Re: [PATCH 1/4] trace-cmd: Add parse error checking target
From: Vaibhav Nagarnaik
Date: Mon Jul 25 2011 - 14:06:37 EST
On Mon, Jul 25, 2011 at 6:32 AM, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> On Fri, 2011-07-15 at 20:00 -0700, Vaibhav Nagarnaik wrote:
>> Add another target 'check-events' which parses all the event formats and
>> returns whether there are any issues with the print format strings.
>>
>> With an error in the format, the return value is 22 (EINVAL) and for
>> success, it is 0.
>>
>> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@xxxxxxxxxx>
>> ---
>> trace-capture.c | 2 +-
>> trace-cmd.c | 22 ++++++++++++++++++++++
>> trace-cmd.h | 2 +-
>> trace-usage.c | 5 +++++
>> trace-util.c | 48 ++++++++++++++++++++++++++++++++----------------
>> 5 files changed, 61 insertions(+), 18 deletions(-)
>>
>> diff --git a/trace-capture.c b/trace-capture.c
>> index 61ff165..5708945 100644
>> --- a/trace-capture.c
>> +++ b/trace-capture.c
>> @@ -1295,7 +1295,7 @@ static void tracing_dialog(struct shark_info *info, const char *tracing)
>> /* Send parse warnings to status display */
>> trace_dialog_register_alt_warning(vpr_stat);
>>
>> - pevent = tracecmd_local_events(tracing);
>> + tracecmd_local_events(tracing, &pevent);
>
> Ug, please no. I don't see any good reason to move the creation of a
> pevent into a pointer than just return it. If you require a different
> return code, or (a even better reason) that this may be called without
> needing to create a pevent at all, then I can understand this. But
> creating an object (sturcture) by passing its address is an anomaly of C
> and I like to avoid when possible. Passing an address of a atom value
> (int, long) or even maybe a string that is allocated is one thing. But
> doing it with a constructor function is just plain ugly.
I agree it is ugly, but I wanted to preserve the legacy behavior where
even with parsing failures, tracecmd_local_events() returns a filled in
parsed events. This is the easiest way to return a filled in pevent and
indicate whether there were *any* parsing failures.
Now that I think about it, I can add the boolean in the returned pevent
structure to have the same effect and keep the same constructor
signature. I will send the updated patch in a moment.
>
>
>> trace_dialog_register_alt_warning(NULL);
>>
>> cap.pevent = pevent;
>> diff --git a/trace-cmd.c b/trace-cmd.c
>> index bff5bbf..a2b6b91 100644
>> --- a/trace-cmd.c
>> +++ b/trace-cmd.c
>> @@ -158,6 +158,28 @@ int main (int argc, char **argv)
>> } else if (strcmp(argv[1], "stack") == 0) {
>> trace_stack(argc, argv);
>> exit(0);
>> + } else if (strcmp(argv[1], "check-events") == 0) {
>> + char *tracing;
>> + int ret;
>> + struct pevent *pevent = NULL;
>> +
>> + tracing = tracecmd_find_tracing_dir();
>> +
>> + if (!tracing) {
>> + printf("Can not find or mount tracing directory!\n"
>> + "Either tracing is not configured for this "
>> + "kernel\n"
>> + "or you do not have the proper permissions to "
>> + "mount the directory");
>> + exit(EINVAL);
>> + }
>> +
>> + ret = tracecmd_local_events(tracing, &pevent);
>> + if (pevent)
>> + pevent_free(pevent);
>> +
>> + ret ? exit(0) : exit(EINVAL);
>> +
>
> And here the code is even uglier. You just free pevent and the ret is
> just a boolean! Also, that ?: trick is even uglier.
>
>
> pevent = tracecmd_local_events(tracing);
> if (!pevent)
> exit(EINVAL);
> pevent_free(pevent);
> exit(0);
>
> Is much more readable.
>
> -- Steve
>
>
>
>
>
Vaibhav Nagarnaik
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