linux-kernel - Re: [PATCH] perf parse-events: Use asprintf() instead of strncpy() for tracepoints

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Message-ID: <20200302182713.GA10335@kernel.org>
Date:   Mon, 2 Mar 2020 15:27:13 -0300
From:   Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf parse-events: Use asprintf() instead of strncpy()
 for tracepoints

Em Mon, Mar 02, 2020 at 04:27:41PM +0100, Jiri Olsa escreveu:
> On Mon, Mar 02, 2020 at 11:55:35AM -0300, Arnaldo Carvalho de Melo wrote:
> 
> SNIP
> 
> >       |          ^~~~~~
> >   CC       /tmp/build/perf/util/call-path.o
> > 
> > So I replaced it with asprintf to make the code shorter, use a bit less
> > memory and deal with the above problem, ok?
> > 
> > - Arnaldo
> > 
> > diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> > index c01ba6f8fdad..a14995835d85 100644
> > --- a/tools/perf/util/parse-events.c
> > +++ b/tools/perf/util/parse-events.c
> > @@ -257,21 +257,15 @@ struct tracepoint_path *tracepoint_id_to_path(u64 config)
> >  				path = zalloc(sizeof(*path));
> >  				if (!path)
> >  					return NULL;
> > -				path->system = malloc(MAX_EVENT_LENGTH);
> > -				if (!path->system) {
> > +				if (asprintf(&path->system, "%.*s", MAX_EVENT_LENGTH, sys_dirent->d_name) < 0) {
> >  					free(path);
> >  					return NULL;
> >  				}
> > -				path->name = malloc(MAX_EVENT_LENGTH);
> > -				if (!path->name) {
> > +				if (asprintf(&path->name, "%.*s", MAX_EVENT_LENGTH, evt_dirent->d_name) < 0) {
> >  					zfree(&path->system);
> >  					free(path);
> >  					return NULL;
> >  				}
> > -				strncpy(path->system, sys_dirent->d_name,
> > -					MAX_EVENT_LENGTH);
> > -				strncpy(path->name, evt_dirent->d_name,
> > -					MAX_EVENT_LENGTH);
> 
> looks good to me, and we can probably remove MAX_EVENT_LENGTH as well?

I left it there, we can remove it if the need arises, this code is not
that exercised from what I could look.

- Arnaldo