iotests: Add test for commit in sub directory

Add a test for committing an overlay in a sub directory to one of the
images in its backing chain, using both relative and absolute filenames.

Signed-off-by: Max Reitz <mreitz@redhat.com>

tests/qemu-iotests/020

@@ -31,6 +31,11 @@ _cleanup()
     _cleanup_test_img
     _rm_test_img "$TEST_IMG.base"
     _rm_test_img "$TEST_IMG.orig"
+
+    _rm_test_img "$TEST_DIR/subdir/t.$IMGFMT.base"
+    _rm_test_img "$TEST_DIR/subdir/t.$IMGFMT.mid"
+    _rm_test_img "$TEST_DIR/subdir/t.$IMGFMT"
+    rmdir "$TEST_DIR/subdir" &> /dev/null
 }
 trap "_cleanup; exit \$status" 0 1 2 3 15
 
@@ -139,6 +144,45 @@ $QEMU_IO -c 'writev 0 64k' "$TEST_IMG" | _filter_qemu_io
 $QEMU_IMG commit "$TEST_IMG"
 _cleanup
 
+
+echo
+echo 'Testing commit in sub-directory with relative filenames'
+echo
+
+pushd "$TEST_DIR" > /dev/null
+
+mkdir subdir
+
+TEST_IMG="subdir/t.$IMGFMT.base" _make_test_img 1M
+TEST_IMG="subdir/t.$IMGFMT.mid" _make_test_img -b "t.$IMGFMT.base" -F $IMGFMT
+TEST_IMG="subdir/t.$IMGFMT" _make_test_img -b "t.$IMGFMT.mid" -F $IMGFMT
+
+# Should work
+$QEMU_IMG commit -b "t.$IMGFMT.mid" "subdir/t.$IMGFMT"
+
+# Might theoretically work, but does not in practice (we have to
+# decide between this and the above; and since we always represent
+# backing file names as relative to the overlay, we go for the above)
+$QEMU_IMG commit -b "subdir/t.$IMGFMT.mid" "subdir/t.$IMGFMT" 2>&1 | \
+    _filter_imgfmt
+
+# This should work as well
+$QEMU_IMG commit -b "$TEST_DIR/subdir/t.$IMGFMT.mid" "subdir/t.$IMGFMT"
+
+popd > /dev/null
+
+# Now let's try with just absolute filenames
+# (This will not work with external data files, though, because when
+# using relative paths for those, qemu will always resolve them
+# relative to its CWD.  Therefore, it cannot find those data files now
+# that we left $TEST_DIR.)
+if _get_data_file '' > /dev/null; then
+    echo 'Image committed.' # Skip test
+else
+    $QEMU_IMG commit -b "$TEST_DIR/subdir/t.$IMGFMT.mid" \
+        "$TEST_DIR/subdir/t.$IMGFMT"
+fi
+
 # success, all done
 echo "*** done"
 rm -f $seq.full

tests/qemu-iotests/020.out

@@ -1083,4 +1083,14 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576 backing_file=json:{'driv
 wrote 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 qemu-img: Block job failed: No space left on device
+
+Testing commit in sub-directory with relative filenames
+
+Formatting 'subdir/t.IMGFMT.base', fmt=IMGFMT size=1048576
+Formatting 'subdir/t.IMGFMT.mid', fmt=IMGFMT size=1048576 backing_file=t.IMGFMT.base backing_fmt=IMGFMT
+Formatting 'subdir/t.IMGFMT', fmt=IMGFMT size=1048576 backing_file=t.IMGFMT.mid backing_fmt=IMGFMT
+Image committed.
+qemu-img: Did not find 'subdir/t.IMGFMT.mid' in the backing chain of 'subdir/t.IMGFMT'
+Image committed.
+Image committed.
 *** done