Support for {reinstall,downgrade,upgrade} operations.

Requires QubesOS/qubes-issues#5946 to be resolved.

qubesadmin/tools/qvm_template.py

@@ -74,6 +74,12 @@ class TemplateState(enum.Enum):
     EXTRA = 'extra'
     UPGRADABLE = 'upgradable'
 
+class VersionSelector(enum.Enum):
+    LATEST = enum.auto()
+    REINSTALL = enum.auto()
+    LATEST_LOWER = enum.auto()
+    LATEST_HIGHER = enum.auto()
+
 # NOTE: Verifying RPMs this way is prone to TOCTOU. This is okay for local
 # files, but may create problems if multiple instances of `qvm-template` are
 # downloading the same file, so a lock is needed in that case.
@@ -117,7 +123,8 @@ def parse_config(path):
     with open(path, 'r') as fd:
         return dict(line.rstrip('\n').split('=', 1) for line in fd)
 
-def install(args, app):
+def install(args, app, version_selector=VersionSelector.LATEST,
+        ignore_existing=False):
     # TODO: Lock, mentioned in the note above
     transaction_set = rpm.TransactionSet()
 
@@ -130,11 +137,11 @@ def install(args, app):
 
     os.makedirs(args.cachedir, exist_ok=True)
 
-    dl_list = get_dl_list(args, app)
+    dl_list = get_dl_list(args, app, version_selector=version_selector)
     dl_list_copy = dl_list.copy()
     # Verify that the templates are not yet installed
     for name, (ver, _) in dl_list.items():
-        if name in app.domains:
+        if not ignore_existing and name in app.domains:
             print(('Template \'%s\' already installed, skipping...'
                 ' (You may want to use the {reinstall,upgrade,downgrade}'
                 ' operations.)') % name, file=sys.stderr)
@@ -147,7 +154,8 @@ def install(args, app):
     dl_list = dl_list_copy
 
     download(args, app, path_override=args.cachedir,
-        dl_list=dl_list, suffix=UNVERIFIED_SUFFIX)
+        dl_list=dl_list, suffix=UNVERIFIED_SUFFIX,
+        version_selector=version_selector)
 
     for rpmfile in rpm_list:
         path = rpmfile + UNVERIFIED_SUFFIX
@@ -166,7 +174,7 @@ def install(args, app):
             name = package_name[len(PACKAGE_NAME_PREFIX):]
 
             # Another check for already-downloaded RPMs
-            if name in app.domains:
+            if not ignore_existing and name in app.domains:
                 print(('Template \'%s\' already installed, skipping...'
                     ' (You may want to use the {reinstall,upgrade,downgrade}'
                     ' operations.)') % name, file=sys.stderr)
@@ -342,28 +350,81 @@ def do_list(args, app):
 
     qubesadmin.tools.print_table(tpl_list)
 
-def get_dl_list(args, app):
-    candid = {}
+def get_dl_list(args, app, version_selector=VersionSelector.LATEST):
+    full_candid = {}
     for template in args.templates:
+        # This will be merged into `full_candid` later.
+        # It is separated so that we can check whether it is empty.
+        candid = {}
+
         # Skip local RPMs
         if template.endswith('.rpm'):
             continue
+
         query_res = qrexec_repoquery(args, app, PACKAGE_NAME_PREFIX + template)
-        if len(query_res) == 0:
-            parser.error('Package \'%s\' not found.' % template)
-            sys.exit(1)
-        # We only select one (latest) package for each distinct package name
+
+        # We only select one package for each distinct package name
         #pylint: disable=unused-variable
         for name, epoch, version, release, reponame, dlsize, summary \
                 in query_res:
             ver = (epoch, version, release)
-            if name not in candid or rpm.labelCompare(candid[name], ver) < 0:
-                candid[name] = (ver, int(dlsize))
+            if version_selector == VersionSelector.LATEST:
+                if name not in candid \
+                        or rpm.labelCompare(candid[name], ver) < 0:
+                    candid[name] = (ver, int(dlsize))
+            elif version_selector == VersionSelector.REINSTALL:
+                if name not in app.domains:
+                    parser.error("Template '%s' not installed." % name)
+                vm = app.domains[name]
+                cur_ver = (
+                    vm.features['template-epoch'],
+                    vm.features['template-version'],
+                    vm.features['template-release'])
+                if rpm.labelCompare(ver, cur_ver) == 0:
+                    candid[name] = (ver, int(dlsize))
+            elif version_selector in [VersionSelector.LATEST_LOWER,
+                    VersionSelector.LATEST_HIGHER]:
+                if name not in app.domains:
+                    parser.error("Template '%s' not installed." % name)
+                vm = app.domains[name]
+                cur_ver = (
+                    vm.features['template-epoch'],
+                    vm.features['template-version'],
+                    vm.features['template-release'])
+                cmp_res = -1 \
+                        if version_selector == VersionSelector.LATEST_LOWER \
+                        else 1
+                if rpm.labelCompare(ver, cur_ver) == cmp_res:
+                    if name not in candid \
+                            or rpm.labelCompare(candid[name], ver) < 0:
+                        candid[name] = (ver, int(dlsize))
+
+        if len(candid) == 0:
+            if version_selector == VersionSelector.LATEST:
+                parser.error('Template \'%s\' not found.' % template)
+            elif version_selector == VersionSelector.REINSTALL:
+                parser.error('Same version of template \'%s\' not found.' \
+                    % template)
+            elif version_selector == VersionSelector.LATEST_LOWER:
+                parser.error('Lower version of template \'%s\' not found.' \
+                    % template)
+            elif version_selector == VersionSelector.LATEST_HIGHER:
+                parser.error('Higher version of template \'%s\' not found.' \
+                    % template)
+            sys.exit(1)
+
+        # Merge & choose the template with the highest version
+        for name, (ver, dlsize) in candid.items():
+            if name not in full_candid \
+                    or rpm.labelCompare(full_candid[name], ver) < 0:
+                full_candid[name] = (ver, dlsize)
+
     return candid
 
-def download(args, app, path_override=None, dl_list=None, suffix=''):
+def download(args, app, path_override=None,
+        dl_list=None, suffix='', version_selector=VersionSelector.LATEST):
     if dl_list is None:
-        dl_list = get_dl_list(args, app)
+        dl_list = get_dl_list(args, app, version_selector=version_selector)
 
     path = path_override if path_override is not None else args.downloaddir
     for name, (ver, dlsize) in dl_list.items():
@@ -416,6 +477,15 @@ def main(args=None, app=None):
 
     if args.operation == 'install':
         install(args, app)
+    elif args.operation == 'reinstall':
+        install(args, app, version_selector=VersionSelector.REINSTALL,
+            ignore_existing=True)
+    elif args.operation == 'downgrade':
+        install(args, app, version_selector=VersionSelector.LATEST_LOWER,
+            ignore_existing=True)
+    elif args.operation == 'upgrade':
+        install(args, app, version_selector=VersionSelector.LATEST_HIGHER,
+            ignore_existing=True)
     elif args.operation == 'list':
         do_list(args, app)
     elif args.operation == 'download':