qemu-iotests: add test for backing file overriding

Test that backing.file.filename option can be parsed and override the
backing file from image (backing file reflected with "info block").
Signed-off-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

tests/qemu-iotests/051

@@ -45,7 +45,14 @@ _supported_os Linux
 function do_run_qemu()
 {
     echo Testing: "$@"
-    echo quit | $QEMU -nographic -monitor stdio -serial none "$@"
+    (
+        if ! test -t 0; then
+            while read cmd; do
+                echo $cmd
+            done
+        fi
+        echo quit
+    ) | $QEMU -nographic -monitor stdio -serial none "$@"
     echo
 }
 
@@ -57,6 +64,9 @@ function run_qemu()
 size=128M
 
 _make_test_img $size
+cp $TEST_IMG $TEST_IMG.orig
+mv $TEST_IMG $TEST_IMG.base
+_make_test_img -b $TEST_IMG.base $size
 
 echo
 echo === Unknown option ===
@@ -67,6 +77,11 @@ run_qemu -drive file=$TEST_IMG,format=qcow2,unknown_opt=on
 run_qemu -drive file=$TEST_IMG,format=qcow2,unknown_opt=1234
 run_qemu -drive file=$TEST_IMG,format=qcow2,unknown_opt=foo
 
+echo
+echo === Overriding backing file ===
+echo
+
+echo "info block" | run_qemu -drive file=$TEST_IMG,driver=qcow2,backing.file.filename=$TEST_IMG.orig -nodefaults
 
 echo
 echo === Enable and disable lazy refcounting on the command line, plus some invalid values ===

tests/qemu-iotests/051.out

 QA output created by 051
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 backing_file='TEST_DIR/t.IMGFMT.base' 
 
 === Unknown option ===
 
@@ -16,6 +17,16 @@ Testing: -drive file=TEST_DIR/t.qcow2,format=qcow2,unknown_opt=foo
 QEMU_PROG: -drive file=TEST_DIR/t.qcow2,format=qcow2,unknown_opt=foo: could not open disk image TEST_DIR/t.qcow2: Block format 'qcow2' used by device 'ide0-hd0' doesn't support the option 'unknown_opt'
 
 
+=== Overriding backing file ===
+
+Testing: -drive file=TEST_DIR/t.qcow2,driver=qcow2,backing.file.filename=TEST_DIR/t.qcow2.orig -nodefaults
+QEMU X.Y.Z monitor - type 'help' for more information
+(qemu) iininfinfoinfo info binfo blinfo bloinfo blocinfo block
+ide0-hd0: TEST_DIR/t.qcow2 (qcow2)
+    Backing file:     TEST_DIR/t.qcow2.orig (chain depth: 1)
+ [not inserted](qemu) qququiquit
+
+
 === Enable and disable lazy refcounting on the command line, plus some invalid values ===
 
 Testing: -drive file=TEST_DIR/t.qcow2,format=qcow2,lazy-refcounts=on