[PULL 2/7] iotests: Skip read-only cases in 118 when run as root

[Kevin Wolf <kwolf@redhat.com>]

Some tests in 118 use chmod to remove write permissions from the file
and assume that the image can indeed not be opened read-write
afterwards. This doesn't work when the test is run as root, because root
can still open the file as writable even when the permission bit isn't
set.

Introduce a @skip_if_root decorator and use it in 118 to skip the tests
in question when the script is run as root.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 tests/qemu-iotests/118        |  3 +++
 tests/qemu-iotests/iotests.py | 10 ++++++++++
 2 files changed, 13 insertions(+)

diff --git a/tests/qemu-iotests/118 b/tests/qemu-iotests/118
index ea0b326ae0..e20080e9a6 100755
--- a/tests/qemu-iotests/118
+++ b/tests/qemu-iotests/118
@@ -446,6 +446,7 @@ class TestChangeReadOnly(ChangeBaseClass):
         self.assert_qmp(result, 'return[0]/inserted/ro', True)
         self.assert_qmp(result, 'return[0]/inserted/image/filename', new_img)
 
+    @iotests.skip_if_user_is_root
     def test_rw_ro_retain(self):
         os.chmod(new_img, 0o444)
         self.vm.add_drive(old_img, 'media=disk', 'none')
@@ -530,6 +531,7 @@ class TestChangeReadOnly(ChangeBaseClass):
         self.assert_qmp(result, 'return[0]/inserted/ro', True)
         self.assert_qmp(result, 'return[0]/inserted/image/filename', new_img)
 
+    @iotests.skip_if_user_is_root
     def test_make_ro_rw(self):
         os.chmod(new_img, 0o444)
         self.vm.add_drive(old_img, 'media=disk', 'none')
@@ -571,6 +573,7 @@ class TestChangeReadOnly(ChangeBaseClass):
         self.assert_qmp(result, 'return[0]/inserted/ro', True)
         self.assert_qmp(result, 'return[0]/inserted/image/filename', new_img)
 
+    @iotests.skip_if_user_is_root
     def test_make_ro_rw_by_retain(self):
         os.chmod(new_img, 0o444)
         self.vm.add_drive(old_img, 'media=disk', 'none')
diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index 693fde155a..709def4d5d 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -931,6 +931,16 @@ def skip_if_unsupported(required_formats=[], read_only=False):
         return func_wrapper
     return skip_test_decorator
 
+def skip_if_user_is_root(func):
+    '''Skip Test Decorator
+       Runs the test only without root permissions'''
+    def func_wrapper(*args, **kwargs):
+        if os.getuid() == 0:
+            case_notrun('{}: cannot be run as root'.format(args[0]))
+        else:
+            return func(*args, **kwargs)
+    return func_wrapper
+
 def execute_unittest(output, verbosity, debug):
     runner = unittest.TextTestRunner(stream=output, descriptions=True,
                                      verbosity=verbosity)
-- 
2.20.1