parse_cdb(), he thought that the traceevent library had a
bug in it because he was getting this error:

Error: expected ')' but read ','
Error: expected ')' but read ','
Error: expected ')' but read ','
Error: expected ')' but read ','

But in truth, he didn't have the write number of arguments for the
function callback, and the error was the library detecting the
discrepancy. A better error message would have prevented the confusion:

Error: function 'scsi_trace_parse_cdb()' only expects 2 arguments but event scsi_dispatch_cmd_timeout has more
Error: function 'scsi_trace_parse_cdb()' only expects 2 arguments but event scsi_dispatch_cmd_start has more
Error: function 'scsi_trace_parse_cdb()' only expects 2 arguments but event scsi_dispatch_cmd_error has more
Error: function 'scsi_trace_parse_cdb()' only expects 2 arguments but event scsi_dispatch_cmd_done has more

Or

Error: function 'scsi_trace_parse_cdb()' expects 4 arguments but event scsi_dispatch_cmd_timeout only uses 3
Error: function 'scsi_trace_parse_cdb()' expects 4 arguments but event scsi_dispatch_cmd_start only uses 3
Error: function 'scsi_trace_parse_cdb()' expects 4 arguments but event scsi_dispatch_cmd_error only uses 3
Error: function 'scsi_trace_parse_cdb()' expects 4 arguments but event scsi_dispatch_cmd_done only uses 3

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---

V2:
Added '[PATCH.*]' in subject. Don't know how I missed that the first time.

Free token and farg. Thanks to Namhyung Kim for pointing that out.


diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 0362d57..87dda60 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -2691,7 +2691,6 @@ process_func_handler(struct event_format *event, struct pevent_function_handler
struct print_arg *farg;
enum event_type type;
char *token;
- const char *test;
int i;

arg->type = PRINT_FUNC;
@@ -2708,15 +2707,19 @@ process_func_handler(struct event_format *event, struct pevent_function_handler
}

type = process_arg(event, farg, &token);
- if (i < (func->nr_args - 1))
- test = ",";
- else
- test = ")";
-
- if (test_type_token(type, token, EVENT_DELIM, test)) {
- free_arg(farg);
- free_token(token);
- return EVENT_ERROR;
+ if (i < (func->nr_args - 1)) {
+ if (type != EVENT_DELIM || strcmp(token, ",") != 0) {
+ warning("Error: function '%s()' expects %d arguments but event %s only uses %d",
+ func->name, func->nr_args,
+ event->name, i + 1);
+ goto err;
+ }
+ } else {
+ if (type != EVENT_DELIM || strcmp(token, ")") != 0) {
+ warning("Error: function '%s()' only expects %d arguments but event %s has more",
+ func->name, func->nr_args, event->name);
+ goto err;
+ }
}

*next_arg = farg;
@@ -2728,6 +2731,11 @@ process_func_handler(struct event_format *event, struct pevent_function_handler
*tok = token;

return type;
+
+err:
+ free_arg(farg);
+ free_token(token);
+ return EVENT_ERROR;
}

static enum event_type

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