multicall: add support for unified option handling

cmd/multicall.c

@@ -13,10 +13,12 @@
  * from the use of this software.
  */
 
+#define _GNU_SOURCE
 #include <libgen.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <getopt.h>
 #include "cmd/multicall.h"
 
 char *argv0;
@@ -33,7 +35,67 @@ struct if_applet *applet_table[] = {
 	&ifupdown_applet,
 };
 
-#define ARRAY_SIZE(x)	(sizeof(x) / sizeof(*x))
+static void
+generic_usage(const struct if_applet *applet, int result)
+{
+	fprintf(stderr, "%s", applet->name);
+	if (applet->desc != NULL)
+		fprintf(stderr, " - %s", applet->desc);
+
+	fprintf(stderr, "\n");
+
+	size_t iter;
+	for (iter = 0; applet->groups[iter] != NULL; iter++)
+	{
+		const struct if_option_group *group = applet->groups[iter];
+
+		fprintf(stderr, "\n%s:\n", group->desc);
+
+		size_t group_iter;
+		for (group_iter = 0; group_iter < group->group_size; group_iter++)
+		{
+			const struct if_option *opt = &group->group[group_iter];
+
+			fprintf(stderr, "  ");
+
+			if (opt->short_opt)
+				fprintf(stderr, "-%c", opt->short_opt);
+			else
+				fprintf(stderr, "  ");
+
+			if (opt->long_opt)
+				fprintf(stderr, "%c --%-30s", opt->short_opt ? ',' : ' ',
+					opt->long_opt);
+			else
+				fprintf(stderr, "%34s", "");
+
+			fprintf(stderr, "%s\n", opt->desc);
+		}
+	}
+
+	exit(result);
+}
+
+static void
+generic_usage_request(int short_opt, const struct if_option *option, const char *opt_arg, const struct if_applet *applet)
+{
+	(void) short_opt;
+	(void) option;
+	(void) opt_arg;
+
+	generic_usage(applet, EXIT_SUCCESS);
+}
+
+static struct if_option global_options[] = {
+	{'h', "help", "displays program help", false, generic_usage_request},
+	{'V', "version", "displays program version", false, (void *) lif_common_version},
+};
+
+struct if_option_group global_option_group = {
+	.desc = "Global options",
+	.group_size = ARRAY_SIZE(global_options),
+	.group = global_options
+};
 
 int
 applet_cmp(const void *a, const void *b)
@@ -46,11 +108,83 @@ applet_cmp(const void *a, const void *b)
 
 void multicall_usage(int status) __attribute__((noreturn));
 
+static const struct if_option *
+lookup_option(const struct if_applet *applet, int opt)
+{
+	size_t iter;
+	for (iter = 0; applet->groups[iter] != NULL; iter++)
+	{
+		const struct if_option_group *group = applet->groups[iter];
+		size_t group_iter;
+
+		for (group_iter = 0; group_iter < group->group_size; group_iter++)
+		{
+			const struct if_option *option = &group->group[group_iter];
+
+			if (option->short_opt == opt)
+				return option;
+		}
+	}
+
+	return NULL;
+}
+
+static void
+process_options(const struct if_applet *applet, int argc, char *argv[])
+{
+	char short_opts[256] = {}, *p = short_opts;
+	struct option long_opts[256] = {};
+
+	size_t iter, long_opt_iter = 0;
+	for (iter = 0; applet->groups[iter] != NULL; iter++)
+	{
+		const struct if_option_group *group = applet->groups[iter];
+		size_t group_iter;
+
+		for (group_iter = 0; group_iter < group->group_size; group_iter++)
+		{
+			const struct if_option *opt = &group->group[group_iter];
+
+			if (opt->short_opt)
+			{
+				*p++ = opt->short_opt;
+				if (opt->require_argument)
+					*p++ = ':';
+			}
+
+			if (opt->long_opt)
+			{
+				/* XXX: handle long-opts without short-opts */
+				long_opts[long_opt_iter] = (struct option) {
+					.name = opt->long_opt,
+					.has_arg = opt->require_argument ? required_argument : no_argument,
+					.val = opt->short_opt
+				};
+
+				long_opt_iter++;
+			}
+		}
+	}
+
+	for (;;)
+	{
+		int c = getopt_long(argc, argv, short_opts, long_opts, NULL);
+		if (c == -1)
+			break;
+
+		const struct if_option *opt = lookup_option(applet, c);
+		if (opt == NULL)
+			break;
+
+		opt->handle(c, opt, optarg, applet);
+	}
+}
+
 int
 main(int argc, char *argv[])
 {
 	argv0 = basename(argv[0]);
-	struct if_applet **app;
+	const struct if_applet **app;
 
 	app = bsearch(argv0, applet_table,
 		      ARRAY_SIZE(applet_table), sizeof(*applet_table),
@@ -62,6 +196,8 @@ main(int argc, char *argv[])
 		multicall_usage(EXIT_FAILURE);
 	}
 
+	process_options(*app, argc, argv);
+
 	return (*app)->main(argc, argv);
 }
 
@@ -74,6 +210,8 @@ multicall_main(int argc, char *argv[])
 	return main(argc - 1, argv + 1);
 }
 
+struct if_applet ifupdown_applet;
+
 void
 multicall_usage(int status)
 {
@@ -97,4 +235,5 @@ struct if_applet ifupdown_applet = {
 	.name = "ifupdown",
 	.main = multicall_main,
 	.usage = multicall_usage,
+	.groups = { &global_option_group, NULL }
 };

cmd/multicall.h

@@ -13,17 +13,40 @@
  * from the use of this software.
  */
 
+#include <stdbool.h>
+
 #ifndef IFUPDOWN_CMD_MULTICALL_H__GUARD
 #define IFUPDOWN_CMD_MULTICALL_H__GUARD
 
 #include "libifupdown/libifupdown.h"
 
+#define ARRAY_SIZE(x)   (sizeof(x) / sizeof(*x))
+
+struct if_applet;
+
+struct if_option {
+	char short_opt;
+	const char *long_opt;
+	const char *desc;
+	bool require_argument;
+	void (*const handle)(int short_opt, const struct if_option *opt, const char *opt_arg, const struct if_applet *applet);
+};
+
+struct if_option_group {
+	const char *desc;
+	size_t group_size;
+	const struct if_option *group;
+};
+
 struct if_applet {
 	const char *name;
+	const char *desc;
 	int (*const main)(int argc, char *argv[]);
 	void (*const usage)(int status);
+	const struct if_option_group *groups[4];
 };
 
 extern char *argv0;
+extern struct if_option_group global_option_group;
 
 #endif