Split $releasever to $releasever_major and $releasever_minor

Whenever the `releasever` substitution variable is set, automatically
derive and set the `releasever_major` and `releasever_minor` vars by
splitting `releasever` on the first ".".

Companion to the DNF 5 implementation here: rpm-software-management/dnf5#800

DNF 5 issue: rpm-software-management/dnf5#710

For https://bugzilla.redhat.com/show_bug.cgi?id=1789346

dnf/conf/substitutions.py

@@ -23,8 +23,10 @@
 import re
 
 from dnf.i18n import _
+from dnf.exceptions import ReadOnlyVariableError
 
 ENVIRONMENT_VARS_RE = re.compile(r'^DNF_VAR_[A-Za-z0-9_]+$')
+READ_ONLY_VARIABLES = frozenset(("releasever_major", "releasever_minor"))
 logger = logging.getLogger('dnf')
 
 
@@ -43,6 +45,35 @@ def _update_from_env(self):
  elif key in numericvars:
  self[key] = val
 
+ @staticmethod
+ def _split_releasever(releasever):
+ # type: (str) -> tuple[str, str]
+ pos = releasever.find(".")
+ if pos == -1:
+ releasever_major = releasever
+ releasever_minor = ""
+ else:
+ releasever_major = releasever[:pos]
+ releasever_minor = releasever[pos + 1:]
+ return releasever_major, releasever_minor
+
+ def __setitem__(self, key, value):
+ if Substitutions.is_read_only(key):
+ raise ReadOnlyVariableError(f"Variable \"{key}\" is read-only", variable_name=key)
+
+ setitem = super(Substitutions, self).__setitem__
+ setitem(key, value)
+
+ if key == "releasever" and value:
+ releasever_major, releasever_minor = Substitutions._split_releasever(value)
+ setitem("releasever_major", releasever_major)
+ setitem("releasever_minor", releasever_minor)
+
+ @staticmethod
+ def is_read_only(key):
+ # type: (str) -> bool
+ return key in READ_ONLY_VARIABLES
+
  def update_from_etc(self, installroot, varsdir=("/etc/yum/vars/", "/etc/dnf/vars/")):
  # :api
 

dnf/exceptions.py

@@ -180,6 +180,12 @@ def __reduce__(self):
  return (ProcessLockError, (self.value, self.pid))
 
 
+class ReadOnlyVariableError(Error):
+ def __init__(self, value, variable_name):
+ super(ReadOnlyVariableError, self).__init__(value)
+ self.variable_name = variable_name
+
+
 class RepoError(Error):
  # :api
  pass

tests/conf/test_substitutions.py

@@ -23,6 +23,8 @@
 import os
 
 import dnf.conf
+from dnf.conf.substitutions import Substitutions
+from dnf.exceptions import ReadOnlyVariableError
 
 import tests.support
 
@@ -52,3 +54,33 @@ def test_named(self):
  conf.substitutions.keys(),
  ['basearch', 'arch', 'GENRE', 'EMPTY'])
  self.assertEqual('opera', conf.substitutions['GENRE'])
+
+
+class SubstitutionsReadOnlyTest(tests.support.TestCase):
+ def test_set_readonly(self):
+ conf = dnf.conf.Conf()
+ variable_name = "releasever_major"
+ self.assertTrue(Substitutions.is_read_only(variable_name))
+ with self.assertRaises(ReadOnlyVariableError) as cm:
+ conf.substitutions["releasever_major"] = "1"
+ self.assertEqual(cm.exception.variable_name, "releasever_major")
+
+
+class SubstitutionsReleaseverTest(tests.support.TestCase):
+ def test_releasever_simple(self):
+ conf = dnf.conf.Conf()
+ conf.substitutions["releasever"] = "1.23"
+ self.assertEqual(conf.substitutions["releasever_major"], "1")
+ self.assertEqual(conf.substitutions["releasever_minor"], "23")
+
+ def test_releasever_major_only(self):
+ conf = dnf.conf.Conf()
+ conf.substitutions["releasever"] = "123"
+ self.assertEqual(conf.substitutions["releasever_major"], "123")
+ self.assertEqual(conf.substitutions["releasever_minor"], "")
+
+ def test_releasever_multipart(self):
+ conf = dnf.conf.Conf()
+ conf.substitutions["releasever"] = "1.23.45"
+ self.assertEqual(conf.substitutions["releasever_major"], "1")
+ self.assertEqual(conf.substitutions["releasever_minor"], "23.45")