Override releasever_{major,minor} with provides

The releasever_major and releasever_minor substitution variables are
usually derived by splitting releasever on the first `.`. However, to
support EPEL 10 [1], we would like a way for distributions to override these
values. Specifically, we would like RHEL 10 to have a releasever of `10`
with a releasever_major of `10` and a releasever_minor of `0` (later
incrementing to `1`, `2`, to correspond with the RHEL minor version).

This commit adds a new API function, `detect_releasevers`, which derives
releasever, releasever_major, and releasever_minor from virtual provides
on the system-release package (any of `DISTROVERPKG`). The detection of
releasever is unchanged. releasever_major and releasever_minor are
specified by the versions of the `system-release-major` and
`system-release-minor` provides, respectively.

If the user specifies a `--releasever=X.Y` on the command line, the
distribution settings for releasever, releasever_major, and releasever_minor
will all be overridden: releasever will be set to X.Y, releasever_major will be
set to X, and releasever_minor will be set to Y, same as before.  If a user
wants to specify a custom releasever_major and releasever_minor, they have to
set all three with `--setopt=releasever=X --setopt=releasever_major=Y
--setopt=releasever_minor=z`, taking care to put `releasever_major` and
`releasever_minor` after `releasever` so they are not overridden.

[1] https://issues.redhat.com/browse/RHEL-68034

dnf/base.py

@@ -157,8 +157,14 @@ def _setup_default_conf():
         conf = dnf.conf.Conf()
         subst = conf.substitutions
         if 'releasever' not in subst:
-            subst['releasever'] = \
-                dnf.rpm.detect_releasever(conf.installroot)
+            releasever, major, minor = \
+                dnf.rpm.detect_releasevers(conf.installroot)
+            subst['releasever'] = releasever
+            if major is not None:
+                subst['releasever_major'] = major
+            if minor is not None:
+                subst['releasever_minor'] = minor
+
         return conf
 
     def _setup_modular_excludes(self):

dnf/cli/cli.py

@@ -951,13 +951,20 @@ def _read_conf_file(self, releasever=None):
             from_root = "/"
         subst = conf.substitutions
         subst.update_from_etc(from_root, varsdir=conf._get_value('varsdir'))
+
         # cachedir, logs, releasever, and gpgkey are taken from or stored in installroot
+        major = None
+        minor = None
         if releasever is None and conf.releasever is None:
-            releasever = dnf.rpm.detect_releasever(conf.installroot)
+            releasever, major, minor = dnf.rpm.detect_releasevers(conf.installroot)
         elif releasever == '/':
-            releasever = dnf.rpm.detect_releasever(releasever)
+            releasever, major, minor = dnf.rpm.detect_releasevers(releasever)
         if releasever is not None:
             conf.releasever = releasever
+            if major is not None:
+                conf.releasever_major = major
+            if minor is not None:
+                conf.releasever_minor = minor
         if conf.releasever is None:
             logger.warning(_("Unable to detect release version (use '--releasever' to specify "
                              "release version)"))

dnf/const.py.in

@@ -25,6 +25,8 @@ CONF_AUTOMATIC_FILENAME='/etc/dnf/automatic.conf'
 DISTROVERPKG=('system-release(releasever)', 'system-release',
               'distribution-release(releasever)', 'distribution-release',
               'redhat-release', 'suse-release')
+DISTROVER_MAJOR_PKG='system-release(releasever_major)'
+DISTROVER_MINOR_PKG='system-release(releasever_minor)'
 GROUP_PACKAGE_TYPES = ('mandatory', 'default', 'conditional') # :api
 INSTALLONLYPKGS=['kernel', 'kernel-PAE',
                  'installonlypkg(kernel)',

dnf/rpm/__init__.py

@@ -26,12 +26,21 @@
 import rpm  # used by ansible (dnf.rpm.rpm.labelCompare in lib/ansible/modules/packaging/os/dnf.py)
 
 
-def detect_releasever(installroot):
+def detect_releasevers(installroot):
     # :api
-    """Calculate the release version for the system."""
+    """Calculate the release version for the system, including releasever_major
+    and releasever_minor if they are overriden by the system-release-major or
+    system-release-minor provides."""
 
     ts = transaction.initReadOnlyTransaction(root=installroot)
     ts.pushVSFlags(~(rpm._RPMVSF_NOSIGNATURES | rpm._RPMVSF_NODIGESTS))
+
+    distrover_major_pkg = dnf.const.DISTROVER_MAJOR_PKG
+    distrover_minor_pkg = dnf.const.DISTROVER_MINOR_PKG
+    if dnf.pycomp.PY3:
+        distrover_major_pkg = bytes(distrover_major_pkg, 'utf-8')
+        distrover_minor_pkg = bytes(distrover_minor_pkg, 'utf-8')
+
     for distroverpkg in dnf.const.DISTROVERPKG:
         if dnf.pycomp.PY3:
             distroverpkg = bytes(distroverpkg, 'utf-8')
@@ -47,6 +56,8 @@ def detect_releasever(installroot):
             msg = 'Error: rpmdb failed to list provides. Try: rpm --rebuilddb'
             raise dnf.exceptions.Error(msg)
         releasever = hdr['version']
+        releasever_major = None
+        releasever_minor = None
         try:
             try:
                 # header returns bytes -> look for bytes
@@ -61,15 +72,39 @@ def detect_releasever(installroot):
                 if hdr['name'] not in (distroverpkg, distroverpkg.decode("utf8")):
                     # override the package version
                     releasever = ver
+
+            for provide, flag, ver in zip(
+                    hdr[rpm.RPMTAG_PROVIDENAME],
+                    hdr[rpm.RPMTAG_PROVIDEFLAGS],
+                    hdr[rpm.RPMTAG_PROVIDEVERSION]):
+                if isinstance(provide, str):
+                    provide = bytes(provide, "utf-8")
+                if provide == distrover_major_pkg and flag == rpm.RPMSENSE_EQUAL and ver:
+                    releasever_major = ver
+                if provide == distrover_minor_pkg and flag == rpm.RPMSENSE_EQUAL and ver:
+                    releasever_minor = ver
+
         except (ValueError, KeyError, IndexError):
             pass
 
         if is_py3bytes(releasever):
             releasever = str(releasever, "utf-8")
-        return releasever
+        if is_py3bytes(releasever_major):
+            releasever_major = str(releasever_major, "utf-8")
+        if is_py3bytes(releasever_minor):
+            releasever_minor = str(releasever_minor, "utf-8")
+        return releasever, releasever_major, releasever_minor
     return None
 
 
+def detect_releasever(installroot):
+    # :api
+    """Calculate the release version for the system."""
+
+    releasever, _, _ = detect_releasevers(installroot)
+    return releasever
+
+
 def _header(path):
     """Return RPM header of the file."""
     ts = transaction.initReadOnlyTransaction()