Minor argument checking patch

[John]

Hi Folks,

   I lost some time recently chasing a bug in a script. Turns
out gstripe (and friends) politely accept a device name as the
label name.

   Anyone want to commit, or mind if I commit, a simple change?

# gstripe label -v /dev/multipath/S6[12345678]
gstripe: Invalid label: /dev/multipath/S61

   I'd also be willing to say that we should validate that the label
name doesn't exceed sizeof(md.md_name) - currently silently truncated.

   Thoughts?

Thanks,
John


Sample patch

--- geom_stripe.c.orig	2012-09-06 21:32:00.000000000 -0400
+++ geom_stripe.c	2012-09-06 21:46:48.000000000 -0400
@@ -136,6 +136,16 @@
 	hardcode = gctl_get_int(req, "hardcode");
 
 	/*
+	 * Validate name prior to any device changes
+	 */
+	name = gctl_get_ascii(req, "arg0");
+	if (strchr(name,'/') != NULL) {
+		gctl_error(req, "Invalid label: %s", name);
+		return;
+	}
+	strlcpy(md.md_name, name, sizeof(md.md_name));
+
+	/*
 	 * Clear last sector first to spoil all components if device exists.
 	 */
 	compsize = 0;
@@ -167,8 +177,6 @@
 
 	strlcpy(md.md_magic, G_STRIPE_MAGIC, sizeof(md.md_magic));
 	md.md_version = G_STRIPE_VERSION;
-	name = gctl_get_ascii(req, "arg0");
-	strlcpy(md.md_name, name, sizeof(md.md_name));
 	md.md_id = arc4random();
 	md.md_all = nargs - 1;
 	stripesize = gctl_get_intmax(req, "stripesize");