iotests.py: qemu_img*("create"): support IMGOPTS='compression_type=zstd'

Adding support of IMGOPTS (like in bash tests) allows user to pass a
lot of different options. Still, some may require additional logic.

Now we want compression_type option, so add some smart logic around it:
ignore compression_type=zstd in IMGOPTS, if test want qcow2 in
compatibility mode. As well, ignore compression_type for non-qcow2
formats.

Note that we may instead add support only to qemu_img_create(), but
that works bad:

1. We'll have to update a lot of tests to use qemu_img_create instead
   of qemu_img('create'). (still, we may want do it anyway, but no
   reason to create a dependancy between task of supporting IMGOPTS and
   updating a lot of tests)

2. Some tests use qemu_img_pipe('create', ..) - even more work on
   updating

3. Even if we update all tests to go through qemu_img_create, we'll
   need a way to avoid creating new tests using qemu_img*('create') -
   add assertions.. That doesn't seem good.

So, let's add support of IMGOPTS to most generic
qemu_img_pipe_and_status().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20211223160144.1097696-5-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

tests/qemu-iotests/iotests.py

@@ -16,6 +16,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 
+import argparse
 import atexit
 import bz2
 from collections import OrderedDict
@@ -161,11 +162,35 @@ def qemu_tool_pipe_and_status(tool: str, args: Sequence[str],
                                {-subp.returncode}: {cmd}\n')
         return (output, subp.returncode)
 
+def qemu_img_create_prepare_args(args: List[str]) -> List[str]:
+    if not args or args[0] != 'create':
+        return list(args)
+    args = args[1:]
+
+    p = argparse.ArgumentParser(allow_abbrev=False)
+    p.add_argument('-f')
+    parsed, remaining = p.parse_known_args(args)
+
+    result = ['create']
+    if parsed.f is not None:
+        result += ['-f', parsed.f]
+
+    # IMGOPTS most probably contain options specific for the selected format,
+    # like extended_l2 or compression_type for qcow2. Test may want to create
+    # additional images in other formats that doesn't support these options.
+    # So, use IMGOPTS only for images created in imgfmt format.
+    if parsed.f == imgfmt and 'IMGOPTS' in os.environ:
+        result += ['-o', os.environ['IMGOPTS']]
+
+    result += remaining
+
+    return result
+
 def qemu_img_pipe_and_status(*args: str) -> Tuple[str, int]:
     """
     Run qemu-img and return both its output and its exit code
     """
-    full_args = qemu_img_args + list(args)
+    full_args = qemu_img_args + qemu_img_create_prepare_args(list(args))
     return qemu_tool_pipe_and_status('qemu-img', full_args)
 
 def qemu_img(*args: str) -> int: