avocado.utils.kernel: fix kernel version parsing

This fixes two problems with the current version parse mechanism:

 1. Recent setuptools' version parse function, which has dropped
    "LegacyVersion" support, raises an InvalidVersion exception
    for common kernel version info as presented by the system and
    returned by os.uname()

 2. The import of the packaging module is broken on systems with no
    setuptools and only the "packaging" module.

This introduces a simple but custom version parse that solves both and
simplifies dependencies.

Fixes: #6058
Signed-off-by: Cleber Rosa <[email protected]>

avocado/utils/kernel.py

@@ -20,14 +20,10 @@
 import logging
 import multiprocessing
 import os
+import re
 import shutil
 import tempfile
 
-try:
-    import packaging
-except ImportError:
-    from pkg_resources import packaging
-
 from avocado.utils import archive, asset, build, distro, process
 
 LOG = logging.getLogger(__name__)
@@ -201,6 +197,14 @@ def __del__(self):
         shutil.rmtree(self.work_dir)
 
 
+def _parse_kernel_version(version):
+    match = re.match(r"(\d+)\.(\d+)\.(\d+)-(\d+).*", version)
+    if match:
+        return tuple(map(int, match.groups()))
+    else:
+        raise AssertionError(f'Malformed kernel version "{version}"')
+
+
 def check_version(version):
     """
     This utility function compares the current kernel version with
@@ -210,6 +214,6 @@ def check_version(version):
     :type version: string
     :param version: version to be compared with current kernel version
     """
-    os_version = packaging.version.parse(os.uname()[2])
-    version = packaging.version.parse(version)
+    os_version = _parse_kernel_version(os.uname()[2])
+    version = _parse_kernel_version(version)
     assert os_version > version, "Old kernel"

selftests/check.py

@@ -27,7 +27,7 @@
     "job-api-7": 1,
     "nrunner-interface": 70,
     "nrunner-requirement": 28,
-    "unit": 678,
+    "unit": 681,
     "jobs": 11,
     "functional-parallel": 314,
     "functional-serial": 7,

selftests/unit/utils/kernel.py

@@ -1,6 +1,6 @@
 import unittest
 
-from avocado.utils.kernel import KernelBuild
+from avocado.utils.kernel import KernelBuild, _parse_kernel_version
 from selftests.utils import setup_avocado_loggers
 
 setup_avocado_loggers()
@@ -25,3 +25,15 @@ def test_build_overrided_url(self):
     def tearDown(self):
         # To make sure that the temporary workdir is cleaned up
         del self.kernel
+
+
+class Version(unittest.TestCase):
+    def test_basic(self):
+        self.assertEqual(_parse_kernel_version("1.2.3-100"), (1, 2, 3, 100))
+
+    def test_uname(self):
+        self.assertEqual(_parse_kernel_version("9.0.1-100.fc50.x86_64"), (9, 0, 1, 100))
+
+    def test_malformed_incomplete(self):
+        with self.assertRaises(AssertionError):
+            _parse_kernel_version("1.2")