Avoid moving old, user-modified qrexec policy to .rpmsave files

Keep it at original files, to still load it using compat rules.
This way the update should not break user's policies.

Note the unchanged policy files are still going to be removed - meaning
those calls will use the new policy.

QubesOS/qubes-issues#4370

rpm_spec/core-dom0.spec.in

@@ -190,6 +190,148 @@ if [ "$1" = 0 ] ; then
     groupdel qubes
 fi
 
+%posttrans
+
+# Preserve user-modified legacy policy at original location, revert rpm adding
+# .rpmsave suffix. This needs to be done in %%posttrans, to be run after
+# uninstalling the old package.
+
+# List policy files explicitly, to not touch files from other packages.
+SERVICES="
+admin.Events
+admin.backup.Cancel
+admin.backup.Execute
+admin.backup.Info
+admin.deviceclass.List
+admin.label.Create
+admin.label.Get
+admin.label.Index
+admin.label.List
+admin.label.Remove
+admin.pool.Add
+admin.pool.Info
+admin.pool.List
+admin.pool.ListDrivers
+admin.pool.Remove
+admin.pool.Set.revisions_to_keep
+admin.pool.UsageDetails
+admin.pool.volume.List
+admin.property.Get
+admin.property.GetAll
+admin.property.GetDefault
+admin.property.Help
+admin.property.List
+admin.property.Reset
+admin.property.Set
+admin.vm.Console
+admin.vm.Create.AppVM
+admin.vm.Create.DispVM
+admin.vm.Create.StandaloneVM
+admin.vm.Create.TemplateVM
+admin.vm.CreateDisposable
+admin.vm.CreateInPool.AppVM
+admin.vm.CreateInPool.DispVM
+admin.vm.CreateInPool.StandaloneVM
+admin.vm.CreateInPool.TemplateVM
+admin.vm.CurrentState
+admin.vm.Kill
+admin.vm.List
+admin.vm.Pause
+admin.vm.Remove
+admin.vm.Shutdown
+admin.vm.Start
+admin.vm.Stats
+admin.vm.Unpause
+admin.vm.device.block.Attach
+admin.vm.device.block.Available
+admin.vm.device.block.Detach
+admin.vm.device.block.List
+admin.vm.device.block.Set.persistent
+admin.vm.device.pci.Attach
+admin.vm.device.pci.Available
+admin.vm.device.pci.Detach
+admin.vm.device.pci.List
+admin.vm.device.pci.Set.persistent
+admin.vm.feature.CheckWithAdminVM
+admin.vm.feature.CheckWithNetvm
+admin.vm.feature.CheckWithTemplate
+admin.vm.feature.CheckWithTemplateAndAdminVM
+admin.vm.feature.Get
+admin.vm.feature.List
+admin.vm.feature.Remove
+admin.vm.feature.Set
+admin.vm.firewall.Get
+admin.vm.firewall.Reload
+admin.vm.firewall.Set
+admin.vm.property.Get
+admin.vm.property.GetAll
+admin.vm.property.GetDefault
+admin.vm.property.Help
+admin.vm.property.List
+admin.vm.property.Reset
+admin.vm.property.Set
+admin.vm.tag.Get
+admin.vm.tag.List
+admin.vm.tag.Remove
+admin.vm.tag.Set
+admin.vm.volume.CloneFrom
+admin.vm.volume.CloneTo
+admin.vm.volume.Import
+admin.vm.volume.ImportWithSize
+admin.vm.volume.Info
+admin.vm.volume.List
+admin.vm.volume.ListSnapshots
+admin.vm.volume.Resize
+admin.vm.volume.Revert
+admin.vm.volume.Set.revisions_to_keep
+admin.vm.volume.Set.rw
+admin.vmclass.List
+include/admin-global-ro
+include/admin-global-rwx
+include/admin-local-ro
+include/admin-local-rwx
+policy.RegisterArgument
+qubes.ConnectTCP
+qubes.FeaturesRequest
+qubes.Filecopy
+qubes.GetDate
+qubes.GetImageRGBA
+qubes.GetRandomizedTime
+qubes.NotifyTools
+qubes.NotifyUpdates
+qubes.OpenInVM
+qubes.OpenURL
+qubes.StartApp
+qubes.UpdatesProxy
+qubes.VMExec
+qubes.VMExecGUI
+qubes.VMRootShell
+qubes.VMShell
+"
+
+for service in $SERVICES; do
+    if [ -f "/etc/qubes-rpc/policy/$service.rpmsave" ] && \
+            ! [ -e "/etc/qubes-rpc/policy/$service" ]; then
+        mv -n "/etc/qubes-rpc/policy/$service.rpmsave" \
+            "/etc/qubes-rpc/policy/$service"
+    fi
+done
+
+# Take extra care about policy files in include/ - if any of them is gone
+# (because unmodified) but user still reference them anywhere, the policy
+# loading will be broken. Check for this case, and avoid the issue by creating
+# a symlink to the new policy.
+
+INCLUDES="admin-global-ro admin-global-rwx admin-local-ro admin-local-rwx"
+
+for include in $INCLUDES; do
+    if grep -qr "include/$include" /etc/qubes-rpc && \
+            ! [ -e "/etc/qubes-rpc/policy/include/$include" ]; then
+        ln -s "../../../qubes/policy.d/include/$include" \
+            "/etc/qubes-rpc/policy/include/$include"
+    fi
+done
+
 %files
 %defattr(-,root,root,-)
 %config(noreplace) %attr(0664,root,qubes) %{_sysconfdir}/qubes/qmemman.conf