[Installer] Graceful close and a way out of a stuck update (#7687)

* [Installer] Stop calling the payload free while an executable is locked

The guard answered "nothing is holding the payload" from two lookups that can
both miss a running instance: Restart Manager does not reliably report a
program's own image or the modules it mapped, and the image path of a process
running under another account cannot be read from the probe at all. A user log
showed exactly that: the first guard passed while cockatrice.exe was running
from the directory, the old uninstaller silently skipped the file it could not
delete, and the update aborted half an uninstall later with "cancelled by user"
after a close attempt the running window ignored.

Ask the file itself. A running image is opened without write sharing, so the
write open replacing it needs is refused with ERROR_SHARING_VIOLATION for as
long as the program runs, while a file that is merely being read still accepts
it. When neither lookup named anybody and a payload executable refuses that
open, the probe answers that the file is in use and that the program holding it
could not be identified - the guard's "could not confirm" dialog, whose Retry
works once the user has closed it - instead of passing the payload as free.

Only the payload executables are tested, not every file the purge removes: a
locked executable proves a program is running and a mapped DLL belongs to a
running executable, while a locked DLL or qt.conf can be the asking process
itself, which is the loop the guard already had. The open is retried once after
300 ms, and only for the files that refused, so a scanner holding a file for a
moment cannot stop an install for nothing.

The Windows probe check now covers that answer: a payload executable held by
the asking process, so that it cannot be named, has to come back as in use
rather than as free.

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

* [Installer] Close running clients over a local socket

The installer could only ask a running client to close with WM_CLOSE, which an instance hidden in the notification area or sitting on its own confirmation cannot answer usefully. Give every client a per-process local socket and have the holder probe ask it there first, falling back to WM_CLOSE for clients from before the socket.

* [Installer] Offer to check again or update by hand when files stay locked

Replace the two-answer guard prompt with force close, close by hand and check again, or cancel. Retry the automatic close while the set of holders changes, and point a cancelled run at the latest release so a user who does not want anything killed has a way forward that is not cancelling the update again.

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

cockatrice/src/interface/window_main.cpp

@@ -986,6 +986,30 @@ bool MainWindow::closeForUpdate()
     return close();
 }
 
+void MainWindow::requestInstallerClose()
+{
+    // The same shutdown the in-app updater asks for: close the window, flush settings and let
+    // the tabs answer their own prompts. Never a forced quit - ending a process that has not
+    // agreed is the installer's separate force-close answer, not this one.
+    if (closeForUpdate()) {
+        QTimer::singleShot(0, qApp, [] { QCoreApplication::exit(0); });
+        return;
+    }
+    // A confirmation is already up, or a shutdown is in progress. Bring it forward: an
+    // installer prompt behind a hidden confirmation is the deadlock this request exists to
+    // break, and the user has to be able to answer it. showWindowIfHidden() also clears
+    // Qt::WindowMinimized, which raise() alone does not: a minimized window can keep the
+    // confirmation behind the installer.
+    showWindowIfHidden();
+    if (QWidget *modal = QApplication::activeModalWidget()) {
+        modal->raise();
+        modal->activateWindow();
+    }
+    raise();
+    activateWindow();
+    QApplication::alert(this, 0);
+}
+
 void MainWindow::changeEvent(QEvent *event)
 {
     if (event->type() == QEvent::LanguageChange) {

cockatrice/src/interface/window_main.h

@@ -255,6 +255,17 @@ public:
      */
     bool closeForUpdate();
 
+    /**
+     * @brief Closes this instance because the installer asked it to over its local socket.
+     *
+     * The request reaches an instance hidden in the notification area or sitting on its own
+     * confirmation, which is exactly where a WM_CLOSE from the installer does not. The close
+     * is still the ordinary one: a clean client exits, one with unsaved work raises the same
+     * confirmation the close button does, and a confirmation already up is brought to the
+     * front instead of being left behind the installer.
+     */
+    void requestInstallerClose();
+
 protected:
     void closeEvent(QCloseEvent *event) override;
     void changeEvent(QEvent *event) override;