From 887a30551ef623e840577f53bd34cbf839bb6d55 Mon Sep 17 00:00:00 2001
From: kre <kre@NetBSD.org>
Date: Thu, 23 Feb 2017 14:09:11 +0000
Subject: [PATCH] Generate usage error for bad usage, before attempting any
 other operations. This means that "mixerctl" (no args) will generate a usage
 msg, even when /dev/mixer cannot be opened (or any other device given via -d
 or $MIXERDEVICE)

While here, get rid of "goto usage" replacing the usage: with a
static inline void __dead function...  The compiler ought to optimise
the calls into essentially the same code as existed with the goto version,
but this is much cleaner.

Also, mixerctl falls back on /dev/mixer0 if /dev/mixer cannot be opened.
(that is old code - probably from when /dev/mixer was first added)

It used to do that when called as mixerctl -d /dev/mixer or with
"MIXERDEVICE=/dev/mixer mixerctl...".   No longer.  Now the fallback (which
is probably obsolete now anyway) only happens when the user doesn't specify
any mixer device (by either method) and the default of /dev/mixer is used.
In other cases, only the device specified is tried.
---
 usr.bin/mixerctl/mixerctl.c | 32 +++++++++++++++++++++-----------
 1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/usr.bin/mixerctl/mixerctl.c b/usr.bin/mixerctl/mixerctl.c
index 2c655b3e9b3a..76d7c20c4bab 100644
--- a/usr.bin/mixerctl/mixerctl.c
+++ b/usr.bin/mixerctl/mixerctl.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: mixerctl.c,v 1.26 2012/10/28 02:01:15 isaki Exp $	*/
+/*	$NetBSD: mixerctl.c,v 1.27 2017/02/23 14:09:11 kre Exp $	*/
 
 /*
  * Copyright (c) 1997 The NetBSD Foundation, Inc.
@@ -31,7 +31,7 @@
 #include <sys/cdefs.h>
 
 #ifndef lint
-__RCSID("$NetBSD: mixerctl.c,v 1.26 2012/10/28 02:01:15 isaki Exp $");
+__RCSID("$NetBSD: mixerctl.c,v 1.27 2017/02/23 14:09:11 kre Exp $");
 #endif
 
 #include <stdio.h>
@@ -61,6 +61,8 @@ struct field {
 mixer_ctrl_t *values;
 mixer_devinfo_t *infos;
 
+static const char mixer_path[] = _PATH_MIXER;
+
 static char *
 catstr(char *p, char *q)
 {
@@ -316,6 +318,15 @@ prarg(int fd, char *arg, const char *sep)
 		prfield(p, sep, vflag), fprintf(out, "\n");
 }
 
+static inline void __dead
+usage(void)
+{
+	fprintf(out, "%s [-d file] [-v] [-n] name ...\n", prog);
+	fprintf(out, "%s [-d file] [-v] [-n] -w name=value ...\n",prog);
+	fprintf(out, "%s [-d file] [-v] [-n] -a\n", prog);
+	exit(0);
+}
+
 int
 main(int argc, char **argv)
 {
@@ -328,7 +339,7 @@ main(int argc, char **argv)
 
 	file = getenv("MIXERDEVICE");
 	if (file == NULL)
-		file = _PATH_MIXER;
+		file = mixer_path;
 
 	prog = *argv;
 
@@ -352,19 +363,18 @@ main(int argc, char **argv)
 			break;
 		case '?':
 		default:
-		usage:
-			fprintf(out, "%s [-d file] [-v] [-n] name ...\n", prog);
-			fprintf(out, "%s [-d file] [-v] [-n] -w name=value ...\n",prog);
-			fprintf(out, "%s [-d file] [-v] [-n] -a\n", prog);
-			exit(0);
+			usage();
 		}
 	}
 	argc -= optind;
 	argv += optind;
 
+	if (aflag ? (argc != 0 || wflag) : argc == 0)
+		usage();
+
 	fd = open(file, O_RDWR);
-	/* Try with mixer0. */
-	if (fd < 0 && strcmp(file, _PATH_MIXER) == 0) {
+	/* Try with mixer0 but only if using the default device. */
+	if (fd < 0 && file == mixer_path) {
 		file = _PATH_MIXER0;
 		fd = open(file, O_RDWR);
 	}
@@ -442,6 +452,6 @@ main(int argc, char **argv)
 			argv++;
 		}
 	} else
-		goto usage;
+		usage();
 	exit(0);
 }