[RFC/PATCH 1/2] tools lib subcmd: Suppport cascading options

[Namhyung Kim <namhyung@kernel.org>]

Sometimes subcommand have common options and it can only handled in the
upper level command unless it duplicates the options.

This patch adds a parent field and fallback to the parent if the given
argument was not found in the current options.

Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/lib/subcmd/parse-options.c | 14 ++++++++++++++
 tools/lib/subcmd/parse-options.h |  2 ++
 2 files changed, 16 insertions(+)

diff --git a/tools/lib/subcmd/parse-options.c b/tools/lib/subcmd/parse-options.c
index 981bb4481fd5..3284bb14ae78 100644
--- a/tools/lib/subcmd/parse-options.c
+++ b/tools/lib/subcmd/parse-options.c
@@ -314,12 +314,19 @@ static int get_value(struct parse_opt_ctx_t *p,
 
 static int parse_short_opt(struct parse_opt_ctx_t *p, const struct option *options)
 {
+retry:
 	for (; options->type != OPTION_END; options++) {
 		if (options->short_name == *p->opt) {
 			p->opt = p->opt[1] ? p->opt + 1 : NULL;
 			return get_value(p, options, OPT_SHORT);
 		}
 	}
+
+	if (options->parent) {
+		options = options->parent;
+		goto retry;
+	}
+
 	return -2;
 }
 
@@ -333,6 +340,7 @@ static int parse_long_opt(struct parse_opt_ctx_t *p, const char *arg,
 	if (!arg_end)
 		arg_end = arg + strlen(arg);
 
+retry:
 	for (; options->type != OPTION_END; options++) {
 		const char *rest;
 		int flags = 0;
@@ -426,6 +434,12 @@ static int parse_long_opt(struct parse_opt_ctx_t *p, const char *arg,
 	}
 	if (abbrev_option)
 		return get_value(p, abbrev_option, abbrev_flags);
+
+	if (options->parent) {
+		options = options->parent;
+		goto retry;
+	}
+
 	return -2;
 }
 
diff --git a/tools/lib/subcmd/parse-options.h b/tools/lib/subcmd/parse-options.h
index d60cab2726da..8866ac438b34 100644
--- a/tools/lib/subcmd/parse-options.h
+++ b/tools/lib/subcmd/parse-options.h
@@ -109,11 +109,13 @@ struct option {
 	intptr_t defval;
 	bool *set;
 	void *data;
+	const struct option *parent;
 };
 
 #define check_vtype(v, type) ( BUILD_BUG_ON_ZERO(!__builtin_types_compatible_p(typeof(v), type)) + v )
 
 #define OPT_END()                   { .type = OPTION_END }
+#define OPT_PARENT(p)               { .type = OPTION_END, .parent = (p) }
 #define OPT_ARGUMENT(l, h)          { .type = OPTION_ARGUMENT, .long_name = (l), .help = (h) }
 #define OPT_GROUP(h)                { .type = OPTION_GROUP, .help = (h) }
 #define OPT_BIT(s, l, v, h, b)      { .type = OPTION_BIT, .short_name = (s), .long_name = (l), .value = check_vtype(v, int *), .help = (h), .defval = (b) }
-- 
2.10.0