Re: [PATCH 1/7] trace-cmd: Implemented new lib API: tracecmd_local_events_system()

[Steven Rostedt <rostedt@goodmis.org>]

On Wed, 16 Jan 2019 21:18:32 +0200
Tzvetomir Stoyanov <tstoyanov@vmware.com> wrote:

> +static int tracecmd_fill_local_events_system(const char *tracing_dir,
> +					     struct tep_handle *pevent,
> +					     char *sys_name)
>  {
>  	struct dirent *dent;
>  	char *events_dir;
> @@ -1189,7 +1161,8 @@ int tracecmd_fill_local_events(const char *tracing_dir, struct tep_handle *peven
>  		if (strcmp(name, ".") == 0 ||
>  		    strcmp(name, "..") == 0)
>  			continue;
> -
> +		if (sys_name && strcmp(name, sys_name))

Small nit. Please compare as: strcmp(name, sys_name) != 0

This to make it look like it is not equal. One of the flaws of the
"strcmp" is that a match is false and a non match is true, which makes
it likely to be done wrong :-p

If you noticed, the strcmp() in the previous if uses "== 0" as a way to
say "this is true on match"


> +			continue;
>  		sys = append_file(events_dir, name);
>  		ret = stat(sys, &st);
>  		if (ret < 0 || !S_ISDIR(st.st_mode)) {
> @@ -1217,6 +1190,58 @@ int tracecmd_fill_local_events(const char *tracing_dir, struct tep_handle *peven
>  	return ret;
>  }
>  
> +/**
> + * tracecmd_local_events_system - create a tep from the
> + * events of the specified subsystem.

Keep the above on one line, even though it breaks the 80 character
limit.

-- Steve

> + *
> + * @tracing_dir: The directory that contains the events.
> + * @sys_name: Name of the subsystem, to load events from
> + *
> + * Returns a tep structure that contains the tep local to
> + * the system.
> + */
> +struct tep_handle *tracecmd_local_events_system(const char *tracing_dir,
> +						char *sys_name)
> +{
> +	struct tep_handle *tep = NULL;
> +
> +	tep = tep_alloc();
> +	if (!tep)
> +		return NULL;
> +
> +	if (tracecmd_fill_local_events_system(tracing_dir, tep, sys_name)) {
> +		tep_free(tep);
> +		tep = NULL;
> +	}
> +
> +	return tep;
> +}
>