qemu-iotests: Test case for backing file deletion

Add a test case for trying to open an image file where it is impossible
to open its backing file (in this case, because it was deleted). When
doing this, qemu (or qemu-io in this case) should not crash but rather
print an appropriate error message.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

tests/qemu-iotests/069

+#!/bin/bash
+#
+# Test case for deleting a backing file
+#
+# Copyright (C) 2013 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+# creator
+owner=mreitz@redhat.com
+
+seq="$(basename $0)"
+echo "QA output created by $seq"
+
+here="$PWD"
+tmp=/tmp/$$
+status=1	# failure is the default!
+
+_cleanup()
+{
+	_cleanup_test_img
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+
+_supported_fmt cow qed qcow qcow2 vmdk
+_supported_proto generic
+_supported_os Linux
+
+IMG_SIZE=128K
+
+echo
+echo "=== Creating an image with a backing file and deleting that file ==="
+echo
+TEST_IMG="$TEST_IMG.base" _make_test_img $IMG_SIZE
+_make_test_img -b "$TEST_IMG.base" $IMG_SIZE
+rm -f "$TEST_IMG.base"
+# Just open the image and close it right again (this should print an error message)
+$QEMU_IO -c quit "$TEST_IMG" 2>&1 | _filter_testdir | _filter_imgfmt
+
+# success, all done
+echo "*** done"
+rm -f $seq.full
+status=0

tests/qemu-iotests/069.out

+QA output created by 069
+
+=== Creating an image with a backing file and deleting that file ===
+
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=131072 
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=131072 backing_file='TEST_DIR/t.IMGFMT.base' 
+qemu-io: can't open device TEST_DIR/t.IMGFMT: Could not open file: No such file or directory
+*** done

tests/qemu-iotests/group

@@ -74,3 +74,4 @@
 066 rw auto
 067 rw auto
 068 rw auto
+069 rw auto