Imagine a situation where:

	# ls -ld /mnt/{foo,bar}
	drwxr-xr-x  3 root  wheel  512 Mar 16 06:56 /mnt/bar
	lrwxr-xr-x  1 root  wheel    3 Mar 16 12:10 /mnt/foo -> bar

	# grep /mnt/foo /etc/fstab
	/dev/da1	/mnt/foo	ufs	rw	0	0

Which means, we give symbolic link as a mount point to mount(8), but mount(8)
use realpath(3) before mounting the file systems, so we get:

	# mount | grep /dev/da1
	/dev/da1 on /mnt/bar (ufs, local)

Before the commit:

	# snapinfo /mnt/foo
	usage: snapinfo [-v] -a
	       snapinfo [-v] mountpoint
	# snapinfo /mnt/bar
	/mnt/bar/snap

This commit makes snapinfo(8) to first realpath(3) the given mount point and
now we have:

	# snapinfo /mnt/foo
	/mnt/bar/snap
	# snapinfo /mnt/bar
	/mnt/bar/snap

1 files changed, 11 insertions, 4 deletions

diff --git a/usr.sbin/snapinfo/snapinfo.c b/usr.sbin/snapinfo/snapinfo.c
index a4b1a13..55b54a5 100644
--- a/usr.sbin/snapinfo/snapinfo.c
+++ b/usr.sbin/snapinfo/snapinfo.c
@@ -81,12 +81,19 @@ main(int argc, char **argv)
 		usage();
 
 	if (!all) {
-		path = *argv;
+		char resolved[PATH_MAX];
 
-		if (strrchr(path, '/') == NULL ||	/* is absolute path */
-		    (stat(path, &st) == -1) || 		/* is it stat'able */
-		    !(st.st_mode & S_IFDIR))  		/* is it a directory */
+		path = *argv;
+		/*
+		 * mount(8) use realpath(3) before mounting file system,
+		 * so let's do the same with the given path.
+		 */
+		if (realpath(path, resolved) == NULL ||	/* can create full path */
+		    stat(resolved, &st) == -1 ||	/* is it stat'able */
+		    !S_ISDIR(st.st_mode)) {		/* is it a directory */
 			usage();
+		}
+		path = resolved;
 	}
 
 	fscount = getmntinfo(&mntbuf, MNT_WAIT);