Do not restore old backups when the upgrade fails

The backup only will be restored when the ID and VERSION_ID matches in
both, the current and backed os-release file.

src/modules/Update.rb

@@ -809,19 +809,60 @@ def clean_backup
       ::FileUtils.rm_r(File.join(Installation.destdir, BACKUP_DIR), :force => true, :secure => true)
     end
 
-    # restores backup
+    # Restores the available backup(s)
+    #
+    # If the VERSION_ID in the backup os-release file matches with the value stored in
+    # /etc/os-release (see bsc#1097297), the available backup scripts (restores-*.sh) will be
+    # executed **in the expected order** (see bsc#1089643).
+    #
+    # @see #restore_backup?
     def restore_backup
-      log.info "Restoring backup"
-      mounted_root = Installation.destdir
-      script_glob = File.join(mounted_root, BACKUP_DIR,"restore-*.sh")
-      # sort the scripts to execute them in the expected order
-      ::Dir.glob(script_glob).sort.each do |path|
-        cmd = "sh #{path} #{File.join("/", mounted_root)}"
-        res = SCR.Execute(path(".target.bash_output"), cmd)
-        log.info "Restoring with script #{cmd} result: #{res}"
+      if restore_backup?
+        log.info "Restoring backup"
+
+        mounted_root = Installation.destdir
+        available_restore_scripts = ::Dir.glob(File.join(mounted_root, BACKUP_DIR, "restore-*.sh"))
+
+        available_restore_scripts.sort.each do |path|
+          cmd = "sh #{path} #{File.join("/", mounted_root)}"
+          res = SCR.Execute(path(".target.bash_output"), cmd)
+
+          log.info "Restoring with script #{cmd} result: #{res}"
+        end
+      else
+        log.error "Backup was not restored because its version info does not match"
       end
     end
 
+    # Check if backup must be restored, based on the version info (bsc#1097297)
+    #
+    # @see #version_from
+    #
+    # @return [Boolean] true if update and backup have the same VERSION_ID; false otherwise
+    def restore_backup?
+      current_release = Pathname.new("#{Installation.destdir}/etc/os-release")
+      backed_release = Pathname.new("#{Installation.destdir}/#{BACKUP_DIR}/os-release")
+
+      version_from(current_release) == version_from(backed_release)
+    end
+
+    # Returns the ID and VERSION_ID from given file
+    #
+    # @see https://www.freedesktop.org/software/systemd/man/os-release.html
+    #
+    # @param file [File|Pathname] Operating system identification file
+    #
+    # @return [String] a string holding the ID and VERSION_ID or empty if something went wrong
+    def version_from(file)
+      content = file.read
+      id = content[/^ID=.*/].split("=", 2).last
+      version_id = content[/^VERSION_ID=.*/].split("=", 2).last
+
+      "#{id}-#{version_id}"
+    rescue
+      ""
+    end
+
     publish :variable => :packages_to_install, :type => "integer"
     publish :variable => :packages_to_update, :type => "integer"
     publish :variable => :packages_to_remove, :type => "integer"

test/data/etc/leap-15-os-release

@@ -0,0 +1,11 @@
+NAME="openSUSE Leap"
+VERSION="15.0"
+ID="opensuse-leap"
+ID_LIKE="suse opensuse"
+VERSION_ID="15.0"
+PRETTY_NAME="openSUSE Leap 15.0"
+ANSI_COLOR="0;32"
+CPE_NAME="cpe:/o:opensuse:leap:15.0"
+BUG_REPORT_URL="https://bugs.opensuse.org"
+HOME_URL="https://www.opensuse.org/"
+

test/data/etc/tw-os-release

@@ -0,0 +1,11 @@
+NAME="openSUSE Tumbleweed"
+VERSION="20180911"
+ID="opensuse-tumbleweed"
+ID_LIKE="opensuse suse"
+VERSION_ID="20180911"
+PRETTY_NAME="openSUSE Tumbleweed"
+ANSI_COLOR="0;32"
+CPE_NAME="cpe:/o:opensuse:tumbleweed:20180911"
+BUG_REPORT_URL="https://bugs.opensuse.org"
+HOME_URL="https://www.opensuse.org/"
+

test/update_test.rb

@@ -151,17 +151,63 @@ def default_SetDesktopPattern_stubs
   end
 
   describe "#restore_backup" do
-    it "call all restore scripts in backup directory" do
-      expect(::Dir).to receive(:glob).and_return(["restore-a.sh", "restore-b.sh"])
-      expect(Yast::SCR).to receive(:Execute).with(Yast::Path.new(".target.bash_output"), /sh .*restore-a.sh \/mnt/).
-        and_return({"exit" => 0})
-      expect(Yast::SCR).to receive(:Execute).with(Yast::Path.new(".target.bash_output"), /sh .*restore-b.sh \/mnt/).
-        and_return({"exit" => 0})
+    let(:os_release_pathname) { double }
+    let(:os_backup_release_pathname) { double }
+    let(:os_release_content) { File.new("#{DATA_DIR}/etc/leap-15-os-release").read }
+    let(:os_backup_release_content) { File.new("#{DATA_DIR}/etc/tw-os-release").read }
+
+    before do
+      allow(::Dir).to receive(:glob).and_return(["restore-a.sh", "restore-b.sh"])
+
+      allow(Pathname).to receive(:new)
+        .with("#{Yast::Installation.destdir}/etc/os-release")
+        .and_return(os_release_pathname)
+      allow(Pathname).to receive(:new)
+        .with("#{Yast::Installation.destdir}/#{Yast::UpdateClass::BACKUP_DIR}/os-release")
+        .and_return(os_backup_release_pathname)
+      allow(os_release_pathname).to receive(:read).and_return(os_release_content)
+      allow(os_backup_release_pathname).to receive(:read).and_return(os_backup_release_content)
+    end
+
+    it "check the release info files" do
+      expect(Pathname).to receive(:new)
+        .with("#{Yast::Installation.destdir}/etc/os-release")
+      expect(Pathname).to receive(:new)
+        .with("#{Yast::Installation.destdir}/#{Yast::UpdateClass::BACKUP_DIR}/os-release")
 
       Yast::Update.restore_backup
     end
-  end
 
+    context "when the release info match" do
+      let(:os_backup_release_content) { os_release_content }
+
+      it "call all restore scripts in backup directory" do
+        expect(Yast::SCR).to receive(:Execute)
+          .with(Yast::Path.new(".target.bash_output"), /sh .*restore-a.sh \/mnt/)
+        expect(Yast::SCR).to receive(:Execute)
+          .with(Yast::Path.new(".target.bash_output"), /sh .*restore-b.sh \/mnt/)
+
+        Yast::Update.restore_backup
+      end
+    end
+
+    context "when the release info does not match" do
+      it "logs an error" do
+        expect(Yast::Update.log).to receive(:error).with(/not restored/)
+
+        Yast::Update.restore_backup
+      end
+
+      it "does not continue" do
+        expect(Yast::SCR).to_not receive(:Execute)
+          .with(Yast::Path.new(".target.bash_output"), /sh .*restore-a.sh \/mnt/)
+        expect(Yast::SCR).to_not receive(:Execute)
+          .with(Yast::Path.new(".target.bash_output"), /sh .*restore-b.sh \/mnt/)
+
+        Yast::Update.restore_backup
+      end
+    end
+  end
 
   describe "#SetDesktopPattern" do
     context "if there is no definition of window manager upgrade path in control file" do