[PATCH] tools lib subcmd: Show parent options in help

[Namhyung Kim <namhyung@kernel.org>]

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:
+	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);
+	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