Question

TL;DR version:

In an InnoSetup script, how can I detect if a restart is needed because of files that were in use?

More detailed version:

I have an Inno Setup script with the following characteristics:

• the ShouldSkipPage function is implemented so that all pages (except the welcome page) are skipped unless a custom “Advanced options” checkbox on the welcome page is checked:

  function ShouldSkipPage(PageID: Integer): Boolean;
  begin
      if ((PageID = wpSelectDir) or
          (PageID = wpSelectProgramGroup) or
          (PageID = wpSelectTasks) or
          (PageID = wpFinished) or
          (PageID = wpReady)) then
      begin
          Result := not advancedCheckBox.Checked;
      end;
  end;
  

• CloseApplications and RestartApplications are set to false (*), and some files have the restartreplace and uninsrestartdelete flags, so a restart will be required to complete the installation if the files were in use

Now, if a restart is needed, I want to show the Finished page regardless of the state of the “Advanced options” checkbox, because I don’t want to cause a restart without prompting the user. So my code would be something like that:

    function ShouldSkipPage(PageID: Integer): Boolean;
    begin
        if ((PageID = wpSelectDir) or
            (PageID = wpSelectProgramGroup) or
            (PageID = wpSelectTasks) or
            (PageID = wpReady)) then
        begin
            Result := not advancedCheckBox.Checked;
        end
        else if ((PageID = wpFinished)) then
        begin
            Result := (not advancedCheckBox.Checked) and (not IsRestartNeeded);
        end
    end;

Unfortunately, there is no IsRestartNeeded function (NeedRestart exists, but it’s an event function). I spent a long time looking at the documentation, but I didn’t find any function that could give me this information.

The only option I can think of is to look at HKLM\System\CurrentControlSet\Control\Session Manager\PendingFileRenameOperations to see if it contains any of my files, but it’s a rather ugly solution…

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(*) The files I want to replace or remove are a shell extension and some DLLs used by this extension. The reason why I’m not relying on the Restart Manager is because it doesn’t seem to work with explorer.exe: the process is immediately restarted, and my files are locked again.

Answer 1

The usual recommendation is to call MakePendingFileRenameOperationsChecksum near the start of your installation process, and then again whenever you want to check whether a restart will be required. As long as it keeps returning the same value, a restart is not required.

Note that this won’t take into account “forced restarts” eg. from you implementing NeedRestart and returning true or from a component marked with the restart flag; you’re expected to be able to figure that out on your own, since you’re in control of that.