qemu-img: fix info --backing-chain --image-opts

Only apply --image-opts to the topmost image when listing an entire
backing chain.  It is incorrect to treat backing filenames as image
options.  Assuming we have the backing chain t.IMGFMT.base <-
t.IMGFMT.mid <- t.IMGFMT, qemu-img info fails as follows:

  $ qemu-img info --backing-chain --image-opts \
      driver=qcow2,file.driver=file,file.filename=t.IMGFMT
  qemu-img: Could not open 'TEST_DIR/t.IMGFMT.mid': Cannot find device=TEST_DIR/t.IMGFMT.mid nor node_name=TEST_DIR/t.IMGFMT.mid

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

qemu-img.c

@@ -2680,7 +2680,10 @@ static ImageInfoList *collect_image_info_list(bool image_opts,
 
         blk_unref(blk);
 
+        /* Clear parameters that only apply to the topmost image */
         filename = fmt = NULL;
+        image_opts = false;
+
         if (chain) {
             if (info->has_full_backing_filename) {
                 filename = info->full_backing_filename;

tests/qemu-iotests/279

@@ -0,0 +1,57 @@
+#!/usr/bin/env bash
+#
+# Test qemu-img --backing-chain --image-opts
+#
+# Copyright (C) 2019 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/>.
+#
+
+seq=$(basename "$0")
+echo "QA output created by $seq"
+
+status=1	# failure is the default!
+
+_cleanup()
+{
+    _cleanup_test_img
+    rm -f "$TEST_IMG.mid"
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+
+# Backing files are required...
+_supported_fmt qcow qcow2 vmdk qed
+_supported_proto file
+_supported_os Linux
+
+TEST_IMG="$TEST_IMG.base" _make_test_img 64M
+TEST_IMG="$TEST_IMG.mid" _make_test_img -b "$TEST_IMG.base"
+_make_test_img -b "$TEST_IMG.mid"
+
+echo
+echo '== qemu-img info --backing-chain =='
+_img_info --backing-chain | _filter_img_info
+
+echo
+echo '== qemu-img info --backing-chain --image-opts =='
+TEST_IMG="driver=qcow2,file.driver=file,file.filename=$TEST_IMG" _img_info --backing-chain --image-opts | _filter_img_info
+
+# success, all done
+echo "*** done"
+rm -f $seq.full
+status=0

tests/qemu-iotests/279.out

@@ -0,0 +1,35 @@
+QA output created by 279
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=67108864
+Formatting 'TEST_DIR/t.IMGFMT.mid', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.base
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.mid
+
+== qemu-img info --backing-chain ==
+image: TEST_DIR/t.IMGFMT
+file format: IMGFMT
+virtual size: 64 MiB (67108864 bytes)
+backing file: TEST_DIR/t.IMGFMT.mid
+
+image: TEST_DIR/t.IMGFMT.mid
+file format: IMGFMT
+virtual size: 64 MiB (67108864 bytes)
+backing file: TEST_DIR/t.IMGFMT.base
+
+image: TEST_DIR/t.IMGFMT.base
+file format: IMGFMT
+virtual size: 64 MiB (67108864 bytes)
+
+== qemu-img info --backing-chain --image-opts ==
+image: TEST_DIR/t.IMGFMT
+file format: IMGFMT
+virtual size: 64 MiB (67108864 bytes)
+backing file: TEST_DIR/t.IMGFMT.mid
+
+image: TEST_DIR/t.IMGFMT.mid
+file format: IMGFMT
+virtual size: 64 MiB (67108864 bytes)
+backing file: TEST_DIR/t.IMGFMT.base
+
+image: TEST_DIR/t.IMGFMT.base
+file format: IMGFMT
+virtual size: 64 MiB (67108864 bytes)
+*** done

tests/qemu-iotests/group

@@ -286,3 +286,4 @@
 272 rw
 273 backing quick
 277 rw quick
+279 rw backing quick