Bug 1685213 - Part 1: Save and access the startup shortcut. r=bytesized

A. The shell provides the startup shortcut in STARTUPINFOW when it
starts a process. If the launcher process runs, we must pass this along
to the real process being created.

B. lpTitle can be overwritten, in particular when the AUMID is set for
WinTaskbar, so save it in XREMain::XRE_mainStartup() in order to access
it later.

C. Add an accessor for the saved shortcut.

Differential Revision: https://phabricator.services.mozilla.com/D106343

Author: agashlin

browser/app/winlauncher/LauncherProcessWin.cpp

@@ -356,6 +356,15 @@ Maybe<int> LauncherMain(int& argc, wchar_t* argv[],
     }
   }
 
+  // Pass on the path of the shortcut used to launch this process, if any.
+  STARTUPINFOW currentStartupInfo;
+  GetStartupInfoW(&currentStartupInfo);
+  if ((currentStartupInfo.dwFlags & STARTF_TITLEISLINKNAME) &&
+      currentStartupInfo.lpTitle) {
+    siex.StartupInfo.dwFlags |= STARTF_TITLEISLINKNAME;
+    siex.StartupInfo.lpTitle = currentStartupInfo.lpTitle;
+  }
+
   PROCESS_INFORMATION pi = {};
   BOOL createOk;
 

toolkit/xre/nsAppRunner.cpp

@@ -302,6 +302,10 @@ bool gIsGtest = false;
 
 nsString gAbsoluteArgv0Path;
 
+#if defined(XP_WIN)
+nsString gProcessStartupShortcut;
+#endif
+
 #if defined(MOZ_WIDGET_GTK)
 #  include <glib.h>
 #  if defined(DEBUG) || defined(NS_BUILD_REFCNT_LOGGING)
@@ -1307,6 +1311,17 @@ nsXULAppInfo::GetRestartedByOS(bool* aResult) {
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsXULAppInfo::GetProcessStartupShortcut(nsAString& aShortcut) {
+#if defined(XP_WIN)
+  if (XRE_IsParentProcess()) {
+    aShortcut.Assign(gProcessStartupShortcut);
+    return NS_OK;
+  }
+#endif
+  return NS_ERROR_NOT_AVAILABLE;
+}
+
 #if defined(XP_WIN) && defined(MOZ_LAUNCHER_PROCESS)
 // Forward declaration
 void SetupLauncherProcessPref();
@@ -4249,6 +4264,20 @@ int XREMain::XRE_mainStartup(bool* aExitFlag) {
   }
 #endif
 
+#if defined(XP_WIN)
+  {
+    // Save the shortcut path before lpTitle is replaced by an AUMID,
+    // such as by WinTaskbar
+    STARTUPINFOW si;
+    GetStartupInfoW(&si);
+    if (si.dwFlags & STARTF_TITLEISAPPID) {
+      NS_WARNING("AUMID was already set, shortcut may have been lost.");
+    } else if ((si.dwFlags & STARTF_TITLEISLINKNAME) && si.lpTitle) {
+      gProcessStartupShortcut.Assign(si.lpTitle);
+    }
+  }
+#endif /* XP_WIN */
+
 #if defined(MOZ_WIDGET_GTK)
   // setup for private colormap.  Ideally we'd like to do this
   // in nsAppShell::Create, but we need to get in before gtk

xpcom/system/nsIXULRuntime.idl

@@ -306,6 +306,19 @@ interface nsIXULRuntime : nsISupports
    */
   readonly attribute boolean restartedByOS;
 
+  /**
+   * The path of the shortcut used to start the current process, or "" if none.
+   *
+   * Windows Main process only, otherwise throws NS_ERROR_NOT_AVAILABLE
+   *
+   * May be mising in some cases where the user did launch from a shortcut:
+   * - If the updater ran on startup
+   * - If the AUMID was set before the shortcut could be saved
+   *
+   * @throw NS_ERROR_NOT_AVAILABLE if not available.
+   */
+  readonly attribute AString processStartupShortcut;
+
   /**
    * Returns a value corresponding to one of the
    * |mozilla::LauncherRegistryInfo::EnabledState| values.