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SubjectRe: [PATCH] tools lib subcmd: Show parent options in help
On Wed, Jun 21, 2023 at 12:05 AM Ian Rogers <irogers@google.com> wrote:
>
> On Thu, May 25, 2023 at 3:09 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > I've just realized that help message in a subcommand didn't show one
> > in the parent command. Since the option parser understands the parent,
> > display code should do the same. For example, `perf ftrace latency -h`
> > should show options in the `perf ftrace` command too.
> >
> > Before:
> >
> > $ perf ftrace latency -h
> >
> > Usage: perf ftrace [<options>] [<command>]
> > or: perf ftrace [<options>] -- [<command>] [<options>]
> > or: perf ftrace {trace|latency} [<options>] [<command>]
> > or: perf ftrace {trace|latency} [<options>] -- [<command>] [<options>]
> >
> > -b, --use-bpf Use BPF to measure function latency
> > -n, --use-nsec Use nano-second histogram
> > -T, --trace-funcs <func>
> > Show latency of given function
> >
> > After:
> >
> > $ perf ftrace latency -h
> >
> > Usage: perf ftrace [<options>] [<command>]
> > or: perf ftrace [<options>] -- [<command>] [<options>]
> > or: perf ftrace {trace|latency} [<options>] [<command>]
> > or: perf ftrace {trace|latency} [<options>] -- [<command>] [<options>]
> >
> > -a, --all-cpus System-wide collection from all CPUs
> > -b, --use-bpf Use BPF to measure function latency
> > -C, --cpu <cpu> List of cpus to monitor
> > -n, --use-nsec Use nano-second histogram
> > -p, --pid <pid> Trace on existing process id
> > -T, --trace-funcs <func>
> > Show latency of given function
> > -v, --verbose Be more verbose
> > --tid <tid> Trace on existing thread id (exclusive to --pid)
> >
> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> > ---
> > tools/lib/subcmd/parse-options.c | 26 ++++++++++++++++++--------
> > 1 file changed, 18 insertions(+), 8 deletions(-)
> >
> > diff --git a/tools/lib/subcmd/parse-options.c b/tools/lib/subcmd/parse-options.c
> > index 9fa75943f2ed..41de97671c72 100644
> > --- a/tools/lib/subcmd/parse-options.c
> > +++ b/tools/lib/subcmd/parse-options.c
> > @@ -806,18 +806,28 @@ static int option__cmp(const void *va, const void *vb)
> >
> > static struct option *options__order(const struct option *opts)
> > {
> > - int nr_opts = 0, nr_group = 0, len;
> > - const struct option *o = opts;
> > - struct option *opt, *ordered, *group;
> > + int nr_opts = 0, nr_group = 0, nr_parent = 0, len;
> > + const struct option *o, *p = opts;
> > + struct option *opt, *ordered = NULL, *group;
> >
> > - for (o = opts; o->type != OPTION_END; o++)
> > +retry:
>
> Why use "goto retry" and not compute the size with the parent upfront?

No specific reason, just followed the same pattern as in
parse_{short,long}_opt(). :)

>
> > + for (o = p; o->type != OPTION_END; o++)
> > ++nr_opts;
> >
> > - len = sizeof(*o) * (nr_opts + 1);
> > - ordered = malloc(len);
> > - if (!ordered)
> > + len = sizeof(*o) * (nr_opts + !o->parent);
>
> It'd be nice to comment on why the "!o->parent" here.

What about this?

/* It needs a terminating NULL entry when there's no parent */

Thanks,
Namhyung


>
> Thanks,
> Ian
>
> > + group = realloc(ordered, len);
> > + if (!group)
> > goto out;
> > - memcpy(ordered, opts, len);
> > + ordered = group;
> > + memcpy(&ordered[nr_parent], p, sizeof(*o) * (nr_opts - nr_parent));
> > +
> > + if (o->parent) {
> > + p = o->parent;
> > + nr_parent = nr_opts;
> > + goto retry;
> > + }
> > + /* copy the last OPTION_END */
> > + memcpy(&ordered[nr_opts], o, sizeof(*o));
> >
> > /* sort each option group individually */
> > for (opt = group = ordered; opt->type != OPTION_END; opt++) {
> > --
> > 2.41.0.rc0.172.g3f132b7071-goog
> >

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