[Lguest] [PATCH 1/3] tools: lguest: redo usage

[Davidlohr Bueso]

From: Davidlohr Bueso <dave at gnu.org>

Add noreturn attribute and allow passing the output file in case of calling
upon error or expected behavior.

Signed-off-by: Davidlohr Bueso <dave at gnu.org>
---
 tools/lguest/lguest.c |   17 ++++++++++-------
 1 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/tools/lguest/lguest.c b/tools/lguest/lguest.c
index f759f4f..931b6ff 100644
--- a/tools/lguest/lguest.c
+++ b/tools/lguest/lguest.c
@@ -1856,12 +1856,15 @@ static struct option opts[] = {
 	{ "chroot", 1, NULL, 'c' },
 	{ NULL },
 };
-static void usage(void)
+
+static void  __attribute__ ((__noreturn__)) usage(FILE *out)
 {
-	errx(1, "Usage: lguest [--verbose] "
-	     "[--tunnet=(<ipaddr>:<macaddr>|bridge:<bridgename>:<macaddr>)\n"
-	     "|--block=<filename>|--initrd=<filename>]...\n"
-	     "<mem-in-mb> vmlinux [args...]");
+	fprintf(out, "Usage: lguest [--verbose] "
+		"[--tunnet=(<ipaddr>:<macaddr>|bridge:<bridgename>:<macaddr>)\n"
+		"|--block=<filename>|--initrd=<filename>]...\n"
+		"<mem-in-mb> vmlinux [args...]\n");
+
+	exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
 }
 
 /*L:105 The main routine is where the real work begins: */
@@ -1948,7 +1951,7 @@ int main(int argc, char *argv[])
 			break;
 		default:
 			warnx("Unknown argument %s", argv[optind]);
-			usage();
+			usage(stderr);
 		}
 	}
 	/*
@@ -1956,7 +1959,7 @@ int main(int argc, char *argv[])
 	 * followed by command line arguments for the kernel.
 	 */
 	if (optind + 2 > argc)
-		usage();
+		usage(stderr);
 
 	verbose("Guest base is at %p\n", guest_base);
 
-- 
1.7.4.1