[PATCH] Re: [btrfs-progs integration] incorrect argument checking for "btrfs sub snap -r"

[Stephane Chazelas <stephane.chazelas@gmail.com>]

2011-06-30 22:55:15 +0200, Andreas Philipp:
> 
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>  
> On 30.06.2011 14:34, Stephane Chazelas wrote:
> > Looks like this was missing in integration-20110626 for the
> > readonly snapshot patch:
> >
> > diff --git a/btrfs.c b/btrfs.c
> > index e117172..be6ece5 100644
> > --- a/btrfs.c
> > +++ b/btrfs.c
> > @@ -49,7 +49,7 @@ static struct Command commands[] = {
> > /*
> > avoid short commands different for the case only
> > */
> > - { do_clone, 2,
> > + { do_clone, -1,
> > "subvolume snapshot", "[-r] <source> [<dest>/]<name>\n"
> > "Create a writable/readonly snapshot of the subvolume <source> with\n"
> > "the name <name> in the <dest> directory.",
> >
> > Without that, "btrfs sub snap -r x y" would fail as it's not *2*
> > arguments.
> Unfortunately, this is not correct either. "-1" means that the minimum
> number of arguments is 1 and since we need at least <source> and
> <name> this is 2. So the correct version should be -2.
[...]

Sorry, without looking closely at the source, I assumed -1 meant
defer the checking to the subcommand handler.

do_clone will indeed return an error if the number of arguments
is less than expected (so with -2, you'll get a different error
message if you do "btrfs sub snap -r foo" or "btrfs sub snap
foo") , but will not if it's more than expected by the way.

So the patch should probably be:

diff --git a/btrfs.c b/btrfs.c
index e117172..b50c58a 100644
--- a/btrfs.c
+++ b/btrfs.c
@@ -49,7 +49,7 @@ static struct Command commands[] = {
 	/*
 		avoid short commands different for the case only
 	*/
-	{ do_clone, 2,
+	{ do_clone, -2,
 	  "subvolume snapshot", "[-r] <source> [<dest>/]<name>\n"
 		"Create a writable/readonly snapshot of the subvolume <source> with\n"
 		"the name <name> in the <dest> directory.",
diff --git a/btrfs_cmds.c b/btrfs_cmds.c
index 1d18c59..3415afc 100644
--- a/btrfs_cmds.c
+++ b/btrfs_cmds.c
@@ -355,7 +355,7 @@ int do_clone(int argc, char **argv)
 			return 1;
 		}
 	}
-	if (argc - optind < 2) {
+	if (argc - optind != 2) {
 		fprintf(stderr, "Invalid arguments for subvolume snapshot\n");
 		free(argv);
 		return 1;

Cheers,
Stephane