[klibc] [PATCH 4/8] switch_root: add + enhance -h help invocation

[maximilian attems]

Enhance help message by shortening it to explicit variables.

The help invocation goes to stdout, the rest to stderr.

Signed-off-by: maximilian attems <max at stro.at>
---
 usr/kinit/switch_root/switch_root.c |   18 ++++++++++--------
 1 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/usr/kinit/switch_root/switch_root.c b/usr/kinit/switch_root/switch_root.c
index f717637..68ef62d 100644
--- a/usr/kinit/switch_root/switch_root.c
+++ b/usr/kinit/switch_root/switch_root.c
@@ -47,12 +47,12 @@
 
 static const char *program;
 
-static void __attribute__ ((noreturn)) usage(void)
+static void __attribute__ ((noreturn)) usage(FILE *output)
 {
-	fprintf(stderr,
-		"Usage: exec %s [-c consoledev] /real-root /sbin/init [args]\n",
+	fprintf(output,
+		"Usage: exec %s [-c consoledev] <newroot> <init> [args]\n",
 		program);
-	exit(1);
+	exit(output == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
 }
 
 int main(int argc, char *argv[])
@@ -70,22 +70,24 @@ int main(int argc, char *argv[])
 	/* Parse the command line */
 	program = argv[0];
 
-	while ((o = getopt(argc, argv, "c:")) != -1) {
+	while ((o = getopt(argc, argv, "c:h")) != -1) {
 		if (o == 'c')
 			console = optarg;
+		else if (o == 'h')
+			usage(stdout);
 		else
-			usage();
+			usage(stderr);
 	}
 
 	if (argc - optind < 2)
-		usage();
+		usage(stderr);
 
 	realroot = argv[optind];
 	init = argv[optind + 1];
 	initargs = argv + optind + 1;
 
 	if (!*realroot || !*init)
-		usage();
+		usage(stderr);
 
 	error = switch_root(realroot, console, init, initargs);
 
-- 
1.7.5.4