btrfs-progs: better option/error handling for btrfs-vol

Today wrong cmdlines give odd results:

	# ./btrfs-vol /dev/sdb1
	Unable to open device (null)
	# ./btrfs-vol -a /dev/sdb1
	usage: btrfs-vol [options] mount_point ...

Make it a bit more informative:

	# ./btrfs-vol /dev/sdb1
	No command specified
	usage: btrfs-vol [options] mount_point ...
	# ./btrfs-vol -a /dev/sdb1
	No mountpoint specified
	usage: btrfs-vol [options] mount_point ...

(even though it's deprecated ...)

Signed-off-by: Eric Sandeen <sandeen@redhat.com>

diff --git a/btrfs-vol.c b/btrfs-vol.c
index 3cc1c32..e37b41a 100644 (file)
--- a/btrfs-vol.c
+++ b/btrfs-vol.c
@@ -106,8 +106,13 @@ int main(int ac, char **av)
                }
        }
        ac = ac - optind;
-       if (ac == 0)
+       if (ac == 0 || !cmd) {
+               if (!ac)
+                       fprintf(stderr, "No mountpoint specified\n");
+               else
+                       fprintf(stderr, "No command specified\n");
                print_usage();
+       }
        mnt = av[optind];
 
        if (device && strcmp(device, "missing") == 0 &&