tests: add zfs_unshare_008_pos checking whitespace escaping

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #13165

tests/zfs-tests/include/libtest.shlib

@@ -1110,6 +1110,18 @@ function datasetnonexists
 	return 0
 }
 
+# FreeBSD breaks exports(5) at whitespace and doesn't process escapes
+# Solaris just breaks
+#
+# cf. https://github.com/openzfs/zfs/pull/13165#issuecomment-1059845807
+#
+# Linux can have spaces (which are \OOO-escaped),
+# but can't have backslashes because they're parsed recursively
+function shares_can_have_whitespace
+{
+	is_linux
+}
+
 function is_shared_freebsd
 {
 	typeset fs=$1

tests/zfs-tests/tests/Makefile.am

@@ -878,6 +878,7 @@ nobase_dist_datadir_zfs_tests_tests_SCRIPTS += \
 	functional/cli_root/zfs_unshare/zfs_unshare_005_neg.ksh \
 	functional/cli_root/zfs_unshare/zfs_unshare_006_pos.ksh \
 	functional/cli_root/zfs_unshare/zfs_unshare_007_pos.ksh \
+	functional/cli_root/zfs_unshare/zfs_unshare_008_pos.ksh \
 	functional/cli_root/zfs_upgrade/cleanup.ksh \
 	functional/cli_root/zfs_upgrade/setup.ksh \
 	functional/cli_root/zfs_upgrade/zfs_upgrade_001_pos.ksh \

tests/zfs-tests/tests/functional/cli_root/zfs_unshare/zfs_unshare_008_pos.ksh

@@ -0,0 +1,58 @@
+#!/bin/ksh -p
+#
+# CDDL HEADER START
+#
+# The contents of this file are subject to the terms of the
+# Common Development and Distribution License (the "License").
+# You may not use this file except in compliance with the License.
+#
+# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+# or http://www.opensolaris.org/os/licensing.
+# See the License for the specific language governing permissions
+# and limitations under the License.
+#
+# When distributing Covered Code, include this CDDL HEADER in each
+# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+# If applicable, add the following below this CDDL HEADER, with the
+# fields enclosed by brackets "[]" replaced with your own identifying
+# information: Portions Copyright [yyyy] [name of copyright owner]
+#
+# CDDL HEADER END
+#
+
+. $STF_SUITE/include/libtest.shlib
+
+#
+# DESCRIPTION:
+# Verify that datasets mounted at directories with whitespace are properly escaped
+# both going in (for mountd consumption) and going out (for removing from export list)
+#
+# STRATEGY:
+# 1. Create and share a dataset with spaces, tabs, and newlines
+# 2. Verify it's shared
+# 3. Unshare it
+# 4. Verify it's not shared
+#
+
+shares_can_have_whitespace || log_unsupported "Platform doesn't permit whitespace in NFS shares"
+basename='a + b
+ c	d'
+escname='a\040+\040b\012\040c\011d'
+
+verify_runnable "global"
+
+function cleanup
+{
+	datasetexists "$TESTPOOL/$TESTFS/shared1" && \
+		destroy_dataset "$TESTPOOL/$TESTFS/shared1" -f
+}
+
+log_assert "Datasets with spaces are properly shared and unshared."
+log_onexit cleanup
+
+log_must    zfs create -o sharenfs=on -o mountpoint="$TESTDIR/$basename" "$TESTPOOL/$TESTFS/shared1"
+log_must    is_shared "$TESTDIR/$escname"
+log_must    zfs unshare "$TESTPOOL/$TESTFS/shared1"
+log_mustnot is_shared "$TESTDIR/$escname"
+
+log_pass "Datasets with spaces are properly shared and unshared."