ZTS: Create xattr helpers to hide platform

Create xattr helpers to hide platform and update usage in tests.

This does not generally aim to enable all xattr tests yet, but it is a
necessary step in that direction.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <ryan@ixsystems.com>
Closes #9826

tests/zfs-tests/include/commands.cfg

@@ -115,13 +115,17 @@ export SYSTEM_FILES_FREEBSD='chflags
     compress
     dumpon
     fsck
+    getextattr
     gpart
+    lsextattr
     md5
     mdconfig
     mkfifo
     newfs
     pw
     random
+    rmextattr
+    setextattr
     sha256
     swapctl
     sysctl

tests/zfs-tests/include/libtest.shlib

@@ -3949,3 +3949,82 @@ function range_shuffle # begin end
 		shuf -i ${begin}-${end}
 	fi
 }
+
+#
+# Cross-platform xattr helpers
+#
+
+function get_xattr # name path
+{
+	typeset name=$1
+	typeset path=$2
+
+	case $(uname) in
+	FreeBSD)
+		getextattr -qq user "${name}" "${path}"
+		;;
+	*)
+		attr -qg "${name}" "${path}"
+		;;
+	esac
+}
+
+function set_xattr # name value path
+{
+	typeset name=$1
+	typeset value=$2
+	typeset path=$3
+
+	case $(uname) in
+	FreeBSD)
+		setextattr user "${name}" "${value}" "${path}"
+		;;
+	*)
+		attr -qs "${name}" -V "${value}" "${path}"
+		;;
+	esac
+}
+
+function set_xattr_stdin # name value
+{
+	typeset name=$1
+	typeset path=$2
+
+	case $(uname) in
+	FreeBSD)
+		setextattr -i user "${name}" "${path}"
+		;;
+	*)
+		attr -qs "${name}" "${path}"
+		;;
+	esac
+}
+
+function rm_xattr # name path
+{
+	typeset name=$1
+	typeset path=$2
+
+	case $(uname) in
+	FreeBSD)
+		rmextattr -q user "${name}" "${path}"
+		;;
+	*)
+		attr -qr "${name}" "${path}"
+		;;
+	esac
+}
+
+function ls_xattr # path
+{
+	typeset path=$1
+
+	case $(uname) in
+	FreeBSD)
+		lsextattr -qq user "${path}"
+		;;
+	*)
+		attr -ql "${path}"
+		;;
+	esac
+}